<?php
// This file is part of the Studyplan plugin for Moodle
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <https://www.gnu.org/licenses/>.
/**
 * Model class for study plan
 * @package    local_treestudyplan
 * @copyright  2023 P.M. Kuipers
 * @license    https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace local_treestudyplan;
defined('MOODLE_INTERNAL') || die();

require_once($CFG->libdir.'/externallib.php');
/**
 * Model class for study plan
 */
class studyplan {

    /** @var string */
    const TABLE = "local_treestudyplan";

    /**
     * Cache retrieved studyitems in this session
     * @var array */
    private static $cache = [];

    /**
     * Cache retrieved pages for the studyplan in this session
     * @var array */
    private static $pagecache = [];

    /**
     * Holds database record
     * @var stdClass
     */
    private $r;
    /** @var int */
    private $id;
    /** @var aggregator */
    private $aggregator;

    /**
     * Hold context object once retrieved.
     * @var \context
     */
    private $context = null;
    /**
     * Cache lookup of linked users (saves queries).
     * @var int[]
     */
    private $linkeduserids = null;

    /**
     * Return configured aggregator for this studyplan
     */
    public function aggregator() : aggregator {
        return $this->aggregator;
    }

    /**
     * Find record in database and return management object
     * Cache objects to avoid multiple creation events in one session.
     * @param int $id Id of database record
     */
    public static function find_by_id($id): self {
        if (!array_key_exists($id, self::$cache)) {
            self::$cache[$id] = new self($id);
        }
        return self::$cache[$id];
    }

    /**
     * Construct new instance from DB record
     * @param int $id Id of database record
     */
    private function __construct($id) {
        global $DB;
        $this->id = $id;
        $this->r = $DB->get_record(self::TABLE, ['id' => $id],"*",MUST_EXIST);

        $this->aggregator = aggregator::create_or_default($this->r->aggregation, $this->r->aggregation_config);
    }

    /**
     * Return database identifier
     * @return int
     */
    public function id() {
        return $this->id;
    }

    /**
     * Return short name
     * @return string
     */
    public function shortname() {
        return $this->r->shortname;
    }

    /**
     * Return full name
     * @return string
     */
    public function name() {
        return $this->r->name;
    }

    private function icon() {
        global $CFG;
        $fs = \get_file_storage();
        // Returns an array of `stored_file` instances.
        $files = $fs->get_area_files(\context_system::instance()->id, 'local_treestudyplan', 'icon', $this->id);

        if (count($files) > 0 ){
            $file = array_shift($files);
            if ($file->get_filename() == ".") {
                // Get next file if the first is the directory itself.
                $file = array_shift($files);
            }

            $url = \moodle_url::make_pluginfile_url(
                $file->get_contextid(),
                $file->get_component(),
                $file->get_filearea(),
                $file->get_itemid(),
                $file->get_filepath(),
                $file->get_filename(),
                false                     // Do not force download of the file.
            );
        } else {
            // Try the configured default in settings.
            $defaulticon = get_config('local_treestudyplan', 'defaulticon');
            if (empty($defaulticon)) {
                   // Fall back to the standard (ugly) default image.
                   $url = new \moodle_url($CFG->wwwroot . "/local/treestudyplan/pix/default_icon.png");
            } else {
                $url = \moodle_url::make_pluginfile_url(\context_system::instance()->id, 'local_treestudyplan', 'defaulticon', 0, "/",
                    $defaulticon);
            }
            
        }
        return $url->out();
    }

    /** 
     * Return description with all file references resolved
     */
    public function description() {
        $text = file_rewrite_pluginfile_urls(
            // The content of the text stored in the database.
            $this->r->description,
            // The pluginfile URL which will serve the request.
            'pluginfile.php',
        
            // The combination of contextid / component / filearea / itemid
            // form the virtual bucket that file are stored in.
            \context_system::instance()->id, // System instance is always used for this
            'local_treestudyplan',
            'studyplan',
            $this->id
        );
        return $text;
    }
    /**
     * Return the studyplan pages associated with this plan
     * @param bool $refresh Set to true to force a refresh of the pages
     * @return studyplanpage[]
     */
    public function pages($refresh=false) : array {
        if ( ((bool)$refresh) || empty($this->pagecache)) {
            $this->pagecache = studyplanpage::find_studyplan_children($this);
        }
        return $this->pagecache;
    }

    /**
     * Return the context the studyplan is associated to
     * @return \context
     */
    public function context(): \context {
        if (!isset($this->context)) {
            try {
                $this->context = contextinfo::by_id($this->r->context_id)->context;
            } catch (\dml_missing_record_exception $x) {
                // Just throw it up again. catch is included here to make sure we know it throws this exception.
                throw new \InvalidArgumentException(
                    "Context {$this->r->context_id} not available");
            }
        }
        return $this->context;
    }

    /**
     * Webservice structure for basic info
     * @param int $value Webservice requirement constant
     */
    public static function simple_structure($value = VALUE_REQUIRED) : \external_description {
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname" => new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "idnumber" => new \external_value(PARAM_TEXT, 'idnumber of curriculum'),
            "context_id" => new \external_value(PARAM_INT, 'context_id of studyplan'),
            "description" => new \external_value(PARAM_RAW, 'description of studyplan'),
            "descriptionformat" => new \external_value(PARAM_INT, 'description format'),
            "icon" => new \external_value(PARAM_RAW,'icon for this plan'),
            "aggregation" => new \external_value(PARAM_TEXT, 'selected aggregator'),
            "aggregation_config" => new \external_value(PARAM_TEXT, 'config string for aggregator'),
            "aggregation_info" => aggregator::basic_structure(),
            "pages" => new \external_multiple_structure(studyplanpage::simple_structure(), 'pages'),
            "progress" => new \external_value(PARAM_FLOAT,"fraction of completed modules",VALUE_OPTIONAL),
        ], 'Basic studyplan info', $value);
    }

    /**
     * Webservice model for basic info
     * @return array Webservice data model
     */
    public function simple_model() {
        $pages = [];
        foreach ($this->pages() as $p) {
            $pages[] = $p->simple_model();
        }

        return [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'idnumber' => $this->r->idnumber,
            'context_id' => $this->context()->id,
            'description' => $this->description(),
            'descriptionformat' => $this->r->descriptionformat,
            'icon' => $this->icon(),
            'aggregation' => $this->r->aggregation,
            'aggregation_config' => $this->aggregator->config_string(),
            'aggregation_info' => $this->aggregator->basic_model(),
            'pages' => $pages,
            // Next line is for development debugging only.
            //"progress" => (\rand(0,100) / 100),
        ];
    }

    /**
     * Webservice structure for editor info
     * @param int $value Webservice requirement constant
     */
    public static function editor_structure($value = VALUE_REQUIRED) : \external_description {
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname" => new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "idnumber" => new \external_value(PARAM_TEXT, 'idnumber of curriculum'),
            "description" => new \external_value(PARAM_RAW, 'description of studyplan'),
            "descriptionformat" => new \external_value(PARAM_INT, 'description format'),
            "icon" => new \external_value(PARAM_RAW,'icon for this plan'),
            "context_id" => new \external_value(PARAM_INT, 'context_id of studyplan'),
            "aggregation" => new \external_value(PARAM_TEXT, 'selected aggregator'),
            "aggregation_config" => new \external_value(PARAM_TEXT, 'config string for aggregator'),
            "aggregation_info" => aggregator::basic_structure(),
            "pages" => new \external_multiple_structure(studyplanpage::editor_structure()),
            "advanced" => new \external_single_structure([
                "force_scales" => new \external_single_structure([
                    "scales" => new \external_multiple_structure(new \external_single_structure([
                            "id" => new \external_value(PARAM_INT, 'id of scale'),
                            "name" => new \external_value(PARAM_TEXT, 'name of scale'),
                        ])),
                    ], "Scale forcing on stuff", VALUE_OPTIONAL),
                ], "Advanced features available", VALUE_OPTIONAL),
            ], 'Studyplan full structure', $value);
    }

    /**
     * Webservice model for editor info
     * @return array Webservice data model
     */
    public function editor_model() {
        global $DB;

        $model = [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'idnumber' => $this->r->idnumber,
            'description' => $this->description(),
            'descriptionformat' => $this->r->descriptionformat,
            'icon' => $this->icon(),
            'context_id' => $this->context()->id,
            "aggregation" => $this->r->aggregation,
            "aggregation_config" => $this->aggregator->config_string(),
            'aggregation_info' => $this->aggregator->basic_model(),
            'pages' => [],
        ];

        foreach ($this->pages() as $p) {
            $model['pages'][] = $p->editor_model();
        }

        if (has_capability('local/treestudyplan:forcescales', \context_system::instance())) {

            if (!array_key_exists('advanced', $model)) {
                // Create advanced node if it does not exist.
                $model['advanced'] = [];
            }

            // Get a list of available scales.
            $scales = array_map( function($scale) {
                return [ "id" => $scale->id, "name" => $scale->name, ];
            }, \grade_scale::fetch_all(['courseid' => 0]) );

            $model['advanced']['force_scales'] = [
                'scales' => $scales,
            ];
        }

        return $model;
    }

    /**
     * Add a new studyplan
     * @param array $fields Properties for study line ['name', 'shortname', 'description', 'idnumber', 'context_id', 'aggregation',
     *                      'aggregation_config', 'periods', 'startdate', 'enddate'];
     * @param bool $bare If true, do not create a first page with copy of studyplan names
     */
    public static function add($fields, $bare = false) : self {
        global $CFG, $DB;

        $addable = ['name', 'shortname', 'description', 'idnumber', 'context_id', 'aggregation', 'aggregation_config'];
        $info = ['enddate' => null ];
        foreach ($addable as $f) {
            if (array_key_exists($f, $fields)) {
                $info[$f] = $fields[$f];
            }
        }
        $id = $DB->insert_record(self::TABLE, $info);
        $plan = self::find_by_id($id); // Make sure the new studyplan is immediately cached.

        // Add a single page and initialize it with placeholder data 
        // This makes it easier to create a new study plan
        // On import, adding an empty page messes things up , so we have an option to skip this....
        if (!$bare) {

            $pageaddable = ['name', 'shortname', 'description', 'periods', 'startdate', 'enddate'];
            $pageinfo = ['studyplan_id' => $id];
            foreach ($pageaddable as $f) {
                if (array_key_exists($f, $fields)) {
                    if ($f == "name") {
                        $pageinfo["fullname"] = $fields[$f];
                    } else {
                        $pageinfo[$f] = $fields[$f];
                    }
                }
            }

            $page = studyplanpage::add($pageinfo);
            $plan->page_cache = [$page];
        }
        // End temporary skräpp code.

        return $plan;
    }

    /**
     * Edit study line properties
     * @param array $fields Changed roperties for study line ['name', 'shortname', 'description', 'idnumber',
     *                      'context_id', 'aggregation', 'aggregation_config']
     */
    public function edit($fields) : self {
        global $DB;
        $editable = ['name', 'shortname', 'description', 'descriptionformat', 'idnumber', 'context_id', 'aggregation', 'aggregation_config'];
        $info = ['id' => $this->id, ];
        foreach ($editable as $f) {
            if (array_key_exists($f, $fields)) {
                $info[$f] = $fields[$f];
            }
        }
        $DB->update_record(self::TABLE, $info);
        // Reload record after edit.
        $this->r = $DB->get_record(self::TABLE, ['id' => $this->id], "*", MUST_EXIST);

        // Reload the context...
        $this->context = null;
        $this->context();
        // Reload aggregator.
        $this->aggregator = aggregator::create_or_default($this->r->aggregation, $this->r->aggregation_config);

        return $this;
    }

    /**
     * Delete studyline
     * @param bool $force Force deletion even if study line contains items
     */
    public function delete($force = false) : success {
        global $DB;

        if ($force) {
            $children = studyplanpage::find_studyplan_children($this);
            foreach ($children as $c) {
                $c->delete($force);
            }
        }

        if ($DB->count_records('local_treestudyplan_page', ['studyplan_id' => $this->id]) > 0) {
            return success::fail('cannot delete studyplan that still has pages');
        } else {
            $DB->delete_records('local_treestudyplan', ['id' => $this->id]);
            return success::success();
        }
    }

    /**
     * Find all studyplans in a given context or the system context
     * @param int $contextid Optional contextid to search in. System context used if left empty
     * @return studyplan[]
     */
    public static function find_all($contextid = -1) : array {
        global $DB, $USER;
        $list = [];

        if ($contextid <= 0) {
            $ids = $DB->get_fieldset_select(self::TABLE, "id", "");
        } else {
            if ($contextid == 1) {
                $contextid = 1;
                $where = "context_id <= :contextid OR context_id IS NULL";
            } else {
                $where = "context_id = :contextid";
            }
            $ids = $DB->get_fieldset_select(self::TABLE, "id", $where, ["contextid" => $contextid]);
        }

        foreach ($ids as $id) {
            $list[] = self::find_by_id($id);
        }
        return $list;
    }

    /**
     * Find all studyplans in a given context or the system context with a specific short name
     * (Used in generating random grades for development)
     * @param string $shortname Shortname to match
     * @param int $contextid Optional contextid to search in. System context used if left empty
     * @return studyplan[]
     */
    public static function find_by_shortname($shortname, $contextid = 0): array {
        global $DB;
        $list = [];

        $where = "shortname = :shortname AND context_id = :contextid";
        if ($contextid == 0) {
            $where .= "OR context_id IS NULL";
        }
        $ids = $DB->get_fieldset_select(self::TABLE, "id", $where, ["shortname" => $shortname, "contextid" => $contextid]);
        foreach ($ids as $id) {
            $list[] = self::find_by_id($id);
        }
        return $list;
    }

    /**
     * Find all studyplans for a given user
     * @param int $userid Id of the user to search for
     * @return studyplan[]
     */
    public static function find_for_user($userid) : array {
        global $DB;

        $sql = "SELECT s.id FROM {local_treestudyplan} s
                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";
        $cohortplanids = $DB->get_fieldset_sql($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";
        $userplanids = $DB->get_fieldset_sql($sql, ['userid' => $userid]);

        $plans = [];
        foreach ($cohortplanids as $id) {
            $plans[$id] = self::find_by_id($id);
        }
        foreach ($userplanids as $id) {
            if (!array_key_exists($id, $plans)) {
                $plans[$id] = self::find_by_id($id);
            }
        }

        return $plans;

    }

    /**
     * Check if a given user has associated studyplans
     * @param int $userid Id of the user to search for
     */
    public static function exist_for_user($userid) : bool {
        global $DB;
        $count = 0;
        $sql = "SELECT s.* FROM {local_treestudyplan} s
                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";
        $count += $DB->count_records_sql($sql, ['userid' => $userid]);

        $sql = "SELECT s.* FROM {local_treestudyplan} s
                INNER JOIN {local_treestudyplan_user} j ON j.studyplan_id = s.id
                WHERE j.user_id = :userid";
        $count += $DB->count_records_sql($sql, ['userid' => $userid]);

        return ($count > 0);
    }

    /**
     * Retrieve the users linked to this studyplan.
     * @return stdClass[] User objects
     */
    public function find_linked_users() : array {
        global $DB;

        $users = [];

        $uids = $this->find_linked_userids();

        foreach ($uids as $uid) {
            $users[] = $DB->get_record("user", ["id" => $uid]);
        }

        return $users;
    }

    /**
     * Retrieve the user id's of the users linked to this studyplan.
     * @return array of int (User Id)
     */
    public function find_linked_userids(): array {
        global $DB;

        if ($this->linkeduserids === null) {
            $uids = [];
            // First get directly linked userids.
            $sql = "SELECT j.user_id FROM {local_treestudyplan_user} j
                    WHERE j.studyplan_id = :planid";
            $ulist = $DB->get_fieldset_sql($sql, ['planid' => $this->id]);

            $uids = array_merge($uids, $ulist);
            foreach ($ulist as $uid) {
                $users[] = $DB->get_record("user", ["id" => $uid]);
            }

            // Next het users linked though cohort.
            $sql = "SELECT cm.userid FROM {local_treestudyplan_cohort} j
                    INNER JOIN {cohort_members} cm ON j.cohort_id = cm.cohortid
                    WHERE j.studyplan_id = :planid";
            $ulist = $DB->get_fieldset_sql($sql, ['planid' => $this->id]);

            $uids = array_merge($uids, $ulist);

            $this->linkeduserids = array_unique($uids);
        }
        return $this->linkeduserids;
    }

    /** Check if this studyplan is linked to a particular user
     * @param bool|stdClass $user The userid or user record of the user
     */
    public function has_linked_user($user) {
        if (is_int($user)) {
            $userid = $user;
        } else {
            $userid = $user->id;
        }
        $uids = $this->find_linked_userids();
        if (in_array($userid, $uids)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Webservice structure for userinfo
     * @param int $value Webservice requirement constant
     */
    public static function user_structure($value = VALUE_REQUIRED) : \external_description {
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname" => new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "description" => new \external_value(PARAM_RAW, 'description of studyplan'),
            "descriptionformat" => new \external_value(PARAM_INT, 'description format'),
            "icon" => new \external_value(PARAM_RAW,'icon for this plan'),
            "progress" => new \external_value(PARAM_FLOAT,"fraction of completed modules"),
            "idnumber" => new \external_value(PARAM_TEXT, 'idnumber of curriculum'),
            "pages" => new \external_multiple_structure(studyplanpage::user_structure()),
            "aggregation_info" => aggregator::basic_structure(),
        ], 'Studyplan with user info', $value);

    }

    /**
     * Scan user progress (completed modules) over all pages for a specific user
     * @param int $userid ID of user to check for
     * @return float Fraction of completion
     */
    private function scanuserprogress($userid) {
        $progress = 0;
        $pages = $this->pages();
        foreach ($pages as $p) {
            $progress += $p->scanuserprogress($userid);
        }
        // Now average it out over the amount of pages
        $progress = $progress / count($pages);
    }

    /**
     * Webservice model for user info
     * @param int $userid ID of user to check specific info for
     * @return array Webservice data model
     */
    public function user_model($userid) {

        $model = [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->description(),
            'descriptionformat' => $this->r->descriptionformat,
            'icon' => $this->icon(),
            'idnumber' => $this->r->idnumber,
            'progress' => $this->scanuserprogress($userid),
            'pages' => [],
            'aggregation_info' => $this->aggregator->basic_model(),
        ];

        foreach ($this->pages() as $p) {
            $model['pages'][] = $p->user_model($userid);
        }
        return $model;
    }

    /**
     * Duplicate a studyplan by id
     * Function used by webservices and returns webservices model
     * @param int $planid Id if studyplan
     * @param string $name New fullname of studyplan
     * @param string $shortname New shortname of studyplan
     * @return array Simple webservices model of plan
     */
    public static function duplicate_plan($planid, $name, $shortname) : array {
        $ori = self::find_by_id($planid);
        $new = $ori->duplicate($name, $shortname);
        return $new->simple_model();
    }

    /**
     * Duplicate this studyplan
     * @param string $name New fullname of studyplan
     * @param string $shortname New shortname of studyplan
     */
    public function duplicate($name, $shortname) : self {
        // First duplicate the studyplan structure.
        $newplan = self::add([
            'name' => $name,
            'shortname' => $shortname,
            'description' => $this->r->description,
            'descriptionformat' => $this->r->descriptionformat,
            'aggregation' => $this->r->aggregation,
            'aggregation_config' => $this->r->aggregation_config
        ]);

        //TODO: Copy any files related to this userid....

        // Next, copy the studylines.

        foreach ($this->pages() as $p) {
            $newchild = $p->duplicate($newplan);
        }

        return $newplan;
    }

    /**
     * Description of export structure for webservices
     */
    public static function export_structure() : \external_description {
        return new \external_single_structure([
            "format" => new \external_value(PARAM_TEXT, 'format of studyplan export'),
            "content" => new \external_value(PARAM_TEXT, 'exported studyplan content'),
        ], 'Exported studyplan');
    }

    /**
     * Export this page into a json model
     * @return array
     */
    public function export_plan() {
        $model = $this->export_model();
        $json = json_encode([
            "type" => "studyplan",
            "version" => 2.0,
            "studyplan" => $model
            ], \JSON_PRETTY_PRINT);
        return [ "format" => "application/json", "content" => $json];
    }

    /**
     * Export essential information for export
     * @return array information model
     */
    public function export_model() {
        $model = [
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            "aggregation" => $this->r->aggregation,
            "aggregation_config" => json_decode($this->aggregator->config_string()),
            'aggregation_info' => $this->aggregator->basic_model(),
            'pages' => $this->export_pages_model(),
        ];
        return $model;
    }

    /**
     * Export all pages
     * @return array information model
     */
    public function export_pages_model() {
        $pages = [];
        foreach ($this->pages() as $p) {
            $pages[] = $p->export_model();
        }
        return $pages;
    }

    /**
     * Import studyplan from file contents
     * @param string $content String
     * @param string $format Format description
     * @param int $contextid The context to import into
     */
    public static function import_studyplan($content, $format = "application/json", $contextid = 1) {
        if ($format != "application/json") {
            return false;
        }

        $content = json_decode($content, true);
        if ($content["type"] == "studyplan" && $content["version"] >= 2.0) {

            // Make sure the aggregation_config is re-encoded as json text.
            $content["studyplan"]["aggregation_config"] = json_encode($content["studyplan"]["aggregation_config"]);

            // And make sure the context_id is set to the provided context for import.
            $content["studyplan"]["context_id"] = $contextid;

            // Create a new plan, based on the given parameters - this is the import studyplan part.
            $plan = self::add($content["studyplan"], true);
            // Now import each page.
            return $plan->import_pages_model($content["studyplan"]["pages"]);

        } else {
            debugging("Invalid format and type: {$content['type']} version {$content['version']}");
            return false;
        }
    }

    /**
     * Import studyplan pages from file contents
     * @param string $content String
     * @param string $format Format description
     */
    public function import_pages($content, $format = "application/json") {
        if ($format != "application/json") {
            return false;
        }
        $content = json_decode($content, true);
        if ($content["version"] >= 2.0) {
            if ($content["type"] == "studyplanpage") {
                // Import single page from a studyplanpage (wrapped in array of one page).
                return $this->import_pages_model([$content["page"]]);
            } else if ($content["type"] == "studyplan") {
                // Import all pages from the studyplan.
                return $this->import_pages_model($content["studyplan"]["pages"]);
            }
        } else {
            return false;
        }
    }


    /**
     * Import pages from decoded array model
     * @param array $model Decoded array
     */
    protected function import_pages_model($model) : bool {
        $this->pages(); // Make sure the page cache is initialized, since we will be adding to it.
        foreach ($model as $p) {
            $p["studyplan_id"] = $this->id();
            $page = studyplanpage::add($p);
            $this->page_cache[] = $page;
            $page->import_periods_model($p["perioddesc"]);
            $page->import_studylines_model($p["studylines"]);
        }
        return true;
    }

    /**
     * Mark the studyplan as changed regarding courses and associated cohorts
     */
    public function mark_csync_changed() {
        global $DB;
        $DB->update_record(self::TABLE, ['id' => $this->id, "csync_flag" => 1]);
        // Manually set it in the cache, if something unexpected happened, an exception has already been thrown anyway.
        $this->r->csync_flag = 1;
    }

    /**
     * Clear the studyplan as changed regarding courses and associated cohorts
     */
    public function clear_csync_changed() {
        global $DB;
        $DB->update_record(self::TABLE, ['id' => $this->id, "csync_flag" => 0]);
        // Manually set it in the cache, if something unexpected happened, an exception has already been thrown anyway.
        $this->r->csync_flag = 0;
    }

    /**
     * Check if  the studyplan as changed regarding courses and associated cohorts
     */
    public function has_csync_changed() : bool {
        return ($this->r->csync_flag > 0) ? true : false;
    }

    /**
     * See if the specified course id is linked in this studyplan
     * @param int $courseid Id of course to check
     */
    public function course_linked($courseid) : bool {
        global $DB;

        $sql = "SELECT COUNT(i.id)
                FROM {local_treestudyplan}
                INNER JOIN {local_treestudyplan_line} l ON p.id = l.studyplan_id
                INNER JOIN {local_treestudyplan_item} i ON l.id = i.line_id
                WHERE p.id = :planid
                   AND i.course_id = :courseid";
        $count = $DB->get_field_sql($sql, ["courseid" => $courseid, "planid" => $this->id]);

        return ($count > 0) ? true : false;
    }

    /**
     * List the course id is linked in this studyplan
     * Used for cohort enrolment cascading
     * @return int[]
     */
    public function get_linked_course_ids() : array {
        global $DB;

        $sql = "SELECT i.course_id
                FROM {local_treestudyplan} p
                INNER JOIN {local_treestudyplan_page} pg ON p.id = pg.studyplan_id
                INNER JOIN {local_treestudyplan_line} l ON pg.id = l.page_id
                INNER JOIN {local_treestudyplan_item} i ON l.id = i.line_id
                WHERE p.id = :studyplan_id AND i.type = :itemtype";
        $fields = $DB->get_fieldset_sql($sql, ["studyplan_id" => $this->id, "itemtype" => studyitem::COURSE]);

        return $fields;
    }

    /**
     * List the cohort id's associated with this studyplan
     */
    public function get_linked_cohort_ids() {
        global $CFG, $DB;

        $sql = "SELECT DISTINCT j.cohort_id FROM {local_treestudyplan_cohort} j
                WHERE j.studyplan_id = :studyplan_id";
        $fields = $DB->get_fieldset_sql($sql, ['studyplan_id' => $this->id]);
        return $fields;
    }

    /**
     * List the user id's explicitly associated with this studyplan
     * @return int[]
     */
    public function get_linked_user_ids() : array {
        global $CFG, $DB;

        $sql = "SELECT DISTINCT j.user_id FROM {local_treestudyplan_user} j
                WHERE j.studyplan_id = :studyplan_id";
        $fields = $DB->get_fieldset_sql($sql, ['studyplan_id' => $this->id]);
        return $fields;
    }
    /**
     * See if the specified badge is linked in this studyplan
     * @param int $badgeid Badge id
     */
    public function badge_linked($badgeid) : bool {
        global $DB;

        $sql = "SELECT COUNT(i.id)
                FROM {local_treestudyplan}
                INNER JOIN {local_treestudyplan_line} l ON p.id = l.studyplan_id
                INNER JOIN {local_treestudyplan_item} i ON l.id = i.line_id
                WHERE p.id = :planid
                   AND i.badge_id = :badgeid";
        $count = $DB->get_field_sql($sql, ["badgeid" => $badgeid, "planid" => $this->id]);

        return ($count > 0) ? true : false;
    }
}