/* vim: set expandtab sw=4 ts=4 sts=4: */
/**
 * This object handles ajax requests for pages. It also
 * handles the reloading of the main menu and scripts.
 */
var AJAX = {
    /**
     * @var bool active Whether we are busy
     */
    active: false,
    /**
     * @var object source The object whose event initialized the request
     */
    source: null,
    /**
     * @var function Callback to execute after a successful request
     *               Used by PMA_commonFunctions from common.js
     */
    _callback: function () {},
    /**
     * @var bool _debug Makes noise in your Firebug console
     */
    _debug: false,
    /**
     * @var object $msgbox A reference to a jQuery object that links to a message
     *                     box that is generated by PMA_ajaxShowMessage()
     */
    $msgbox: null,
    /**
     * Given the filename of a script, returns a hash to be
     * used to refer to all the events registered for the file
     *
     * @param string key The filename for which to get the event name
     *
     * @return int
     */
    hash: function (key){
        /* http://burtleburtle.net/bob/hash/doobs.html#one */
        key += "";
        var len = key.length, hash=0, i=0;
        for (; i<len; ++i) {
            hash += key.charCodeAt(i);
            hash += (hash << 10);
            hash ^= (hash >> 6);
        }
        hash += (hash << 3);
        hash ^= (hash >> 11);
        hash += (hash << 15);
        return Math.abs(hash);
    },
    /**
     * Registers an onload event for a file
     *
     * @param string   file The filename for which to register the event
     * @param function func The function to execute when the page is ready
     *
     * @return self For chaining
     */
    registerOnload: function (file, func) {
        var eventName = 'onload_' + AJAX.hash(file);
        $(document).bind(eventName, func);
        this._debug && console.log(
            // no need to translate
            "Registered event " + eventName + " for file " + file
        );
        return this;
    },
    /**
     * Registers a teardown event for a file. This is useful to execute functions
     * that unbind events for page elements that are about to be removed.
     *
     * @param string   file The filename for which to register the event
     * @param function func The function to execute when
     *                      the page is about to be torn down
     *
     * @return self For chaining
     */
    registerTeardown: function (file, func) {
        var eventName = 'teardown_' + AJAX.hash(file);
        $(document).bind(eventName, func);
        this._debug && console.log(
            // no need to translate
            "Registered event " + eventName + " for file " + file
        );
        return this;
    },
    /**
     * Called when a page has finished loading, once for every
     * file that registered to the onload event of that file.
     *
     * @param string file The filename for which to fire the event
     *
     * @return void
     */
    fireOnload: function (file) {
        var eventName = 'onload_' + AJAX.hash(file);
        $(document).trigger(eventName);
        this._debug && console.log(
            // no need to translate
            "Fired event " + eventName + " for file " + file
        );
    },
    /**
     * Called just before a page is torn down, once for every
     * file that registered to the teardown event of that file.
     *
     * @param string file The filename for which to fire the event
     *
     * @return void
     */
    fireTeardown: function (file) {
        var eventName = 'teardown_' + AJAX.hash(file);
        $(document).triggerHandler(eventName);
        this._debug && console.log(
            // no need to translate
            "Fired event " + eventName + " for file " + file
        );
    },
    /**
     * Event handler for clicks on links and form submissions
     *
     * @param object e Event data
     *
     * @return void
     */
    requestHandler: function (event) {
        // In some cases we don't want to handle the request here and either
        // leave the browser deal with it natively (e.g: file download)
        // or leave an existing ajax event handler present elsewhere deal with it
        var href = $(this).attr('href');
        if (typeof event != 'undefined' && (event.shiftKey || event.ctrlKey)) {
            return true;
        } else if ($(this).attr('target')) {
            return true;
        } else if ($(this).hasClass('ajax') || $(this).hasClass('disableAjax')) {
            return true;
        } else if (href && href.match(/^#/)) {
            return true;
        } else if (href && href.match(/^mailto/)) {
            return true;
        } else if ($(this).hasClass('ui-datepicker-next') ||
                   $(this).hasClass('ui-datepicker-prev')
                  ) {
            return true;
        }

        if (typeof event != 'undefined') {
            event.preventDefault();
            event.stopImmediatePropagation();
        }
        if (AJAX.active == true) {
            // Silently bail out, there is already a request in progress.
            // TODO: save a reference to the request and cancel the old request
            // when the user requests something else. Something like this is
            // already implemented in the PMA_fastFilter object in navigation.js
            return false;
        }

        AJAX.source = $(this);

        $('html, body').animate({scrollTop: 0}, 'fast');

        var isLink = !! href || false;
        var url = isLink ? href : $(this).attr('action');
        var params = 'ajax_request=true&ajax_page_request=true';
        if (! isLink) {
            params += '&' + $(this).serialize();
        }
        // Add a list of menu hashes that we have in the cache to the request
        params += AJAX.cache.menus.getRequestParam();

        AJAX._debug && console.log("Loading: " + url); // no need to translate

        if (isLink) {
            AJAX.active = true;
            AJAX.$msgbox = PMA_ajaxShowMessage();
            $.get(url, params, AJAX.responseHandler);
        } else {
            /**
             * Manually fire the onsubmit event for the form, if any.
             * The event was saved in the jQuery data object by an onload
             * handler defined below. Workaround for bug #3583316
             */
            var onsubmit = $(this).data('onsubmit');
            // Submit the request if there is no onsubmit handler
            // or if it returns a value that evaluates to true
            if (typeof onsubmit !== 'function' || onsubmit.apply(this, [event])) {
                AJAX.active = true;
                AJAX.$msgbox = PMA_ajaxShowMessage();
                $.post(url, params, AJAX.responseHandler);
            }
        }
    },
    /**
     * Called after the request that was initiated by this.requestHandler()
     * has completed successfully or with a caught error. For completely
     * failed requests or requests with uncaught errors, see the .ajaxError
     * handler at the bottom of this file.
     *
     * To refer to self use 'AJAX', instead of 'this' as this function
     * is called in the jQuery context.
     *
     * @param object e Event data
     *
     * @return void
     */
    responseHandler: function (data) {
        if (data.success) {
            $table_clone = false;
            PMA_ajaxRemoveMessage(AJAX.$msgbox);

            if (data._redirect) {
                PMA_ajaxShowMessage(data._redirect, false);
                AJAX.active = false;
                return;
            }

            AJAX.scriptHandler.reset(function () {
                if (data._reloadNavigation) {
                    PMA_reloadNavigation();
                }
                if (data._reloadQuerywindow) {
                    var params = data._reloadQuerywindow;
                    PMA_querywindow.reload(
                        params.db,
                        params.table,
                        params.sql_query
                    );
                }
                if (data._focusQuerywindow) {
                    PMA_querywindow.focus(
                        data._focusQuerywindow
                    );
                }
                if (data._title) {
                    $('title').replaceWith(data._title);
                }
                if (data._menu) {
                    AJAX.cache.menus.replace(data._menu);
                    AJAX.cache.menus.add(data._menuHash, data._menu);
                } else if (data._menuHash) {
                    AJAX.cache.menus.replace(AJAX.cache.menus.get(data._menuHash));
                }

                // Remove all containers that may have
                // been added outside of #page_content
                $('body').children()
                    .not('#pma_navigation')
                    .not('#floating_menubar')
                    .not('#goto_pagetop')
                    .not('#page_content')
                    .not('#selflink')
                    .not('#session_debug')
                    .remove();
                // Replace #page_content with new content
                if (data.message && data.message.length > 0) {
                    $('#page_content').replaceWith(
                        "<div id='page_content'>" + data.message + "</div>"
                    );
                }

                if (data._selflink) {
                    $('#selflink > a').attr('href', data._selflink);
                }
                if (data._scripts) {
                    AJAX.scriptHandler.load(data._scripts);
                }
                if (data._selflink && data._scripts && data._menuHash && data._params) {
                    AJAX.cache.add(
                        data._selflink,
                        data._scripts,
                        data._menuHash,
                        data._params,
                        AJAX.source.attr('rel')
                    );
                }
                if (data._params) {
                    PMA_commonParams.setAll(data._params);
                }
                if (data._displayMessage) {
                    $('#page_content').prepend(data._displayMessage);
                }

                $('#pma_errors').remove();
                if (data._errors) {
                    $('<div/>', {id:'pma_errors'})
                        .insertAfter('#selflink')
                        .append(data._errors);
                }

                if (typeof AJAX._callback === 'function') {
                    AJAX._callback.call();
                }
                AJAX._callback = function () {};
            });
        } else {
            PMA_ajaxShowMessage(data.error, false);
            AJAX.active = false;
        }
    },
    /**
     * This object is in charge of downloading scripts,
     * keeping track of what's downloaded and firing
     * the onload event for them when the page is ready.
     */
    scriptHandler: {
        /**
         * @var array _scripts The list of files already downloaded
         */
        _scripts: [],
        /**
         * @var array _scriptsToBeLoaded The list of files that
         *                               need to be downloaded
         */
        _scriptsToBeLoaded: [],
        /**
         * @var array _scriptsToBeFired The list of files for which
         *                              to fire the onload event
         */
        _scriptsToBeFired: [],
        /**
         * Records that a file has been downloaded
         *
         * @param string file The filename
         * @param string fire Whether this file will be registering
         *                    onload/teardown events
         *
         * @return self For chaining
         */
        add: function (file, fire) {
            this._scripts.push(file);
            if (fire) {
                // Record whether to fire any events for the file
                // This is necessary to correctly tear down the initial page
                this._scriptsToBeFired.push(file);
            }
            return this;
        },
        /**
         * Download a list of js files in one request
         *
         * @param array files An array of filenames and flags
         *
         * @return void
         */
        load: function (files) {
            var self = this;
            self._scriptsToBeLoaded = [];
            self._scriptsToBeFired = [];
            for (var i in files) {
                self._scriptsToBeLoaded.push(files[i].name);
                if (files[i].fire) {
                    self._scriptsToBeFired.push(files[i].name);
                }
            }
            // Generate a request string
            var request = [];
            var needRequest = false;
            for (var index in self._scriptsToBeLoaded) {
                var script = self._scriptsToBeLoaded[index];
                // Only for scripts that we don't already have
                if ($.inArray(script, self._scripts) == -1) {
                    needRequest = true;
                    this.add(script);
                    request.push("scripts[]=" + script);
                }
            }
            // Download the composite js file, if necessary
            if (needRequest) {
                $.ajax({
                    url: "js/get_scripts.js.php?" + request.join("&"),
                    cache: true,
                    success: function () {
                        self.done();
                    },
                    dataType: "script"
                });
            } else {
                self.done();
            }
        },
        /**
         * Called whenever all files are loaded
         *
         * @return void
         */
        done: function () {
            for (var i in this._scriptsToBeFired) {
                AJAX.fireOnload(this._scriptsToBeFired[i]);
            }
            AJAX.active = false;
        },
        /**
         * Fires all the teardown event handlers for the current page
         * and rebinds all forms and links to the request handler
         *
         * @param function callback The callback to call after resetting
         *
         * @return void
         */
        reset: function (callback) {
            for (var i in this._scriptsToBeFired) {
                AJAX.fireTeardown(this._scriptsToBeFired[i]);
            }
            this._scriptsToBeFired = [];
            /**
             * Re-attach a generic event handler to clicks
             * on pages and submissions of forms
             */
            $('a').die('click').live('click', AJAX.requestHandler);
            $('form').die('submit').live('submit', AJAX.requestHandler);
            AJAX.cache.update();
            callback();
        }
    }
};

/**
 * Here we register a function that will remove the onsubmit event from all
 * forms that will be handled by the generic page loader. We then save this
 * event handler in the "jQuery data", so that we can fire it up later in
 * AJAX.requestHandler().
 *
 * See bug #3583316
 */
AJAX.registerOnload('functions.js', function () {
    // Registering the onload event for functions.js
    // ensures that it will be fired for all pages
    $('form').not('.ajax').not('.disableAjax').each(function () {
        if ($(this).attr('onsubmit')) {
            $(this).data('onsubmit', this.onsubmit).attr('onsubmit', '');
        }
    });
});

/**
 * An implementation of a client-side page cache.
 * This object also uses the cache to provide a simple microhistory,
 * that is the ability to use the back and forward buttons in the browser
 */
AJAX.cache = {
    /**
     * @var int The maximum number of pages to keep in the cache
     */
    MAX: 6,
    /**
     * @var object A hash used to prime the cache with data about the initially
     *             loaded page. This is set in the footer, and then loaded
     *             by a double-queued event further down this file.
     */
    primer: {},
    /**
     * @var array Stores the content of the cached pages
     */
    pages: [],
    /**
     * @var int The index of the currently loaded page
     *          This is used to know at which point in the history we are
     */
    current: 0,
    /**
     * Saves a new page in the cache
     *
     * @param string hash    The hash part of the url that is being loaded
     * @param array  scripts A list of scripts that is requured for the page
     * @param string menu    A hash that links to a menu stored
     *                       in a dedicated menu cache
     * @param array  params  A list of parameters used by PMA_commonParams()
     * @param string rel     A relationship to the current page:
     *                       'samepage': Forces the response to be treated as
     *                                   the same page as the current one
     *                       'newpage':  Forces the response to be treated as
     *                                   a new page
     *                       undefined:  Default behaviour, 'samepage' if the
     *                                   selflinks of the two pages are the same.
     *                                   'newpage' otherwise
     *
     * @return void
     */
    add: function (hash, scripts, menu, params, rel) {
        if (this.pages.length > AJAX.cache.MAX) {
            // Trim the cache, to the maximum number of allowed entries
            // This way we will have a cached menu for every page
            for (var i=0; i<this.pages.length-this.MAX; i++) {
                delete this.pages[i];
            }
        }
        while (this.current < this.pages.length) {
            // trim the cache if we went back in the history
            // and are now going forward again
            this.pages.pop();
        }
        if (rel === 'newpage' ||
            (
                typeof rel === 'undefined' && (
                    typeof this.pages[this.current - 1] === 'undefined'
                    ||
                    this.pages[this.current - 1].hash !== hash
                )
            )
        ) {
            this.pages.push({
                hash: hash,
                content: $('#page_content').html(),
                scripts: scripts,
                selflink: $('#selflink').html(),
                menu: menu,
                params: params
            });
            AJAX.setUrlHash(this.current, hash);
            this.current++;
        }
    },
    /**
     * Restores a page from the cache. This is called when the hash
     * part of the url changes and it's structure appears to be valid
     *
     * @param string index Which page from the history to load
     *
     * @return void
     */
    navigate: function (index) {
        if (typeof this.pages[index] === 'undefined') {
            PMA_ajaxShowMessage(
                '<div class="error">' + PMA_messages['strInvalidPage'] + '</div>',
                false
            );
        } else {
            AJAX.active = true;
            var record = this.pages[index];
            AJAX.scriptHandler.reset(function () {
                $('#page_content').html(record.content);
                $('#selflink').html(record.selflink);
                AJAX.cache.menus.replace(AJAX.cache.menus.get(record.menu));
                PMA_commonParams.setAll(record.params);
                AJAX.scriptHandler.load(record.scripts);
                AJAX.cache.current = ++index;
            });
        }
    },
    /**
     * Resaves the content of the current page in the cache.
     * Necessary in order not to show the user some outdated version of the page
     *
     * @return void
     */
    update: function () {
        var page = this.pages[this.current - 1];
        if (page) {
            page.content = $('#page_content').html();
        }
    },
    /**
     * @var object Dedicated menu cache
     */
    menus: {
        /**
         * Returns the number of items in an associative array
         *
         * @return int
         */
        size: function(obj) {
            var size = 0, key;
            for (key in obj) {
                if (obj.hasOwnProperty(key)) {
                    size++;
                }
            }
            return size;
        },
        /**
         * @var hash Stores the content of the cached menus
         */
        data: {},
        /**
         * Saves a new menu in the cache
         *
         * @param string hash    The hash (trimmed md5) of the menu to be saved
         * @param string content The HTML code of the menu to be saved
         *
         * @return void
         */
        add: function (hash, content) {
            if (this.size(this.data) > AJAX.cache.MAX) {
                // when the cache grows, we remove the oldest entry
                var oldest, key, init = 0;
                for (var i in this.data) {
                    if (this.data[i]) {
                        if (! init || this.data[i].timestamp.getTime() < oldest.getTime()) {
                            oldest = this.data[i].timestamp;
                            key = i;
                            init = 1;
                        }
                    }
                }
                delete this.data[key];
            }
            this.data[hash] = {
                content: content,
                timestamp: new Date()
            };
        },
        /**
         * Retrieves a menu given its hash
         *
         * @param string hash The hash of the menu to be retrieved
         *
         * @return string
         */
        get: function (hash) {
            if (this.data[hash]) {
                return this.data[hash].content;
            } else {
                // This should never happen as long as the number of stored menus
                // is larger or equal to the number of pages in the page cache
                return '';
            }
        },
        /**
         * Prepares part of the parameter string used during page requests,
         * this is necessary to tell the server which menus we have in the cache
         *
         * @return string
         */
        getRequestParam: function () {
            var param = '';
            var menuHashes = [];
            for (var i in this.data) {
                menuHashes.push(i);
            }
            var menuHashesParam = menuHashes.join('-');
            if (menuHashesParam) {
                param = '&menuHashes=' + menuHashesParam;
            }
            return param;
        },
        /**
         * Replaces the menu with new content
         *
         * @return void
         */
        replace: function (content) {
            $('#floating_menubar').html(content)
                // Remove duplicate wrapper
                // TODO: don't send it in the response
                .children().first().remove();
            $('#topmenu').menuResizer(PMA_mainMenuResizerCallback);
        }
    }
};

/**
 * URL hash management module.
 * Allows direct bookmarking and microhistory.
 */
AJAX.setUrlHash = (function (jQuery, window) {
    "use strict";
    /**
     * Indictaes whether we have already completed
     * the initialisation of the hash
     *
     * @access private
     */
    var ready = false;
    /**
     * Stores a hash that needed to be set when we were not ready
     *
     * @access private
     */
    var savedHash = "";
    /**
     * Flag to indicate if the change of hash was triggered
     * by a user pressing the back/forward button or if
     * the change was triggered internally
     *
     * @access private
     */
    var userChange = true;

    // Fix favicon disappearing in Firefox when setting location.hash
    function resetFavicon() {
        if (jQuery.browser.mozilla) {
            // Move the link tags for the favicon to the bottom
            // of the head element to force a reload of the favicon
            $('head > link[href=favicon\\.ico]').appendTo('head');
        }
    }

    /**
     * Sets the hash part of the URL
     *
     * @access public
     */
    function setUrlHash(index, hash) {
        /*
         * Known problem:
         * Setting hash leads to reload in webkit:
         * http://www.quirksmode.org/bugreports/archives/2005/05/Safari_13_visual_anomaly_with_windowlocationhref.html
         *
         * so we expect that users are not running an ancient Safari version
         */

        userChange = false;
        if (ready) {
            window.location.hash = "PMAURL-" + index + ":" + hash;
            resetFavicon();
        } else {
            savedHash = "PMAURL-" + index + ":" + hash;
        }
    }
    /**
     * Start initialisation
     */
    if (window.location.hash.substring(0, 8) == '#PMAURL-') {
        // We have a valid hash, let's redirect the user
        // to the page that it's pointing to
        var colon_position = window.location.hash.indexOf(':');
        var questionmark_position = window.location.hash.indexOf('?');
        if (colon_position != -1 && questionmark_position != -1 && colon_position < questionmark_position) {
            var hash_url = window.location.hash.substring(colon_position + 1, questionmark_position);
            if (PMA_gotoWhitelist.indexOf(hash_url) != -1) {
                window.location = window.location.hash.substring(
                    colon_position + 1
                );
            }
        }
    } else {
        // We don't have a valid hash, so we'll set it up
        // when the page finishes loading
        jQuery(function(){
            /* Check if we should set URL */
            if (savedHash != "") {
                window.location.hash = savedHash;
                savedHash = "";
                resetFavicon();
            }
            // Indicate that we're done initialising
            ready = true;
        });
    }
    /**
     * Register an event handler for when the url hash changes
     */
    jQuery(function(){
        jQuery(window).hashchange(function () {
            if (userChange === false) {
                // Ignore internally triggered hash changes
                userChange = true;
            } else if (/^#PMAURL-\d+:/.test(window.location.hash)) {
                // Change page if the hash changed was triggered by a user action
                var index = window.location.hash.substring(
                    8, window.location.hash.indexOf(':')
                );
                AJAX.cache.navigate(index);
            }
        });
    });
    /**
     * Publicly exposes a reference to the otherwise private setUrlHash function
     */
    return setUrlHash;
})(jQuery, window);

/**
 * Page load event handler
 */
$(function () {
    // Add the menu from the initial page into the cache
    // The cache primer is set by the footer class
    if (AJAX.cache.primer.url) {
        AJAX.cache.menus.add(
            AJAX.cache.primer.menuHash,
            $('<div></div>')
                .append('<div></div>')
                .append($('#serverinfo').clone())
                .append($('#topmenucontainer').clone())
                .html()
        );
    }
    $(function () {
        // Queue up this event twice to make sure that we get a copy
        // of the page after all other onload events have been fired
        if (AJAX.cache.primer.url) {
            AJAX.cache.add(
                AJAX.cache.primer.url,
                AJAX.cache.primer.scripts,
                AJAX.cache.primer.menuHash
            );
        }
    });
});

/**
 * Attach a generic event handler to clicks
 * on pages and submissions of forms
 */
$('a').live('click', AJAX.requestHandler);
$('form').live('submit', AJAX.requestHandler);

/**
 * Gracefully handle fatal server errors
 * (e.g: 500 - Internal server error)
 */
$(document).ajaxError(function(event, request, settings){
    if (request.status !== 0) { // Don't handle aborted requests
        var errorCode = $.sprintf(PMA_messages['strErrorCode'], request.status);
        var errorText = $.sprintf(PMA_messages['strErrorText'], request.statusText);
        PMA_ajaxShowMessage(
            '<div class="error">'
            + PMA_messages['strErrorProcessingRequest']
            + '<div>' + escapeHtml(errorCode) + '</div>'
            + '<div>' + escapeHtml(errorText) + '</div>'
            + '</div>',
            false
        );
        AJAX.active = false;
    }
});
