<?php

namespace local_treestudyplan\privacy;
use core_privacy\local\metadata\collection;
use \core_privacy\local\request\userlist;
use core_privacy\local\request\contextlist;
use \core_privacy\local\request\approved_contextlist;
use \core_privacy\local\request\approved_userlist;
use \core_privacy\local\request\deletion_criteria;
use \core_privacy\local\request\writer;
use \core_privacy\local\request\helper;
use \core_privacy\local\request\transform;
use tool_dataprivacy\context_instance;

class provider implements   \core_privacy\local\metadata\provider, 
                            \core_privacy\local\request\plugin\provider,
                            \core_privacy\local\request\core_userlist_provider
{
   /**
     * Get the language string identifier with the component's language
     * file to explain why this plugin stores no data.
     *
     * @return  string
     */
    public static function get_reason(): string {
        return 'privacy:metadata';
    }

    public static function get_metadata(collection $collection): collection {

        $collection->add_database_table(
            'local_treestudyplan_invit',
             [
                'user_id' => 'privacy:metadata:invit:user_id',
                'name' => 'privacy:metadata:invit:name',
                'email' => 'privacy:metadata:invit:email',
                'date' => 'privacy:metadata:invit:date',
             ],
            'privacy:metadata:invit'
        );
        $collection->add_database_table(
            'local_treestudyplan_user',
             [
                'user_id' => 'privacy:metadata:user:user_id',
                'studyplan_id' => 'privacy:metadata:user:studyplan_id',
             ],
            'privacy:metadata:user'
        );
        return $collection;
    }

    /**
     * Get the list of contexts that contain user information for the specified user.
     *
     * @param   int         $userid     The user to search.
     * @return  contextlist   $contextlist  The contextlist containing the list of contexts used in this plugin.
     */
    public static function get_contexts_for_userid(int $userid) : contextlist {
        $contextlist = new \core_privacy\local\request\contextlist();
        $contextlist->add_system_context(); // For invitations

        // add contexts for linked studyplans
        $sql = "SELECT s.context_id FROM {local_treestudyplan} s
                    INNER JOIN {local_treestudyplan_user} a ON a.studyplan_id = s.id
                WHERE ( a.user_id = :userid )
        ";
        $contextlist->add_from_sql($sql, ['userid'  => $userid]);
    
        return $contextlist;
    }

    /**
     * Export all user data for the specified user, in the specified contexts.
     *
     * @param   approved_contextlist    $contextlist    The approved contexts to export information for.
     */
    public static function export_user_data(approved_contextlist $contextlist){
        global $DB;

        foreach ($contextlist->get_contexts() as $context) {
            $user = $contextlist->get_user();

            if($context instanceof \context_system){
                // Export invitations
                $sql = "SELECT * FROM {local_treestudyplan_invit} i
                        WHERE ( aiuser_id = :userid )
                ";
                $records = $DB->get_records_sql($sql,["userid" => $user->id]);
                foreach($records as $r) {
                    static::export_invitation_data_for_user($r);
                }
                
                // Export empty associations
                $sql = "SELECT * FROM {local_treestudyplan} s
                        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)
                ";
                $records = $DB->get_records_sql($sql,["userid" => $user->id, "contextid" => $context->id]);
                foreach($records as $r) {
                    static::export_studyplan_data_for_user($r);
                }  
            } else if ($context->contextlevel == CONTEXT_COURSECAT){
               // Export studyplan associations
                $sql = "SELECT * FROM {local_treestudyplan} s
                        INNER JOIN {local_treestudyplan_user} a ON a.studyplan_id = s.id
                    WHERE ( a.user_id = :userid AND s.context_id = :contextid)
                ";
                $records = $DB->get_records_sql($sql,["userid" => $user->id, "contextid" => $context->id]);
                foreach($records as $r) {
                    static::export_studyplan_data_for_user($r);
                }
            }
        }
    }

    /**
     * Export the supplied personal data for an invitation.
     *
     * @param $invit The invitation record.
     */
    protected static function export_invitation_data_for_user($invit) {
        $context = \context_system::instance();
        $subcontext = ["invitations"];

        writer::with_context($context)
            ->export_data($subcontext, (object)["recipient" => $invit->name, "email" => $invit->email]);

    }

    /**
     * Export the supplied personal data for an invitation.
     *
     * @param $invit The invitation record.
     */
    protected static function export_studyplan_data_for_user($studyplan) {
        $context = \context_system::instance();
        $subcontext = ["studyplans"];

        writer::with_context($context)
            ->export_data($subcontext, (object)["fullname" => $studyplan->fullname, "shortname" => $studyplan->shortname]);

    }


    /**
     * Delete all data for all users in the specified context.
     * Used when a context is past it's data retention period
     *
     * @param   context                 $context   The specific context to delete data for.
     */
    public static function delete_data_for_all_users_in_context(\context $context){
        global $DB;
        // find studyplans in context
        if($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]);
            
            foreach($plan_ids as $plan_id){
                $DB->delete_records("local_treestudyplan_user",["studyplan_id" => $plan_id]);
            }
        }
    }

    /**
     * Delete all user data for the specified user, in the specified contexts.
     *
     * @param   approved_contextlist    $contextlist    The approved contexts and user information to delete information for.
     */
    public static function delete_data_for_user(approved_contextlist $contextlist){
        global $DB;
        $user = $contextlist->get_user();

        foreach ($contextlist->get_contexts() as $context) {
            

            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]);
                
                foreach($plan_ids as $plan_id){
                    $DB->delete_records("local_treestudyplan_user",["studyplan_id" => $plan_id,"user_id" => $user->id]);
                }

                // Also delete all invitations for this user
                $DB->delete_records("local_treestudyplan_invit",["user_id" => $user->id]);

            } 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]);
                
                foreach($plan_ids as $plan_id){
                    $DB->delete_records("local_treestudyplan_user",["studyplan_id" => $plan_id,"user_id" => $user->id]);
                }
            }
        }        
    }

    /**
     * Get the list of users who have data within a context.
     *
     * @param   userlist    $userlist   The userlist containing the list of users who have data in this context/plugin combination.
     */
    public static function get_users_in_context(userlist $userlist){
        $context = $userlist->get_context();

        if ($context instanceof \context_system) {
            // Add all invitations
            $sql = "SELECT i.user_id as userid
            FROM {local_treestudyplan_invit} i;";
            $userlist->add_from_sql('userid', $sql, []);

            // also add "contextless studyplans, they are considered in system context"
            $sql = "SELECT a.user_id as userid FROM {local_treestudyplan_user} a
                    INNER JOIN {local_treestudyplan} s ON a.studyplan_id = s.id
                WHERE ( a.context_id is NULL or a.context_id = 0)
            ";
            $userlist->add_from_sql('userid', $sql, []);

        }

        // add the links to all study plans in this context
        $sql = "SELECT a.user_id as userid FROM {local_treestudyplan_user} a
                    INNER JOIN {local_treestudyplan} s ON a.studyplan_id = s.id
                WHERE ( a.context_id = :contextid )
        ";
        $userlist->add_from_sql('userid', $sql, ["contextid" => $context->id]);

    }

    /**
     * Delete multiple users within a single context.
     *
     * @param   approved_userlist       $userlist The approved context and user information to delete information for.
     */
    public static function delete_data_for_users(approved_userlist $userlist){
        global $DB;

        $context = $userlist->get_context();
        $users = $userlist->get_userids();
        list($userinsql, $userinparams) = $DB->get_in_or_equal($users, SQL_PARAMS_NAMED,'user');

        $plan_ids = [];
        if($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,]);
            // If plan ids not empty, they will be processed later
            
            // Also delete all invitations for these users
            $sql = "user_id {$userinsql}";
            $DB->delete_records_select("local_treestudyplan_invit",$sql,$userinparams);

        } 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,]);
            // 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){

            list($planinsql,$planinputparams) = $DB->get_in_or_equal($plan_ids, SQL_PARAMS_NAMED,'plan');
            $params = $userinparams+$planinputparams;
            $sql = "user_id {$userinsql} and studyplan_id {$planinsql}";
            $DB->delete_records_select('local_treestudyplan_user', $sql, $params);
        }
    }

}