My first attempt at a Matrix box. Fist off, I wanted to get a list of events (messages). There was an event stream in the docs, but that's been deprecated.

You can get a list of events from a particular channel by sending a request to /messages (see the documentation here: https://matrix.org/docs/api/client-server/#!/Room32participation/getRoomEvents). So, a simple way to get the events is something like this:

function get_new_events($room) {
   $homeserver = "glasgow.social";
   $access_token = "access_token_goes_here"
   $url = "https://$homeserver/_matrix/client/r0/rooms/$room/messages?access_token=$access_token&from=$tracking_id";
   $data = json_decode(file_get_contents($url), true);
   return $data;
}

The way to get all events (i.e. all messages on channels you are a member of is to use the /sync endpoint. The documentation for that is at: https://matrix.org/docs/api/client-server/#!/Room32participation/sync

I run this in a terminal and it shows me everything happening on the rooms I'm in, in a simple way.

ListToMatrix.php

$homeserver = "glasgow.social";
$access_token = "access_token_goes_here";
 
$tracking_file = "/tmp/listen_matrix.json";
 
while(true) {
 
$since = file_get_contents($tracking_file);
$messages = get_new_events($since);
if(!empty($messages['rooms']['join'] and is_array($messages['rooms']['join']))) {
   foreach($messages['rooms']['join'] as $room_id=>$data) {
      foreach($data['timeline']['events'] as $event_id=>$event) {
         if($event['type'] == "m.room.message") {
            $sender = $event['sender'];
            $content = "Image/Video/Audio";
            if($event['content']['msgtype'] == "m.text")
               $content = $event['content']['body'];
            echo "$sender (".$rooms[$room_id].") $content\n";
         }
      }
   }
}
$new_tracking_data = $messages['next_batch'];
file_put_contents($tracking_file, $new_tracking_data);
 
}
 
 
function get_new_events($since) {
   global $homeserver,$access_token;
   $url = "https://$homeserver/_matrix/client/r0/sync?access_token=$access_token&timeout=30000";
   if(!empty($since))
      $url .= "&since=$since";
   $data = json_decode(file_get_contents($url), true);
   return $data;
}

Now, to make an actual functioning bot, replace the echo line with whatever you want to do (in my case, I look up a list of rules [i.e. pairs of regexes and their response functions] I use in IRC from a database and act accordingly). See the Matrix tools page for notes on how to post your reply to a room.