<?php
namespace local_treestudyplan;

require_once($CFG->libdir.'/externallib.php');

class studyplan {


    const TABLE = "local_treestudyplan";
    private static $STUDYPLAN_CACHE = [];


    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;

    public function aggregator(){ 
        return $this->aggregator;
    }

    // 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);
        } 
        return self::$STUDYPLAN_CACHE[$id];
    }

    private function __construct($id) {
        global $DB;
        $this->id = $id;
        $this->r = $DB->get_record(self::TABLE,['id' => $id]);

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

    public function id(){
        return $this->id;
    }

    public function shortname(){
        return $this->r->shortname;
    }

    public function name(){
        return $this->r->name;
    }

    public function pages(){
        // cached version of find_studyplan_children.
        // (may be premature optimization, since 
        // find_studyplan_children also does some caching)
        if(empty($this->page_cache)){
            $this->page_cache = studyplanpage::find_studyplan_children($this);
        }
        return $this->page_cache;
    }

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

    public static function simple_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "context_id" => new \external_value(PARAM_INT, 'context_id of studyplan'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan'),
            "aggregation" => new \external_value(PARAM_TEXT, 'selected aggregator'),
            "aggregation_config" => new \external_value(PARAM_TEXT, 'config string for aggregator'),
            "aggregation_info" => aggregator::basic_structure(),
            "pages" => new \external_multiple_structure(studyplanpage::simple_structure(),'pages'),
        ],'Basic studyplan info',$value);
    }

    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,
            'context_id' => $this->context()->id,
            'description' => $this->r->description,
            'aggregation' => $this->r->aggregation,
            'aggregation_config' => $this->aggregator->config_string(),
            'aggregation_info' => $this->aggregator->basic_model(),
            'pages' => $pages,
        ];
    }

    public static function editor_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan'),
            "context_id" => new \external_value(PARAM_INT, 'context_id of studyplan'),
            "aggregation" => new \external_value(PARAM_TEXT, 'selected aggregator'),
            "aggregation_config" => new \external_value(PARAM_TEXT, 'config string for aggregator'),
            "aggregation_info" => aggregator::basic_structure(),
            "pages" => new \external_multiple_structure(studyplanpage::editor_structure()),
            "advanced" => new \external_single_structure([
                "force_scales" => new \external_single_structure([
                    "scales" => new \external_multiple_structure(new \external_single_structure([
                            "id" => new \external_value(PARAM_INT, 'id of scale'),
                            "name" => new \external_value(PARAM_TEXT, 'name of scale'),
                        ])),
                    ],"Scale forcing on stuff", VALUE_OPTIONAL), 
                ],"Advanced features available", VALUE_OPTIONAL),
            ],'Studyplan full structure',$value);
    }

    public function editor_model(){
        global $DB;

        $model = [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            '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(array('courseid'=>0)) ) ;

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


        return $model;
    }

    public static function add($fields,$bare=false){
        global $CFG, $DB;
 
        $addable = ['name','shortname','description','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);
        $plan = self::findById($id); // make sure the new studyplan is immediately cached


        // Start temporary skräpp code
        // Add a single page and copy the names.This keeps the data sane until the upgrade to 
        // real page management is done
        // On import, adding an empty page messes things up for now, so we have an option to skip this....
        // TODO: Remove this when proper page management is implemented
        if(!$bare){

            $pageaddable = ['name','shortname','description',];
            $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;
    }

    public function edit($fields){
        global $DB;
        $editable = ['name','shortname','description','context_id','periods','startdate','enddate','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
        $this->aggregator = aggregator::createOrDefault($this->r->aggregation, $this->r->aggregation_config); 

        // Start temporary skräpp code
        // TODO: Until proper page editing is implemented, copy data from studyplan to it's first page
        // This keeps the data sane until the upgrade is done.
        if(count($this->pages()) == 1){
            // update the info to the page as well
            $page = $this->pages()[0];
            $pageeditable = ['name','shortname','description'];
            $pageinfo = [];
            foreach($pageeditable as $f){
                if(array_key_exists($f,$fields)){
                    if($f == "name"){
                        $pageinfo["fullname"] = $fields[$f];
                    }else {
                        $pageinfo[$f] = $fields[$f];
                    }
                }
            }
            $page->edit($pageinfo);
        }
        // End temporary skräpp code

        return $this;
    }

    public function delete($force=false){
        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();
        }
    }

    public static function find_all($contextid=-1){
        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)
        {
            $list[] = studyplan::findById($id);
        }
        return $list;
    }

    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)
        {
            $list[] = studyplan::findById($id);
        }
        return $list;
    }

    public static function find_for_user($userid)
    {
        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";
        $cohort_plan_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]);

        $plans = [];
        foreach($cohort_plan_ids as $id) {
            $plans[$id] = self::findById($id);
        }
        foreach($user_plan_ids as $id) {
            if(!array_key_exists($id,$plans)){
                $plans[$id] = self::findById($id);
            }
        }

        return $plans;

    }

    static public function exist_for_user($userid)
    {
        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 array of User objects
     */
    public function find_linked_users(){
        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->linked_userids === 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);

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

    /** 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;
        }
    }

    public static function user_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan'),
            "pages" => new \external_multiple_structure(studyplanpage::user_structure()),
            "aggregation_info" => aggregator::basic_structure(),
        ],'Studyplan with user info',$value);

    }

    public function user_model($userid){

        $model = [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            'pages' => [],
            'aggregation_info' => $this->aggregator->basic_model(),
        ];

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

    public static function duplicate_plan($plan_id,$name,$shortname)
    {
        $ori = self::findById($plan_id);
        $new = $ori->duplicate($name,$shortname);
        return $new->simple_model();
    }

    public function duplicate($name,$shortname)
    {
        // First duplicate the studyplan structure
        $newplan =studyplan::add([
            'name' => $name,
            'shortname' => $shortname,
            'description' => $this->r->description,
        ]);
        
        // next, copy the studylines

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

        return $newplan;
    }   

    public static function export_structure()
    {
        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');
    }

    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];
    }

    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;
    }

    public function export_pages_model()
    {
        $pages = [];
        foreach($this->pages() as $p)
        {
            $pages[] = $p->export_model();
        }
        return $pages;
    }

    public static function import_studyplan($content,$format="application/json",$context_id=1)
    {
        if($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"] = $context_id;

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

    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;
        }
    }

    protected function import_pages_model($model)
    {
        $this->pages(); // make sure the page cache is initialized, since we will be adding to it.
        foreach($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]);
        $this->r->csync_flag = 1; //manually set it in the cache, if something unexpected happened, an exception has already been thrown anyway
    }

    /**
     * Clear the csync mark
     */
    public function clear_csync_changed(){
        global $DB;
        $DB->update_record(self::TABLE, ['id' => $this->id,"csync_flag" => 0]);
        $this->r->csync_flag = 0; //manually set it in the cache, if something unexpected happened, an exception has already been thrown anyway
    }

    public function has_csync_changed(){
        return ($this->r->csync_flag > 0)?true:false;
    }

    /**
     * See if the specified course id is linked in this studyplan
     */
    public function course_linked($courseid){
        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
     */
    public function get_linked_course_ids(){
        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
     */
    public function get_linked_user_ids(){
		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 $fields;
    }
    /**
     * See if the specified course id is linked in this studyplan
     */
    public function badge_linked($badgeid){
        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;
    }


}