From cdf8dab86c3e25e50ecc8673762faaf6852e0d13 Mon Sep 17 00:00:00 2001
From: Manuel Araoz <manuelaraoz@gmail.com>
Date: Fri, 20 Feb 2015 17:52:49 -0300
Subject: [PATCH] promisify event bus

---
 lib/eventbus.js  | 42 ++++++++++++++++++++++++++----------------
 test/eventbus.js | 17 +++++++++++++++++
 2 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/lib/eventbus.js b/lib/eventbus.js
index fc999435..20da9316 100644
--- a/lib/eventbus.js
+++ b/lib/eventbus.js
@@ -2,6 +2,7 @@
 
 
 var bitcore = require('bitcore');
+var Promise = require('bluebird');
 var $ = bitcore.util.preconditions;
 var _ = bitcore.deps._;
 var EventEmitter = require('events').EventEmitter;
@@ -16,24 +17,33 @@ EventBus.prototype.process = function(e) {
   $.checkArgument(_.isObject(e));
 
   var self = this;
-  var queue = [];
   var done = [];
-  queue.push(e);
-  while (queue.length !== 0) {
-    var event = queue.shift();
-    var handlers = this.handlers[event.constructor.name] || [];
-    handlers.forEach(function(handler) {
-      var responses = handler(event);
-      if (responses && responses.length > 0) {
-        queue = queue.concat(responses);
-      }
-    });
-    done.push(event);
-  }
-  done.forEach(function(event) {
-    self.emit(event.name || event.constructor.name, event);
-  });
 
+  var processEvent = function(event) {
+    done = done.concat(event);
+    var handlers = self.handlers[event.constructor.name] || [];
+    var whenHandlersResolve = Promise.all(handlers.map(function(handler) {
+      return handler(event);
+    }));
+    return whenHandlersResolve.each(function(events) {
+      if (_.isUndefined(events)) {
+        events = [];
+      }
+      if (!_.isArray(events)) {
+        events = [events];
+      }
+      return Promise.all(
+        events.map(processEvent)
+      );
+    });
+  };
+  var eventsEmitted = processEvent(e)
+    .then(function() {
+      done.forEach(function(event) {
+        self.emit(event.name || event.constructor.name, event);
+      });
+    });
+  return eventsEmitted;
 };
 
 
diff --git a/test/eventbus.js b/test/eventbus.js
index 1e7bba65..ccd74df5 100644
--- a/test/eventbus.js
+++ b/test/eventbus.js
@@ -5,6 +5,7 @@ var should = chai.should();
 var sinon = require('sinon');
 
 var EventBus = require('../lib/eventbus');
+require('bluebird').longStackTraces();
 
 describe('EventBus', function() {
 
@@ -15,6 +16,7 @@ describe('EventBus', function() {
 
   describe('process', function() {
     function FooEvent() {}
+
     function BarEvent() {}
     var foo = new FooEvent();
     var bar = new BarEvent();
@@ -65,6 +67,21 @@ describe('EventBus', function() {
       bus.process(foo);
       spy.callCount.should.equal(2);
     });
+    it('foo returns two bars and emits external events', function(cb) {
+      var bus = new EventBus();
+      var b1 = new BarEvent();
+      var b2 = new BarEvent();
+      var spy = sinon.spy(bus, 'emit');
+      bus.register(FooEvent, function() {
+        return [b1, b2];
+      });
+      bus.process(foo)
+        .then(function() {
+          spy.calledWith('BarEvent', b1).should.equal(true);
+          spy.calledWith('BarEvent', b2).should.equal(true);
+        })
+        .then(cb);
+    });
   });
 
 });