<?php
/*
* SMS.inc.php
*
* This is the domain logic managing the fundamental behaviors and data of SMSs.
*
* @author   Quinn Comendant <quinn@strangecode.com>
* @version  1.0
* @since    20 Aug 2014 17:20:09
*/

class SMS
{
    /*
    * Sends an SMS containing $text to the number given in $to. This is a wrapper for
    * the various SMS API provider methods. The provider used is defined
    * in `$cfg['sms_provider']` in _config.inc.php.
    *
    * @access   public
    * @param    string  $to     Recipient's mobile phone number.
    * @param    string  $text   The message
    * @return   null
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    09 Nov 2013 16:35:10
    */
    static public function send($to, $text)
    {
        global $cfg, $twilio, $nexmo_sms;

        switch ($cfg['sms_provider']) {
        case 'twilio' :
            $twilio->account->messages->sendMessage('425-242-6153', $to, $text);
            break;

        case 'nexmo' :
            $nexmo_sms->sendText($to, '525549998248', $text);
            break;

        default :
            $app->logMsg(sprintf('Unknown SMS provider: %s', $cfg['sms_provider']), LOG_ERR, __FILE__, __LINE__);
            break;
        }
    }

    /*
    * Receives the request to our webhook from the various SMS API providers, setting the values in a consistent return value.
    * The provider used is defined in `$cfg['sms_provider']` in _config.inc.php. Works with GET and POST.
    *
    * @access   public
    * @return   array   Array contining 'sender_number' and 'text' from the $_REQUEST response.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    09 Nov 2013 17:09:57
    */
    static public function receive()
    {
        global $cfg, $twilio, $nexmo_sms;
        $app =& App::getInstance();

        $app->logMsg(sprintf('Receiving SMS: %s', getDump(getFormData())), LOG_DEBUG, __FILE__, __LINE__);

        switch ($cfg['sms_provider']) {
        case 'twilio' :
            $sender = preg_replace('/\D/', '', getFormData('From'));
            return array(
                'virtual_number' => getFormData('…'), // TODO: check key value.
                'sender_number' => (is_numeric($sender) ? '+' . $sender : ''),
                'text' => getFormData('Body'),
            );

        case 'nexmo' :
            $sender = preg_replace('/\D/', '', getFormData('msisdn'));
            return array(
                'virtual_number' => getFormData('to'),
                'sender_number' => (is_numeric($sender) ? '+' . $sender : $sender),
                'text' => getFormData('text'),
                'keyword' => getFormData('keyword'),
                'concat' => getFormData('concat'),
                'concat-ref' => getFormData('concat-ref'),
                'concat-total' => getFormData('concat-total'),
                'concat-part' => getFormData('concat-part'),
            );

        default :
            $app->logMsg(sprintf('Unknown SMS provider: %s', $cfg['sms_provider']), LOG_ERR, __FILE__, __LINE__);
            return false;
        }
    }

    /*
    * Nexmo can send messages in multiple parts if it is longer than 160 characters.
    * Because these will be delivered in subsequent GET requests, the parts must be
    * stored in a temporary db table and assembled once the last part is returned.
    * This method should be called on the GET variables submitted by the Nexmo client.
    * https://docs.nexmo.com/index.php/sms-api/handle-inbound-message
    *
    * @access   public
    * @param    array   $sms    Array of values returned by SMS::receive().
    * @return   mixed           If the message is fully formed, the same values from $sms are returned. False is returned if the message is in multiple parts and not all of them have been received yet.
    * @author   Quinn Comendant <quinn@strangecode.com>
    * @version  1.0
    * @since    26 Nov 2014 19:20:58
    */
    static public function processMultipart($sms)
    {
        $app =& App::getInstance();
        $db =& DB::getInstance();

        // This method is Nexmo-specific. Check that, and also if the message is a long 'concatenated' Inbound.
        if ('nexmo' == $cfg['sms_provider'] && isset($sms['concat']) && $sms['concat']) {
            // This sms is part of a multipart message, save it temporarily to the db.
            $sms = array_map('trim', $sms);
            $db->query("
                REPLACE INTO response_concat_tbl (
                    `concat-ref`,
                    `concat-total`,
                    `concat-part`,
                    `text`,
                    `added_datetime`
                ) VALUES (
                    '" . $db->escapeString($sms['concat-ref']) . "',
                    '" . $db->escapeString($sms['concat-total']) . "',
                    '" . $db->escapeString($sms['concat-part']) . "',
                    '" . $db->escapeString($sms['text']) . "',
                    NOW()
                )
            ");
            $app->logMsg(sprintf('Received multipart SMS part %s of %s ref %s', $sms['concat-part'], $sms['concat-total'], $sms['concat-ref']), LOG_DEBUG, __FILE__, __LINE__);

            if ($sms['concat-total'] > $sms['concat-part']) {
                // Not all the parts have been received; return false to signal the fact we don't have a complete message yet.
                return false;
            }
            // Otherwise, it means the last part has just been received. Concatonate all the parts and return it.

            // Increase the max length returned by MySQL's GROUP_CONCAT function.
            $db->query("SET SESSION group_concat_max_len = 32000");

            // Group the sms responses by concat-ref and return them as a concatonated string.
            $qid = $db->query("
                SELECT GROUP_CONCAT(text ORDER BY `concat-part` ASC SEPARATOR ' ')
                FROM response_concat_tbl
                WHERE `concat-ref` = '" . $db->escapeString($sms['concat-ref']) . "'
                GROUP BY `concat-ref`
            ");
            list($sms['text']) = mysql_fetch_row($qid);

            // Delete the temporary records.
            $db->query("
                DELETE FROM response_concat_tbl
                WHERE `concat-ref` = '" . $db->escapeString($sms['concat-ref']) . "'
            ");
            $app->logMsg(sprintf('Final multipart SMS ref %s: %s', $sms['concat-ref'], $sms['text']), LOG_DEBUG, __FILE__, __LINE__);
        }

        // If this is not a multipart message, the original sms data is returned. If it is a multipart message, we're returning here the fully-concatonated message.
        return $sms;
    }
}