'use strict';

/*
 * Logger module: ability to dynamically turn on/off logging for http requests & socket.io events
 */

var fs = require('fs'),
	path = require('path'),
	express = require('express'),
	winston = require('winston'),
	util = require('util'),
	socketio = require('socket.io'),
	meta = require('./meta');

var opts = {
	/*
	 * state used by Logger
	 */
	express : {
		app : {},
		set : 0,
		ofn : null,
	},
	streams : {
		log : { f : process.stdout },
	}
};


/* -- Logger -- */

(function(Logger) {


	Logger.init = function(app) {
		opts.express.app = app;
		/* Open log file stream & initialize express logging if meta.config.logger* variables are set */
		Logger.setup();
	};

	Logger.setup = function() {
		Logger.setup_one('loggerPath', meta.config.loggerPath);
	};

	Logger.setup_one = function(key, value) {
		/*
		 * 1. Open the logger stream: stdout or file
		 * 2. Re-initialize the express logger hijack
		 */
		if (key === 'loggerPath') {
			Logger.setup_one_log(value);
			Logger.express_open();
		}
	};

	Logger.setup_one_log = function(value) {
		/*
		 * If logging is currently enabled, create a stream.
		 * Otherwise, close the current stream
		 */
		if(meta.config.loggerStatus > 0 || meta.config.loggerIOStatus) {
			var stream = Logger.open(value);
			if(stream) {
				opts.streams.log.f = stream;
			} else {
				opts.streams.log.f = process.stdout;
			}
		}
		else {
			Logger.close(opts.streams.log);
		}
	};

	Logger.open = function(value) {
		/* Open the streams to log to: either a path or stdout */
		var stream;
		if(value) {
			if(fs.existsSync(value)) {
				var stats = fs.statSync(value);
				if(stats) {
					if(stats.isDirectory()) {
						stream = fs.createWriteStream(path.join(value, 'nodebb.log'), {flags: 'a'});
					} else {
						stream = fs.createWriteStream(value, {flags: 'a'});
					}
				}
			} else {
				stream = fs.createWriteStream(value, {flags: 'a'});

			}

			if(stream) {
				stream.on('error', function(err) {
					winston.error(err.message);
				});
			}
		} else {
			stream = process.stdout;
		}
		return stream;
	};

	Logger.close = function(stream) {
		if(stream.f !== process.stdout && stream.f) {
			stream.end();
		}
		stream.f = null;
	};

	Logger.monitorConfig = function(socket, data) {
		/*
		 * This monitor's when a user clicks "save" in the Logger section of the admin panel
		 */
		Logger.setup_one(data.key,data.value);
		Logger.io_close(socket);
		Logger.io(socket);
	};

	Logger.express_open = function() {
		if(opts.express.set !== 1) {
			opts.express.set = 1;
			opts.express.app.use(Logger.expressLogger);
		}
		/*
		 * Always initialize "ofn" (original function) with the original logger function
		 */
		opts.express.ofn = express.logger({stream : opts.streams.log.f});
	};

	Logger.expressLogger = function(req,res,next) {
		/*
		 * The new express.logger
		 *
		 * This hijack allows us to turn logger on/off dynamically within express
		 */
		if(meta.config.loggerStatus > 0) {
			return opts.express.ofn(req,res,next);
		} else {
			return next();
		}
	};

	Logger.prepare_io_string = function(_type, _uid, _args) {
		/*
		 * This prepares the output string for intercepted socket.io events
		 *
		 * The format is: io: <uid> <event> <args>
		 */
		try {
			return 'io: '+_uid+' '+_type+' '+util.inspect(Array.prototype.slice.call(_args))+'\n';
		} catch(err) {
			winston.info("Logger.prepare_io_string: Failed", err);
			return "error";
		}
	};

	Logger.io_close = function(socket) {
		/*
		 * Restore all hijacked sockets to their original emit/on functions
		 */
		var clients = socket.io.sockets.clients();
		clients.forEach(function(client) {
			if(client.oEmit && client.oEmit !== client.emit) {
				client.emit = client.oEmit;
			}

			if(client.$oEmit && client.$oEmit !== client.$emit) {
				client.$emit = client.$oEmit;
			}
		});
	};

	Logger.io = function(socket) {
		/*
		 * Go through all of the currently established sockets & hook their .emit/.on
		 */
		if(!socket && !socket.io.sockets) {
			return;
		}

		var clients = socket.io.sockets.clients();

		clients.forEach(function(client) {
			Logger.io_one(client, client.uid);
		});
	};

	Logger.io_one = function(socket, uid) {
		/*
		 * This function replaces a socket's .emit/.on functions in order to intercept events
		 */
		if(socket && meta.config.loggerIOStatus > 0) {

			(function() {
				function override(method, name, errorMsg) {
					return function() {
						if(opts.streams.log.f) {
							opts.streams.log.f.write(Logger.prepare_io_string(name, uid, arguments));
						}

						try {
							method.apply(socket, arguments);
						} catch(err) {
							winston.info(errorMsg, err);
						}
					};
				}

				// courtesy of: http://stackoverflow.com/a/9674248
				socket.oEmit = socket.emit;
				var emit = socket.emit;
				socket.emit = override(emit, 'emit', 'Logger.io_one: emit.apply: Failed');

				socket.$oEmit = socket.$emit;
				var $emit = socket.$emit;
				socket.$emit = override($emit, 'on', 'Logger.io_one: $emit.apply: Failed');

			})();
		}
	};

}(exports));