<?php
namespace local_treestudyplan;

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

class studyplanpage {


    const TABLE = "local_treestudyplan_page";
    private static $CACHE = [];


    private $r; // Holds database record
    private $id;
    private $studyplan;

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

    // Cache constructors to avoid multiple creation events in one session.
    public static function findById($id): self {
        if(!array_key_exists($id,self::$CACHE)){
            self::$CACHE[$id] = new self($id);
        } 
        return self::$CACHE[$id];
    }

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

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

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

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

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

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

    public function startdate(){
        return new \DateTime($this->r->startdate);
    }

    public function enddate(){
        if($this->r->enddate && strlen($this->r->enddate) > 0){
            return new \DateTime($this->r->enddate);
        }
        else{
            // return a date 100 years into the future
            return (new \DateTime($this->r->startdate))->add(new \DateInterval("P100Y"));
        }

    }

    public static function simple_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan page'),
            "fullname" => new \external_value(PARAM_TEXT, 'name of studyplan page'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan page'),
            "periods" => new \external_value(PARAM_INT, 'number of periods in studyplan page'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan page'),
            "startdate" => new \external_value(PARAM_TEXT, 'start date of studyplan'),
            "enddate" => new \external_value(PARAM_TEXT, 'end date of studyplan'),
        ],'Studyplan page basic info',$value);
    }

    public function simple_model(){
        return [
            'id' => $this->r->id,
            'fullname' => $this->r->fullname,
            'shortname' => $this->r->shortname,
            'periods' => $this->r->periods,
            'description' => $this->r->description,
            'startdate' => $this->r->startdate,
            'enddate' => $this->r->enddate,
        ];
    }

    public static function editor_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan'),
            "name" => new \external_value(PARAM_TEXT, 'name of studyplan page'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan page'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan page'),
            "periods" => new \external_value(PARAM_INT, 'number of periods in studyplan page'),
            "startdate" => new \external_value(PARAM_TEXT, 'start date of studyplan page'),
            "enddate" => new \external_value(PARAM_TEXT, 'end date of studyplan page'),
            "studylines" => new \external_multiple_structure(studyline::editor_structure()),
            ],'Studyplan page full structure',$value);
    }

    public function editor_model(){
        global $DB;

        $model = [
            'id' => $this->r->id,
            'name' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            'periods' => $this->r->periods,
            'startdate' => $this->r->startdate,
            'enddate' => $this->r->enddate,
            'studylines' => [],
        ];

        $children = studyline::find_page_children($this);
        foreach($children as $c)
        {
            $model['studylines'][] = $c->editor_model();
        }
        return $model;
    }

    public static function add($fields){
        global $CFG, $DB;
 
        if(!isset($fields['studyplan_id'])){
            throw new \InvalidArgumentException("parameter 'studyplan_id' missing");
        }

        $addable = ['studyplan_id','fullname','shortname','description','periods','startdate','enddate'];
        $info = ['enddate' => null ];
        foreach($addable as $f){
            if(array_key_exists($f,$fields)){
                $info[$f] = $fields[$f];
            }
        }
        $id = $DB->insert_record(self::TABLE, $info);
        return self::findById($id); // make sure the new page is immediately cached
    }

    public function edit($fields){
        global $DB;
        $editable = ['fullname','shortname','description','periods','startdate','enddate'];
        $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);
        
        return $this;
    }

    public function delete($force=false){
        global $DB;

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

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

    public static function user_structure($value=VALUE_REQUIRED){
        return new \external_single_structure([
            "id" => new \external_value(PARAM_INT, 'id of studyplan page'),
            "fullname" => new \external_value(PARAM_TEXT, 'name of studyplan page'),
            "shortname"=> new \external_value(PARAM_TEXT, 'shortname of studyplan page'),
            "description"=> new \external_value(PARAM_TEXT, 'description of studyplan page'),
            "periods" => new \external_value(PARAM_INT, 'number of slots in studyplan page'),
            "startdate" => new \external_value(PARAM_TEXT, 'start date of studyplan page'),
            "enddate" => new \external_value(PARAM_TEXT, 'end date of studyplan page'),
            "studylines" => new \external_multiple_structure(studyline::user_structure()),
        ],'Studyplan page with user info',$value);
    }

    public function user_model($userid){

        $model = [
            'id' => $this->r->id,
            'fullname' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            'periods' => $this->r->periods,
            'startdate' => $this->r->startdate,
            'enddate' => $this->r->enddate,
            'studylines' => [],
        ];

        $children = studyline::find_page_children($this);
        foreach($children as $c)
        {
            $model['studylines'][] = $c->user_model($userid);
        }
        return $model;
    }

    public static function find_studyplan_children(studyplan $plan)
    {
        global $DB;
        $list = [];
        $ids = $DB->get_fieldset_select(self::TABLE,"id","studyplan_id = :plan_id ORDER BY startdate",
                                        ['plan_id' => $plan->id()]);
        foreach($ids as $id) {
            $list[] = self::findById($id);
        }
        return $list;
    }

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

    public function duplicate($name,$shortname)
    {
        // First duplicate the studyplan structure
        $new = studyplanpage::add([
            'fullname' => $name,
            'shortname' => $shortname,
            'description' => $this->r->description,
            'pages' => $this->r->pages,
            'startdate' => $this->r->startdate,
            'enddate' => empty($this->r->enddate)?null:$this->r->enddate,
        ]);
        
        // next, copy the studylines

        $children = studyline::find_page_children($this);
        $itemtranslation = [];
        $linetranslation = [];
        foreach($children as $c){
            $newchild = $c->duplicate($this,$itemtranslation);
            $linetranslation[$c->id()] = $newchild->id();
        }

        // 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){
            // copy based on the outgoing connections of each item, to avoid duplicates
            $connections  = studyitemconnection::find_outgoing($item_id);
            foreach($connections as $conn){
                studyitemconnection::connect($itemtranslation[$conn->from_id],$itemtranslation[$conn->to_id]);
            }
        }
        return $new;
    }   

    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_page()
    {
        $model = $this->export_model();
        $json = json_encode([
            "type"=>"studyplanpage",
            "version"=>2.0,
            "page"=>$model
            ],\JSON_PRETTY_PRINT);
        return [ "format" => "application/json", "content" => $json];
    }

    public function export_page_csv()
    {
        //TODO: Period shortnames instead of just P1, P2, P3 etc

        $model = $this->editor_model();
        
        $slots = intval($model["slots"]);
        // First line
        $csv = "\"Studyline[{$slots}]\"";
        for($i = 1; $i <= $slots; $i++){
            $csv .= ",\"P{$i}\"";
        }
        $csv .= "\r\n";
        // next, make one line per studyline
        foreach($model["studylines"] as $line){
            // determine how many fields are simultaneous in the line at maximum
            $maxlines = 1;
            for($i = 1; $i <= $slots; $i++){
                if(count($line["slots"]) > $i){
                    $ct = 0;
                    foreach($line["slots"][$i][studyline::SLOTSET_COMPETENCY] as $itm){
                        if($itm["type"] == "course"){
                            $ct += 1;
                        }
                    }
                    if($ct > $maxlines){
                        $maxlines = $ct;
                    }

                }
            }

            for($lct = 0; $lct < $maxlines; $lct++){
                $csv .= "\"{$line["name"]}\"";
                for($i = 1; $i <= $slots; $i++){
                    $filled = false;
                    if(count($line["slots"]) > $i){
                        $ct = 0;
                        foreach($line["slots"][$i][studyline::SLOTSET_COMPETENCY] as $itm){
                            if($itm["type"] == "course"){
                                if($ct == $lct){
                                    $csv .= ",\"";
                                    $csv .= $itm["course"]["fullname"];
                                    $csv .= "\r\n";
                                    $first = true;
                                    foreach($itm["course"]["grades"] as $g){
                                        if($g["selected"]){
                                            if($first){
                                                $first = false;
                                            }
                                            else{ 
                                                $csv .= "\r\n";
                                            }
                                            $csv .= "- ".str_replace('"', '\'', $g["name"]);
                                        }
                                    }
                                    $csv .= "\"";
                                    $filled = true;
                                    break;
                                }
                                $ct++;
                            }
                        }
                    } 
                    if(!$filled) {
                        $csv .= ",\"\"";
                    }
                }
                $csv .= "\r\n";
            }
        }

        return [ "format" => "text/csv", "content" => $csv];
    }

    public function export_studylines(){
        $model = $this->export_studylines_model();
        $json = json_encode([
            "type"=>"studylines",
            "version"=>1.0,
            "studylines"=>$model,
            ],\JSON_PRETTY_PRINT);
        return [ "format" => "application/json", "content" => $json];
    }

    public function export_model()
    {
        $model = [
            'fullname' => $this->r->name,
            'shortname' => $this->r->shortname,
            'description' => $this->r->description,
            'periods' => $this->r->periods,
            'startdate' => $this->r->startdate,
            'enddate' => $this->r->enddate,
            'studylines' => $this->export_studylines_model(),
        ];
        return $model;
    }

    public function export_studylines_model()
    {
        $children = studyline::find_page_children($this);
        $lines = [];
        foreach($children as $c)
        {
            $lines[] = $c->export_model();
        }
        return $lines;
    }

    public function import_studylines($content,$format="application/json")
    {
        if($format != "application/json") { return false;}
        $content = json_decode($content,true);
        if($content["type"] == "studylines" && $content["version"] >= 2.0){
            return $this->import_studylines_model($content["studylines"]);
        }
        else if($content["type"] == "studyplanpage" && $content["version"] >= 2.0){
            return $this->import_studylines_model($content["page"]["studylines"]);
        }
        else {
            return false;
        }
    }

    protected function find_studyline_by_shortname($shortname){
        $children = studyline::find_page_children($this);
        foreach($children as $l){
            if($shortname == $l->shortname()){
                return $l;
            }
        }
        return null;
    }

    public function import_studylines_model($model)
    {
        // First attempt to map each studyline model to an existing or new line
        $line_map = [];
        foreach($model as $ix => $linemodel){
            $line = $this->find_studyline_by_shortname($linemodel["shortname"]);
            if(empty($line)){
                $linemodel["studyplan_id"] = $this->id;
                $line = studyline::add($linemodel);
            } else {
                //$line->edit($linemodel); // Update the line with the settings from the imported file
            }
            $line_map[$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);
        }

        // Finally, create the links between the study items
        foreach($connections as $from => $dests){
            foreach($dests as $to){
                studyitemconnection::connect($from,$itemtranslation[$to]);
            }
        }
        return true;
    }

}