From c0a564b765b1e1559a59cdafda02273880985747 Mon Sep 17 00:00:00 2001
From: Manuel Araoz <manuelaraoz@gmail.com>
Date: Thu, 19 Feb 2015 18:07:48 -0300
Subject: [PATCH] Add simple funnel implementation

---
 lib/funnel.js  | 45 ++++++++++++++++++++++++++++++++
 test/funnel.js | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 lib/funnel.js
 create mode 100644 test/funnel.js

diff --git a/lib/funnel.js b/lib/funnel.js
new file mode 100644
index 00000000..e0592528
--- /dev/null
+++ b/lib/funnel.js
@@ -0,0 +1,45 @@
+'use strict';
+
+
+var bitcore = require('bitcore');
+var $ = bitcore.util.preconditions;
+var _ = bitcore.deps._;
+var EventEmitter = require('events').EventEmitter;
+var util = require('util');
+
+function Funnel() {
+  this.handlers = {};
+}
+util.inherits(Funnel, EventEmitter);
+
+Funnel.prototype.process = function(e) {
+  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) {
+    //that.emit(event.name, event);
+  });
+
+};
+
+
+Funnel.prototype.register = function(clazz, handler) {
+  $.checkArgument(_.isFunction(handler));
+  var name = clazz.name;
+  this.handlers[name] = this.handlers[name] || [];
+  this.handlers[name].push(handler);
+};
+
+
+module.exports = Funnel;
diff --git a/test/funnel.js b/test/funnel.js
new file mode 100644
index 00000000..54672667
--- /dev/null
+++ b/test/funnel.js
@@ -0,0 +1,70 @@
+'use strict';
+
+var chai = require('chai');
+var should = chai.should();
+var sinon = require('sinon');
+
+var Funnel = require('../lib/funnel');
+
+describe('Funnel', function() {
+
+  it('instantiate', function() {
+    var f = new Funnel();
+    should.exist(f);
+  });
+
+  describe('process', function() {
+    function FooEvent() {}
+    function BarEvent() {}
+    var foo = new FooEvent();
+    var bar = new BarEvent();
+    foo.x = 2;
+    bar.y = 3;
+
+    it('no handlers registered', function() {
+      var f = new Funnel();
+      f.process.bind(f, foo).should.not.throw();
+    });
+    it('simple handler gets called', function(cb) {
+      var f = new Funnel();
+      f.register(FooEvent, function(e) {
+        e.x.should.equal(foo.x);
+        cb();
+      });
+      f.process(foo);
+    });
+    it('other event does not get called', function() {
+      var f = new Funnel();
+      var spy = sinon.spy();
+      f.register(FooEvent, spy);
+      f.process(bar);
+      spy.callCount.should.equal(0);
+    });
+    it('foo returns bar', function(cb) {
+      var f = new Funnel();
+      f.register(FooEvent, function(e) {
+        var b = new BarEvent();
+        b.y = e.x;
+        return [b];
+      });
+      f.register(BarEvent, function(e) {
+        e.y.should.equal(foo.x);
+        cb();
+      });
+      f.process(foo);
+    });
+    it('foo returns two bars', function() {
+      var f = new Funnel();
+      var spy = sinon.spy();
+      f.register(FooEvent, function() {
+        var b1 = new BarEvent();
+        var b2 = new BarEvent();
+        return [b1, b2];
+      });
+      f.register(BarEvent, spy);
+      f.process(foo);
+      spy.callCount.should.equal(2);
+    });
+  });
+
+});