From ba91d7aba677c0ea32232206daece5dd6a8ae7dd Mon Sep 17 00:00:00 2001
From: Julian Lam <julian@designcreateplay.com>
Date: Sun, 24 Aug 2014 12:30:49 -0400
Subject: [PATCH] proof-of-concept for hot-swapping of routes

---
 src/hotswap.js      |  33 +++++++++++++++
 src/plugins.js      |  34 ++++++++++++++-
 src/routes/debug.js |   6 ++-
 src/routes/index.js | 100 +++++++++++++++++++++++---------------------
 src/webserver.js    |   1 +
 5 files changed, 123 insertions(+), 51 deletions(-)
 create mode 100644 src/hotswap.js

diff --git a/src/hotswap.js b/src/hotswap.js
new file mode 100644
index 0000000000..717c099052
--- /dev/null
+++ b/src/hotswap.js
@@ -0,0 +1,33 @@
+var HotSwap = {},
+	winston = require('winston'),
+	stack;
+
+HotSwap.prepare = function(app) {
+	stack = app._router.stack;
+};
+
+HotSwap.find = function(id) {
+	if (stack) {
+		for(var x=0,numEntries=stack.length;x<numEntries;x++) {
+			if (stack[x].handle.hotswapId === id) {
+				return x;
+				break;
+			}
+		}
+	} else {
+		winston.error('[hotswap] HotSwap module has not been prepared!');
+	}
+};
+
+HotSwap.replace = function(id, middleware) {
+	var idx = HotSwap.find(id);
+	if (idx) {
+		delete stack[idx].handle;	// Destroy the old middleware
+		stack[idx].handle = middleware;	// Replace with the new one
+		winston.info('[hotswap] Middleware with id `' + id + '` replaced successfully');
+	} else {
+		winston.warn('[hotswap] Could not find middleware in stack with hotswapId `' + id + '`');
+	}
+};
+
+module.exports = HotSwap;
\ No newline at end of file
diff --git a/src/plugins.js b/src/plugins.js
index d554edd6d3..b2578ed51e 100644
--- a/src/plugins.js
+++ b/src/plugins.js
@@ -6,13 +6,18 @@ var fs = require('fs'),
 	winston = require('winston'),
 	nconf = require('nconf'),
 	semver = require('semver'),
+	express = require('express'),
 
 	db = require('./database'),
 	emitter = require('./emitter'),
 	meta = require('./meta'),
 	translator = require('../public/src/translator'),
 	utils = require('../public/src/utils'),
-	pkg = require('../package.json');
+	hotswap = require('./hotswap'),
+	pkg = require('../package.json'),
+
+	controllers = require('./controllers'),
+	app, middleware;
 
 (function(Plugins) {
 
@@ -57,6 +62,12 @@ var fs = require('fs'),
 		});
 	};
 
+	Plugins.prepareApp = function(nbbApp, nbbMiddleware) {
+		app = nbbApp;
+		middleware = nbbMiddleware;
+		hotswap.prepare(nbbApp);
+	};
+
 	Plugins.ready = function(callback) {
 		if (!Plugins.initialized) {
 			emitter.once('plugins:loaded', callback);
@@ -107,10 +118,29 @@ var fs = require('fs'),
 				});
 
 				next();
-			}
+			},
+			async.apply(Plugins.reloadRoutes)
 		], callback);
 	};
 
+	Plugins.reloadRoutes = function(callback) {
+		if (!app || !middleware || !controllers) {
+			return;
+		} else {
+			var router = express.Router();
+			router.hotswapId = 'plugins';
+
+			// Deprecated as of v0.5.0, remove this hook call for NodeBB v0.6.0-1
+			Plugins.fireHook('action:app.load', router, middleware, controllers);
+
+			Plugins.fireHook('static:app.load', router, middleware, controllers, function() {
+				hotswap.replace('plugins', router);
+			});
+
+			callback();
+		}
+	};
+
 	Plugins.loadPlugin = function(pluginPath, callback) {
 		fs.readFile(path.join(pluginPath, 'plugin.json'), function(err, data) {
 			if (err) {
diff --git a/src/routes/debug.js b/src/routes/debug.js
index a03c5b2649..30f6eaf8b8 100644
--- a/src/routes/debug.js
+++ b/src/routes/debug.js
@@ -56,6 +56,10 @@ module.exports = function(app, middleware, controllers) {
 	});
 
 	router.get('/test', function(req, res) {
-		res.redirect('404');
+		res.redirect(404);
+		var plugins = require('../plugins');
+		plugins.reloadRoutes(function() {
+			res.send(200, 'routes replaced');
+		});
 	});
 };
diff --git a/src/routes/index.js b/src/routes/index.js
index e843175098..2d2cd8730e 100644
--- a/src/routes/index.js
+++ b/src/routes/index.js
@@ -152,57 +152,61 @@ function groupRoutes(app, middleware, controllers) {
 
 
 module.exports = function(app, middleware) {
-	plugins.ready(function() {
-		var router = express.Router(),
-			relativePath = nconf.get('relative_path');
-
-		router.render = function() {
-			app.render.apply(app, arguments);
-		};
-
-		app.all(relativePath + '/api/?*', middleware.updateLastOnlineTime, middleware.prepareAPI);
-		app.all(relativePath + '/api/admin/*', middleware.admin.isAdmin, middleware.prepareAPI);
-		app.all(relativePath + '/admin/*', middleware.admin.isAdmin);
-		app.get(relativePath + '/admin', middleware.admin.isAdmin);
-
-		// Deprecated as of v0.5.0, remove this hook call for NodeBB v0.6.0-1
-		plugins.fireHook('action:app.load', router, middleware, controllers);
-
-		adminRoutes(router, middleware, controllers);
-		metaRoutes(router, middleware, controllers);
-		apiRoutes(router, middleware, controllers);
-		feedRoutes(router, middleware, controllers);
-		pluginRoutes(router, middleware, controllers);
-		authRoutes.createRoutes(router, middleware, controllers);
-
-		/**
-		* Every view has an associated API route.
-		*
-		*/
-		mainRoutes(router, middleware, controllers);
-		staticRoutes(router, middleware, controllers);
-		topicRoutes(router, middleware, controllers);
-		tagRoutes(router, middleware, controllers);
-		categoryRoutes(router, middleware, controllers);
-		accountRoutes(router, middleware, controllers);
-		userRoutes(router, middleware, controllers);
-		groupRoutes(router, middleware, controllers);
-
-		plugins.fireHook('static:app.load', router, middleware, controllers, function() {
-			app.use(relativePath, router);
-
-			app.use(relativePath, express.static(path.join(__dirname, '../../', 'public'), {
-				maxAge: app.enabled('cache') ? 5184000000 : 0
-			}));
-			app.use(catch404);
-			app.use(handleErrors);
-		});
-	});
-
+	var router = express.Router(),
+		pluginRouter = express.Router(),
+		relativePath = nconf.get('relative_path');
+
+	pluginRouter.render = function() {
+		app.render.apply(app, arguments);
+	};
+	pluginRouter.hotswapId = 'plugins';
+
+	app.all(relativePath + '/api/?*', middleware.updateLastOnlineTime, middleware.prepareAPI);
+	app.all(relativePath + '/api/admin/*', middleware.admin.isAdmin, middleware.prepareAPI);
+	app.all(relativePath + '/admin/*', middleware.admin.isAdmin);
+	app.get(relativePath + '/admin', middleware.admin.isAdmin);
+
+	adminRoutes(router, middleware, controllers);
+	metaRoutes(router, middleware, controllers);
+	apiRoutes(router, middleware, controllers);
+	feedRoutes(router, middleware, controllers);
+	pluginRoutes(router, middleware, controllers);
+	authRoutes.createRoutes(router, middleware, controllers);
+
+	/**
+	* Every view has an associated API route.
+	*
+	*/
+	mainRoutes(router, middleware, controllers);
+	staticRoutes(router, middleware, controllers);
+	topicRoutes(router, middleware, controllers);
+	tagRoutes(router, middleware, controllers);
+	categoryRoutes(router, middleware, controllers);
+	accountRoutes(router, middleware, controllers);
+	userRoutes(router, middleware, controllers);
+	groupRoutes(router, middleware, controllers);
+
+	// Add the routers to the application
+	app.use(relativePath, router);
+	app.use(relativePath, pluginRouter);
+	app.use(relativePath, express.static(path.join(__dirname, '../../', 'public'), {
+		maxAge: app.enabled('cache') ? 5184000000 : 0
+	}));
 	if (process.env.NODE_ENV === 'development') {
 		require('./debug')(app, middleware, controllers);
 	}
-
+	app.use(catch404);
+	app.use(handleErrors);
+
+	// Add plugin routes
+	plugins.reloadRoutes();
+	// plugins.ready(function() {
+	// 	plugins.fireHook('static:app.load', pluginRouter, middleware, controllers, function() {
+			
+
+			
+	// 	});
+	// });
 };
 
 function handleErrors(err, req, res, next) {
diff --git a/src/webserver.js b/src/webserver.js
index 9b50f0b553..f2595ddabc 100644
--- a/src/webserver.js
+++ b/src/webserver.js
@@ -56,6 +56,7 @@ if(nconf.get('ssl')) {
 	}, function(err, data) {
 		middleware = middleware(app, data);
 		routes(app, middleware);
+		plugins.prepareApp(app, middleware);
 
 		if (err) {
 			winston.error('Errors were encountered while attempting to initialise NodeBB.');