transform.patch

diff --git a/chat/components/public/prplIConversation.idl b/chat/components/public/prplIConversation.idl
--- a/chat/components/public/prplIConversation.idl
+++ b/chat/components/public/prplIConversation.idl
@@ -6,16 +6,17 @@
 #include "nsISupports.idl"
 #include "nsISimpleEnumerator.idl"
 #include "nsIObserver.idl"
 
 interface imIAccountBuddy;
 interface imIAccount;
 interface nsIURI;
 interface nsIDOMDocument;
+interface prplIMessage;
 
 /*
  * This is the XPCOM purple conversation component, a proxy for PurpleConversation.
  */
 
 [scriptable, uuid(e40dc3e5-c9ff-457b-a6cc-655cce81042c)]
 interface prplIConversation: nsISupports {
 
@@ -57,18 +58,29 @@ interface prplIConversation: nsISupports
 
   /* When the conversation is closed from the UI. */
   void close();
 
   /* Method to add or remove an observer */
   void addObserver(in nsIObserver aObserver);
   void removeObserver(in nsIObserver aObserver);
 
-  /* Observers will be all receive new-text notifications.
-     aSubject will contain the message (prplIMessage) */
+ /* Observers will be notified of messaging events.
+  *  aSubject will contain the message (prplIMessage)
+  *
+  *  Fired notifications:
+  *   new-text
+  *     Tells the UI to display the message in the conversation.
+  *   sending-message
+  *     Where the message can be modified, or cancelled, by observers.
+  *   receiving-message
+  *     Observers can modify the message, or stop its processing.
+  */
+  void notifyObservers(in prplIMessage aSubject, in string aTopic,
+                       [optional] in wstring aData);
 };
 
 [scriptable, uuid(0c072a80-103a-4992-b249-8e442b5f0d46)]
 interface prplIConvIM: prplIConversation {
 
   /* The buddy at the remote end of the conversation */
   readonly attribute imIAccountBuddy buddy;
 
diff --git a/chat/components/public/prplIMessage.idl b/chat/components/public/prplIMessage.idl
--- a/chat/components/public/prplIMessage.idl
+++ b/chat/components/public/prplIMessage.idl
@@ -21,17 +21,17 @@ interface prplIMessageAction: nsIRunnabl
 [scriptable, uuid(d9f0ca7f-ee59-4657-a3dd-f458c204ca45)]
 interface prplIMessage: nsISupports {
   /* The uniqueness of the message id is only guaranteed across
      messages of a conversation, not across all messages created
      during the execution of the application. */
   readonly attribute unsigned long id;
   readonly attribute AUTF8String who;
   readonly attribute AUTF8String alias;
-  readonly attribute AUTF8String originalMessage;
+           attribute AUTF8String originalMessage;
            attribute AUTF8String message;
   readonly attribute AUTF8String iconURL;
   readonly attribute PRTime time;
   readonly attribute prplIConversation conversation;
 
   /* Holds the sender color for Chats.
      Empty string by default, it is set by the conversation binding. */
   attribute AUTF8String color;
@@ -51,17 +51,17 @@ interface prplIMessage: nsISupports {
                                                 internal UI purposes
                                                 (e.g. for contact-aware
                                                  conversions).           */
   /*  PURPLE_MESSAGE_NICK        = 0x0020, /**< Contains your nick.      */
   readonly attribute boolean containsNick;
   /*  PURPLE_MESSAGE_NO_LOG      = 0x0040, /**< Do not log.              */
   readonly attribute boolean noLog;
   /*  PURPLE_MESSAGE_ERROR       = 0x0200, /**< Error message.           */
-  readonly attribute boolean error;
+           attribute boolean error;
   /*  PURPLE_MESSAGE_DELAYED     = 0x0400, /**< Delayed message.         */
   readonly attribute boolean delayed;
   /*  PURPLE_MESSAGE_RAW         = 0x0800, /**< "Raw" message - don't
                                                 apply formatting         */
   readonly attribute boolean noFormat;
   /*  PURPLE_MESSAGE_IMAGES      = 0x1000, /**< Message contains images  */
   readonly attribute boolean containsImages;
   /*  PURPLE_MESSAGE_NOTIFY      = 0x2000, /**< Message is a notification */
diff --git a/chat/components/src/imConversations.js b/chat/components/src/imConversations.js
--- a/chat/components/src/imConversations.js
+++ b/chat/components/src/imConversations.js
@@ -16,16 +16,17 @@ XPCOMUtils.defineLazyGetter(this, "bundl
 );
 
 function UIConversation(aPrplConversation)
 {
   this._prplConv = {};
   this.id = ++gLastUIConvId;
   this._observers = [];
   this._messages = [];
+  this._msgBuffer = [];
   this.changeTargetTo(aPrplConversation);
   let iface = Ci["prplIConv" + (aPrplConversation.isChat ? "Chat" : "IM")];
   this._interfaces = this._interfaces.concat(iface);
   // XPConnect will create a wrapper around 'this' after here,
   // so the list of exposed interfaces shouldn't change anymore.
   this.updateContactObserver();
   Services.obs.notifyObservers(this, "new-ui-conversation", null);
 }
@@ -261,16 +262,21 @@ UIConversation.prototype = {
   },
 
   observeConv: function(aTargetId, aSubject, aTopic, aData) {
     if (aTargetId != this._currentTargetId &&
         (aTopic == "new-text" ||
          (aTopic == "update-typing" &&
           this._prplConv[aTargetId].typingState == Ci.prplIConvIM.TYPING)))
       this.target = this._prplConv[aTargetId];
+
+    // Process new texts and possibly cancel the message at this point.
+    if (aTopic == "new-text" && !this.processText(aSubject))
+      return;
+
     this.notifyObservers(aSubject, aTopic, aData);
     if (aTopic == "new-text") {
       Services.obs.notifyObservers(aSubject, aTopic, aData);
       if (aSubject.incoming && !aSubject.system &&
           (!this.isChat || aSubject.containsNick)) {
         this.notifyObservers(aSubject, "new-directed-incoming-message", aData);
         Services.obs.notifyObservers(aSubject, "new-directed-incoming-message", aData);
       }
@@ -284,17 +290,81 @@ UIConversation.prototype = {
 
   // prplIConversation
   get isChat() this.target.isChat,
   get account() this.target.account,
   get name() this.target.name,
   get normalizedName() this.target.normalizedName,
   get title() this.target.title,
   get startDate() this.target.startDate,
-  sendMsg: function (aMsg) { this.target.sendMsg(aMsg); },
+
+  sendMsg: function (aMsg) {
+    // Create a new message with aMsg to satisfy the observer interface.
+    let nMsg = new Message(this.target.name, aMsg, { outgoing: true });
+
+    // Notify observers that now is the time to modify the message
+    // before sending. After modifications,
+    //   "message" will contain the outgoing text
+    //   "originalMessage" will be displayed to the user
+    this.target.notifyObservers(nMsg, "sending-message", null);
+
+    // If an observer cancelled the message, abort here.
+    if (nMsg.error)
+      return;
+
+    // Because of the libpurple context restriction, we're forced
+    // to buffer messages here. When "new-text" is fired, we'll
+    // grab this message to display the intended content.
+    this.bufferMsg(this.target, nMsg);
+    
+    // Send just the outgoing text.
+    this.target.sendMsg(nMsg.message);
+  },
+
+  bufferMsg: function(aConv, aMsg) {
+    this._msgBuffer.push({ conv: aConv, msg: aMsg });
+  },
+
+  // If we don't find the message, it was injected directly
+  // and was intended to be ignored.
+  pluckMsg: function(aConv, aMsg) {
+    let mb = this._msgBuffer;
+    return mb.some(function(a, i) {
+      if (a.conv === aConv && a.msg.message === aMsg.message) {
+        // This is likely the message we stored.
+        // Replace the text to be displayed with its contents.
+        aMsg.originalMessage = a.msg.originalMessage;
+        // And remove it from the buffer.
+        mb.splice(i, 1);
+        // Indicate the message was located.
+        return true;
+      }
+    });
+  },
+
+  processText: function(aMsg) {
+    if (!aMsg.system) {
+      if (aMsg.outgoing) {
+        // If the message isn't located, suppress it.
+        return this.pluckMsg(this.target, aMsg);
+      } else if (aMsg.incoming) {
+        // Notify observers that now is the time to modify the incoming
+        // message. After modifications,
+        //   "message" will still contain the incoming text
+        //   "originalMessage" will be displayed to the user
+        this.target.notifyObservers(aMsg, "receiving-message", null);
+
+        // If an observer cancelled the message, abort here.
+        if (aMsg.error)
+          return false;
+      }
+    }
+    return true;
+  },
+
   unInit: function() {
     for each (let conv in this._prplConv)
       gConversationsService.forgetConversation(conv);
     if (this._observedContact) {
       this._observedContact.removeObserver(this);
       delete this._observedContact;
     }
     this._prplConv = {}; // Prevent .close from failing.