<?php

/*
 *  Copyright (c) 2013  Rasmus Fuhse <fuhse@data-quest.de>
 *
 *  This program 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 2 of
 *  the License, or (at your option) any later version.
 */

/**
 * Class to handle entries in the mail-queue in Stud.IP.
 * Use MailQueueEntry::add($mail, $message_id, $user_id) to add a mail to the queue
 * and MailQueueEntry::sendAll() or MailQueueEntry::sendNew() to flush the queue
 * and send the mails.
 *
 * @property string $id alias column for mail_queue_id
 * @property string $mail_queue_id database column
 * @property JSONArrayObject $mail database column
 * @property string|null $message_id database column
 * @property string|null $user_id database column
 * @property int $tries database column
 * @property int $last_try database column
 * @property int $mkdate database column
 * @property int $chdate database column
 */
class MailQueueEntry extends SimpleORMap
{
    protected static function configure($config = [])
    {
        $config['db_table'] = 'mail_queue_entries';

        $config['serialized_fields']['mail'] = JSONArrayObject::class;

        parent::configure($config);
    }

    /**
     * Add an email to the queue.
     * @param StudipMail $mail : the mailobject that should be added and sent later.
     * @param string|null $message_id : the id of the Stud.IP internal message the
     * mail is related to. Leave this null if it isn't related to any internal message.
     * @param string|null $user_id : user_id of the receiver. Leave null if the
     * receiver has no account in Stud.IP.
     * @return MailQueueEntry : object in the mailqueue.
     */
    public static function add(StudipMail $mail, $message_id = null, $user_id = null)
    {
        $queue_entry = new self();
        $queue_entry['mail'] = $mail->toArray();
        $queue_entry['message_id'] = $message_id;
        $queue_entry['user_id'] = $user_id;
        $queue_entry['tries'] = 0;
        $queue_entry->store();

        return $queue_entry;
    }

    /**
     * Sends all new mails in the mailqueue (which means they haven't been sent yet).
     */
    public static function sendNew()
    {
        self::findEachBySQL(function ($m) {
            $m->send();
        }, "tries = 0 ORDER BY mkdate");
    }

    /**
     * Sends all mails in the mailqueue. Stud.IP will give each mail 24 tries to
     * deliver it. If the mail could not be sent after 24 tries (which are 24
     * hours) it will stay in the mailqueue table but won't be sent anymore.
     * Each mail will only be tried to deliver once per hour. So if it fails
     * Stud.IP will try again next hour.
     *
     * @param int $limit The maximum amount of messages to be sent.
     * @return array An empty array if no status messages are output
     *     or an array with status messages, one for each mail.
     */
    public static function sendAll($limit = null)
    {
        //The status messages will be returned
        $status_messages = [];

        self::findEachBySQL(function ($m) use (&$status_messages) {
            // Reconstruct the StudipMail object
            $mail = new StudipMail($m->mail);
            $status_message = sprintf(
                'sending message %1$s (sender: %2$s, %3$u recipient(s))...',
                $m->message_id,
                $mail->getSenderEmail(),
                count($mail->getRecipients())
            );

            $was_sent = $m->send();
            $status_message .= $was_sent ? 'DONE' : 'FAILURE';

            if ($m->tries > 0) {
                // If sending the message has failed at least once
                // we add the amount of tries to the status message.
                $status_message .= "(t={$m->tries})";
            }

            $status_messages[] = $status_message;
        }, "tries = 0 " .
           "OR (last_try > (UNIX_TIMESTAMP() - 60 * 60) AND tries < 25) ORDER BY tries, mkdate".
           ($limit > 0 ? " LIMIT ". (int) $limit : "")
        );

        return $status_messages;
    }

    /**
     * Sends the object in the mailqueue. If this succeeds, the object will be
     * deleted immediately. Otherwise the field "tries" in the mailqueue table
     * will be incremented by one.
     *
     * @return bool True, if the mail in the mailqueue entry could be sent,
     *     false otherwise.
     */
    public function send()
    {
        $mail = new StudipMail($this->mail);

        if ($mail->getRecipients()) {
            $success = $mail->send();
            if ($success) {
                $this->delete();
            } else {
                $this['tries'] = $this['tries'] + 1;
                $this['last_try'] = time();
                $this->store();
            }
        } else {
            $success = false;
            $this->delete();
        }
        return $success;
    }
}