diff --git a/cfg_grades.php b/cfg_grades.php
index ae055e3..0a7074b 100644
--- a/cfg_grades.php
+++ b/cfg_grades.php
@@ -36,13 +36,13 @@ const GRADECFG_TABLE = "local_treestudyplan_gradecfg";
 
 $scales = \grade_scale::fetch_all_global();
 $mappings = $DB->get_records(GRADECFG_TABLE);
-$scale_cfgs = [];
-$grade_cfgs = [];
+$scalecfgs = [];
+$gradecfgs = [];
 foreach ($mappings as $cfg) {
     if (!empty($cfg->scale_id)) {
-        $scale_cfgs[$cfg->scale_id] = $cfg;
+        $scalecfgs[$cfg->scale_id] = $cfg;
     } else if (!empty($cfg->grade_points)) {
-        $grade_cfgs[$cfg->grade_points] = $cfg;
+        $gradecfgs[$cfg->grade_points] = $cfg;
     }
 }
 
@@ -51,8 +51,8 @@ print $OUTPUT->header();
 if ($_POST["action"] == "update") {
     // First loop through the scales to see which need to be updated.
     foreach ($scales as $scale) {
-        if (array_key_exists($scale->id, $scale_cfgs)) {
-            $scalecfg = $scale_cfgs[$scale->id];
+        if (array_key_exists($scale->id, $scalecfgs)) {
+            $scalecfg = $scalecfgs[$scale->id];
 
             $needupdate = false;
             foreach (["min_progress", "min_completed"] as $handle) {
@@ -84,19 +84,18 @@ if ($_POST["action"] == "update") {
                 // Insert into database and add to the list of scale configs.
                 $id = $DB->insert_record(GRADECFG_TABLE, $scalecfg);
                 $scalecfg = $DB->get_record(GRADECFG_TABLE, ['id' => $id]);
-                $scale_cfgs[$id] = $scalecfg;
+                $scalecfgs[$id] = $scalecfg;
             }
         }
     }
     // Now, loop through the gradepoints to parse .
     $deletelist = [];
-    foreach ($grade_cfgs as $gradecfg) {
+    foreach ($gradecfgs as $gradecfg) {
         $deletekey = "g_{$gradecfg->grade_points}_delete";
         if (array_key_exists($deletekey, $_POST) && boolval($_POST[$deletekey]) === true) {
             $DB->delete_records(GRADECFG_TABLE, ["id" => $gradecfg->id]);
             $deletelist[] = $gradecfg;
-        } else
-        {
+        } else {
             foreach (["min_progress", "min_completed"] as $handle) {
                 $key = "g_{$gradecfg->grade_points}_{$handle}";
                 if (array_key_exists($key, $_POST) && is_numeric($_POST[$key])) {
@@ -105,19 +104,21 @@ if ($_POST["action"] == "update") {
             }
             $DB->update_record(GRADECFG_TABLE, $gradecfg);
             // reload to ensure proper rounding is done.
-            $grade_cfgs[$gradecfg->grade_points] = $DB->get_record(GRADECFG_TABLE, ['id' => $gradecfg->id]);
+            $gradecfgs[$gradecfg->grade_points] = $DB->get_record(GRADECFG_TABLE, ['id' => $gradecfg->id]);
         }
     }
 
     foreach ($deletelist as $gradeconfig) {
-        unset($grade_cfgs[$gradecfg->grade_points]);
+        unset($gradecfgs[$gradecfg->grade_points]);
     }
     unset($deletelist);
 
     // And add an optionally existing new gradepoint setting.
-    if (array_key_exists("g_new_gradepoints", $_POST) && !empty($_POST["g_new_gradepoints"])  && is_numeric($_POST["g_new_gradepoints"]) ) {
+    if (array_key_exists("g_new_gradepoints", $_POST) 
+        && !empty($_POST["g_new_gradepoints"])  
+        && is_numeric($_POST["g_new_gradepoints"]) ) {
         $gp = intval($_POST["g_new_gradepoints"]);
-        if (!array_key_exists($gp, $grade_cfgs)) {
+        if (!array_key_exists($gp, $gradecfgs)) {
             $gradecfg = (object)[ "grade_points" => $gp];
             $requireinsert = false;
             foreach (["min_progress", "min_completed"] as $handle) {
@@ -132,7 +133,7 @@ if ($_POST["action"] == "update") {
                 $id = $DB->insert_record(GRADECFG_TABLE, $gradecfg);
                 // reload to ensure proper rounding is done.
                 $gradecfg = $DB->get_record(GRADECFG_TABLE, ['id' => $id]);
-                $grade_cfgs[$id] = $gradecfg;
+                $gradecfgs[$id] = $gradecfg;
             }
         }
     }
@@ -146,45 +147,45 @@ $data = [];
 foreach ($scales as $scale) {
     $scale->load_items();
     $scalecfg = null;
-    if (array_key_exists($scale->id, $scale_cfgs)) {
-        $scalecfg = $scale_cfgs[$scale->id];
+    if (array_key_exists($scale->id, $scalecfgs)) {
+        $scalecfg = $scalecfgs[$scale->id];
     }
 
-    $attrs_c = ['value' => '', 'disabled' => 'disabled', ];
-    $attrs_p = ['value' => '', 'disabled' => 'disabled', ];
+    $attrsc = ['value' => '', 'disabled' => 'disabled', ];
+    $attrsp = ['value' => '', 'disabled' => 'disabled', ];
 
     if (!isset($scalecfg) || $scalecfg->min_completed == "") {
-        $attrs_c["selected"] = "selected";
+        $attrsc["selected"] = "selected";
     }
     if (!isset($scalecfg) || $scalecfg->min_progress == "") {
-        $attrs_p["selected"] = "selected";
+        $attrsp["selected"] = "selected";
     }
 
-    $options_completed = html_writer::tag("option", get_string('select_scaleitem', 'local_treestudyplan'), $attrs_c);
-    $options_progress = html_writer::tag("option", get_string('select_scaleitem', 'local_treestudyplan'), $attrs_p);
+    $optionscompleted = html_writer::tag("option", get_string('select_scaleitem', 'local_treestudyplan'), $attrsc);
+    $optionsprogress = html_writer::tag("option", get_string('select_scaleitem', 'local_treestudyplan'), $attrsp);
     $key = 1; // Start counting by one, as used in sum aggregations.
 
     foreach ($scale->scale_items as $value) {
-        $attrs_c = ["value" => $key];
-        $attrs_p = ["value" => $key];
+        $attrsc = ["value" => $key];
+        $attrsp = ["value" => $key];
 
         if (isset($scalecfg)) {
             if (intval($scalecfg->min_completed) == $key) {
-                $attrs_c["selected"] = "selected";
+                $attrsc["selected"] = "selected";
             }
             if (intval($scalecfg->min_progress) == $key) {
-                $attrs_p["selected"] = "selected";
+                $attrsp["selected"] = "selected";
             }
         }
-        $options_progress .= html_writer::tag("option", $value, $attrs_p);
-        $options_completed .= html_writer::tag("option", $value, $attrs_c);
+        $optionsprogress .= html_writer::tag("option", $value, $attrsp);
+        $optionscompleted .= html_writer::tag("option", $value, $attrsc);
         $key++;
     }
 
 	$row = [];
 	$row[] = $scale->name;
-	//$row[] = html_writer::tag("select", $options_progress, ['name' => "s_{$scale->id}_min_progress", 'autocomplete' => 'off']) ;.
-	$row[] = html_writer::tag("select", $options_completed, ['name' => "s_{$scale->id}_min_completed", 'autocomplete' => 'off']) ;
+	//$row[] = html_writer::tag("select", $optionsprogress, ['name' => "s_{$scale->id}_min_progress", 'autocomplete' => 'off']) ;.
+	$row[] = html_writer::tag("select", $optionscompleted, ['name' => "s_{$scale->id}_min_completed", 'autocomplete' => 'off']) ;
 	$data[] = $row;
 }
 
@@ -209,7 +210,7 @@ print $OUTPUT->heading(get_string('cfg_grades_scales', 'local_treestudyplan'));
 print html_writer::tag('div', html_writer::table($table), ['class'=>'flexible-wrap']);
 
 $data = [];
-foreach ($grade_cfgs as $g) {
+foreach ($gradecfgs as $g) {
     $row = [];
 	$row[] = $g->grade_points;
 //    $row[] = html_writer::tag("input", null, ['name' => "g_{$g->grade_points}_min_progress", 'value' => "{$g->min_progress}", 'type' => 'text', "class" => "float", 'autocomplete' => 'off']) ;.
diff --git a/classes/aggregator.php b/classes/aggregator.php
index f67b321..cb383a8 100644
--- a/classes/aggregator.php
+++ b/classes/aggregator.php
@@ -26,13 +26,13 @@ require_once($CFG->libdir.'/externallib.php');
 
 abstract class aggregator {
     private const FALLBACK = "bistate";
-    private static $mod_supported = [];
+    private static $modsupported = [];
 
     public static function supported($mod) {
-        if (!array_key_exists($mod, self::$mod_supported)) {
-            self::$mod_supported[$mod] = class_exists(self::aggregator_name($mod));
+        if (!array_key_exists($mod, self::$modsupported)) {
+            self::$modsupported[$mod] = class_exists(self::aggregator_name($mod));
         }
-        return self::$mod_supported[$mod];
+        return self::$modsupported[$mod];
     }
 
     private static function aggregator_name($mod) {
@@ -51,8 +51,8 @@ abstract class aggregator {
 
     public static function create($mod, $configstr) {
         if (self::supported($mod)) {
-            $ag_class = self::aggregator_name($mod);
-            return new $ag_class($configstr);
+            $agclass = self::aggregator_name($mod);
+            return new $agclass($configstr);
         } else {
             throw new \InvalidArgumentException("Cannot find aggregator '{$mod}'");
         }
diff --git a/classes/associationservice.php b/classes/associationservice.php
index 44d25e2..abc34b3 100644
--- a/classes/associationservice.php
+++ b/classes/associationservice.php
@@ -112,12 +112,12 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function list_cohort($like='', $exclude_id=null, $context_id=1)
+	public static function list_cohort($like='', $excludeid=null, $contextid=1)
 	{
         global $CFG, $DB;
 
         // Only allow this if the user has the right to edit in this context.
-        $context = webservicehelper::find_context($context_id);
+        $context = webservicehelper::find_context($contextid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $context);
 
         $pattern = "%{$like}%";
@@ -126,14 +126,14 @@ class associationservice extends \external_api
 
         $sql =  "SELECT c.* from {cohort} c LEFT JOIN {local_treestudyplan_cohort} j ON c.id = j.cohort_id";
         $sql .= " WHERE c.visible = 1 AND(name LIKE :pattern_nm OR idnumber LIKE :pattern_id)";
-        if (isset($exclude_id) && is_numeric($exclude_id)) {
+        if (isset($excludeid) && is_numeric($excludeid)) {
             $sql .= " AND  (j.studyplan_id IS NULL OR j.studyplan_id != :exclude_id)";
-            $params['exclude_id'] = $exclude_id;
+            $params['exclude_id'] = $excludeid;
         }
-        if ($context_id > 1) { // system context returns all cohorts, including system cohorts.
+        if ($contextid > 1) { // system context returns all cohorts, including system cohorts.
             // otherwise, .
             $sql .= " AND contextid = :context_id";
-            $params['context_id'] = $context_id;
+            $params['context_id'] = $contextid;
         }
 
         $cohorts = [];
@@ -160,12 +160,12 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function find_user($like, $exclude_id=null, $context_id=1)
+	public static function find_user($like, $excludeid=null, $contextid=1)
 	{
 		global $CFG, $DB;
 
         // Only allow this if the user has the right to edit in this context (using system rights would make things more confusing).
-        $context = webservicehelper::find_context($context_id);
+        $context = webservicehelper::find_context($contextid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $context);
 
         $pattern = "%{$like}%";
@@ -175,9 +175,9 @@ class associationservice extends \external_api
                   ];
         $sql =  "SELECT u.* from {user} u LEFT JOIN {local_treestudyplan_user} j ON u.id = j.user_id";
         $sql .= " WHERE u.deleted != 1 AND (firstname LIKE :pattern_fn OR lastname LIKE :pattern_ln OR username LIKE :pattern_un)";
-        if (isset($exclude_id) && is_numeric($exclude_id)) {
+        if (isset($excludeid) && is_numeric($excludeid)) {
             $sql .= " AND  (j.studyplan_id IS NULL OR j.studyplan_id != :exclude_id)";
-            $params['exclude_id'] = $exclude_id;
+            $params['exclude_id'] = $excludeid;
         }
 
         $users = [];
@@ -208,17 +208,17 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function connect_cohort($studyplan_id, $cohort_id)
+	public static function connect_cohort($studyplanid, $cohortid)
 	{
         global $CFG, $DB;
 
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $studyplan->context());
 
-        if (!$DB->record_exists('local_treestudyplan_cohort', ['studyplan_id' => $studyplan_id, 'cohort_id' => $cohort_id])) {
+        if (!$DB->record_exists('local_treestudyplan_cohort', ['studyplan_id' => $studyplanid, 'cohort_id' => $cohortid])) {
             $id = $DB->insert_record('local_treestudyplan_cohort', [
-                'studyplan_id' => $studyplan_id,
-                'cohort_id' => $cohort_id,
+                'studyplan_id' => $studyplanid,
+                'cohort_id' => $cohortid,
             ]);
 
             $studyplan->mark_csync_changed();
@@ -247,17 +247,17 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function disconnect_cohort($studyplan_id, $cohort_id)
+	public static function disconnect_cohort($studyplanid, $cohortid)
 	{
 		global $CFG, $DB;
 
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $studyplan->context());
 
-        if ($DB->record_exists('local_treestudyplan_cohort', ['studyplan_id' => $studyplan_id, 'cohort_id' => $cohort_id])) {
+        if ($DB->record_exists('local_treestudyplan_cohort', ['studyplan_id' => $studyplanid, 'cohort_id' => $cohortid])) {
             $DB->delete_records('local_treestudyplan_cohort', [
-                'studyplan_id' => $studyplan_id,
-                'cohort_id' => $cohort_id,
+                'studyplan_id' => $studyplanid,
+                'cohort_id' => $cohortid,
             ]);
 
             $studyplan->mark_csync_changed();
@@ -286,17 +286,17 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function connect_user($studyplan_id, $user_id)
+	public static function connect_user($studyplanid, $userid)
 	{
 		global $CFG, $DB;
 
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $studyplan->context());
 
-        if (!$DB->record_exists('local_treestudyplan_user', ['studyplan_id' => $studyplan_id, 'user_id' => $user_id])) {
+        if (!$DB->record_exists('local_treestudyplan_user', ['studyplan_id' => $studyplanid, 'user_id' => $userid])) {
             $id = $DB->insert_record('local_treestudyplan_user', [
-                'studyplan_id' => $studyplan_id,
-                'user_id' => $user_id,
+                'studyplan_id' => $studyplanid,
+                'user_id' => $userid,
             ]);
             $studyplan->mark_csync_changed();
 
@@ -324,16 +324,16 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function disconnect_user($studyplan_id, $user_id)
+	public static function disconnect_user($studyplanid, $userid)
 	{
 		global $CFG, $DB;
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $studyplan->context());
 
-        if ($DB->record_exists('local_treestudyplan_user', ['studyplan_id' => $studyplan_id, 'user_id' => $user_id])) {
+        if ($DB->record_exists('local_treestudyplan_user', ['studyplan_id' => $studyplanid, 'user_id' => $userid])) {
             $DB->delete_records('local_treestudyplan_user', [
-                'studyplan_id' => $studyplan_id,
-                'user_id' => $user_id,
+                'studyplan_id' => $studyplanid,
+                'user_id' => $userid,
             ]);
 
             $studyplan->mark_csync_changed();
@@ -357,15 +357,15 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function associated_users($studyplan_id)
+	public static function associated_users($studyplanid)
 	{
 		global $CFG, $DB;
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_VIEW, $studyplan->context());
 
         $sql = "SELECT DISTINCT u.* FROM {user} u INNER JOIN {local_treestudyplan_user} j ON j.user_id = u.id";
         $sql .= " WHERE j.studyplan_id = :studyplan_id";
-        $rs = $DB->get_recordset_sql($sql, ['studyplan_id' => $studyplan_id]);
+        $rs = $DB->get_recordset_sql($sql, ['studyplan_id' => $studyplanid]);
 
         $users = [];
         foreach ($rs as $u) {
@@ -389,15 +389,15 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function associated_cohorts($studyplan_id)
+	public static function associated_cohorts($studyplanid)
 	{
 		global $CFG, $DB;
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_VIEW, $studyplan->context());
 
         $sql = "SELECT DISTINCT c.* FROM {cohort} c INNER JOIN {local_treestudyplan_cohort} j ON j.cohort_id = c.id";
         $sql .= " WHERE j.studyplan_id = :studyplan_id";
-        $rs = $DB->get_recordset_sql($sql, ['studyplan_id' => $studyplan_id]);
+        $rs = $DB->get_recordset_sql($sql, ['studyplan_id' => $studyplanid]);
         $cohorts = [];
         foreach ($rs as $c) {
             $cohorts[] = self::make_cohort_model($c);
@@ -420,11 +420,11 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function all_associated($studyplan_id)
+	public static function all_associated($studyplanid)
 	{
 		global $CFG, $DB;
 
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_VIEW, $studyplan->context());
 
 
@@ -436,8 +436,8 @@ class associationservice extends \external_api
                 LEFT JOIN {cohort_members}              cm ON u.id = cm.userid
                 LEFT JOIN {local_treestudyplan_cohort}  tc ON cm.cohortid = tc.cohort_id
                 LEFT JOIN {local_treestudyplan_user}    tu ON u.id = tu.user_id
-                WHERE tc.studyplan_id = {$studyplan_id}
-                   OR tu.studyplan_id = {$studyplan_id}
+                WHERE tc.studyplan_id = {$studyplanid}
+                   OR tu.studyplan_id = {$studyplanid}
                 ORDER BY u.lastname, u.firstname";
         $rs = $DB->get_recordset_sql($sql);
 
@@ -454,16 +454,16 @@ class associationservice extends \external_api
         return usort($list, function($a, $b) {
             $m= [];
             if (preg_match("/.*?([A-Z].*)/", $a['lastname'], $m)) {
-                $sort_ln_a = $m[1];
+                $sortln_a = $m[1];
             } else {
-                $sort_ln_a = $a['lastname'];
+                $sortln_a = $a['lastname'];
             }
             if (preg_match("/.*?([A-Z].*)/", $b['lastname'], $m)) {
-                $sort_ln_b = $m[1];
+                $sortln_b = $m[1];
             } else {
-                $sort_ln_b = $b['lastname'];
+                $sortln_b = $b['lastname'];
             }
-            $cmp= $sort_ln_a <=> $sort_ln_b;
+            $cmp= $sortln_a <=> $sortln_b;
             return  ($cmp != 0)?$cmp:$a['firstname'] <=> $b['firstname'];
         });
     }
@@ -481,9 +481,9 @@ class associationservice extends \external_api
     }
 
 	// Actual functions.
-	public static function cascade_cohortsync($studyplan_id)
+	public static function cascade_cohortsync($studyplanid)
 	{
-        $studyplan = studyplan::findById($studyplan_id);
+        $studyplan = studyplan::findById($studyplanid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $studyplan->context());
 
         $enroller = new cascadecohortsync($studyplan);
diff --git a/classes/badgeinfo.php b/classes/badgeinfo.php
index bda081e..01e9b26 100644
--- a/classes/badgeinfo.php
+++ b/classes/badgeinfo.php
@@ -154,10 +154,10 @@ class badgeinfo {
         return $badge;
     }
 
-    function count_issued(array $student_ids) {
+    function count_issued(array $studentids) {
         $issuecount = 0;
 
-        foreach ($student_ids as $userid) {
+        foreach ($studentids as $userid) {
             if ($this->badge->is_issued($userid)) {
                 $issuecount++;
             }
diff --git a/classes/completion.php b/classes/completion.php
index 9a7a48a..e1c2b75 100644
--- a/classes/completion.php
+++ b/classes/completion.php
@@ -45,8 +45,7 @@ class completion {
     public static function label($completion) {
         if (array_key_exists($completion, self::LABELS)) {
             return self::LABELS[$completion];
-        } else
-        {
+        } else {
             return self::LABELS[self::INCOMPLETE];
         }
     }
diff --git a/classes/completionscanner.php b/classes/completionscanner.php
index f69515a..dda0d77 100644
--- a/classes/completionscanner.php
+++ b/classes/completionscanner.php
@@ -27,33 +27,33 @@ use \grade_item;
 
 class completionscanner
 {
-    private static $mod_supported = [];
-    private static $course_students = [];
+    private static $modsupported = [];
+    private static $coursestudents = [];
     private $scanner = null;
     private $course = null;
     private $cm = null;
     private $gi = null;
-    private $pending_cache = [];
+    private $pendingcache = [];
 
     public static function supported($mod) {
-        if (!array_key_exists($mod, self::$mod_supported)) {
-            self::$mod_supported[$mod] = class_exists("\local_treestudyplan\\local\\ungradedscanners\\{$mod}_scanner");
+        if (!array_key_exists($mod, self::$modsupported)) {
+            self::$modsupported[$mod] = class_exists("\local_treestudyplan\\local\\ungradedscanners\\{$mod}_scanner");
         }
-        return self::$mod_supported[$mod];
+        return self::$modsupported[$mod];
     }
 
     public static function get_course_students($courseid) {
         global $CFG;
-        if (!array_key_exists($courseid, self::$course_students)) {
+        if (!array_key_exists($courseid, self::$coursestudents)) {
             $students = [];
             $context = \context_course::instance($courseid);
             foreach (explode(', ', $CFG->gradebookroles) as $roleid) {
                 $roleid = trim($roleid);
                 $students = array_keys(get_role_users($roleid, $context, false, 'u.id', 'u.id ASC'));
             }
-            self::$course_students[$courseid] = $students;
+            self::$coursestudents[$courseid] = $students;
         }
-        return self::$course_students[$courseid];
+        return self::$coursestudents[$courseid];
     }
 
     public function __construct(\completion_criteria $crit, $course) {
@@ -112,8 +112,8 @@ class completionscanner
         $students = self::get_course_students($this->courseid);
         $completed = 0;
         $ungraded = 0;
-        $completed_pass = 0;
-        $completed_fail = 0;
+        $completedpass = 0;
+        $completedfail = 0;
         foreach ($students as $userid) {
             if ($this->pending($userid)) {
                 // First check if the completion needs grading.
@@ -123,13 +123,13 @@ class completionscanner
 
                 if ($this->crit->criteriatype == COMPLETION_CRITERIA_TYPE_ACTIVITY) {
                     // If it's an activity completion, add all the relevant activities as sub-items.
-                    $completion_status = $this->completioninfo->get_grade_completion($this->cm, $userid);
+                    $completionstatus = $this->completioninfo->get_grade_completion($this->cm, $userid);
 
-                    if ($completion_status == COMPLETION_COMPLETE_PASS) {
-                        $completed_pass++;
-                    } else if ($completion_status == COMPLETION_COMPLETE_FAIL) {
-                        $completed_fail++;
-                    } else if ($completion_status == COMPLETION_COMPLETE) {
+                    if ($completionstatus == COMPLETION_COMPLETE_PASS) {
+                        $completedpass++;
+                    } else if ($completionstatus == COMPLETION_COMPLETE_FAIL) {
+                        $completedfail++;
+                    } else if ($completionstatus == COMPLETION_COMPLETE) {
                         $completed++;
                     }
                 } else{
@@ -145,8 +145,8 @@ class completionscanner
         return [
             'ungraded' => $ungraded,
             'completed' => $completed,
-            'completed_pass' => $completed_pass,
-            'completed_fail' => $completed_fail,
+            'completed_pass' => $completedpass,
+            'completed_fail' => $completedfail,
             'students' => count($students),
         ];
     }
diff --git a/classes/corecompletioninfo.php b/classes/corecompletioninfo.php
index 92452a0..9a315e4 100644
--- a/classes/corecompletioninfo.php
+++ b/classes/corecompletioninfo.php
@@ -35,7 +35,7 @@ class corecompletioninfo {
     private $course;
     private $completion;
     private $modinfo;
-    private static $COMPLETION_HANDLES = null;
+    private static $COMPLETIONHANDLES = null;
 
     public function id() {
         return $this->course->id;
@@ -48,10 +48,10 @@ class corecompletioninfo {
     }
 
     static public function completiontypes() {
-        global $COMPLETION_CRITERIA_TYPES;
+        global $COMPLETIONCRITERIA_TYPES;
         // Just return the keys of the global array COMPLETION_CRITERIA_TYPES, so we don't have to manually.
         // add any completion types....
-        return \array_keys($COMPLETION_CRITERIA_TYPES);
+        return \array_keys($COMPLETIONCRITERIA_TYPES);
     }
 
     /**
@@ -59,16 +59,16 @@ class corecompletioninfo {
      * @param $completion The completion code as defined in completionlib.php to translate to a text handle
      */
     static public function completion_handle($completion) {
-        if (empty(self::$COMPLETION_HANDLES)) {
+        if (empty(self::$COMPLETIONHANDLES)) {
             // Cache the translation table, to avoid overhead.
-            self::$COMPLETION_HANDLES = [
+            self::$COMPLETIONHANDLES = [
                 COMPLETION_INCOMPLETE => "incomplete",
                 COMPLETION_COMPLETE => "complete",
                 COMPLETION_COMPLETE_PASS => "complete-pass",
                 COMPLETION_COMPLETE_FAIL => "complete-fail",
                 COMPLETION_COMPLETE_FAIL_HIDDEN => "complete-fail"]; // the front end won't differentiate between hidden or not.
         }
-        return self::$COMPLETION_HANDLES[$completion] ?? "undefined";
+        return self::$COMPLETIONHANDLES[$completion] ?? "undefined";
     }
 
     public static function completion_item_editor_structure($value=VALUE_REQUIRED) {
@@ -155,7 +155,7 @@ class corecompletioninfo {
     }
 
     public function editor_model() {
-        global $DB, $CFG, $COMPLETION_CRITERIA_TYPES;
+        global $DB, $CFG, $COMPLETIONCRITERIA_TYPES;
 
         $conditions = [];
         $aggregation = "all"; // default.
@@ -174,7 +174,7 @@ class corecompletioninfo {
                 if (count($criterias) > 0 ) // Only take it into account if the criteria count is > 0.
                 {
                     $cinfo = [
-                        "type" => $COMPLETION_CRITERIA_TYPES[$type],
+                        "type" => $COMPLETIONCRITERIA_TYPES[$type],
                         "aggregation" => self::aggregation_handle($this->completion->get_aggregation_method($type)),
                         "title" => reset($criterias)->get_type_title(),
                         "items" => [],
@@ -325,7 +325,7 @@ class corecompletioninfo {
     }
 
     public function user_model($userid) {
-        global $DB, $COMPLETION_CRITERIA_TYPES;
+        global $DB, $COMPLETIONCRITERIA_TYPES;
 
         $progress = $this->get_advanced_progress_percentage($userid);
         $info = [
@@ -349,7 +349,7 @@ class corecompletioninfo {
                     $typeaggregation = $this->completion->get_aggregation_method($type);
                     $completed = $this->aggregate_completions($typeaggregation, $completions);
                     $cinfo = [
-                        "type" => $COMPLETION_CRITERIA_TYPES[$type],
+                        "type" => $COMPLETIONCRITERIA_TYPES[$type],
                         "aggregation" => self::aggregation_handle($typeaggregation),
                         "completed" => $completed,
                         "status" => $completed?"complete":"incomplete",
@@ -376,10 +376,10 @@ class corecompletioninfo {
                         if ($type == COMPLETION_CRITERIA_TYPE_ACTIVITY) {
                             $cm = $this->modinfo->get_cm($criteria->moduleinstance);
                             // If it's an activity completion, add all the relevant activities as sub-items.
-                            $completion_status = $this->completion->get_grade_completion($cm, $userid);
-                            $iinfo['status'] = self::completion_handle($completion_status);
+                            $completionstatus = $this->completion->get_grade_completion($cm, $userid);
+                            $iinfo['status'] = self::completion_handle($completionstatus);
                             // Re-evaluate the completed value, to make sure COMPLETE_FAIL doesn't creep in as completed.
-                            $iinfo['completed'] = in_array($completion_status, [COMPLETION_COMPLETE, COMPLETION_COMPLETE_PASS]);
+                            $iinfo['completed'] = in_array($completionstatus, [COMPLETION_COMPLETE, COMPLETION_COMPLETE_PASS]);
                             // Determine the grade (retrieve from grade item, not from completion).
                             $grade = $this->get_grade($cm, $userid);
                             $iinfo['grade'] = $grade->grade;
@@ -388,7 +388,7 @@ class corecompletioninfo {
 
                             $anypending = $anypending || $grade->pending;
                             // Overwrite the status with progress if something has been graded, or is pending.
-                            if ($completion_status != COMPLETION_INCOMPLETE || $anypending) {
+                            if ($completionstatus != COMPLETION_INCOMPLETE || $anypending) {
                                 if ($cinfo["status"] == "incomplete") {
                                     $cinfo["status"] = "progress";
                                 }
@@ -455,8 +455,7 @@ class corecompletioninfo {
                     if (isset($scale)) {
                         // get scale value.
                         $result->grade = $scale->get_nearest_item($grade->finalgrade);
-                    } else
-                    {
+                    } else {
                         // round final grade to 1 decimal point.
                         $result->grade =  round($grade->finalgrade, 1);
                     }
@@ -496,8 +495,7 @@ class corecompletioninfo {
                     if (isset($scale)) {
                         // get scale value.
                         return $scale->get_nearest_item($grade->finalgrade);
-                    } else
-                    {
+                    } else {
                         // round final grade to 1 decimal point.
                         return round($grade->finalgrade, 1);
                     }
@@ -627,7 +625,7 @@ class corecompletioninfo {
         // Now that we have all completions sorted by type, we can be smart about how to do the count.
         $count = 0;
         $completed = 0;
-        $completion_percentage = 0;
+        $completionpercentage = 0;
         foreach ($critcount as $c) {
             // Take only types that are actually present into account.
             if ($c->count > 0) {
@@ -644,10 +642,10 @@ class corecompletioninfo {
                 // Overwrite data if current type is more complete.
                 if ($aggregation == COMPLETION_AGGREGATION_ANY) {
                     $pct = $cmpl/$ct;
-                    if ($pct > $completion_percentage) {
+                    if ($pct > $completionpercentage) {
                         $count = $ct;
                         $completed = $cmpl;
-                        $completion_percentage = $pct;
+                        $completionpercentage = $pct;
                     }
                 }
                 // if ALL completion for the types, add the count for this type to that of the others.
diff --git a/classes/courseinfo.php b/classes/courseinfo.php
index 39c73f5..01bac12 100644
--- a/classes/courseinfo.php
+++ b/classes/courseinfo.php
@@ -78,8 +78,7 @@ class courseinfo {
         global $USER, $DB;
         if ($userid <= 0) {
             $usr = $USER;
-        } else
-        {
+        } else {
             $usr = $DB->get_record('user', ['id' => $userid, 'deleted' => 0]);
         }
         return($usr && is_enrolled($this->coursecontext, $usr, 'local/treestudyplan:selectowngradables'));
diff --git a/classes/coursemoduleinfo.php b/classes/coursemoduleinfo.php
index 26c5957..ecb744d 100644
--- a/classes/coursemoduleinfo.php
+++ b/classes/coursemoduleinfo.php
@@ -32,8 +32,8 @@ use \grade_item;
 class coursemoduleinfo {
     private $id;
     private $cm;
-    private $cm_info;
-    private $db_record;
+    private $cminfo;
+    private $dbrecord;
 
     public function __construct($id) {
         global $DB;
diff --git a/classes/courseservice.php b/classes/courseservice.php
index 00a34dd..6a92de6 100644
--- a/classes/courseservice.php
+++ b/classes/courseservice.php
@@ -69,10 +69,10 @@ class courseservice extends \external_api
         return  new \external_single_structure($s, "CourseCat info", $value);
     }
 
-    public static function map_categories($root_id = 0) {
+    public static function map_categories($rootid = 0) {
         global $CFG, $DB;
 
-        $root = \core_course_category::get($root_id);
+        $root = \core_course_category::get($rootid);
         $context = $root->get_context();
         // Make sure the user has access to the context for editing purposes.
         webservicehelper::require_capabilities(self::CAP_EDIT, $context);
@@ -81,11 +81,11 @@ class courseservice extends \external_api
 
         if ($root->id == 0) {
             // on the system level, determine the user's topmost allowed catecories.
-            $user_top = \core_course_category::user_top();
-            if ($user_top->id == 0) { // top category..
+            $usertop = \core_course_category::user_top();
+            if ($usertop->id == 0) { // top category..
                 $children = $root->get_children(); // returns a list of çore_course_category, let it overwrite $children.
             } else {
-                $children = [$user_top];
+                $children = [$usertop];
             }
         } else if ($root->is_uservisible()) {
             $children = [$root];
@@ -117,13 +117,13 @@ class courseservice extends \external_api
     protected static function map_category(\core_course_category $cat, $lazy=false) {
         global $DB;
         $catcontext = $cat->get_context();
-        $ctx_info = new contextinfo($catcontext);
+        $ctxinfo = new contextinfo($catcontext);
         $children = $cat->get_children(); // only shows children visible to the current user.
         $courses = $cat->get_courses();
         $model = [
             "id" => $cat->id,
             "context_id" => $catcontext->id,
-            "category" => $ctx_info->model(),
+            "category" => $ctxinfo->model(),
             "haschildren" => !empty($children),
             "hascourses" => !empty($courses),
         ];
@@ -236,11 +236,11 @@ class courseservice extends \external_api
         } else { // $operation == "view" || default.
             $capability = self::CAP_VIEW;
         }
-        $context_ids = [];
+        $contextids = [];
         $rs = $DB->get_recordset_sql("SELECT DISTINCT context_id, COUNT(*) as num FROM {local_treestudyplan}
                                          GROUP BY context_id");
         foreach ($rs as $r) {
-            $context_ids[$r->context_id] = $r->num;
+            $contextids[$r->context_id] = $r->num;
         }
         $rs->close();
 
@@ -253,8 +253,8 @@ class courseservice extends \external_api
         foreach ($cats as $cat) {
             $count = 0;
             $ctxid = $cat->get_context()->id;
-            if (array_key_exists($ctxid, $context_ids)) {
-                $count = $context_ids[$ctxid];
+            if (array_key_exists($ctxid, $contextids)) {
+                $count = $contextids[$ctxid];
             }
 
             $o = static::map_category($cat, true);
@@ -272,11 +272,11 @@ class courseservice extends \external_api
             $capability = self::CAP_VIEW;
         }
         // retrieve context ids used.
-        $context_ids = [];
+        $contextids = [];
         $rs = $DB->get_recordset_sql("SELECT DISTINCT context_id, COUNT(*) as num FROM {local_treestudyplan}
                                          GROUP BY context_id");
         foreach ($rs as $r) {
-            $context_ids[$r->context_id] = $r->num;
+            $contextids[$r->context_id] = $r->num;
         }
         $rs->close();
 
@@ -288,8 +288,8 @@ class courseservice extends \external_api
         foreach ($cats as $cat) {
             $count = 0;
             $ctxid = $cat->get_context()->id;
-            if (array_key_exists($ctxid, $context_ids)) {
-                $count = $context_ids[$ctxid];
+            if (array_key_exists($ctxid, $contextids)) {
+                $count = $contextids[$ctxid];
             }
             $o = new \stdClass();
             $o->cat = $cat;
diff --git a/classes/gradeinfo.php b/classes/gradeinfo.php
index 8bd450b..1313609 100644
--- a/classes/gradeinfo.php
+++ b/classes/gradeinfo.php
@@ -245,12 +245,10 @@ class gradeinfo {
                 $finalgrade = "-";
             } else if (isset($this->scale)) {
                 $finalgrade = $this->scale->get_nearest_item($grade->finalgrade);
-            } else
-            {
+            } else {
                 $finalgrade = round($grade->finalgrade, 1);
             }
-        } else
-        {
+        } else {
             $finalgrade = "-";
         }
 
@@ -290,13 +288,13 @@ class gradeinfo {
     }
     public static function import(studyitem $item, array $model) {
         if ($item->type() == studyitem::COURSE) {
-            $course_id = $item->courseid();
-            $gradeitems= grade_item::fetch_all(['itemtype' => 'mod', 'courseid' => $course_id]);
+            $courseid = $item->courseid();
+            $gradeitems= grade_item::fetch_all(['itemtype' => 'mod', 'courseid' => $courseid]);
             foreach ($gradeitems as $gi) {
-                $gi_name =  empty($outcome)?$gi->itemname:$outcome->name;
-                $gi_type = $gi->itemmodule;
+                $giname =  empty($outcome)?$gi->itemname:$outcome->name;
+                $gitype = $gi->itemmodule;
 
-                if ($gi_name == $model["name"] && $gi_type == $model["type"]) {
+                if ($giname == $model["name"] && $gitype == $model["type"]) {
                     // we have a match.
                     if (!isset($model["selected"])) { $model["selected"] = true;}
                     if (!isset($model["required"])) { $model["required"] = false;}
@@ -368,27 +366,27 @@ class gradeinfo {
         return $list;
     }
 
-    public static function include_grade(int $grade_id, int $item_id, bool $include, bool $required=false) {
+    public static function include_grade(int $gradeid, int $itemid, bool $include, bool $required=false) {
         global $DB;
         $table = 'local_treestudyplan_gradeinc';
         if ($include) {
             // make sure a record exits.
-            $r = $DB->get_record($table, ['studyitem_id' => $item_id, 'grade_item_id' => $grade_id]);
+            $r = $DB->get_record($table, ['studyitem_id' => $itemid, 'grade_item_id' => $gradeid]);
             if ($r) {
                 $r->include = 1;
                 $r->required = boolval($required)?1:0;
                 $id = $DB->update_record($table, $r);
             } else {
                 $DB->insert_record($table, [
-                    'studyitem_id' => $item_id,
-                    'grade_item_id' => $grade_id,
+                    'studyitem_id' => $itemid,
+                    'grade_item_id' => $gradeid,
                     'include' => 1,
                     'required' =>boolval($required)?1:0]
                 );
             }
         } else {
             // remove if it should not be included.
-            $r = $DB->get_record($table, ['studyitem_id' => $item_id, 'grade_item_id' => $grade_id]);
+            $r = $DB->get_record($table, ['studyitem_id' => $itemid, 'grade_item_id' => $gradeid]);
             if ($r) {
                 $DB->delete_records($table, ['id' => $r->id]);
             }
diff --git a/classes/gradingscanner.php b/classes/gradingscanner.php
index 10d00ee..3b75445 100644
--- a/classes/gradingscanner.php
+++ b/classes/gradingscanner.php
@@ -30,31 +30,31 @@ use \grade_item;
 // $gi->iteminstance.
 class gradingscanner
 {
-    private static $mod_supported = [];
-    private static $course_students = [];
+    private static $modsupported = [];
+    private static $coursestudents = [];
     private $scanner = null;
     private $gi = null;
-    private $pending_cache = [];
+    private $pendingcache = [];
 
     public static function supported($mod) {
-        if (!array_key_exists($mod, self::$mod_supported)) {
-            self::$mod_supported[$mod] = class_exists("\local_treestudyplan\\local\\ungradedscanners\\{$mod}_scanner");
+        if (!array_key_exists($mod, self::$modsupported)) {
+            self::$modsupported[$mod] = class_exists("\local_treestudyplan\\local\\ungradedscanners\\{$mod}_scanner");
         }
-        return self::$mod_supported[$mod];
+        return self::$modsupported[$mod];
     }
 
     public static function get_course_students($courseid) {
         global $CFG;
-        if (!array_key_exists($courseid, self::$course_students)) {
+        if (!array_key_exists($courseid, self::$coursestudents)) {
             $students = [];
             $context = \context_course::instance($courseid);
             foreach (explode(', ', $CFG->gradebookroles) as $roleid) {
                 $roleid = trim($roleid);
                 $students = array_keys(get_role_users($roleid, $context, false, 'u.id', 'u.id ASC'));
             }
-            self::$course_students[$courseid] = $students;
+            self::$coursestudents[$courseid] = $students;
         }
-        return self::$course_students[$courseid];
+        return self::$coursestudents[$courseid];
     }
 
     public function __construct(grade_item $gi) {
@@ -96,8 +96,8 @@ class gradingscanner
         $students = self::get_course_students($this->courseid);
         $completed = 0;
         $ungraded = 0;
-        $completed_pass = 0;
-        $completed_fail = 0;
+        $completedpass = 0;
+        $completedfail = 0;
         foreach ($students as $userid) {
             if ($this->pending($userid)) {
                 // First check if the completion needs grading.
@@ -106,13 +106,12 @@ class gradingscanner
                 $grade = $this->gi->get_final($userid);
                 if (!is_numeric($grade->finalgrade) && empty($grade->finalgrade)) {
                     //skip.
-                } else
-                {
+                } else {
                     //compare grade to minimum grade.
                     if ($this->grade_passed($grade)) {
-                        $completed_pass++;
+                        $completedpass++;
                     } else {
-                        $completed_fail++;
+                        $completedfail++;
                     }
                 }
             }
@@ -121,8 +120,8 @@ class gradingscanner
         return [
             'ungraded' => $ungraded,
             'completed' => $completed,
-            'completed_pass' => $completed_pass,
-            'completed_fail' => $completed_fail,
+            'completed_pass' => $completedpass,
+            'completed_fail' => $completedfail,
             'students' => count($students),
         ];
 
@@ -139,8 +138,7 @@ class gradingscanner
             $gradecfg = $DB->get_record($table, ["scale_id"=>$scale->id]);
         } else if ($this->gi->grademin == 0) {
             $gradecfg = $DB->get_record($table, ["grade_points"=>$this->gi->grademax]);
-        } else
-        {
+        } else {
             $gradecfg = null;
         }
 
diff --git a/classes/local/aggregators/bistate_aggregator.php b/classes/local/aggregators/bistate_aggregator.php
index 0512a5d..55c41b6 100644
--- a/classes/local/aggregators/bistate_aggregator.php
+++ b/classes/local/aggregators/bistate_aggregator.php
@@ -33,12 +33,12 @@ class bistate_aggregator extends \local_treestudyplan\aggregator {
     public const DEPRECATED = false;
     private const DEFAULT_CONDITION = "50";
 
-    private $thresh_excellent = 1.0;            // Minimum fraction that must be completed to aggregate as excellent (usually 1.0).
-    private $thresh_good = 0.8;                 // Minimum fraction that must be completed to aggregate as good.
-    private $thresh_completed = 0.66;           // Minimum fraction that must be completed to aggregate as completed.
-    private $use_failed = True;                 // Support failed completion yes/no.
-    private $thresh_progress = 0.33;              // Minimum fraction that must be failed to aggregate as failed instead of progress.
-    private $accept_pending_as_submitted = False;  // Also count ungraded but submitted .
+    private $threshexcellent = 1.0;            // Minimum fraction that must be completed to aggregate as excellent (usually 1.0).
+    private $threshgood = 0.8;                 // Minimum fraction that must be completed to aggregate as good.
+    private $threshcompleted = 0.66;           // Minimum fraction that must be completed to aggregate as completed.
+    private $usefailed = True;                 // Support failed completion yes/no.
+    private $threshprogress = 0.33;              // Minimum fraction that must be failed to aggregate as failed instead of progress.
+    private $acceptpending_as_submitted = False;  // Also count ungraded but submitted .
 
     public function __construct($configstr) {
         // allow public constructor for testing purposes.
@@ -104,10 +104,10 @@ class bistate_aggregator extends \local_treestudyplan\aggregator {
 
         // return te following conditions.
         // Possible states:.
-        // - completion::EXCELLENT  - At least $thresh_excellent fraction of goals are complete and all required goals are met.
-        // - completion::GOOD       - At least $thresh_good fraction of goals are complete and all required goals are met.
-        // - completion::COMPLETED  - At least $thresh_complete fraction of goals are completed and all required goals are met.
-        // - completion::FAILED     - At least $thresh_progress fraction of goals is not failed.
+        // - completion::EXCELLENT  - At least $threshexcellent fraction of goals are complete and all required goals are met.
+        // - completion::GOOD       - At least $threshgood fraction of goals are complete and all required goals are met.
+        // - completion::COMPLETED  - At least $threshcomplete fraction of goals are completed and all required goals are met.
+        // - completion::FAILED     - At least $threshprogress fraction of goals is not failed.
         // - completion::INCOMPLETE - No goals have been started.
         // - completion::PROGRESS   - All other states.
 
@@ -118,33 +118,33 @@ class bistate_aggregator extends \local_treestudyplan\aggregator {
         $failed = 0;
         $started = 0;
 
-        $total_required = 0;
-        $required_met = 0;
+        $totalrequired = 0;
+        $requiredmet = 0;
 
-        $MIN_PROGRESS = ($this->accept_pending_as_submitted)?completion::PENDING:completion::PROGRESS;
+        $MINPROGRESS = ($this->accept_pending_as_submitted)?completion::PENDING:completion::PROGRESS;
 
         foreach ($completions as $index => $c) {
 
             $completed += ($c >= completion::COMPLETED)?1:0;
-            $progress  += ($c >= $MIN_PROGRESS)?1:0;
+            $progress  += ($c >= $MINPROGRESS)?1:0;
             $failed    += ($c <= completion::FAILED)?1:0;
         }
         $started = $progress + $failed;
-        $allrequiredmet = ($required_met >= $total_required);
+        $allrequiredmet = ($requiredmet >= $totalrequired);
 
-        $fraction_completed = ($total >0)?(floatval($completed)/floatval($total)):0.0;
-        $fraction_progress  = ($total >0)?(floatval($progress)/floatval($total)):0.0;
-        $fraction_failed    = ($total >0)?(floatval($failed)/floatval($total)):0.0;
-        $fraction_started   = ($total >0)?(floatval($started)/floatval($total)):0.0;
+        $fractioncompleted = ($total >0)?(floatval($completed)/floatval($total)):0.0;
+        $fractionprogress  = ($total >0)?(floatval($progress)/floatval($total)):0.0;
+        $fractionfailed    = ($total >0)?(floatval($failed)/floatval($total)):0.0;
+        $fractionstarted   = ($total >0)?(floatval($started)/floatval($total)):0.0;
 
         if ($total == 0) {
             return completion::INCOMPLETE;
         }
-        if ($fraction_completed >= $this->thresh_excellent && $allrequiredmet) {
+        if ($fractioncompleted >= $this->thresh_excellent && $allrequiredmet) {
             return completion::EXCELLENT;
-        } else if ($fraction_completed >= $this->thresh_good && $allrequiredmet) {
+        } else if ($fractioncompleted >= $this->thresh_good && $allrequiredmet) {
             return completion::GOOD;
-        } else if ($fraction_completed >= $this->thresh_completed && $allrequiredmet) {
+        } else if ($fractioncompleted >= $this->thresh_completed && $allrequiredmet) {
             return completion::COMPLETED;
         } else if ($started == 0) {
             return completion::INCOMPLETE;
@@ -239,8 +239,7 @@ class bistate_aggregator extends \local_treestudyplan\aggregator {
                 $gradecfg = $DB->get_record($table, ["scale_id"=>$scale->id]);
             } else if ($gradeitem->grademin == 0) {
                 $gradecfg = $DB->get_record($table, ["grade_points"=>$gradeitem->grademax]);
-            } else
-            {
+            } else {
                 $gradecfg = null;
             }
 
diff --git a/classes/local/aggregators/core_aggregator.php b/classes/local/aggregators/core_aggregator.php
index 2313e41..ebf34fc 100644
--- a/classes/local/aggregators/core_aggregator.php
+++ b/classes/local/aggregators/core_aggregator.php
@@ -32,7 +32,7 @@ use \local_treestudyplan\debug;
 
 class core_aggregator extends \local_treestudyplan\aggregator {
     public const DEPRECATED = false;
-    private $accept_pending_as_submitted = False;  // Also count ungraded but submitted .
+    private $acceptpending_as_submitted = False;  // Also count ungraded but submitted .
 
     public function __construct($configstr) {
         // allow public constructor for testing purposes.
@@ -192,8 +192,7 @@ class core_aggregator extends \local_treestudyplan\aggregator {
                 $gradecfg = $DB->get_record($table, ["scale_id"=>$scale->id]);
             } else if ($gradeitem->grademin == 0) {
                 $gradecfg = $DB->get_record($table, ["grade_points"=>$gradeitem->grademax]);
-            } else
-            {
+            } else {
                 $gradecfg = null;
             }
 
diff --git a/classes/local/aggregators/tristate_aggregator.php b/classes/local/aggregators/tristate_aggregator.php
index 190f09f..fa7986c 100644
--- a/classes/local/aggregators/tristate_aggregator.php
+++ b/classes/local/aggregators/tristate_aggregator.php
@@ -40,19 +40,19 @@ class tristate_aggregator extends \local_treestudyplan\aggregator {
     protected function aggregate_completion(array $a, $condition = "50") {
         if (in_array($condition, ['ALL', '67', '50', 'ANY'])) {
             // condition is one of the valid conditions.
-            $c_completed = 0;
-            $c_excellent = 0;
-            $c_progress = 0;
-            $c_pending = 0;
+            $ccompleted = 0;
+            $cexcellent = 0;
+            $cprogress = 0;
+            $cpending = 0;
             $count = sizeof($a);
 
             if ($count > 0) {
 
                 foreach ($a as $c) {
-                    $c_progress += ($c>=completion::PROGRESS)?1:0;
-                    $c_completed += ($c>=completion::COMPLETED)?1:0;
-                    $c_excellent += ($c>=completion::EXCELLENT)?1:0;
-                    $c_pending += ($c>=completion::PENDING)?1:0;
+                    $cprogress += ($c>=completion::PROGRESS)?1:0;
+                    $ccompleted += ($c>=completion::COMPLETED)?1:0;
+                    $cexcellent += ($c>=completion::EXCELLENT)?1:0;
+                    $cpending += ($c>=completion::PENDING)?1:0;
                 }
 
                 $required = [
@@ -62,16 +62,16 @@ class tristate_aggregator extends \local_treestudyplan\aggregator {
                     'ANY' => 1,
                     ][$condition];
 
-                if ($c_excellent >= $required) {
+                if ($cexcellent >= $required) {
                     return completion::EXCELLENT;
-                } else if ($c_completed >= $required) {
+                } else if ($ccompleted >= $required) {
                     return completion::COMPLETED;
                 } else {
                     // Return PROGRESS if one or more completions are COMPLETED or EXCELLENT, but the aggregation margin is not met.
                     // state PROGRESS will not carry on if aggregations are chained.
-                    if ($c_progress > 0) {
+                    if ($cprogress > 0) {
                         return completion::PROGRESS;
-                    } else if ($c_pending > 0) {
+                    } else if ($cpending > 0) {
                         return completion::PENDING;
                     } else {
                         return completion::INCOMPLETE;
@@ -80,8 +80,7 @@ class tristate_aggregator extends \local_treestudyplan\aggregator {
             } else {
                 return completion::INCOMPLETE;
             }
-        } else
-        {
+        } else {
             // indeterminable, return null.
             return null;
         }
diff --git a/classes/local/gradegenerator.php b/classes/local/gradegenerator.php
index a1d4c89..6964f2e 100644
--- a/classes/local/gradegenerator.php
+++ b/classes/local/gradegenerator.php
@@ -184,8 +184,7 @@ class gradegenerator {
                 $gradecfg = $DB->get_record($table, ["scale_id"=>$scale->id]);
             } else if ($gi->grademin == 0) {
                 $gradecfg = $DB->get_record($table, ["grade_points"=>$gi->grademax]);
-            } else
-            {
+            } else {
                 $gradecfg = null;
             }
 
diff --git a/classes/local/helpers/webservicehelper.php b/classes/local/helpers/webservicehelper.php
index 376d124..f31d908 100644
--- a/classes/local/helpers/webservicehelper.php
+++ b/classes/local/helpers/webservicehelper.php
@@ -28,7 +28,7 @@ require_once($CFG->dirroot.'/webservice/lib.php');
 class webservicehelper {
     /** @var \context_system */
     private static $systemcontext = null;
-    private static $validated_contexts = [];
+    private static $validatedcontexts = [];
 
     /**
      * Test for capability in the given context for the current user and throw a \webservice_access_exception if not
@@ -120,7 +120,7 @@ class webservicehelper {
     public static function find_context($contextid): \context{
         if (isset($contextid) && is_int($contextid) && $contextid > 0) {
 
-            if (!in_array($contextid, self::$validated_contexts)) { // Cache the context and make sure it is only validated once...
+            if (!in_array($contextid, self::$validatedcontexts)) { // Cache the context and make sure it is only validated once...
                 try {
                     $context = \context::instance_by_id($contextid);
                 }
@@ -129,9 +129,9 @@ class webservicehelper {
                 }
                 // Validate the found context.
                 \external_api::validate_context($context);
-                self::$validated_contexts[$contextid] = $context;
+                self::$validatedcontexts[$contextid] = $context;
             }
-            return self::$validated_contexts[$contextid];
+            return self::$validatedcontexts[$contextid];
         } else{
             return static::system_context(); // This function ensures the system context is validated just once this call.
         }
diff --git a/classes/local/ungradedscanners/assign_scanner.php b/classes/local/ungradedscanners/assign_scanner.php
index b2b2d9c..833228a 100644
--- a/classes/local/ungradedscanners/assign_scanner.php
+++ b/classes/local/ungradedscanners/assign_scanner.php
@@ -54,22 +54,22 @@ class assign_scanner extends scanner_base {
     }
 
 
-    public function count_ungraded($course_userids=[]) {
+    public function count_ungraded($courseuserids=[]) {
         $ungraded = $this->get_ungraded_submissions();
 
-        if (count($course_userids) > 0) {
-            $ungraded = array_intersect($ungraded, $course_userids);
+        if (count($courseuserids) > 0) {
+            $ungraded = array_intersect($ungraded, $courseuserids);
         }
         return count($ungraded);
     }
 
-    public function count_graded($course_userids=[]) {
+    public function count_graded($courseuserids=[]) {
         $ungraded = $this->get_ungraded_submissions();
         $graded = $this->get_graded_users();
 
-        if (count($course_userids) > 0) {
-            $ungraded = array_intersect($ungraded, $course_userids);
-            $graded = array_intersect($graded, $course_userids);
+        if (count($courseuserids) > 0) {
+            $ungraded = array_intersect($ungraded, $courseuserids);
+            $graded = array_intersect($graded, $courseuserids);
         }
 
         // determine how many id's have a grade, but also an ungraded submission.
diff --git a/classes/local/ungradedscanners/quiz_scanner.php b/classes/local/ungradedscanners/quiz_scanner.php
index e6aa1b6..951989a 100644
--- a/classes/local/ungradedscanners/quiz_scanner.php
+++ b/classes/local/ungradedscanners/quiz_scanner.php
@@ -43,8 +43,8 @@ class quiz_scanner extends scanner_base {
         $submissions = [];
         foreach ($rs as $r) {
             // Now, check if .
-            $maxstate_sql = "SELECT MAX(qas.sequencenumber) FROM {question_attempt_steps} qas WHERE qas.questionattemptid = {$r->attempt_id}";
-            $max = $DB->get_field_sql($maxstate_sql);
+            $maxstatesql = "SELECT MAX(qas.sequencenumber) FROM {question_attempt_steps} qas WHERE qas.questionattemptid = {$r->attempt_id}";
+            $max = $DB->get_field_sql($maxstatesql);
             if ($r->sequencenumber == $max) {
                 $submissions[$r->userid] = true; // set array index based on user id, to avoid checking if value is in array.
             }
@@ -53,15 +53,15 @@ class quiz_scanner extends scanner_base {
         return array_keys($submissions);
     }
 
-    public function count_ungraded($course_userids=[]) {
+    public function count_ungraded($courseuserids=[]) {
         $ungraded = $this->get_ungraded_submissions();
-        if (count($course_userids) > 0) {
-            $ungraded = array_intersect($ungraded, $course_userids);
+        if (count($courseuserids) > 0) {
+            $ungraded = array_intersect($ungraded, $courseuserids);
         }
         return count($ungraded);
     }
 
-    public function count_graded($course_userids=[]) {
+    public function count_graded($courseuserids=[]) {
         // count all users who submitted one or more finished tests.
         global $DB;
         $sql = "SELECT DISTINCT g.userid
@@ -72,8 +72,8 @@ class quiz_scanner extends scanner_base {
 
         $graded = $DB->get_fieldset_sql($sql);
 
-        if (count($course_userids) > 0) {
-            $graded = array_intersect($graded, $course_userids);
+        if (count($courseuserids) > 0) {
+            $graded = array_intersect($graded, $courseuserids);
         }
 
         return count($graded);
diff --git a/classes/local/ungradedscanners/scanner_base.php b/classes/local/ungradedscanners/scanner_base.php
index 7600667..69666b6 100644
--- a/classes/local/ungradedscanners/scanner_base.php
+++ b/classes/local/ungradedscanners/scanner_base.php
@@ -31,9 +31,9 @@ abstract class scanner_base {
         $this->gi = $gi;
     }
 
-    public abstract function count_ungraded($course_userids=[]);
+    public abstract function count_ungraded($courseuserids=[]);
 
-    public abstract function count_graded($course_userids=[]);
+    public abstract function count_graded($courseuserids=[]);
 
     public abstract function has_ungraded_submission($userid);
 
diff --git a/classes/privacy/provider.php b/classes/privacy/provider.php
index 48a9610..fb26944 100644
--- a/classes/privacy/provider.php
+++ b/classes/privacy/provider.php
@@ -175,10 +175,10 @@ class provider implements   \core_privacy\local\metadata\provider,
         // find studyplans in context.
         if ($context->contextlevel == CONTEXT_COURSECAT) {
             $sql = "SELECT s.id FROM {local_treestudyplan} WHERE ( a.user_id = :userid AND s.context_id = :contextid)";
-            $plan_ids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id]);
+            $planids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id]);
 
-            foreach ($plan_ids as $plan_id) {
-                $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $plan_id]);
+            foreach ($planids as $planid) {
+                $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $planid]);
             }
         }
     }
@@ -198,10 +198,10 @@ class provider implements   \core_privacy\local\metadata\provider,
             if ($context->contextlevel == CONTEXT_SYSTEM) {
                 $sql = "SELECT s.id FROM {local_treestudyplan} INNER JOIN {local_treestudyplan_user} a ON a.studyplan_id = s.id
                         WHERE ( a.user_id = :userid AND ( s.context_id IS NULL OR s.context_id == 0 OR s.context_id = :contextid))";
-                $plan_ids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, "userid" => $user->id]);
+                $planids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, "userid" => $user->id]);
 
-                foreach ($plan_ids as $plan_id) {
-                    $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $plan_id, "user_id" => $user->id]);
+                foreach ($planids as $planid) {
+                    $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $planid, "user_id" => $user->id]);
                 }
 
                 // Also delete all invitations for this user.
@@ -210,10 +210,10 @@ class provider implements   \core_privacy\local\metadata\provider,
             } else if ($context->contextlevel == CONTEXT_COURSECAT) {
                 $sql = "SELECT s.id FROM {local_treestudyplan} INNER JOIN {local_treestudyplan_user} a ON a.studyplan_id = s.id
                         WHERE ( a.user_id = :userid AND s.context_id = :contextid)";
-                $plan_ids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, "userid" => $user->id]);
+                $planids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, "userid" => $user->id]);
 
-                foreach ($plan_ids as $plan_id) {
-                    $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $plan_id, "user_id" => $user->id]);
+                foreach ($planids as $planid) {
+                    $DB->delete_records("local_treestudyplan_user", ["studyplan_id" => $planid, "user_id" => $user->id]);
                 }
             }
         }
@@ -263,12 +263,12 @@ class provider implements   \core_privacy\local\metadata\provider,
         $users = $userlist->get_userids();
         list($userinsql, $userinparams) = $DB->get_in_or_equal($users, SQL_PARAMS_NAMED, 'user');
 
-        $plan_ids = [];
+        $planids = [];
         if ($context->contextlevel == CONTEXT_SYSTEM) {
             // Determine the relevant plan_ids for this context.
             $sql = "SELECT s.id FROM {local_treestudyplan}
                     WHERE ( s.context_id IS NULL OR s.context_id == 0 OR s.context_id = :contextid)) ";
-            $plan_ids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, ]);
+            $planids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, ]);
             // If plan ids not empty, they will be processed later.
 
             // Also delete all invitations for these users.
@@ -278,14 +278,14 @@ class provider implements   \core_privacy\local\metadata\provider,
         } else if ($context->contextlevel == CONTEXT_COURSECAT) {
             $sql = "SELECT s.id FROM {local_treestudyplan}
                     WHERE (s.context_id = :contextid)";
-            $plan_ids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, ]);
+            $planids = $DB->get_fieldset_sql($sql, ["contextid"=>$context->id, ]);
             // If plan ids not empty, they will be processed later.
         }
 
         // Now delete the studyplan associations if relevant.
-        if (count($plan_ids) >0 && count($users) >0) {
+        if (count($planids) >0 && count($users) >0) {
 
-            list($planinsql, $planinputparams) = $DB->get_in_or_equal($plan_ids, SQL_PARAMS_NAMED, 'plan');
+            list($planinsql, $planinputparams) = $DB->get_in_or_equal($planids, SQL_PARAMS_NAMED, 'plan');
             $params = $userinparams+$planinputparams;
             $sql = "user_id {$userinsql} and studyplan_id {$planinsql}";
             $DB->delete_records_select('local_treestudyplan_user', $sql, $params);
diff --git a/classes/studyitem.php b/classes/studyitem.php
index 788845d..2496a34 100644
--- a/classes/studyitem.php
+++ b/classes/studyitem.php
@@ -36,7 +36,7 @@ class studyitem {
 
     public const TABLE = "local_treestudyplan_item";
 
-    private static $STUDYITEM_CACHE = [];
+    private static $STUDYITEMCACHE = [];
     private $r; // Holds database record.
     private $id;
 
@@ -57,10 +57,10 @@ class studyitem {
     }
 
     public static function findById($id): self {
-        if (!array_key_exists($id, self::$STUDYITEM_CACHE)) {
-            self::$STUDYITEM_CACHE[$id] = new self($id);
+        if (!array_key_exists($id, self::$STUDYITEMCACHE)) {
+            self::$STUDYITEMCACHE[$id] = new self($id);
         }
-        return self::$STUDYITEM_CACHE[$id];
+        return self::$STUDYITEMCACHE[$id];
     }
 
 
@@ -187,18 +187,18 @@ class studyitem {
 
 
         // Add incoming and outgoing connection info.
-        $conn_out = studyitemconnection::find_outgoing($this->id);
+        $connout = studyitemconnection::find_outgoing($this->id);
 
         if ($mode == "export") {
-            foreach ($conn_out as $c) {
+            foreach ($connout as $c) {
                 $model["connections"][] = $c->to_id();
             }
         } else {
-            foreach ($conn_out as $c) {
+            foreach ($connout as $c) {
                 $model['connections']['out'][$c->to_id()] = $c->model();
             }
-            $conn_in = studyitemconnection::find_incoming($this->id);
-            foreach ($conn_in as $c) {
+            $connin = studyitemconnection::find_incoming($this->id);
+            foreach ($connin as $c) {
                 $model['connections']['in'][$c->from_id()] = $c->model();
             }
         }
@@ -268,8 +268,7 @@ class studyitem {
 
         if ($DB->count_records(self::TABLE, ['continuation_id' => $this->id]) > 0) {
             return success::fail('Cannot remove: item is referenced by another item');
-        } else
-        {
+        } else {
             // delete al related connections to this item.
             studyitemconnection::clear($this->id);
             // delete all grade inclusion references to this item.
@@ -381,8 +380,8 @@ class studyitem {
 
         // Add continuation_info if available.
         if (self::exists($this->r->continuation_id)) {
-            $c_item = self::findById($this->r->continuation_id);
-            $model['continuation'] = $c_item->link_model($userid);
+            $citem = self::findById($this->r->continuation_id);
+            $model['continuation'] = $citem->link_model($userid);
         }
 
         // Add course if available.
@@ -392,12 +391,12 @@ class studyitem {
         }
 
         // Add incoming and outgoing connection info.
-        $conn_out = studyitemconnection::find_outgoing($this->id);
-        foreach ($conn_out as $c) {
+        $connout = studyitemconnection::find_outgoing($this->id);
+        foreach ($connout as $c) {
             $model['connections']['out'][$c->to_id()] = $c->model();
         }
-        $conn_in = studyitemconnection::find_incoming($this->id);
-        foreach ($conn_in as $c) {
+        $connin = studyitemconnection::find_incoming($this->id);
+        foreach ($connin as $c) {
             $model['connections']['in'][$c->from_id()] = $c->model();
         }
 
@@ -424,21 +423,21 @@ class studyitem {
                 // Does not need to use aggregator.
                 // Either true, or the completion of the reference.
                 if (self::exists($this->r->continuation_id)) {
-                    $c_item = self::findById($this->r->continuation_id);
-                    return $c_item->completion($userid);
+                    $citem = self::findById($this->r->continuation_id);
+                    return $citem->completion($userid);
                 } else {
                     return completion::COMPLETED;
                 }
             } else if (in_array(strtolower($this->r->type), ['junction', 'finish'])) {
                 // completion of the linked items, according to the rule.
-                $in_completed = [];
+                $incompleted = [];
                 // Retrieve incoming connections.
                 $incoming = $DB->get_records(studyitemconnection::TABLE, ['to_id' => $this->r->id]);
                 foreach ($incoming as $conn) {
                     $item = self::findById($conn->from_id);
-                    $in_completed[] = $item->completion($userid);
+                    $incompleted[] = $item->completion($userid);
                 }
-                return $this->aggregator->aggregate_junction($in_completed, $this, $userid);
+                return $this->aggregator->aggregate_junction($incompleted, $this, $userid);
             } else if (strtolower($this->r->type) =='badge') {
                 global $DB;
                 // badge awarded.
@@ -447,10 +446,10 @@ class studyitem {
                     if ($badge->is_issued($userid)) {
                         if ($badge->can_expire()) {
                             // get the issued badges and check if any of them have not expired yet.
-                            $badges_issued = $DB->get_records("badge_issued", ["badge_id" => $this->r->badge_id, "user_id" => $userid]);
+                            $badgesissued = $DB->get_records("badge_issued", ["badge_id" => $this->r->badge_id, "user_id" => $userid]);
                             $notexpired = false;
                             $now = time();
-                            foreach ($badges_issued as $bi) {
+                            foreach ($badgesissued as $bi) {
                                 if ($bi->dateexpire == null || $bi->dateexpire > $now) {
                                     $notexpired = true;
                                     break;
@@ -476,16 +475,16 @@ class studyitem {
         }
     }
 
-    public function duplicate($new_line) {
+    public function duplicate($newline) {
         global $DB;
         // clone the database fields.
         $fields = clone $this->r;
         // set new line id.
         unset($fields->id);
-        $fields->line_id = $new_line->id();
+        $fields->line_id = $newline->id();
         //create new record with the new data.
         $id = $DB->insert_record(self::TABLE, (array)$fields);
-        $new = self::findById($id, $new_line);
+        $new = self::findById($id, $newline);
 
         // copy the grading info if relevant.
         $gradables = gradeinfo::list_studyitem_gradables($this);
diff --git a/classes/studyitemconnection.php b/classes/studyitemconnection.php
index 5e7e23d..7dc678e 100644
--- a/classes/studyitemconnection.php
+++ b/classes/studyitemconnection.php
@@ -65,51 +65,51 @@ class studyitemconnection {
     }
 
 
-    public static function find_outgoing($item_id) {
+    public static function find_outgoing($itemid) {
         global $DB;
         $list = [];
-        $conn_out = $DB->get_records(self::TABLE, ['from_id' => $item_id]);
-        foreach ($conn_out as $c) {
+        $connout = $DB->get_records(self::TABLE, ['from_id' => $itemid]);
+        foreach ($connout as $c) {
             $list[] = new self($c);
         }
         return $list;
     }
 
-    public static function find_incoming($item_id) {
+    public static function find_incoming($itemid) {
         global $DB;
         $list = [];
-        $conn_in = $DB->get_records(self::TABLE, ['to_id' => $item_id]);
-        foreach ($conn_in as $c) {
+        $connin = $DB->get_records(self::TABLE, ['to_id' => $itemid]);
+        foreach ($connin as $c) {
             $list[] = new self($c);
         }
         return $list;
     }
 
-    public static function connect($from_id, $to_id) {
+    public static function connect($fromid, $toid) {
         global $DB;
 
         //check if link already exists.
 
-        if (!$DB->record_exists(self::TABLE, ['from_id' => $from_id, 'to_id' => $to_id])) {
+        if (!$DB->record_exists(self::TABLE, ['from_id' => $fromid, 'to_id' => $toid])) {
             $id = $DB->insert_record(self::TABLE, [
-                'from_id' => $from_id,
-                'to_id' => $to_id,
+                'from_id' => $fromid,
+                'to_id' => $toid,
             ]);
 
             return new self($DB->get_record(self::TABLE, ['id' => $id]));
 
         } else {
-            return new self($DB->get_record(self::TABLE, ['from_id' => $from_id, 'to_id' => $to_id]));
+            return new self($DB->get_record(self::TABLE, ['from_id' => $fromid, 'to_id' => $toid]));
         }
     }
 
-    public static function disconnect($from_id, $to_id) {
+    public static function disconnect($fromid, $toid) {
         global $DB;
 
-        if ($DB->record_exists(self::TABLE, ['from_id' => $from_id, 'to_id' => $to_id])) {
+        if ($DB->record_exists(self::TABLE, ['from_id' => $fromid, 'to_id' => $toid])) {
             $DB->delete_records(self::TABLE, [
-                'from_id' => $from_id,
-                'to_id' => $to_id,
+                'from_id' => $fromid,
+                'to_id' => $toid,
             ]);
 
             return success::success('Items Disconnected');
diff --git a/classes/studyline.php b/classes/studyline.php
index cf04b33..d227706 100644
--- a/classes/studyline.php
+++ b/classes/studyline.php
@@ -43,7 +43,7 @@ class studyline {
 
     public const TABLE = "local_treestudyplan_line";
 
-    private static $STUDYLINE_CACHE = [];
+    private static $STUDYLINECACHE = [];
 
     private $r; // Holds database record.
     private $id;
@@ -63,10 +63,10 @@ class studyline {
     }
 
     public static function findById($id): self {
-        if (!array_key_exists($id, self::$STUDYLINE_CACHE)) {
-            self::$STUDYLINE_CACHE[$id] = new self($id);
+        if (!array_key_exists($id, self::$STUDYLINECACHE)) {
+            self::$STUDYLINECACHE[$id] = new self($id);
         }
-        return self::$STUDYLINE_CACHE[$id];
+        return self::$STUDYLINECACHE[$id];
     }
 
     private function __construct($id) {
@@ -132,11 +132,11 @@ class studyline {
         // As a safety data integrity measure, if there are any items in a higher slot than currently allowed, .
         // make sure there are enought slots to account for them.
         // Alternatively, we could ensure that on reduction of slots, the items that no longer have a slot will be removed.
-        $max_slot = $DB->get_field_select(studyitem::TABLE, "MAX(slot)", "line_id = :lineid", ['lineid' => $this->id]);
-        $num_slots = max($this->page->periods(), $max_slot +1);
+        $maxslot = $DB->get_field_select(studyitem::TABLE, "MAX(slot)", "line_id = :lineid", ['lineid' => $this->id]);
+        $numslots = max($this->page->periods(), $maxslot +1);
 
         // Create the required amount of slots.
-        for($i=0; $i < $num_slots+1; $i++) {
+        for($i=0; $i < $numslots+1; $i++) {
             if ($mode == "export") {
                 // Export mode does not separate between filter or competency type, since that is determined automatically.
                 $slots = [];
@@ -180,8 +180,8 @@ class studyline {
             throw new \InvalidArgumentException("parameter 'page_id' missing");
         }
 
-        $page_id = $fields['page_id'];
-        $sqmax = $DB->get_field_select(self::TABLE, "MAX(sequence)", "page_id = :page_id", ['page_id' => $page_id]);
+        $pageid = $fields['page_id'];
+        $sqmax = $DB->get_field_select(self::TABLE, "MAX(sequence)", "page_id = :page_id", ['page_id' => $pageid]);
         $addable = ['page_id', 'name', 'shortname', 'color'];
         $info = ['sequence' => $sqmax+1];
         foreach ($addable as $f) {
@@ -220,8 +220,7 @@ class studyline {
         // check if this item has study items in it.
         if ($DB->count_records(studyitem::TABLE, ['line_id' => $this->id]) > 0) {
             return success::fail('cannot delete studyline with items');
-        } else
-        {
+        } else {
             $DB->delete_records(self::TABLE, ['id' => $this->id]);
             return success::success();
         }
@@ -285,11 +284,11 @@ class studyline {
         // As a safety data integrity measure, if there are any items in a higher slot than currently allowed, .
         // make sure there are enought slots to account for them.
         // Alternatively, we could ensure that on reduction of slots, the items that no longer have a slot will be removed.
-        $max_slot = $DB->get_field_select(studyitem::TABLE, "MAX(slot)", "line_id = :lineid", ['lineid' => $this->id]);
-        $num_slots = max($this->page->periods(), $max_slot +1);
+        $maxslot = $DB->get_field_select(studyitem::TABLE, "MAX(slot)", "line_id = :lineid", ['lineid' => $this->id]);
+        $numslots = max($this->page->periods(), $maxslot +1);
 
         // Create the required amount of slots.
-        for($i=0; $i < $num_slots+1; $i++) {
+        for($i=0; $i < $numslots+1; $i++) {
             if ($i > 0) {
                 $slots = [self::SLOTSET_COMPETENCY => [], self::SLOTSET_FILTER => []];
             } else {
@@ -322,14 +321,14 @@ class studyline {
 
     }
 
-    public function duplicate($new_studyplan, &$translation) {
+    public function duplicate($newstudyplan, &$translation) {
         global $DB;
 
         // clone the database fields.
         $fields = clone $this->r;
         // set new studyplan id.
         unset($fields->id);
-        $fields->studyplan_id = $new_studyplan->id();
+        $fields->studyplan_id = $newstudyplan->id();
         // create new record with the new data.
         $id = $DB->insert_record(self::TABLE, (array)$fields);
         $new = self::findById($id);
@@ -375,8 +374,8 @@ class studyline {
                         if (! isset($connections[$item->id()]) || ! is_array($connections[$item->id()])) {
                             $connections[$item->id()] = [];
                         }
-                        foreach ($itemmodel["connections"] as $to_id) {
-                            $connections[$item->id()][] = $to_id;
+                        foreach ($itemmodel["connections"] as $toid) {
+                            $connections[$item->id()][] = $toid;
                         }
                     }
                 }
diff --git a/classes/studyplan.php b/classes/studyplan.php
index 7e22a7e..15f5d03 100644
--- a/classes/studyplan.php
+++ b/classes/studyplan.php
@@ -28,15 +28,15 @@ class studyplan {
 
 
     const TABLE = "local_treestudyplan";
-    private static $STUDYPLAN_CACHE = [];
+    private static $STUDYPLANCACHE = [];
 
 
     private $r; // Holds database record.
     private $id;
     private $aggregator;
     private $context = null; // Hold context object once retrieved.
-    private $linked_userids = null; // cache lookup of linked users (saves queries).
-    private $page_cache = null;
+    private $linkeduserids = null; // cache lookup of linked users (saves queries).
+    private $pagecache = null;
 
     public function aggregator() {
         return $this->aggregator;
@@ -44,10 +44,10 @@ class studyplan {
 
     // Cache constructors to avoid multiple creation events in one session.
     public static function findById($id): self {
-        if (!array_key_exists($id, self::$STUDYPLAN_CACHE)) {
-            self::$STUDYPLAN_CACHE[$id] = new self($id);
+        if (!array_key_exists($id, self::$STUDYPLANCACHE)) {
+            self::$STUDYPLANCACHE[$id] = new self($id);
         }
-        return self::$STUDYPLAN_CACHE[$id];
+        return self::$STUDYPLANCACHE[$id];
     }
 
     private function __construct($id) {
@@ -290,8 +290,7 @@ class studyplan {
 
         if ($DB->count_records('local_treestudyplan_page', ['studyplan_id' => $this->id]) > 0) {
             return success::fail('cannot delete studyplan that still has pages');
-        } else
-        {
+        } else {
             $DB->delete_records('local_treestudyplan', ['id' => $this->id]);
             return success::success();
         }
@@ -341,18 +340,18 @@ class studyplan {
                 INNER JOIN {local_treestudyplan_cohort} j ON j.studyplan_id = s.id
                 INNER JOIN {cohort_members} cm ON j.cohort_id = cm.cohortid
                 WHERE cm.userid = :userid";
-        $cohort_plan_ids = $DB->get_fieldset_sql($sql, ['userid' => $userid]);
+        $cohortplan_ids = $DB->get_fieldset_sql($sql, ['userid' => $userid]);
 
         $sql = "SELECT s.id FROM {local_treestudyplan} s
                 INNER JOIN {local_treestudyplan_user} j ON j.studyplan_id = s.id
                 WHERE j.user_id = :userid";
-        $user_plan_ids = $DB->get_fieldset_sql($sql, ['userid' => $userid]);
+        $userplan_ids = $DB->get_fieldset_sql($sql, ['userid' => $userid]);
 
         $plans = [];
-        foreach ($cohort_plan_ids as $id) {
+        foreach ($cohortplan_ids as $id) {
             $plans[$id] = self::findById($id);
         }
-        foreach ($user_plan_ids as $id) {
+        foreach ($userplan_ids as $id) {
             if (!array_key_exists($id, $plans)) {
                 $plans[$id] = self::findById($id);
             }
@@ -477,8 +476,8 @@ class studyplan {
         return $model;
     }
 
-    public static function duplicate_plan($plan_id, $name, $shortname) {
-        $ori = self::findById($plan_id);
+    public static function duplicate_plan($planid, $name, $shortname) {
+        $ori = self::findById($planid);
         $new = $ori->duplicate($name, $shortname);
         return $new->simple_model();
     }
@@ -538,7 +537,7 @@ class studyplan {
         return $pages;
     }
 
-    public static function import_studyplan($content, $format="application/json", $context_id=1) {
+    public static function import_studyplan($content, $format="application/json", $contextid=1) {
         if ($format != "application/json") { return false;}
 
         $content = json_decode($content, true);
@@ -548,7 +547,7 @@ class studyplan {
             $content["studyplan"]["aggregation_config"] = json_encode($content["studyplan"]["aggregation_config"]);
 
             // And make sure the context_id is set to the provided context for import.
-            $content["studyplan"]["context_id"] = $context_id;
+            $content["studyplan"]["context_id"] = $contextid;
 
             // Create a new plan, based on the given parameters - this is the import studyplan part.
             $plan = self::add($content["studyplan"], true);
diff --git a/classes/studyplanpage.php b/classes/studyplanpage.php
index 4b3b5c7..9090879 100644
--- a/classes/studyplanpage.php
+++ b/classes/studyplanpage.php
@@ -206,8 +206,7 @@ class studyplanpage {
 
         if ($DB->count_records('local_treestudyplan_line', ['page_id' => $this->id]) > 0) {
             return success::fail('cannot delete studyplan page that still has studylines');
-        } else
-        {
+        } else {
             $DB->delete_records(self::TABLE, ['id' => $this->id]);
             return success::success();
         }
@@ -259,16 +258,16 @@ class studyplanpage {
         return $list;
     }
 
-    public static function duplicate_page($page_id, $name, $shortname) {
-        $ori = self::findById($page_id);
+    public static function duplicate_page($pageid, $name, $shortname) {
+        $ori = self::findById($pageid);
         $new = $ori->duplicate($name, $shortname);
         return $new->simple_model();
     }
 
-    public function duplicate($new_studyplan) {
+    public function duplicate($newstudyplan) {
         // First duplicate the studyplan structure.
         $new = studyplanpage::add([
-            'studyplan_id' => $new_studyplan->id(),
+            'studyplan_id' => $newstudyplan->id(),
             'fullname' => $this->r->fullname,
             'shortname' => $this->r->shortname,
             'description' => $this->r->description,
@@ -290,9 +289,9 @@ class studyplanpage {
         // now the itemtranslation array contains all of the old child id's as keys and all of the related new ids as values.
         // (feature of the studyline::duplicate function).
         // use this to recreate the lines in the new plan.
-        foreach (array_keys($itemtranslation) as $item_id) {
+        foreach (array_keys($itemtranslation) as $itemid) {
             // copy based on the outgoing connections of each item, to avoid duplicates.
-            $connections  = studyitemconnection::find_outgoing($item_id);
+            $connections  = studyitemconnection::find_outgoing($itemid);
             foreach ($connections as $conn) {
                 studyitemconnection::connect($itemtranslation[$conn->from_id], $itemtranslation[$conn->to_id]);
             }
@@ -484,7 +483,7 @@ class studyplanpage {
 
     public function import_studylines_model($model) {
         // First attempt to map each studyline model to an existing or new line.
-        $line_map = [];
+        $linemap = [];
         foreach ($model as $ix => $linemodel) {
             $line = $this->find_studyline_by_shortname($linemodel["shortname"]);
             if (empty($line)) {
@@ -493,14 +492,14 @@ class studyplanpage {
             } else {
                 //$line->edit($linemodel); // Update the line with the settings from the imported file.
             }
-            $line_map[$ix] = $line;
+            $linemap[$ix] = $line;
         }
 
         // next, let each study line import the study items.
         $itemtranslation = [];
         $connections = [];
         foreach ($model as $ix => $linemodel) {
-            $line_map[$ix]->import_studyitems($linemodel["slots"], $itemtranslation, $connections);
+            $linemap[$ix]->import_studyitems($linemodel["slots"], $itemtranslation, $connections);
         }
 
         // Finally, create the links between the study items.
diff --git a/classes/studyplanservice.php b/classes/studyplanservice.php
index 583a636..257cfa8 100644
--- a/classes/studyplanservice.php
+++ b/classes/studyplanservice.php
@@ -53,16 +53,16 @@ class studyplanservice extends \external_api
         return new \external_multiple_structure( studyplan::simple_structure() );
     }
 
-    public static function list_studyplans($context_id = 0) {
+    public static function list_studyplans($contextid = 0) {
         global $CFG, $DB;
 
         // Check if the user has the correct permissions for this context.
-        $context = webservicehelper::find_context($context_id);
+        $context = webservicehelper::find_context($contextid);
         webservicehelper::require_capabilities([self::CAP_EDIT, self::CAP_VIEW], $context);
 
         // Now list all the studyplans in the relevant context.
         $list = [];
-        $studyplans = studyplan::find_all($context_id);
+        $studyplans = studyplan::find_all($contextid);
         foreach ($studyplans as $studyplan) {
             $list[] = $studyplan->simple_model();
         }
@@ -144,9 +144,9 @@ class studyplanservice extends \external_api
         return studyplan::simple_structure();
     }
 
-    public static function add_studyplan($name, $shortname, $idnumber, $description, $periods, $startdate, $enddate, $aggregation="bistate", $aggregation_config='', $context_id=0) {
+    public static function add_studyplan($name, $shortname, $idnumber, $description, $periods, $startdate, $enddate, $aggregation="bistate", $aggregationconfig='', $contextid=0) {
         // Check if we have the proper rights for the requested context.
-        $context = webservicehelper::find_context($context_id);
+        $context = webservicehelper::find_context($contextid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $context);
 
         $o = studyplan::add([
@@ -158,8 +158,8 @@ class studyplanservice extends \external_api
             'startdate' => $startdate,
             'enddate' => empty($enddate)?null:$enddate,
             'aggregation' => $aggregation,
-            'aggregation_config' => $aggregation_config,
-            'context_id' => $context_id,
+            'aggregation_config' => $aggregationconfig,
+            'context_id' => $contextid,
         ]);
         return $o->simple_model();
     }
@@ -190,9 +190,9 @@ class studyplanservice extends \external_api
         return studyplan::simple_structure();
     }
 
-    public static function edit_studyplan($id, $name, $shortname, $idnumber, $description, $periods, $startdate, $enddate, $aggregation="bistate", $aggregation_config='', $context_id=0) {
+    public static function edit_studyplan($id, $name, $shortname, $idnumber, $description, $periods, $startdate, $enddate, $aggregation="bistate", $aggregationconfig='', $contextid=0) {
         // Validate access in the intended context.
-        $context = webservicehelper::find_context($context_id);
+        $context = webservicehelper::find_context($contextid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $context, false); // do not validate the context in this case, just check the permissions.
 
         $o = studyplan::findById($id);
@@ -207,8 +207,8 @@ class studyplanservice extends \external_api
             'startdate' => $startdate,
             'enddate' => $enddate,
             'aggregation' => $aggregation,
-            'aggregation_config' => $aggregation_config,
-            'context_id' => $context_id,
+            'aggregation_config' => $aggregationconfig,
+            'context_id' => $contextid,
         ]);
         return $o->simple_model();
     }
@@ -257,13 +257,13 @@ class studyplanservice extends \external_api
         return studyline::editor_structure();
     }
 
-    public static function add_studyline($page_id, $name, $shortname, $color, $sequence) {
+    public static function add_studyline($pageid, $name, $shortname, $color, $sequence) {
         // validate if the requesting user has the right to edit the plan in it's current context.
-        $page = studyplanpage::findById($page_id);
+        $page = studyplanpage::findById($pageid);
         webservicehelper::require_capabilities(self::CAP_EDIT, $page->studyplan()->context());
 
         $o = studyline::add([
-            'page_id' => $page_id,
+            'page_id' => $pageid,
             'name' => $name,
             'shortname' => $shortname,
             'color' => $color,
@@ -415,11 +415,11 @@ class studyplanservice extends \external_api
         return studyitem::editor_structure();
     }
 
-    public static function add_studyitem($line_id, $type, $details, $slot=-1, $layer=0) {
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyline::findById($line_id)->context());
+    public static function add_studyitem($lineid, $type, $details, $slot=-1, $layer=0) {
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyline::findById($lineid)->context());
 
         $o = studyitem::add([
-            'line_id' => $line_id,
+            'line_id' => $lineid,
             'type' => $type,
             //'conditions' => $conditions,.
             'slot' => $slot,
@@ -450,7 +450,7 @@ class studyplanservice extends \external_api
         return studyitem::editor_structure();
     }
 
-    public static function edit_studyitem($id, $conditions, $continuation_id=false) {
+    public static function edit_studyitem($id, $conditions, $continuationid=false) {
 
         $o = studyitem::findById($id);
         webservicehelper::require_capabilities(self::CAP_EDIT, $o->context());
@@ -458,8 +458,8 @@ class studyplanservice extends \external_api
         $config = [
             'conditions' => $conditions,
         ];
-        if ($continuation_id !== false) {
-            $config['continuation_id'] = $continuation_id;
+        if ($continuationid !== false) {
+            $config['continuation_id'] = $continuationid;
         }
 
         $o->edit($config);
@@ -540,12 +540,12 @@ class studyplanservice extends \external_api
         return studyitemconnection::structure();
     }
 
-    public static function connect_studyitems($from_id, $to_id) {
+    public static function connect_studyitems($fromid, $toid) {
         // Validate permissions.
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($from_id)->context());
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($to_id)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($fromid)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($toid)->context());
 
-        $o = studyitemconnection::connect($from_id, $to_id);
+        $o = studyitemconnection::connect($fromid, $toid);
         return $o->model();
     }
 
@@ -566,11 +566,11 @@ class studyplanservice extends \external_api
         return success::structure();
     }
 
-    public static function disconnect_studyitems($from_id, $to_id) {
+    public static function disconnect_studyitems($fromid, $toid) {
         // Validate permissions.
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($from_id)->context());
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($to_id)->context());
-        return studyitemconnection::disconnect($from_id, $to_id)->model();
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($fromid)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyitem::findById($toid)->context());
+        return studyitemconnection::disconnect($fromid, $toid)->model();
     }
 
     /****************************
@@ -624,19 +624,19 @@ class studyplanservice extends \external_api
         return success::structure();
     }
 
-    public static function include_grade($grade_id, $item_id, $include, $required=false) {
+    public static function include_grade($gradeid, $itemid, $include, $required=false) {
         global $USER;
 
         // find related course and course context.
-        $coursecontext = gradeinfo::getCourseContextById($grade_id);
+        $coursecontext = gradeinfo::getCourseContextById($gradeid);
         // do sanity checks.
         \external_api::validate_context($coursecontext);
 
 
         // check correct capabilities.
-        if (has_capability('local/treestudyplan:editstudyplan', studyitem::findById($item_id)->context()) ||
+        if (has_capability('local/treestudyplan:editstudyplan', studyitem::findById($itemid)->context()) ||
            is_enrolled($coursecontext, $USER, 'local/treestudyplan:selectowngradables')) {
-            return gradeinfo::include_grade($grade_id, $item_id, $include, $required)->model();
+            return gradeinfo::include_grade($gradeid, $itemid, $include, $required)->model();
         } else {
             return success::fail("Access denied")->model();
         }
@@ -686,16 +686,16 @@ class studyplanservice extends \external_api
         ]));
     }
 
-    public static function force_studyplan_scale($studyplan_id, $scale_id) {
+    public static function force_studyplan_scale($studyplanid, $scaleid) {
         global $DB;
         $dbman = $DB->get_manager();
 
         // Validate permissions.
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplan_id)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplanid)->context());
 
         $list = [];
         // check if scaleid is valid.
-        $scale = \grade_scale::fetch(['id' => $scale_id]);
+        $scale = \grade_scale::fetch(['id' => $scaleid]);
         $scale->load_items();
 
         if ($scale) {
@@ -704,13 +704,13 @@ class studyplanservice extends \external_api
             $scalemax = count($scale->scale_items);
 
             // find studyline id's.
-            $studyline_ids = $DB->get_fieldset_select(studyline::TABLE, "id", "studyplan_id = :plan_id", ['plan_id' => $studyplan_id]);
-            foreach ($studyline_ids as $studyline_id) {
+            $studylineids = $DB->get_fieldset_select(studyline::TABLE, "id", "studyplan_id = :plan_id", ['plan_id' => $studyplanid]);
+            foreach ($studylineids as $studylineid) {
                 // find id's of studyitems of type course.
-                $records = $DB->get_records(studyitem::TABLE, ['line_id' => $studyline_id]);
+                $records = $DB->get_records(studyitem::TABLE, ['line_id' => $studylineid]);
 
-                foreach ($records as $item_r) {
-                    $studyitem = new studyitem($item_r->id);
+                foreach ($records as $itemr) {
+                    $studyitem = new studyitem($itemr->id);
                     if ($studyitem->isValid() && $studyitem->type() == studyitem::COURSE) {
                         $courseinfo = $studyitem->getcourseinfo();
                         $gradables = gradeinfo::list_studyitem_gradables($studyitem);
@@ -742,9 +742,9 @@ class studyplanservice extends \external_api
                                 $fieldname = "grade";
                                 if ($result && $gi->itemtype == "mod" && $dbman->table_exists($tablename)) {
                                     if ($dbman->field_exists($tablename, $fieldname)) {
-                                        $grade_value = intval(0-($scale->id));
+                                        $gradevalue = intval(0-($scale->id));
                                         try {
-                                            $DB->set_field($tablename, $fieldname, $grade_value, ["id" => $gi->iteminstance]);
+                                            $DB->set_field($tablename, $fieldname, $gradevalue, ["id" => $gi->iteminstance]);
                                         }
                                         catch(\dml_exception $x) {
                                             $updated = "fail";
@@ -826,20 +826,20 @@ class studyplanservice extends \external_api
         return success::structure();
     }
 
-    public static function disable_autoenddate($studyplan_id) {
+    public static function disable_autoenddate($studyplanid) {
         global $DB;
 
         // Validate permissions.
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplan_id)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplanid)->context());
 
         // find studyline id's.
-        $studyline_ids = $DB->get_fieldset_select(studyline::TABLE, "id", "studyplan_id = :plan_id", ['plan_id' => $studyplan_id]);
-        foreach ($studyline_ids as $studyline_id) {
+        $studylineids = $DB->get_fieldset_select(studyline::TABLE, "id", "studyplan_id = :plan_id", ['plan_id' => $studyplanid]);
+        foreach ($studylineids as $studylineid) {
             // find id's of studyitems of type course.
-            $records = $DB->get_records(studyitem::TABLE, ['line_id' => $studyline_id]);
+            $records = $DB->get_records(studyitem::TABLE, ['line_id' => $studylineid]);
 
-            foreach ($records as $item_r) {
-                $studyitem = new studyitem($item_r->id);
+            foreach ($records as $itemr) {
+                $studyitem = new studyitem($itemr->id);
                 if ($studyitem->isValid() && $studyitem->type() == studyitem::COURSE) {
                     $record = $DB->get_record("course_format_options", ["courseid" => $studyitem->courseid(), "name" => "automaticenddate"]);
                     if ($record && $record->value) {
@@ -870,11 +870,11 @@ class studyplanservice extends \external_api
         return studyplan::simple_structure();
     }
 
-    public static function duplicate_plan($studyplan_id, $name, $shortname) {
+    public static function duplicate_plan($studyplanid, $name, $shortname) {
         // Validate permissions.
-        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplan_id)->context());
+        webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplanid)->context());
 
-        return studyplan::duplicate_plan($studyplan_id, $name, $shortname);
+        return studyplan::duplicate_plan($studyplanid, $name, $shortname);
     }
 
     /****************************
@@ -894,12 +894,12 @@ class studyplanservice extends \external_api
         return studyplan::export_structure();
     }
 
-    public static function export_plan($studyplan_id, $format="json") {
+    public static function export_plan($studyplanid, $format="json") {
         try {
             // Validate permissions.
-            webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplan_id)->context());
+            webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplanid)->context());
 
-            $plan = studyplan::findById($studyplan_id);
+            $plan = studyplan::findById($studyplanid);
             if ($format == "csv") {
                 // FIXME: Make sure this webservice function gets called for the page instead of the studyplan.
                 return $plan->pages()[0]->export_page_csv();
@@ -922,12 +922,12 @@ class studyplanservice extends \external_api
         return studyplan::export_structure();
     }
 
-    public static function export_studylines($studyplan_id) {
+    public static function export_studylines($studyplanid) {
         $systemcontext = webservicehelper::system_context();
 
         try {
-            webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplan_id)->context());
-            $plan = studyplan::findById($studyplan_id);
+            webservicehelper::require_capabilities(self::CAP_EDIT, studyplan::findById($studyplanid)->context());
+            $plan = studyplan::findById($studyplanid);
             // FIXME: Make sure this gets called for the page instead of the studyplan.
             return $plan->pages()[0]->export_studylines();
         }
@@ -953,14 +953,14 @@ class studyplanservice extends \external_api
         return success::structure();
     }
 
-    public static function import_plan($content, $format="application/json", $context_id=1) {
+    public static function import_plan($content, $format="application/json", $contextid=1) {
 
         try {
             // Validate import context.
-            $context = webservicehelper::find_context($context_id);
+            $context = webservicehelper::find_context($contextid);
             webservicehelper::require_capabilities(self::CAP_EDIT, $context);
 
-            $result = studyplan::import_studyplan($content, $format, $context_id);
+            $result = studyplan::import_studyplan($content, $format, $contextid);
             return (new success($result, "During study plan import"))->model();
         }
         catch(\webservice_access_exception $x) {
@@ -980,10 +980,10 @@ class studyplanservice extends \external_api
         return success::structure();
     }
 
-    public static function import_studylines($studyplan_id, $content, $format="application/json") {
+    public static function import_studylines($studyplanid, $content, $format="application/json") {
 
         try {
-            $plan = studyplan::findById($studyplan_id);
+            $plan = studyplan::findById($studyplanid);
             // Validate import context.
             webservicehelper::require_capabilities(self::CAP_EDIT, $plan->context());
 
@@ -1130,15 +1130,15 @@ class studyplanservice extends \external_api
          return courseinfo::editor_structure();
      }
 
-     public static function course_period_timing($period_id, $course_id, $span=1) {
+     public static function course_period_timing($periodid, $courseid, $span=1) {
         global $DB;
-        $period = period::findById($period_id);
+        $period = period::findById($periodid);
         $periodnr = $period->period();
         $page = $period->page();
         // Check for studyplan edit permissions.
         webservicehelper::require_capabilities(self::CAP_EDIT, $page->studyplan()->context());
-        $course = \get_course($course_id);
-        $coursecontext = \context_course::instance($course_id);
+        $course = \get_course($courseid);
+        $coursecontext = \context_course::instance($courseid);
 
         if (webservicehelper::has_capabilities("moodle/course:update", $coursecontext)) {
 
diff --git a/classes/task/refreshteacherlist.php b/classes/task/refreshteacherlist.php
index 6db0ad1..b67e1c9 100644
--- a/classes/task/refreshteacherlist.php
+++ b/classes/task/refreshteacherlist.php
@@ -41,8 +41,8 @@ class refreshteacherlist extends \core\task\scheduled_task  {
      */
     public function execute() {
         \mtrace("Ververs lijst met leraren");
-        $teacher_ids = teachingfinder::list_teacher_ids();
-        foreach ($teacher_ids as $tid) {
+        $teacherids = teachingfinder::list_teacher_ids();
+        foreach ($teacherids as $tid) {
             $utime = teachingfinder::get_update_time($tid);
             if (time() - $utime > self::CACHE_TIME) {
                 \mtrace("Teacher {$tid} is due for a refresh of the list");
diff --git a/classes/teachingfinder.php b/classes/teachingfinder.php
index 0dc4565..318056e 100644
--- a/classes/teachingfinder.php
+++ b/classes/teachingfinder.php
@@ -57,19 +57,19 @@ class teachingfinder {
 
         $sql = "SELECT p.id FROM {local_treestudyplan_page} p
             WHERE startdate <= NOW() and enddate >= NOW()";
-        $page_ids = $DB->get_fieldset_sql($sql, []);
+        $pageids = $DB->get_fieldset_sql($sql, []);
 
         // then parse them to see if the user has the grading permission in any of them .
         // (Which would make them a teacher for all intents and purposes).
 
-        foreach ($page_ids as $page_id) {
+        foreach ($pageids as $pageid) {
             $sql = "SELECT i.course_id FROM {local_treestudyplan_item} i
                     INNER JOIN {local_treestudyplan_line} l ON i.line_id = l.id
                     WHERE l.page_id = :page_id AND i.course_id IS NOT NULL";
-            $course_ids = $DB->get_fieldset_sql($sql, ["page_id" => $page_id]);
+            $courseids = $DB->get_fieldset_sql($sql, ["page_id" => $pageid]);
 
             $linked = false;
-            foreach ($course_ids as $cid) {
+            foreach ($courseids as $cid) {
                 $coursecontext =  \context_course::instance($cid);
                 if (is_enrolled($coursecontext, $userid, 'mod/assign:grade')) {
                     $linked = true;
@@ -78,7 +78,7 @@ class teachingfinder {
             }
 
             if ($linked) {
-                $list[] = $page_id;
+                $list[] = $pageid;
             }
 
         }
@@ -87,10 +87,10 @@ class teachingfinder {
         $DB->delete_records(self::TABLE, ["teacher_id"=>$userid]);
         // And add new records for the found studyplans.
         $now = time();
-        foreach ($list as $page_id) {
+        foreach ($list as $pageid) {
             // Retrieve the studyplan id from the page.
             //TODO: Change this when page management is implemented to return the page instead of the plan.
-            $planid = $DB->get_field("local_treestudyplan_page", "studyplan_id", ["id" => $page_id]);
+            $planid = $DB->get_field("local_treestudyplan_page", "studyplan_id", ["id" => $pageid]);
             $DB->insert_record(self::TABLE, ["teacher_id"=>$userid, "studyplan_id"=>$planid, "update_time"=>$now]);
         }
 
@@ -102,10 +102,10 @@ class teachingfinder {
         return $DB->get_fieldset_sql("SELECT DISTINCT teacher_id FROM {".self::TABLE."}");
     }
 
-    public static function get_update_time($teacher_id): int {
+    public static function get_update_time($teacherid): int {
         global $DB;
         $r = $DB->get_field_sql("SELECT MIN(update_time)FROM {".self::TABLE."} WHERE teacher_id=:teacher_id",
-                                ["teacher_id" => $teacher_id]);
+                                ["teacher_id" => $teacherid]);
         return (int)($r->update_time);
     }
 
diff --git a/cli/randomize_grades.php b/cli/randomize_grades.php
index 4083b01..58e3d75 100644
--- a/cli/randomize_grades.php
+++ b/cli/randomize_grades.php
@@ -143,8 +143,8 @@ foreach ($plans as $plan) {
                                         if ($gi->itemmodule == "assign") {
                                             // If it is an assignment, submit though that interface .
                                             list($c, $cminfo) = get_course_and_cm_from_instance($gi->iteminstance, $gi->itemmodule);
-                                            $cm_ctx = \context_module::instance($cminfo->id);
-                                            $a = new \assign($cm_ctx, $cminfo, $c);
+                                            $cmctx = \context_module::instance($cminfo->id);
+                                            $a = new \assign($cmctx, $cminfo, $c);
 
                                             $ug = $a->get_user_grade($u->id, true);
                                             $ug->grade = grade_floatval($gg->grade);
@@ -174,8 +174,7 @@ foreach ($plans as $plan) {
                                 }
                             }
                         }
-                    } else
-                    {
+                    } else {
                         cli_writeln("      Skipping since it has not started yet");
                     }
                 }
diff --git a/doc.php b/doc.php
index 379821b..55b944f 100644
--- a/doc.php
+++ b/doc.php
@@ -41,9 +41,9 @@ if (!file_exists($file)) {
 }
 
 $mime = mime_content_type($file);
-$text_types = ["text/html", "text/plain"];
+$texttypes = ["text/html", "text/plain"];
 
-if ( in_array($mime, $text_types)) {
+if ( in_array($mime, $texttypes)) {
 	print $OUTPUT->header();
 	print file_get_contents($file);
 	print $OUTPUT->footer();
diff --git a/edit-invite.php b/edit-invite.php
index fa5a9fa..d96a737 100644
--- a/edit-invite.php
+++ b/edit-invite.php
@@ -40,8 +40,7 @@ $PAGE->set_context($systemcontext);
 if ($update > 0) {
 	$PAGE->set_title(get_string('invite_desc_edit', 'local_treestudyplan'));
 	$PAGE->set_heading(get_string('invite_desc_edit', 'local_treestudyplan'));
-} else
-{
+} else {
 	$PAGE->set_title(get_string('invite_desc_new', 'local_treestudyplan'));
 	$PAGE->set_heading(get_string('invite_desc_new', 'local_treestudyplan'));
 }
@@ -144,8 +143,7 @@ if ($mform->is_cancelled()) {
 
 	exit;
 	
-} else
-{
+} else {
 	$data = null;
 	if ($unitid > 0)
 	{
diff --git a/edit-plan.php b/edit-plan.php
index b8e660c..dc715ce 100644
--- a/edit-plan.php
+++ b/edit-plan.php
@@ -47,12 +47,11 @@ if ($categoryid > 0) {
 	{
 		$studyplancontext = $systemcontext;
 	}
-} else
-{
+} else {
 	// If no context is selected, find the first available one.
-	$available_contexts = courseservice::list_accessible_categories_with_usage("edit");
+	$availablecontexts = courseservice::list_accessible_categories_with_usage("edit");
 	$contextid=1; // fallback to system context.
-	foreach ($available_contexts as $ctx) {
+	foreach ($availablecontexts as $ctx) {
 		if ($ctx->count > 0) {
 			$contextid = $ctx->ctxid;
 			break;
diff --git a/invitations.php b/invitations.php
index e586378..524b362 100644
--- a/invitations.php
+++ b/invitations.php
@@ -25,8 +25,7 @@ if (isset($_SERVER['SCRIPT_FILENAME'])) {
 	$root = dirname(dirname(dirname($_SERVER['SCRIPT_FILENAME'])));
 	error_log("Using {$root}/config.php");
 	require_once($root."/config.php");
-} else
-{
+} else {
 	// If not, assume the cwd is not symlinked and proceed as we are used to.
 	require_once("../../config.php");
 }
@@ -36,7 +35,7 @@ require_once($CFG->dirroot.'/grade/querylib.php');
 
 use local_treestudyplan;
 
-$INVITED_URL = "/local/treestudyplan/invited.php";
+$INVITEDURL = "/local/treestudyplan/invited.php";
 
 //admin_externalpage_setup('major');.
 $systemcontext = context_system::instance();
@@ -80,7 +79,7 @@ print "<tbody>";
 if (count($invites) > 0) {
 	foreach ($invites as $invite)
 	{
-		$testlink  = $INVITED_URL."?key={$invite->invitekey}";
+		$testlink  = $INVITEDURL."?key={$invite->invitekey}";
 		print "<tr data-id='{$invite->id}'>";
 		print "<td data-field='name'>{$invite->name}</td>";
 		print "<td data-field='email'>{$invite->email}</td>";
@@ -104,8 +103,7 @@ if (count($invites) > 0) {
 
 		print "</td>";
 	}
-} else
-{
+} else {
 	print "<tr><td colspan='6'>".get_string('invite_table_empty', 'local_treestudyplan')."</td></tr>";
 }
 print "</tbody></table>";
diff --git a/invited.php b/invited.php
index f7d8aa8..175ed02 100644
--- a/invited.php
+++ b/invited.php
@@ -54,8 +54,7 @@ if (empty($invite)) {
 	print $OUTPUT->footer();
 
 	exit;
-} else
-{
+} else {
 	// Load javascripts and specific css.
 	$PAGE->requires->css(new moodle_url($CFG->wwwroot.'/local/treestudyplan/css/bootstrap-vue/bootstrap-vue.css'));
 	$PAGE->requires->css(new moodle_url($CFG->wwwroot.'/local/treestudyplan/css/devstyles.css'));
diff --git a/lib.php b/lib.php
index ce92146..177356e 100644
--- a/lib.php
+++ b/lib.php
@@ -50,7 +50,7 @@ function local_treestudyplan_extend_navigation(global_navigation $navigation) {
 	// (Since the Output API does not easily support inline style tags, adding one through Javascript is easier,.
 	//  and not much more complex than loading a separate stylesheet for each link we want to hide).
 	// we will add all the hrefs that should be hidden to this variable below.
-	$hide_primary_hrefs = [];
+	$hideprimary_hrefs = [];
 
 	if ($USER->id > 1) // Don't show if user is not logged in (id == 0) or is guest user (id == 1).
 	{
@@ -87,7 +87,7 @@ function local_treestudyplan_extend_navigation(global_navigation $navigation) {
 			$navigation->add_node($node, 'mycourses');
 		}
 		else {
-			$hide_primary_hrefs[] = "/local/treestudyplan/myreport.php";
+			$hideprimary_hrefs[] = "/local/treestudyplan/myreport.php";
 		}
 		if (	has_capability('local/treestudyplan:viewuserreports', context_system::instance())
 			|| webservicehelper::has_capability_in_any_category('local/treestudyplan:viewuserreports'))
@@ -105,7 +105,7 @@ function local_treestudyplan_extend_navigation(global_navigation $navigation) {
 			$navigation->add_node($node, 'mycourses');
 		}
 		else {
-			$hide_primary_hrefs[] = "/local/treestudyplan/view-plan.php";
+			$hideprimary_hrefs[] = "/local/treestudyplan/view-plan.php";
 		}
 		if (	has_capability('local/treestudyplan:editstudyplan', context_system::instance())
 		  	|| webservicehelper::has_capability_in_any_category('local/treestudyplan:editstudyplan')
@@ -124,13 +124,13 @@ function local_treestudyplan_extend_navigation(global_navigation $navigation) {
 			$navigation->add_node($node, 'mycourses');
 		}
 		else {
-			$hide_primary_hrefs[] = "/local/treestudyplan/edit-plan.php";
+			$hideprimary_hrefs[] = "/local/treestudyplan/edit-plan.php";
 		}
 	}
 	else {
-		$hide_primary_hrefs[] = "/local/treestudyplan/myreport.php";
-		$hide_primary_hrefs[] = "/local/treestudyplan/edit-plan.php";
-		$hide_primary_hrefs[] = "/local/treestudyplan/view-plan.php";
+		$hideprimary_hrefs[] = "/local/treestudyplan/myreport.php";
+		$hideprimary_hrefs[] = "/local/treestudyplan/edit-plan.php";
+		$hideprimary_hrefs[] = "/local/treestudyplan/view-plan.php";
 	}
 	// create invitenode node.
 	$invitenode = navigation_node::create(
@@ -146,7 +146,7 @@ function local_treestudyplan_extend_navigation(global_navigation $navigation) {
 
 
 	// Now using some javascript magic, we'll hide the links that are not accessible.
-	$PAGE->requires->js_call_amd('local_treestudyplan/primary-nav-tools', 'hide_primary', [$hide_primary_hrefs]);
+	$PAGE->requires->js_call_amd('local_treestudyplan/primary-nav-tools', 'hide_primary', [$hideprimary_hrefs]);
 
 
 
@@ -292,8 +292,7 @@ function local_treestudyplan_get_cohort_path($cohort) {
         $ctxpath[] = $cohort->name;
 
         return implode(" / ", $ctxpath);
-    } else
-    {
+    } else {
         return $cohort->name;
     }
 }
diff --git a/settings.php b/settings.php
index 5a8c8cf..ed10428 100644
--- a/settings.php
+++ b/settings.php
@@ -146,46 +146,46 @@ if ($hassiteconfig) {
 	 *
 	 *************************************/
 	
-	$page_csync = new admin_settingpage('local_treestudyplan_settings_cohortsync',
+	$pagecsync = new admin_settingpage('local_treestudyplan_settings_cohortsync',
 		get_string('settingspage_csync', 'local_treestudyplan', null, true));
 
 
 	// Description heading.
-	$page_csync->add(new admin_setting_heading('local_treestudyplan/csync_heading',
+	$pagecsync->add(new admin_setting_heading('local_treestudyplan/csync_heading',
 		get_string('setting_csync_heading', 'local_treestudyplan'),
 		get_string('settingdesc_csync_heading', 'local_treestudyplan')
 	));
 
 	// Enable/disable cohort sync.
-	$page_csync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_enable',
+	$pagecsync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_enable',
 		get_string('setting_csync_enable_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_enable_field', 'local_treestudyplan'),
 		false
 	));
 
 	// Enable/disable autoremove.
-	$page_csync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_autoremove',
+	$pagecsync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_autoremove',
 		get_string('setting_csync_autoremove_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_autoremove_field', 'local_treestudyplan'),
 		true
 	));
 
 	// Enable/disable remembering previously added cohort syncs so they're not automatically deleted.
-	$page_csync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_remember_manual_csync',
+	$pagecsync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_remember_manual_csync',
 		get_string('setting_csync_remember_manual_csync_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_remember_manual_csync_field', 'local_treestudyplan'),
 		true
 	));
 
 	// Enable/disable group creation.
-	$page_csync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_creategroup',
+	$pagecsync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_creategroup',
 		get_string('setting_csync_creategroup_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_creategroup_field', 'local_treestudyplan'),
 		true
 	));
 
 	// Sync users too yes/no?.
-	$page_csync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_users',
+	$pagecsync->add(new admin_setting_configcheckbox('local_treestudyplan/csync_users',
 		get_string('setting_csync_users_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_users_field', 'local_treestudyplan'),
 		true
@@ -196,14 +196,14 @@ if ($hassiteconfig) {
 		$options = get_default_enrol_roles(context_system::instance());
 		$student = get_archetype_roles('student');
 		$student = reset($student);
-		$page_csync->add(new admin_setting_configselect('local_treestudyplan/csync_roleid',
+		$pagecsync->add(new admin_setting_configselect('local_treestudyplan/csync_roleid',
 		get_string('setting_csync_role_field', 'local_treestudyplan'),
 		get_string('settingdesc_csync_role_field', 'local_treestudyplan'),
 		$student->id ?? null, $options));
 	}
 
 	// Add settings page2 to the admin settings category.
-	$ADMIN->add('local_treestudyplan', $page_csync);
+	$ADMIN->add('local_treestudyplan', $pagecsync);
 
 	/**************************************
 	 *
diff --git a/view-plan.php b/view-plan.php
index fc51461..baedb9b 100644
--- a/view-plan.php
+++ b/view-plan.php
@@ -47,12 +47,11 @@ if ($categoryid > 0) {
 	{
 		$studyplancontext = $systemcontext;
 	}
-} else
-{
+} else {
 	// If no context is selected, find the first available one.
-	$available_contexts = courseservice::list_accessible_categories_with_usage("view");
+	$availablecontexts = courseservice::list_accessible_categories_with_usage("view");
 	$contextid=1; // fallback to system context.
-	foreach ($available_contexts as $ctx) {
+	foreach ($availablecontexts as $ctx) {
 		if ($ctx->count > 0) {
 			$contextid = $ctx->ctxid;
 			break;