/* $This file is distributed under the terms of the license in /doc/license.txt$ */

var menuManagement = {

    // Initial page setup
    onLoad: function() {
        this.mergeFromTemplate();
        this.initMenuItemData();
        this.initObjects();
        this.initMenuItemsDD();
    },
    
    // Add variables from menupage template
    mergeFromTemplate: function() {
        $.extend(this, menuManagementData);
    },
    
    // Create references to frequently used elements for convenience
    initObjects: function() {
        this.menuItemsList = $('ul.menuItems');
    },
        
    // Drag-and-drop
    initMenuItemsDD: function() {
        var menuItems = this.menuItemsList.children('li');
        
        if (menuItems.length < 2) {
            return;
        }
        
        this.menuItemsList.addClass('dragNdrop');
        
        menuItems.attr('title', 'Drag and drop to reorder menu items');
        
        this.menuItemsList.sortable({
            cursor: 'move',
            update: function(event, ui) {
                alert("Congrats! You just reordered a menu item. (not really)");
                // Once we figure out how the editing will work, we'll call reorderMenuItems
                // and get rid of the debug alert.
                    // menuManagement.reorderMenutItems(event, ui);
            }
        });
    },
    
    // Reorder menu items. Called after menu item drag-and-drop
    // This is all make-believe at the moment. Just an example to demonstrate to Huda how this could work.
    reorderMenuItems: function(event, ui) {
        var menuItems = $('li.menuItem').map(function(index, el) {
            return $(this).data('menuItemUri');
        }).get();

        $.ajax({
            url: menuManagement.reorderUrl,
            data: {
                predicate: menuManagement.positionPredicate,
                individuals: menuItems
            },
            traditional: true, // serialize the array of individuals for the server
            dataType: 'json',
            type: 'POST',
            success: function(data, status, request) {
                var pos;
                $('.menuItem').each(function(index){
                    pos = index + 1;
                    // Set the new position for this element. The only function of this value 
                    // is so we can reset an element to its original position in case reordering fails.
                    menuManagement.setPosition(this, pos);                
                });
                // Set the form rank field value.
                $('#rank').val(pos + 1);        
            },
            error: function(request, status, error) {
                // ui is undefined after removal of a menu item.
                if (ui) {
                    // Put the moved item back to its original position.
                    // Seems we need to do this by hand. Can't see any way to do it with jQuery UI. ??
                    var pos = menuManagement.getPosition(ui.item),
                        nextpos = pos + 1, 
                        menuItems = menuManagement.menuItemsList,
                        next = menuManagement.findMenuItem('position', nextpos);
                    
                    if (next.length) {
                        ui.item.insertBefore(next);
                    }
                    else {
                        ui.item.appendTo(menuItems);
                    }
                    
                    alert('Reordering of menu items failed.');
                }
            }
        });
    },
    
    // On page load, associate data with each menu item list element. Then we don't
    // have to keep retrieving data from or modifying the DOM as we manipulate the
    // menu items.
    initMenuItemData: function() {
        $('.menuItem').each(function(index) {
            $(this).data(menuItemData[index]);    
            
            // RY We might still need position to put back an element after reordering
            // failure. Position might already have been reset? Check.
            // We also may need position to implement undo links: we want the removed menu item
            // to show up in the list, but it has no position.
            $(this).data('position', index+1);      
        });
    },

    getPosition: function(menuItem) {
        return $(menuItem).data('position');
    },
    
    setPosition: function(menuItem, pos) {
        $(menuItem).data('position', pos);
    },
    
    findMenuItem: function(key, value) {
        var matchingMenuItem = $(); // if we don't find one, return an empty jQuery set
        
        $('.menuItem').each(function() {
            var menuItem = $(this);
            if ( menuItem.data(key) === value ) {
                matchingMenuItem = menuItem; 
                return false; // stop the loop
            }
        });
         
        return matchingMenuItem;       
    },
    
    // Event listeners
    
    // Disable drag-n-drop and associated cues if only one menu item remains
    // Good chance we won't need this if Huda's able to hook into standard delete for n3 editing (loads confirmation in separate page)
    disableMenuItemsDD: function() {
        var menuItems = this.menuItemsList.children('li');
        
        this.menuItemsList.sortable({ disable: true } );

        this.menuItemsList.removeClass('dragNdrop');
        
        menuItems.removeAttr('title');
    }
};

$(document).ready(function() {   
    menuManagement.onLoad();
});