'use strict';

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

var fs = require('fs');
var path = require('path');
var winston = require('winston');
var util = require('util');

var file = require('./file');
var meta = require('./meta');
var morgan = require('morgan');

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 (file.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 = morgan('combined', { 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);
		}
		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
		 */
		if (!socket || !socket.io || !socket.io.sockets || !socket.io.sockets.sockets) {
			return;
		}
		var clients = socket.io.sockets.sockets;
		for (var sid in clients) {
			if (clients.hasOwnProperty(sid)) {
				var client = clients[sid];
				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 || !socket.io.sockets || !socket.io.sockets.sockets) {
			return;
		}

		var clients = socket.io.sockets.sockets;
		for (var sid in clients) {
			if (clients.hasOwnProperty(sid)) {
				Logger.io_one(clients[sid], clients[sid].uid);
			}
		}
	};

	Logger.io_one = function (socket, uid) {
		/*
		 * This function replaces a socket's .emit/.on functions in order to intercept events
		 */
		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);
				}
			};
		}

		if (socket && meta.config.loggerIOStatus > 0) {
			// 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));