/*
 * Copyright 2014 XWiki SAS
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
define([
    '/common/messages.js',
    '/bower_components/reconnectingWebsocket/reconnecting-websocket.js',
    '/common/crypto.js',
    '/common/toolbar.js',
    '/common/sharejs_textarea.js',
    '/common/chainpad.js',
    '/bower_components/jquery/dist/jquery.min.js',
], function (Messages, ReconnectingWebSocket, Crypto, Toolbar, sharejs) {
    var $ = window.jQuery;
    var ChainPad = window.ChainPad;
    var PARANOIA = true;
    var module = { exports: {} };

    /**
     * If an error is encountered but it is recoverable, do not immediately fail
     * but if it keeps firing errors over and over, do fail.
     */
    var MAX_RECOVERABLE_ERRORS = 15;

    /** Maximum number of milliseconds of lag before we fail the connection. */
    var MAX_LAG_BEFORE_DISCONNECT = 20000;

    var debug = function (x) { console.log(x); },
        warn = function (x) { console.error(x); },
        verbose = function (x) { /*console.log(x);*/ };

    // ------------------ Trapping Keyboard Events ---------------------- //

    var bindEvents = function (element, events, callback, unbind) {
        for (var i = 0; i < events.length; i++) {
            var e = events[i];
            if (element.addEventListener) {
                if (unbind) {
                    element.removeEventListener(e, callback, false);
                } else {
                    element.addEventListener(e, callback, false);
                }
            } else {
                if (unbind) {
                    element.detachEvent('on' + e, callback);
                } else {
                    element.attachEvent('on' + e, callback);
                }
            }
        }
    };

    var bindAllEvents = function (textarea, docBody, onEvent, unbind)
    {
        /*
            we use docBody for the purposes of CKEditor.
            because otherwise special keybindings like ctrl-b and ctrl-i
            would open bookmarks and info instead of applying bold/italic styles
        */
        if (docBody) {
            bindEvents(docBody,
               ['textInput', 'keydown', 'keyup', 'select', 'cut', 'paste'],
               onEvent,
               unbind);
        }
        bindEvents(textarea,
                   ['mousedown','mouseup','click','change'],
                   onEvent,
                   unbind);
    };

    var isSocketDisconnected = function (socket, realtime) {
        var sock = socket._socket;
        return sock.readyState === sock.CLOSING
            || sock.readyState === sock.CLOSED
            || (realtime.getLag().waiting && realtime.getLag().lag > MAX_LAG_BEFORE_DISCONNECT);
    };

    // this differs from other functions with similar names in that
    // you are expected to pass a socket into it.
    var checkSocket = function (socket) {
        if (isSocketDisconnected(socket, socket.realtime) &&
            !socket.intentionallyClosing) {
            return true;
        } else {
            return false;
        }
    };

    var abort = function (socket, realtime) {
        realtime.abort();
        try { socket._socket.close(); } catch (e) { warn(e); }
    };

    var handleError = function (socket, realtime, err, docHTML, allMessages) {
        // var internalError = createDebugInfo(err, realtime, docHTML, allMessages);
        abort(socket, realtime);
    };

    var makeWebsocket = function (url) {
        var socket = new ReconnectingWebSocket(url);
        var out = {
            onOpen: [],
            onClose: [],
            onError: [],
            onMessage: [],
            send: function (msg) { socket.send(msg); },
            close: function () { socket.close(); },
            _socket: socket
        };
        var mkHandler = function (name) {
            return function (evt) {
                for (var i = 0; i < out[name].length; i++) {
                    if (out[name][i](evt) === false) {
                        console.log(name +"Handler");
                        return;
                    }
                }
            };
        };
        socket.onopen = mkHandler('onOpen');
        socket.onclose = mkHandler('onClose');
        socket.onerror = mkHandler('onError');
        socket.onmessage = mkHandler('onMessage');
        return out;
    };

    var start = module.exports.start =
        function (textarea, websocketUrl, userName, channel, cryptKey, config)
    {

        var passwd = 'y';

        // make sure configuration is defined
        config = config || {};

        var doc = config.doc || null;

        // trying to deprecate onRemote, prefer loading it via the conf
        onRemote = config.onRemote || null;

        transformFunction = config.transformFunction || null;

        var socket = makeWebsocket(websocketUrl);
        // define this in case it gets called before the rest of our stuff is ready.
        var onEvent = function () { };

        var allMessages = [];
        var isErrorState = false;
        var initializing = true;
        var recoverableErrorCount = 0;

        var $textarea = $(textarea);

        var bump = function () {};

        socket.onOpen.push(function (evt) {
            if (!initializing) {
                console.log("Starting");
                socket.realtime.start();
                return;
            }

            var realtime = socket.realtime = ChainPad.create(userName,
                                passwd,
                                channel,
                                $(textarea).val(),
                                {
                                    transformFunction: config.transformFunction
                                });

            if (config.onInit) {
                config.onInit({
                    realtime: realtime
                });
            }

            onEvent = function () {
                if (isErrorState || initializing) { return; }
            };

            realtime.onUserListChange(function (userList) {
                if (!initializing || userList.indexOf(userName) === -1) {
                    return;
                }
                // if we spot ourselves being added to the document, we'll switch
                // 'initializing' off because it means we're fully synced.
                initializing = false;

                // execute an onReady callback if one was supplied
                // pass an object so we can extend this later
                if (config.onReady) {
                    config.onReady({
                        userList: userList
                    });
                }
            });

            var whoami = new RegExp(userName.replace(/\/\+/g, function (c) {
                return '\\' +c;
            }));

            // when you receive a message...
            socket.onMessage.push(function (evt) {
                verbose(evt.data);
                if (isErrorState) { return; }

                var message = Crypto.decrypt(evt.data, cryptKey);
                verbose(message);
                allMessages.push(message);
                if (!initializing) {
                    if (PARANOIA) {
                        onEvent();
                    }
                }
                realtime.message(message);
                if (/\[5,/.test(message)) { verbose("pong"); }

                if (!initializing) {
                    if (/\[2,/.test(message)) {
                        //verbose("Got a patch");
                        if (whoami.test(message)) {
                            //verbose("Received own message");
                        } else {
                            //verbose("Received remote message");
                            // obviously this is only going to get called if
                            if (onRemote) { onRemote(realtime.getUserDoc()); }
                        }
                    }
                }
            });

            // when a message is ready to send
            realtime.onMessage(function (message) {
                if (isErrorState) { return; }
                message = Crypto.encrypt(message, cryptKey);
                try {
                    socket.send(message);
                } catch (e) {
                    warn(e);
                }
            });

            // actual socket bindings
            socket.onmessage = function (evt) {
                for (var i = 0; i < socket.onMessage.length; i++) {
                    if (socket.onMessage[i](evt) === false) { return; }
                }
            };
            socket.onclose = function (evt) {
                for (var i = 0; i < socket.onMessage.length; i++) {
                    if (socket.onClose[i](evt) === false) { return; }
                }
            };

            socket.onerror = warn;

            var socketChecker = setInterval(function () {
                if (checkSocket(socket)) {
                    warn("Socket disconnected!");

                    recoverableErrorCount += 1;

                    if (recoverableErrorCount >= MAX_RECOVERABLE_ERRORS) {
                        warn("Giving up!");
                        abort(socket, realtime);
                        if (socketChecker) { clearInterval(socketChecker); }
                    }
                } else {
                    // TODO
                }
            },200);

            bindAllEvents(textarea, doc, onEvent, false);

            // attach textarea?
            sharejs.attach(textarea, realtime);

            realtime.start();
            debug('started');

            bump = realtime.bumpSharejs;
        });
        return {
            onEvent: function () {
                onEvent();
            },
            bumpSharejs: function () { bump(); }
        };
    };
    return module.exports;
});