/**
 * editor_plugin_src.js
 *
 * Copyright 2009, Moxiecode Systems AB
 * Released under LGPL License.
 *
 * License: http://tinymce.moxiecode.com/license
 * Contributing: http://tinymce.moxiecode.com/contributing
 *
 * Adds auto-save capability to the TinyMCE text editor to rescue content
 * inadvertently lost. This plugin was originally developed by Speednet
 * and that project can be found here: http://code.google.com/p/tinyautosave/
 *
 * TECHNOLOGY DISCUSSION:
 * 
 * The plugin attempts to use the most advanced features available in the current browser to save
 * as much content as possible.  There are a total of four different methods used to autosave the
 * content.  In order of preference, they are:
 * 
 * 1. localStorage - A new feature of HTML 5, localStorage can store megabytes of data per domain
 * on the client computer. Data stored in the localStorage area has no expiration date, so we must
 * manage expiring the data ourselves.  localStorage is fully supported by IE8, and it is supposed
 * to be working in Firefox 3 and Safari 3.2, but in reality is is flaky in those browsers.  As
 * HTML 5 gets wider support, the AutoSave plugin will use it automatically. In Windows Vista/7,
 * localStorage is stored in the following folder:
 * C:\Users\[username]\AppData\Local\Microsoft\Internet Explorer\DOMStore\[tempFolder]
 * 
 * 2. sessionStorage - A new feature of HTML 5, sessionStorage works similarly to localStorage,
 * except it is designed to expire after a certain amount of time.  Because the specification
 * around expiration date/time is very loosely-described, it is preferrable to use locaStorage and
 * manage the expiration ourselves.  sessionStorage has similar storage characteristics to
 * localStorage, although it seems to have better support by Firefox 3 at the moment.  (That will
 * certainly change as Firefox continues getting better at HTML 5 adoption.)
 * 
 * 3. UserData - A very under-exploited feature of Microsoft Internet Explorer, UserData is a
 * way to store up to 128K of data per "document", or up to 1MB of data per domain, on the client
 * computer.  The feature is available for IE 5+, which makes it available for every version of IE
 * supported by TinyMCE.  The content is persistent across browser restarts and expires on the
 * date/time specified, just like a cookie.  However, the data is not cleared when the user clears
 * cookies on the browser, which makes it well-suited for rescuing autosaved content.  UserData,
 * like other Microsoft IE browser technologies, is implemented as a behavior attached to a
 * specific DOM object, so in this case we attach the behavior to the same DOM element that the
 * TinyMCE editor instance is attached to.
 */

(function(tinymce) {
    // Setup constants to help the compressor to reduce script size
    var PLUGIN_NAME = 'autosave',
        RESTORE_DRAFT = 'restoredraft',
        TRUE = true,
        undefined,
        unloadHandlerAdded,
        Dispatcher = tinymce.util.Dispatcher;

    /**
     * This plugin adds auto-save capability to the TinyMCE text editor to rescue content
     * inadvertently lost. By using localStorage.
     *
     * @class tinymce.plugins.AutoSave
     */
    tinymce.create('tinymce.plugins.AutoSave', {
        /**
         * Initializes the plugin, this will be executed after the plugin has been created.
         * This call is done before the editor instance has finished it's initialization so use the onInit event
         * of the editor instance to intercept that event.
         *
         * @method init
         * @param {tinymce.Editor} ed Editor instance that the plugin is initialized in.
         * @param {string} url Absolute URL to where the plugin is located.
         */
        init : function(ed, url) {
            var self = this, settings = ed.settings;

            self.editor = ed;

            // Parses the specified time string into a milisecond number 10m, 10s etc.
            function parseTime(time) {
                var multipels = {
                    s : 1000,
                    m : 60000
                };

                time = /^(\d+)([ms]?)$/.exec('' + time);

                return (time[2] ? multipels[time[2]] : 1) * parseInt(time);
            };

            // Default config
            tinymce.each({
                ask_before_unload : TRUE,
                interval : '30s',
                retention : '20m',
                minlength : 50
            }, function(value, key) {
                key = PLUGIN_NAME + '_' + key;

                if (settings[key] === undefined)
                    settings[key] = value;
            });

            // Parse times
            settings.autosave_interval = parseTime(settings.autosave_interval);
            settings.autosave_retention = parseTime(settings.autosave_retention);

            // Register restore button
            ed.addButton(RESTORE_DRAFT, {
                title : PLUGIN_NAME + ".restore_content",
                onclick : function() {
                    if (ed.getContent({draft: true}).replace(/\s|&nbsp;|<\/?p[^>]*>|<br[^>]*>/gi, "").length > 0) {
                        // Show confirm dialog if the editor isn't empty
                        ed.windowManager.confirm(
                            PLUGIN_NAME + ".warning_message",
                            function(ok) {
                                if (ok)
                                    self.restoreDraft();
                            }
                        );
                    } else
                        self.restoreDraft();
                }
            });

            // Enable/disable restoredraft button depending on if there is a draft stored or not
            ed.onNodeChange.add(function() {
                var controlManager = ed.controlManager;

                if (controlManager.get(RESTORE_DRAFT))
                    controlManager.setDisabled(RESTORE_DRAFT, !self.hasDraft());
            });

            ed.onInit.add(function() {
                // Check if the user added the restore button, then setup auto storage logic
                if (ed.controlManager.get(RESTORE_DRAFT)) {
                    // Setup storage engine
                    self.setupStorage(ed);

                    // Auto save contents each interval time
                    setInterval(function() {
                        if (!ed.removed) {
                            self.storeDraft();
                            ed.nodeChanged();
                        }
                    }, settings.autosave_interval);
                }
            });

            /**
             * This event gets fired when a draft is stored to local storage.
             *
             * @event onStoreDraft
             * @param {tinymce.plugins.AutoSave} sender Plugin instance sending the event.
             * @param {Object} draft Draft object containing the HTML contents of the editor.
             */
            self.onStoreDraft = new Dispatcher(self);

            /**
             * This event gets fired when a draft is restored from local storage.
             *
             * @event onStoreDraft
             * @param {tinymce.plugins.AutoSave} sender Plugin instance sending the event.
             * @param {Object} draft Draft object containing the HTML contents of the editor.
             */
            self.onRestoreDraft = new Dispatcher(self);

            /**
             * This event gets fired when a draft removed/expired.
             *
             * @event onRemoveDraft
             * @param {tinymce.plugins.AutoSave} sender Plugin instance sending the event.
             * @param {Object} draft Draft object containing the HTML contents of the editor.
             */
            self.onRemoveDraft = new Dispatcher(self);

            // Add ask before unload dialog only add one unload handler
            if (!unloadHandlerAdded) {
                window.onbeforeunload = tinymce.plugins.AutoSave._beforeUnloadHandler;
                unloadHandlerAdded = TRUE;
            }
        },

        /**
         * Returns information about the plugin as a name/value array.
         * The current keys are longname, author, authorurl, infourl and version.
         *
         * @method getInfo
         * @return {Object} Name/value array containing information about the plugin.
         */
        getInfo : function() {
            return {
                longname : 'Auto save',
                author : 'Moxiecode Systems AB',
                authorurl : 'http://tinymce.moxiecode.com',
                infourl : 'http://wiki.moxiecode.com/index.php/TinyMCE:Plugins/autosave',
                version : tinymce.majorVersion + "." + tinymce.minorVersion
            };
        },

        /**
         * Returns an expiration date UTC string.
         *
         * @method getExpDate
         * @return {String} Expiration date UTC string.
         */
        getExpDate : function() {
            return new Date(
                new Date().getTime() + this.editor.settings.autosave_retention
            ).toUTCString();
        },

        /**
         * This method will setup the storage engine. If the browser has support for it.
         *
         * @method setupStorage
         */
        setupStorage : function(ed) {
            var self = this, testKey = PLUGIN_NAME + '_test', testVal = "OK";

            self.key = PLUGIN_NAME + ed.id;

            // Loop though each storage engine type until we find one that works
            tinymce.each([
                function() {
                    // Try HTML5 Local Storage
                    if (localStorage) {
                        localStorage.setItem(testKey, testVal);

                        if (localStorage.getItem(testKey) === testVal) {
                            localStorage.removeItem(testKey);

                            return localStorage;
                        }
                    }
                },

                function() {
                    // Try HTML5 Session Storage
                    if (sessionStorage) {
                        sessionStorage.setItem(testKey, testVal);

                        if (sessionStorage.getItem(testKey) === testVal) {
                            sessionStorage.removeItem(testKey);

                            return sessionStorage;
                        }
                    }
                },

                function() {
                    // Try IE userData
                    if (tinymce.isIE) {
                        ed.getElement().style.behavior = "url('#default#userData')";

                        // Fake localStorage on old IE
                        return {
                            autoExpires : TRUE,

                            setItem : function(key, value) {
                                var userDataElement = ed.getElement();

                                userDataElement.setAttribute(key, value);
                                userDataElement.expires = self.getExpDate();

                                try {
                                    userDataElement.save("TinyMCE");
                                } catch (e) {
                                    // Ignore, saving might fail if "Userdata Persistence" is disabled in IE
                                }
                            },

                            getItem : function(key) {
                                var userDataElement = ed.getElement();

                                try {
                                    userDataElement.load("TinyMCE");
                                    return userDataElement.getAttribute(key);
                                } catch (e) {
                                    // Ignore, loading might fail if "Userdata Persistence" is disabled in IE
                                    return null;
                                }
                            },

                            removeItem : function(key) {
                                ed.getElement().removeAttribute(key);
                            }
                        };
                    }
                },
            ], function(setup) {
                // Try executing each function to find a suitable storage engine
                try {
                    self.storage = setup();

                    if (self.storage)
                        return false;
                } catch (e) {
                    // Ignore
                }
            });
        },

        /**
         * This method will store the current contents in the the storage engine.
         *
         * @method storeDraft
         */
        storeDraft : function() {
            var self = this, storage = self.storage, editor = self.editor, expires, content;

            // Is the contents dirty
            if (storage) {
                // If there is no existing key and the contents hasn't been changed since
                // it's original value then there is no point in saving a draft
                if (!storage.getItem(self.key) && !editor.isDirty())
                    return;

                // Store contents if the contents if longer than the minlength of characters
                content = editor.getContent({draft: true});
                if (content.length > editor.settings.autosave_minlength) {
                    expires = self.getExpDate();

                    // Store expiration date if needed IE userData has auto expire built in
                    if (!self.storage.autoExpires)
                        self.storage.setItem(self.key + "_expires", expires);

                    self.storage.setItem(self.key, content);
                    self.onStoreDraft.dispatch(self, {
                        expires : expires,
                        content : content
                    });
                }
            }
        },

        /**
         * This method will restore the contents from the storage engine back to the editor.
         *
         * @method restoreDraft
         */
        restoreDraft : function() {
            var self = this, storage = self.storage, content;

            if (storage) {
                content = storage.getItem(self.key);

                if (content) {
                    self.editor.setContent(content);
                    self.onRestoreDraft.dispatch(self, {
                        content : content
                    });
                }
            }
        },

        /**
         * This method will return true/false if there is a local storage draft available.
         *
         * @method hasDraft
         * @return {boolean} true/false state if there is a local draft.
         */
        hasDraft : function() {
            var self = this, storage = self.storage, expDate, exists;

            if (storage) {
                // Does the item exist at all
                exists = !!storage.getItem(self.key);
                if (exists) {
                    // Storage needs autoexpire
                    if (!self.storage.autoExpires) {
                        expDate = new Date(storage.getItem(self.key + "_expires"));

                        // Contents hasn't expired
                        if (new Date().getTime() < expDate.getTime())
                            return TRUE;

                        // Remove it if it has
                        self.removeDraft();
                    } else
                        return TRUE;
                }
            }

            return false;
        },

        /**
         * Removes the currently stored draft.
         *
         * @method removeDraft
         */
        removeDraft : function() {
            var self = this, storage = self.storage, key = self.key, content;

            if (storage) {
                // Get current contents and remove the existing draft
                content = storage.getItem(key);
                storage.removeItem(key);
                storage.removeItem(key + "_expires");

                // Dispatch remove event if we had any contents
                if (content) {
                    self.onRemoveDraft.dispatch(self, {
                        content : content
                    });
                }
            }
        },

        "static" : {
            // Internal unload handler will be called before the page is unloaded
            _beforeUnloadHandler : function(e) {
                var msg;

                tinymce.each(tinyMCE.editors, function(ed) {
                    // Store a draft for each editor instance
                    if (ed.plugins.autosave)
                        ed.plugins.autosave.storeDraft();

                    // Never ask in fullscreen mode
                    if (ed.getParam("fullscreen_is_enabled"))
                        return;

                    // Setup a return message if the editor is dirty
                    if (!msg && ed.isDirty() && ed.getParam("autosave_ask_before_unload"))
                        msg = ed.getLang("autosave.unload_msg");
                });

                return msg;
            }
        }
    });

    tinymce.PluginManager.add('autosave', tinymce.plugins.AutoSave);
})(tinymce);
