<?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/>.

/**
 * Airnotifier manager class
 *
 * @package    message_airnotifier
 * @category   external
 * @copyright  2012 Jerome Mouneyrac <jerome@moodle.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since Moodle 2.7
 */

defined('MOODLE_INTERNAL') || die;

/**
 * Airnotifier helper manager class
 *
 * @copyright  2012 Jerome Mouneyrac <jerome@moodle.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class message_airnotifier_manager {

    /**
     * Include the relevant javascript and language strings for the device
     * toolbox YUI module
     *
     * @return bool
     */
    public function include_device_ajax() {
        global $PAGE, $CFG;

        $config = new stdClass();
        $config->resturl = '/message/output/airnotifier/rest.php';
        $config->pageparams = array();

        // Include toolboxes.
        $PAGE->requires->yui_module('moodle-message_airnotifier-toolboxes', 'M.message.init_device_toolbox', array(array(
                'ajaxurl' => $config->resturl,
                'config' => $config,
                ))
        );

        // Required strings for the javascript.
        $PAGE->requires->strings_for_js(array('deletecheckdevicename'), 'message_airnotifier');
        $PAGE->requires->strings_for_js(array('show', 'hide'), 'moodle');

        return true;
    }

    /**
     * Return the user devices for a specific app.
     *
     * @param string $appname the app name .
     * @param int $userid if empty take the current user.
     * @return array all the devices
     */
    public function get_user_devices($appname, $userid = null) {
        global $USER, $DB;

        if (empty($userid)) {
            $userid = $USER->id;
        }

        $devices = array();

        $params = array('appid' => $appname, 'userid' => $userid);

        // First, we look all the devices registered for this user in the Moodle core.
        // We are going to allow only ios devices (since these are the ones that supports PUSH notifications).
        $userdevices = $DB->get_records('user_devices', $params);
        foreach ($userdevices as $device) {
            if (core_text::strtolower($device->platform)) {
                // Check if the device is known by airnotifier.
                if (!$airnotifierdev = $DB->get_record('message_airnotifier_devices',
                        array('userdeviceid' => $device->id))) {

                    // We have to create the device token in airnotifier.
                    if (! $this->create_token($device->pushid)) {
                        continue;
                    }

                    $airnotifierdev = new stdClass;
                    $airnotifierdev->userdeviceid = $device->id;
                    $airnotifierdev->enable = 1;
                    $airnotifierdev->id = $DB->insert_record('message_airnotifier_devices', $airnotifierdev);
                }
                $device->id = $airnotifierdev->id;
                $device->enable = $airnotifierdev->enable;
                $devices[] = $device;
            }
        }

        return $devices;
    }

    /**
     * Request and access key to Airnotifier
     *
     * @return mixed The access key or false in case of error
     */
    public function request_accesskey() {
        global $CFG, $USER;

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

        // Sending the request access key request to Airnotifier.
        $serverurl = $CFG->airnotifierurl . ':' . $CFG->airnotifierport . '/accesskeys/';
        // We use an APP Key "none", it can be anything.
        $header = array('Accept: application/json', 'X-AN-APP-NAME: ' . $CFG->airnotifierappname,
            'X-AN-APP-KEY: none');
        $curl = new curl();
        $curl->setHeader($header);

        // Site ids are stored as secrets in md5 in the Moodle public hub.
        $params = array(
            'url' => $CFG->wwwroot,
            'siteid' => md5($CFG->siteidentifier),
            'contact' => $USER->email,
            'description' => $CFG->wwwroot
            );
        $resp = $curl->post($serverurl, $params);

        if ($key = json_decode($resp, true)) {
            if (!empty($key['accesskey'])) {
                return $key['accesskey'];
            }
        }
        debugging("Unexpected response from the Airnotifier server: $resp");
        return false;
    }

    /**
     * Create a device token in the Airnotifier instance
     * @param string $token The token to be created
     * @return bool True if all was right
     */
    private function create_token($token) {
        global $CFG;

        if (!$this->is_system_configured()) {
            return false;
        }

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

        $serverurl = $CFG->airnotifierurl . ':' . $CFG->airnotifierport . '/tokens/' . $token;
        $header = array('Accept: application/json', 'X-AN-APP-NAME: ' . $CFG->airnotifierappname,
            'X-AN-APP-KEY: ' . $CFG->airnotifieraccesskey);
        $curl = new curl;
        $curl->setHeader($header);
        $params = array();
        $resp = $curl->post($serverurl, $params);

        if ($token = json_decode($resp, true)) {
            if (!empty($token['status'])) {
                return $token['status'] == 'ok' || $token['status'] == 'token exists';
            }
        }
        debugging("Unexpected response from the Airnotifier server: $resp");
        return false;
    }

    /**
     * Tests whether the airnotifier settings have been configured
     * @return boolean true if airnotifier is configured
     */
    public function is_system_configured() {
        global $CFG;

        return (!empty($CFG->airnotifierurl) && !empty($CFG->airnotifierport) &&
                !empty($CFG->airnotifieraccesskey)  && !empty($CFG->airnotifierappname) &&
                !empty($CFG->airnotifiermobileappname));
    }

    /**
     * Enables or disables a registered user device so it can receive Push notifications
     *
     * @param  int $deviceid the device id
     * @param  bool $enable  true to enable it, false to disable it
     * @return bool true if the device was enabled, false in case of error
     * @since  Moodle 3.2
     */
    public static function enable_device($deviceid, $enable) {
        global $DB, $USER;

        if (!$device = $DB->get_record('message_airnotifier_devices', array('id' => $deviceid), '*')) {
            return false;
        }

        // Check that the device belongs to the current user.
        if (!$userdevice = $DB->get_record('user_devices', array('id' => $device->userdeviceid, 'userid' => $USER->id), '*')) {
            return false;
        }

        $device->enable = $enable;
        return $DB->update_record('message_airnotifier_devices', $device);
    }

}
