first pass at plugin system -- not tested!

app.js

@@ -57,6 +57,7 @@ if (!nconf.get('setup') && nconf.get('base_url')) {
 			templates = require('./public/src/templates.js'),
 			webserver = require('./src/webserver.js'),
 			websockets = require('./src/websockets.js'),
+			plugins = require('./src/plugins'),
 			admin = {
 				'categories': require('./src/admin/categories.js')
 			};

src/plugins.js

@@ -0,0 +1,115 @@
+var	fs = require('fs'),
+	path = require('path'),
+	RDB = require('./redis.js'),
+	plugins = {
+		libraries: [],
+		loaded_hooks: {},
+		init: function() {
+			if (this.initialized) return;
+			if (global.env === 'development') console.log('Info: [plugins] Initializing plugins system');
+
+			var	_self = this;
+
+			// Read the list of activated plugins and require their libraries
+			async.waterfall([
+				function(next) {
+					RDB.smembers('plugins:active', next);
+				},
+				function(plugins, next) {
+					async.each(plugins, function(plugin) {
+						// TODO: Update this check to also check node_modules
+						var	pluginPath = path.join(__dirname, '../plugins/', plugin);
+						fs.exists(pluginPath, function(exists) {
+							if (exists) {
+								fs.readFile(path.join(pluginPath, 'plugin.json'), function(err, data) {
+									if (err) return next(err);
+
+									var	pluginData = JSON.parse(data);
+									_self.libraries[pluginData.id] = require(path.join(pluginPath, pluginData.library));
+									if (pluginData.hooks) {
+										for(var x=0,numHooks=pluginData.hooks.length;x<numHooks;x++) {
+											_self.register_hook(pluginData.id, pluginData.hooks[x]);
+										}
+									}
+									if (global.env === 'development') console.log('Info: [plugins] Loaded plugin: ' + pluginData.id);
+
+									next();
+								});
+							} else {
+								if (global.env === 'development') console.log('Info: [plugins] Plugin \'' + plugin + '\' not found');
+								next();	// Ignore this plugin silently
+							}
+						})
+					}, next);
+				}
+			], function(err) {
+				if (err) {
+					if (global.env === 'development') console.log('Info: [plugins] NodeBB encountered a problem while loading plugins', err.message);
+					return;
+				}
+
+				if (global.env === 'development') console.log('Info: [plugins] Plugins OK');
+			});
+		},
+		initialized: false,
+		register_hook: function(id, data) {
+			/*
+				`data` is an object consisting of (* is required):
+					`data.hook`*, the name of the NodeBB hook
+					`data.method`*, the method called in that plugin
+					`data.callbacked`, whether or not the hook expects a callback (true), or a return (false). (Default: false)
+					(Not implemented) `data.priority`, the relative priority of the method when it is eventually called (default: 10)
+			*/
+			var	_self = this;
+
+			if (data.hook && data.method) {
+				_self.loaded_hooks[data.hook] = _self.loaded_hooks[data.hook] || [];
+				_self.loaded_hooks[data.hook].push([id, data.method]);
+				if (global.env === 'development') console.log('Info: [plugins] Hook registered: ' + data.hook + ' will call ' + id);
+			} else return;
+		},
+		fire_hook: function(hook, args, callback) {
+			// TODO: Implement priority hook firing
+			var	_self = this
+				hookList = loaded_hooks[hook];
+
+			if(loaded_hooks[hook] && Array.isArray(hookList)) {
+				if (global.env === 'development') console.log('Info: [plugins] Firing hook: ' + hook);
+				var	hookType = hook.split(':')[0];
+				switch(hookType) {
+					case 'filter':
+						// Filters only take one argument, so only args[0] will be passed in
+						var	returnVal = args[0];
+
+						async.each(hookList, function(hookObj, next) {
+							if (hookObj.callbacked) {
+								_self.libraries[hookObj.id][hookObj.method](returnVal, function(err, afterVal) {
+									returnVal = afterVal;
+									next(err);
+								});
+							} else {
+								returnVal = _self.libraries[hookObj.id][hookObj.method](returnVal);
+								next();
+							}
+						}, function(err) {
+							if (err) {
+								if (global.env === 'development') console.log('Info: [plugins] Problem executing hook: ' + hook);
+							}
+
+							callback(returnVal);
+						});
+					break;
+					case 'action':
+
+					break;
+					default:
+						// Do nothing...
+					break;
+				}
+			}
+		}
+	}
+
+plugins.init();
+
+module.exports = plugins;