<?php
// This file is part of Moodle - http://moodle.org/
//
// 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 <http://www.gnu.org/licenses/>.

/**
 * Privacy Subsystem implementation for block_html.
 *
 * @package    block_html
 * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace block_html\privacy;

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

use \core_privacy\local\request\userlist;
use \core_privacy\local\request\approved_contextlist;
use \core_privacy\local\request\approved_userlist;
use \core_privacy\local\request\writer;
use \core_privacy\local\request\helper;
use \core_privacy\local\request\deletion_criteria;
use \core_privacy\local\metadata\collection;

/**
 * Privacy Subsystem implementation for block_html.
 *
 * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class provider implements
        // The block_html block stores user provided data.
        \core_privacy\local\metadata\provider,

        // This plugin is capable of determining which users have data within it.
        \core_privacy\local\request\core_userlist_provider,

        // The block_html block provides data directly to core.
        \core_privacy\local\request\plugin\provider {

    /**
     * Returns information about how block_html stores its data.
     *
     * @param   collection     $collection The initialised collection to add items to.
     * @return  collection     A listing of user data stored through this system.
     */
    public static function get_metadata(collection $collection) : collection {
        $collection->link_subsystem('block', 'privacy:metadata:block');

        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) : \core_privacy\local\request\contextlist {
        // This block doesn't know who information is stored against unless it
        // is at the user context.
        $contextlist = new \core_privacy\local\request\contextlist();

        $sql = "SELECT c.id
                  FROM {block_instances} b
            INNER JOIN {context} c ON c.instanceid = b.id AND c.contextlevel = :contextblock
            INNER JOIN {context} bpc ON bpc.id = b.parentcontextid
                 WHERE b.blockname = 'html'
                   AND bpc.contextlevel = :contextuser
                   AND bpc.instanceid = :userid";

        $params = [
            'contextblock' => CONTEXT_BLOCK,
            'contextuser' => CONTEXT_USER,
            'userid' => $userid,
        ];

        $contextlist->add_from_sql($sql, $params);

        return $contextlist;
    }

    /**
     * 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 (!is_a($context, \context_block::class)) {
            return;
        }

        $params = [
            'contextid'    => $context->id,
            'contextuser' => CONTEXT_USER,
        ];

        $sql = "SELECT bpc.instanceid AS userid
                  FROM {context} c
                  JOIN {block_instances} bi ON bi.id = c.instanceid AND bi.blockname = 'html'
                  JOIN {context} bpc ON bpc.id = bi.parentcontextid AND bpc.contextlevel = :contextuser
                 WHERE c.id = :contextid";

        $userlist->add_from_sql('userid', $sql, $params);
    }

    /**
     * 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;

        $user = $contextlist->get_user();

        list($contextsql, $contextparams) = $DB->get_in_or_equal($contextlist->get_contextids(), SQL_PARAMS_NAMED);

        $sql = "SELECT
                    c.id AS contextid,
                    bi.*
                  FROM {context} c
            INNER JOIN {block_instances} bi ON bi.id = c.instanceid AND c.contextlevel = :contextlevel
                 WHERE bi.blockname = 'html'
                   AND(
                    c.id {$contextsql}
                )
        ";

        $params = [
            'contextlevel' => CONTEXT_BLOCK,
        ];
        $params += $contextparams;

        $instances = $DB->get_recordset_sql($sql, $params);
        foreach ($instances as $instance) {
            $context = \context_block::instance($instance->id);
            $block = block_instance('html', $instance);
            if (empty($block->config)) {
                // Skip this block. It has not been configured.
                continue;
            }

            $html = writer::with_context($context)
                ->rewrite_pluginfile_urls([], 'block_html', 'content', null, $block->config->text);

            // Default to FORMAT_HTML which is what will have been used before the
            // editor was properly implemented for the block.
            $format = isset($block->config->format) ? $block->config->format : FORMAT_HTML;

            $filteropt = (object) [
                'overflowdiv' => true,
                'noclean' => true,
            ];
            $html = format_text($html, $format, $filteropt);

            $data = helper::get_context_data($context, $user);
            helper::export_context_files($context, $user);
            $data->title = $block->config->title;
            $data->content = $html;

            writer::with_context($context)->export_data([], $data);
        }
        $instances->close();
    }

    /**
     * Delete all data for all users in the specified context.
     *
     * @param   context                 $context   The specific context to delete data for.
     */
    public static function delete_data_for_all_users_in_context(\context $context) {

        if (!$context instanceof \context_block) {
            return;
        }

        // The only way to delete data for the html block is to delete the block instance itself.
        if ($blockinstance = static::get_instance_from_context($context)) {
            blocks_delete_instance($blockinstance);
        }
    }

    /**
     * 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) {
        $context = $userlist->get_context();

        if ($context instanceof \context_block && ($blockinstance = static::get_instance_from_context($context))) {
            blocks_delete_instance($blockinstance);
        }
    }

    /**
     * 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 $contextlist) {
        // The only way to delete data for the html block is to delete the block instance itself.
        foreach ($contextlist as $context) {

            if (!$context instanceof \context_block) {
                continue;
            }
            if ($blockinstance = static::get_instance_from_context($context)) {
                blocks_delete_instance($blockinstance);
            }
        }
    }

    /**
     * Get the block instance record for the specified context.
     *
     * @param   \context_block $context The context to fetch
     * @return  \stdClass
     */
    protected static function get_instance_from_context(\context_block $context) {
        global $DB;

        return $DB->get_record('block_instances', ['id' => $context->instanceid, 'blockname' => 'html']);
    }
}
