#!/usr/bin/php
<?php
// © Copyright 2017 2AS Sistemas Ltda
// © Copyright 2017 Arnaldo H Viegas de Lima
// 
// External handler to Cyrus IMAP notifyd to process Apple Push Notifications 
// Version 1.0
// Version 1.1 - Added registration timestamp to allow for a future cleanup option

$debug=false;

// Apple Push Notification Service configuration 
$apns['url']='gateway.push.apple.com';
$apns['cert']='/etc/pki/tls/certs/apns_mobilemail.pem';    // Certificate from OSX Server - must renew annually
$apns['timeout']=5;

// Database configuration
$db['host']='';
$db['userid']='';
$db['password']='';
$db['database']='apns_mobilemail';

// Open connectiopn to syslog, we need it even if no debug
openlog(basename(__FILE__),LOG_CONS||LOG_NDELAY||LOG_PERROR||LOG_PID,LOG_LOCAL6);

// Lets read the notification message. We will retrieve all the information we need from there
$message=json_decode(file_get_contents("php://stdin"),true);
if ($debug) syslog(LOG_INFO,"Event: $message[event]");

// Check and process
switch ($message['event']) {
case 'ApplePushService':                // Registration
    if ($debug) {
        syslog(LOG_INFO,"User: $message[user]");
        syslog(LOG_INFO,"APS Version: $message[apsVersion]");
        syslog(LOG_INFO,"APS Account Id: $message[apsAccountId]");
        syslog(LOG_INFO,"APS Device Token: $message[apsDeviceToken]");
        syslog(LOG_INFO,"APS Subtopic: $message[apsSubtopic]");
    }
    // Register or retrieve existing device registration
    $result=dbQuery("SELECT * FROM devices WHERE aps_account_id='$message[apsAccountId]' AND aps_device_token='$message[apsDeviceToken]'");
    if ($result) {
        dbTimeStamp('devices','last_registration',"aps_account_id='$message[apsAccountId]' AND aps_device_token='$message[apsDeviceToken]'");
        $device=$result[0]['id']; 
    } else {
        $device=dbWrite('devices',['aps_account_id'=>$message['apsAccountId'],'aps_device_token'=>$message['apsDeviceToken']]);
    }
    dbDelete('mailboxes',"device=$device AND user='$message[user]'");         // Erase previous subscriptions for user on this device
    foreach ($message['mailboxes'] as $mb) {    
        if ($debug) syslog(LOG_INFO,"Mailbox: $mb");
        dbWrite('mailboxes',['device'=>$device,'user'=>$message['user'],'mailbox'=>$mb]);
    }
    break;
case 'MessageNew':                      // New message in mailbox - this is the most important one
        $mb=mbInfoFromURI($message['uri']);
        if ($debug) {
            syslog(LOG_INFO,"User: $mb[user]");
            syslog(LOG_INFO,"Mailbox: $mb[mb]");
        }
        tryPush($mb);
        break;
case 'MessageRead':                     // User reads message. Only if INBOX, to allow for badge/msglist to update
case 'MessageTrash':                    // User trash message. Only if INBOX, to allow for badge/msglist to update
        $mb=mbInfoFromURI($message['uri']);
        if ($debug) {
            syslog(LOG_INFO,"User: $mb[user]");
            syslog(LOG_INFO,"Mailbox: $mb[mb]");
        }
        if ($mb['mb']=='INBOX') tryPush($mb);
        break;
case 'vnd.cmu.MessageMove':             // This may seem a bit too much, but one may move message out of inbox without reading it
        $fromMB=mbInfoFromURI($message['oldMailboxID']);
        $toMB=mbInfoFromURI($message['uri']);
        if ($debug) {
            syslog(LOG_INFO,"From User: $fromMB[user]");
            syslog(LOG_INFO,"From Mailbox: $fromMB[mb]");
            syslog(LOG_INFO,"To User: $toMB[user]");
            syslog(LOG_INFO,"To Mailbox: $toMB[mb]");
        }
        tryPush($fromMB);
        break;
case 'vnd.cmu.MessageCopy':             // Some clients copy message to trash (MessageTrash gets called, so I guess we don't need this)             
case 'MessageExpunge':                  // My guess that we do not need to push  on this one too, but leave it here
default:
}

// Done
exit;

// Check if [user+mailbox] need a nudge and do it
function tryPush($mb) {
    $result=dbQuery("SELECT * FROM devices,mailboxes WHERE mailbox='$mb[mb]' AND user='$mb[user]' AND device=devices.id");
    if ($result) {
        foreach ($result as $device) {
            $payload['aps']['account-id']=$device['aps_account_id'];
            apnsPushPayload($payload,$device['aps_device_token']);          // This is a single MB, so we need to call once for each device registered
        }
    }
}

// Quick MySQL interface
//
// Auto connect code
function _dbConnect() {
    global $db;
    // If we already have a connection
    if (isset($db['current'])) return $db['current'];

    // Connect
    if ($db['host']=='' || $db['host']=='*') $db['host']='localhost';
    $db_conn=mysqli_connect($db['host'],$db['userid'],$db['password'],$db['database'])
            or terminate('Cannot connect to database');

    // Save it for future use and we are done!
    $db['current']=$db_conn;             // Save it for direct access
    return $db['current'];
};


// Generic query, returning array of associative arrays (rows)
function dbQuery($query) {
    // This is simple, so let's get to it
    $result=mysqli_query(_dbConnect(),$query)
        or terminate('Database query error');
    
    // Group result in array
    if (mysqli_num_rows($result)>0) {
        while ($row=mysqli_fetch_assoc($result)) $rows[]=$row;
    } else {
        $rows=null;
    }
    mysqli_free_result($result);

    // Done
    return $rows;
}

// Generic insert/replace from associative array into id based table 
function dbWrite($table,$values) {
    // Prepare data
    $cols=$data="";
    foreach ($values as $c => $d) {
        $cols=$cols.",`".$c."`";
        $data=$data.",'$d'";
    }
    $cols=substr($cols,1);
    $data=substr($data,1);

    // Perform insert/replace
    $replace=(isset($values['id']) && $values['id']>0);
    if ($replace) {
        $query="REPLACE INTO $table ($cols) VALUES ($data)";
    } else {
        $query="INSERT INTO $table ($cols) VALUES ($data)";
    }
    $db_conn=_dbConnect();
    mysqli_query($db_conn,$query)
        or terminate('Database write error');

    // We are done, return the associated id
    if ($replace) {
        return $values['id'];
    } else {
        return mysqli_insert_id($db_conn);
    }
};

// Generic delete from table
function dbDelete($table,$query) {
    $query="DELETE FROM $table WHERE $query";
    mysqli_query(_dbConnect(),$query)
        or terminate('Database delete error');
};

// Generic timestamp col updater
function dbTimeStamp($table,$col,$query) {
    $query="UPDATE $table SET $col=NOW() WHERE $query";
    mysqli_query(_dbConnect(),$query)
        or terminate('Database timestamp update error');
};

// Retrive user and mailbox name from Cyrus Style IMAP URI
function mbInfoFromURI($uri) {
    $uri=explode(';',$uri,2)[0];   // Take care of ";"
    $path=parse_url($uri,PHP_URL_PATH);
    $path=explode('/',$path,4);   // [0] will be "" as starts with "/"
    $user=$path[2];
    $mb=(isset($path[3])) ? $path[3] : 'INBOX';
    return ['user'=>$user,'mb'=>$mb];
}

// Push payload to a list of devices
function apnsPushPayload($payload,$deviceTokens) {
    global $apns, $debug;
    // Initialize socket
    $sc=stream_context_create();
    stream_context_set_option($sc,'ssl','local_cert',$apns['cert']);
    $socket=stream_socket_client("ssl://$apns[url]:2195",$error,$errorstr,$apns['timeout'],STREAM_CLIENT_CONNECT,$sc);
    if (!$socket) return false;
    
    // Loop to send the same payload to all user's registered devices
    $payload=json_encode($payload);
    foreach ((array) $deviceTokens as $dt) {
        $dt=str_replace(' ','', $dt);               // No blanks
        $message="\x00\x00\x20".pack('H*',$dt)."\x00".chr(strlen($payload)).$payload;
        $result=fwrite($socket, $message);
        if (1 || $debug && $result) syslog(LOG_INFO, 'Push notification sent');
    }

    // Finish up
    @socket_close($socket);
    @fclose($socket);
    return true;
}

// Simple termination funcion (send simple error to syslog)
function terminate($msg) {
    global $db;
    // Dump the error to syslog
    syslog(LOG_ERR,$msg); 

    // Now check for an MySQL error
    if (isset($db['current'])) {        // We have a connection, so check for possible error
        $mySQLError=mysqli_error($db['current']);
        if ($mySQLError!='') syslog(LOG_INFO,'MySQL: '.$mySQLError);
    }
    exit;                               // No need for a status code     
}

// debug: var_dump to syslog
function syslogDumpit() {
  $n=func_num_args();
  $v=func_get_args();
  ob_start();
  for ($i=0;$i<$n;$i++) var_dump($v[$i]);
  syslog(LOG_INFO,ob_get_clean());
}
?>