[ADD/WIP] Make basic XMPP->Matrix redactions

I'll need to use the actual redaction endpoint eventually, hence the
WIP status.

src/XMPP/Stanza.c

@@ -290,6 +290,34 @@ XMPPGetReplacedID(XMLElement *stanza)
     return replace ? HashMapGet(replace->attrs, "id") : NULL;
 }
 char *
+XMPPGetRetractedID(XMLElement *stanza)
+{
+    XMLElement *retract = XMLookForTKV(
+        stanza, "retract", 
+        "xmlns", "urn:xmpp:message-retract:1"
+    );
+    char *id = retract ? HashMapGet(retract->attrs, "id") : NULL;
+    if (!id)
+    {
+        /* Pretend its fastened */
+        XMLElement *fasten = XMLookForTKV(
+            stanza, "apply-to", 
+            "xmlns", "urn:xmpp:fasten:0"
+        );
+        retract = XMLookForTKV(
+            fasten, "retract", 
+            "xmlns", "urn:xmpp:message-retract:0"
+        );
+
+        if (retract)
+        {
+            id = HashMapGet(fasten->attrs, "id");
+        }
+    }
+
+    return id;
+}
+char *
 XMPPGetReply(XMLElement *elem)
 {
     XMLElement *rep = XMLookForTKV(elem, "reply", "xmlns", "urn:xmpp:reply:0");

src/XMPPThread.c

@@ -527,6 +527,7 @@ MessageStanza(ParseeData *args, XMLElement *stanza, XMPPThread *thr)
         char *encoded   = ParseeEncodeJID(args->config, decode_from, false);
         char *event_id  = NULL;
         char *replaced  = XMPPGetReplacedID(stanza);
+        char *retracted = XMPPGetRetractedID(stanza);
         char *reply_to  = XMPPGetReply(stanza);
         bool chat       = false;
 
@@ -618,11 +619,26 @@ MessageStanza(ParseeData *args, XMLElement *stanza, XMPPThread *thr)
                 Free(event_id);
                 event_id = NULL;
             }
+            else if (retracted)
+            {
+                /* TODO: Use an actual redact. Not doing it now because it's not 
+                 * fun to do at the moment... */
+                event_id = ParseeGetEventFromID(args, stanza, retracted);
+                Free(ASSend(
+                    args->config, mroom_id, encoded, "m.room.message", 
+                    MatrixCreateReplace(event_id, "[Retracted]")
+                ));
+                ParseePushAllStanza(args, stanza, event_id);
+                pthread_mutex_unlock(&thr->info->chk_lock);
+
+                Free(event_id);
+                event_id = NULL;
+            }
             else
             {
                 /* TODO: Use HTML-formatted bodies, and respect the fallback 
-                 * trims the stanza provides us if possible. Element does 
+                 * trims the stanza provides us if possible. Element does not 
-                 * not like raw bodies on replies too. Go figure. */
+                 * like raw bodies on replies too. Go figure. */
                 size_t off = 
                     reply_to ? ParseeFindDatastart(data->data) : 0;
                 HashMap *ev = MatrixCreateMessage(data->data + off);

src/include/XMPP.h

@@ -67,6 +67,7 @@ extern char * XMPPGetOriginID(XMLElement *);
 /* Returns the origin ID of the replaced stanza, if the current one 
  * is a replacement notice */
 extern char * XMPPGetReplacedID(XMLElement *);
+extern char * XMPPGetRetractedID(XMLElement *);
 
 /* Get the replied-to stanza ID, if existent. */
 extern char * XMPPGetReply(XMLElement *elem);