<?php

require_once realpath(__DIR__ . '/../../libcalendaring/lib/libcalendaring_itip.php');

/**
 * iTIP functions for the Calendar plugin
 *
 * Class providing functionality to manage iTIP invitations
 *
 * @version @package_version@
 * @author Thomas Bruederli <bruederli@kolabsys.com>
 * @package @package_name@
 *
 * Copyright (C) 2011, Kolab Systems AG <contact@kolabsys.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
class calendar_itip extends libcalendaring_itip
{
    /**
     * Constructor to set text domain to calendar
     */
    function __construct($plugin, $domain = 'calendar')
    {
        parent::__construct($plugin, $domain);

        $this->db_itipinvitations = $this->rc->db->table_name('itipinvitations', true);
    }

    /**
     * Handler for calendar/itip-status requests
     */
    public function get_itip_status($event, $existing = null)
    {
        $status = parent::get_itip_status($event, $existing);

        // don't ask for deleting events when declining
        if ($this->rc->config->get('kolab_invitation_calendars')) {
            $status['saved'] = false;
        }

        return $status;
    }

    /**
     * Find invitation record by token
     *
     * @param string $token Invitation token
     *
     * @return mixed Invitation record as hash array or False if not found
     */
    public function get_invitation($token)
    {
        if ($parts = $this->decode_token($token)) {
            $result = $this->rc->db->query("SELECT * FROM $this->db_itipinvitations WHERE `token` = ?", $parts['base']);
            if ($result && ($rec = $this->rc->db->fetch_assoc($result))) {
                $rec['event']    = unserialize($rec['event']);
                $rec['attendee'] = $parts['attendee'];

                return $rec;
            }
        }

        return false;
    }

    /**
     * Update the attendee status of the given invitation record
     *
     * @param array  $invitation Invitation record as fetched with calendar_itip::get_invitation()
     * @param string $email      Attendee email address
     * @param string $newstatus  New attendee status
     */
    public function update_invitation($invitation, $email, $newstatus)
    {
        if (is_string($invitation)) {
            $invitation = $this->get_invitation($invitation);
        }

        if (!empty($invitation['token']) && !empty($invitation['event'])) {
            // update attendee record in event data
            foreach ($invitation['event']['attendees'] as $i => $attendee) {
                if ($attendee['role'] == 'ORGANIZER') {
                    $organizer = $attendee;
                }
                else if ($attendee['email'] == $email) {
                    // nothing to be done here
                    if ($attendee['status'] == $newstatus) {
                        return true;
                    }

                    $invitation['event']['attendees'][$i]['status'] = $newstatus;
                    $this->sender = $attendee;
                }
            }

            $invitation['event']['changed'] = new DateTime();

            // send iTIP REPLY message to organizer
            if (!empty($organizer)) {
                $status = strtolower($newstatus);
                if ($this->send_itip_message($invitation['event'], 'REPLY', $organizer, 'itipsubject' . $status, 'itipmailbody' . $status)) {
                    $mailto = !empty($organizer['name']) ? $organizer['name'] : $organizer['email'];
                    $message = $this->plugin->gettext([
                            'name' => 'sentresponseto',
                            'vars' => ['mailto' => $mailto]
                    ]);
                    $this->rc->output->command('display_message', $message, 'confirmation');
                }
                else {
                    $this->rc->output->command('display_message', $this->plugin->gettext('itipresponseerror'), 'error');
                }
            }

            // update record in DB
            $query = $this->rc->db->query(
                "UPDATE $this->db_itipinvitations SET `event` = ? WHERE `token` = ?",
                self::serialize_event($invitation['event']),
                $invitation['token']
            );

            if ($this->rc->db->affected_rows($query)) {
                return true;
            }
        }

        return false;
    }

    /**
     * Create iTIP invitation token for later replies via URL
     *
     * @param array  $event    Hash array with event properties
     * @param string $attendee Attendee email address
     *
     * @return string Invitation token
     */
    public function store_invitation($event, $attendee)
    {
        static $stored = [];

        if (empty($event['uid']) || !$attendee) {
            return false;
        }

        // generate token for this invitation
        $token = $this->generate_token($event, $attendee);
        $base = substr($token, 0, 40);

        // already stored this
        if (!empty($stored[$base])) {
            return $token;
        }

        // delete old entry
        $this->rc->db->query("DELETE FROM $this->db_itipinvitations WHERE `token` = ?", $base);

        $event_uid = $event['uid'] . (!empty($event['_instance']) ? '-' . $event['_instance'] : '');

        $query = $this->rc->db->query(
            "INSERT INTO $this->db_itipinvitations"
            . " (`token`, `event_uid`, `user_id`, `event`, `expires`)"
            . " VALUES(?, ?, ?, ?, ?)",
            $base,
            $event_uid,
            $this->rc->user->ID,
            self::serialize_event($event),
            date('Y-m-d H:i:s', $event['end']->format('U') + 86400 * 2)
        );

        if ($this->rc->db->affected_rows($query)) {
            $stored[$base] = 1;
            return $token;
        }

        return false;
    }

    /**
     * Mark invitations for the given event as cancelled
     *
     * @param array $event Hash array with event properties
     */
    public function cancel_itip_invitation($event)
    {
        $event_uid = $event['uid'] . (!empty($event['_instance']) ? '-' . $event['_instance'] : '');

        // flag invitation record as cancelled
        $this->rc->db->query(
            "UPDATE $this->db_itipinvitations SET `cancelled` = 1"
            . " WHERE `event_uid` = ? AND `user_id` = ?",
           $event_uid,
           $this->rc->user->ID
        );
    }

    /**
     * Generate an invitation request token for the given event and attendee
     *
     * @param array  $event    Event hash array
     * @param string $attendee Attendee email address
     */
    public function generate_token($event, $attendee)
    {
        $event_uid = $event['uid'] . (!empty($event['_instance']) ? '-' . $event['_instance'] : '');
        $base = sha1($event_uid . ';' . $this->rc->user->ID);
        $mail = base64_encode($attendee);
        $hash = substr(md5($base . $mail . $this->rc->config->get('des_key')), 0, 6);

        return "$base.$mail.$hash";
    }

    /**
     * Decode the given iTIP request token and return its parts
     *
     * @param string $token Request token to decode
     *
     * @return mixed Hash array with parts or False if invalid
     */
    public function decode_token($token)
    {
        list($base, $mail, $hash) = explode('.', $token);

        // validate and return parts
        if ($mail && $hash && $hash == substr(md5($base . $mail . $this->rc->config->get('des_key')), 0, 6)) {
            return ['base' => $base, 'attendee' => base64_decode($mail)];
        }

        return false;
    }

    /**
     * Helper method to serialize the given event for storing in invitations table
     */
    private static function serialize_event($event)
    {
        $ev = $event;

        if (!empty($ev['description'])) {
            $ev['description'] = abbreviate_string($ev['description'], 100);
        }

        unset($ev['attachments']);

        return serialize($ev);
    }
}