add promises to sendMsg, receiveMsg and endOtr (fix #80)

Author: sualko

lib/otr.js

@@ -560,6 +560,8 @@
   }
 
   OTR.prototype.sendMsg = function (msg, meta) {
+    var promise = (typeof Promise === 'function') ? new Promise(function(){}) : undefined;
+
     if ( this.REQUIRE_ENCRYPTION ||
          this.msgstate !== CONST.MSGSTATE_PLAINTEXT
     ) {
@@ -572,7 +574,7 @@
         if (this.REQUIRE_ENCRYPTION) {
           this.storedMgs.push({msg: msg, meta: meta})
           this.sendQueryMsg()
-          return
+          return promise
         }
         if (this.SEND_WHITESPACE_TAG && !this.receivedPlaintext) {
           msg += CONST.WHITESPACE_TAG  // 16 byte tag
@@ -583,45 +585,53 @@
       case CONST.MSGSTATE_FINISHED:
         this.storedMgs.push({msg: msg, meta: meta})
         this.notify('Message cannot be sent at this time.', 'warn')
-        return
+        return promise
       case CONST.MSGSTATE_ENCRYPTED:
         msg = this.prepareMsg(msg)
         break
       default:
         throw new Error('Unknown message state.')
     }
 
-    if (msg) this.io(msg, meta)
+    if (msg) {
+      this.io(msg, meta)
+
+      if (typeof Promise !== 'undefined' && typeof Promise.resolve === 'function')
+        return Promise.resolve(msg)
+    }
+
+    return promise
   }
 
   OTR.prototype.receiveMsg = function (msg, meta) {
+    var promise = (typeof Promise === 'function') ? new Promise(function(){}) : undefined;
 
     // parse type
     msg = Parse.parseMsg(this, msg)
 
-    if (!msg) return
+    if (!msg) return promise
 
     switch (msg.cls) {
       case 'error':
         this.notify(msg.msg)
-        return
+        return promise
       case 'ake':
         if ( msg.version === CONST.OTR_VERSION_3 &&
           this.checkInstanceTags(msg.instance_tags)
         ) {
           this.notify(
             'Received a message intended for a different session.', 'warn')
-          return  // ignore
+          return promise  // ignore
         }
         this.ake.handleAKE(msg)
-        return
+        return promise
       case 'data':
         if ( msg.version === CONST.OTR_VERSION_3 &&
           this.checkInstanceTags(msg.instance_tags)
         ) {
           this.notify(
             'Received a message intended for a different session.', 'warn')
-          return  // ignore
+          return promise  // ignore
         }
         msg.msg = this.handleDataMsg(msg)
         msg.encrypted = true
@@ -645,7 +655,14 @@
           this.doAKE(msg)
     }
 
-    if (msg.msg) this.trigger('ui', [msg.msg, !!msg.encrypted, meta])
+    if (msg.msg) {
+      this.trigger('ui', [msg.msg, !!msg.encrypted, meta])
+
+      if (typeof Promise !== 'undefined' && typeof Promise.resolve === 'function')
+        return Promise.resolve([msg.msg, !!msg.encrypted])
+    }
+
+    return promise;
   }
 
   OTR.prototype.checkInstanceTags = function (it) {
@@ -718,6 +735,20 @@
   }
 
   OTR.prototype.endOtr = function (cb) {
+    var promise
+
+    if (typeof Promise === 'function') {
+      promise = new Promise(function(resolve) {
+        var original_cb = cb
+
+        cb = function() {
+          if (typeof original_cb === 'function')
+            original_cb()
+          resolve()
+        }
+      })
+    }
+
     if (this.msgstate === CONST.MSGSTATE_ENCRYPTED) {
       if (typeof cb === 'function')
         cb = new OTRCB(cb)
@@ -732,6 +763,8 @@
     this.msgstate = CONST.MSGSTATE_PLAINTEXT
     this.receivedPlaintext = false
     this.trigger('status', [CONST.STATUS_END_OTR])
+
+    if (promise) return promise
   }
 
   // attach methods