/*
Copyright (c) 2006 Author
Author: Anil Sharma for the book "Real-World AJAX: Secrets of the Masters"

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
documentation files (the "Software"), to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions
of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

/** Implements navigation bar behavior. */
function NavBar() {
   // list of selectable items (anchor elements)
   this.items = null;
   // the html element that acts as the container of the navigation bar
   this.topElement = null;
   // currently selected item
   this.currentSelection = null;
}


// associates the HTML element used fot the navigation bar with this component
NavBar.prototype.setHtmlElement = function(e) {
    this.topElement = e;
    this.items = new ElementCollection(e).getElementsIndexedById('A');
}

// given the id of an item, associates on click event handler.
// The handler is invoked when the user clicks on the item.
NavBar.prototype.setHandler = function(itemId, handler) {
    if (this.items[itemId]) {
        var self = this;
        var iid = itemId;
        this.items[itemId].handler = handler;
        this.items[itemId].onclick = function(event) {self.selectItem(iid); self.items[iid].handler(event)};
    }
}

// Sets the given item as selected.
// De-selects any previously selected item (displays it using normal style)
// Selects the new item (displays it using selected style)
NavBar.prototype.selectItem = function(itemId) {
    var newSelection = this.items[itemId];
    if (newSelection == this.currentSelection) {
        return false;
    }
    if (this.currentSelection != null) {
        this.currentSelection.className = 'HBarItem';
    }
    this.currentSelection = newSelection;
    if (this.currentSelection != null) {
        this.currentSelection.className = 'HBarItemSelected';
    }
    return true;
}