// Copyright 2007. Adobe Systems Incorporated. All Rights Reserved.
package fl.accessibility {
	import flash.events.Event;
	import flash.accessibility.Accessibility;
	import fl.controls.listClasses.ICellRenderer;
	import fl.controls.SelectableList;
	import fl.core.UIComponent;

	/**
	 *  The student_ar_fl_accessibility_SelectableListAccImpl class, also called the SelectableList Accessibility Implementation class,
     *  is used to make a SelectableList component accessible.
     *
     * @see fl.controls.SelectableList SelectableList
     *
     * @langversion 3.0
     * @playerversion Flash 9.0.28.0
	 */
	public class student_ar_fl_accessibility_SelectableListAccImpl extends AccImpl {
		/**
		 *  @private
         *  Static variable triggering the <code>hookAccessibility()</code> method.
		 *  This is used for initializing student_ar_fl_accessibility_SelectableListAccImpl class to hook its
         *  <code>createAccessibilityImplementation()</code> method to SelectableList class 
         *  before it gets called from UIComponent.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static var accessibilityHooked:Boolean = hookAccessibility();

		/**
		 *  @private
         *  Static method for swapping the <code>createAccessibilityImplementation()</code>
         *  method of SelectableList with the student_ar_fl_accessibility_SelectableListAccImpl class.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */ 
		private static function hookAccessibility():Boolean {
			SelectableList.createAccessibilityImplementation = createAccessibilityImplementation;
			return true;
		}

		//--------------------------------------------------------------------------
		//  Class constants
		//--------------------------------------------------------------------------

		/**
		 *  @private
         *  Role of listItem.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const ROLE_SYSTEM_LISTITEM:uint = 0x22; 
		
		/**
         *  @private
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const STATE_SYSTEM_FOCUSED:uint = 0x00000004;
		
		/**
         *  @private
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const STATE_SYSTEM_INVISIBLE:uint = 0x00008000;
		
		/**
         *  @private
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const STATE_SYSTEM_OFFSCREEN:uint = 0x00010000;
		
		/**
         *  @private
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const STATE_SYSTEM_SELECTABLE:uint = 0x00200000;
		
		/**
         *  @private
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const STATE_SYSTEM_SELECTED:uint = 0x00000002;
		
		/**
		 *  @private
         *  Event emitted if 1 item is selected.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const EVENT_OBJECT_FOCUS:uint = 0x8005; 
		
		/**
		 *  @private
         *  Event emitted if 1 item is selected.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		private static const EVENT_OBJECT_SELECTION:uint = 0x8006; 
		
		//--------------------------------------------------------------------------
		//  Class methods
		//--------------------------------------------------------------------------

		/**
		 *  @private
		 *  Method for creating the Accessibility class.
		 *  This method is called from UIComponent.
		 * 
		 *  @param component The UIComponent instance that this AccImpl instance
         *  is making accessible.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		public static function createAccessibilityImplementation(component:UIComponent):void {
			component.accessibilityImplementation = new student_ar_fl_accessibility_SelectableListAccImpl(component);
		}

		/**
		 *  Enables accessibility for a SelectableList component.
		 *  This method is required for the compiler to activate
         *  the accessibility classes for a component.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		public static function enableAccessibility():void {
		}

		//--------------------------------------------------------------------------
		//  Constructor
		//--------------------------------------------------------------------------

        /**
         * @private
         * @internal Nivesh says: I don't think we should document the constructors 
         *           for the accessibility classes.  End-users just have to call the 
         *           static enableAccessibility method.  They don't really create an 
         *           instance of the classes.
         *
		 *  Creates a new SelectableList Accessibility Implementation.
		 *
		 *  @param master The UIComponent instance that this AccImpl instance
         *  is making accessible.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		public function student_ar_fl_accessibility_SelectableListAccImpl(master:UIComponent) {
			super(master);
			role = 0x21;
		}

		//--------------------------------------------------------------------------
		//  Overridden properties: AccImpl
		//--------------------------------------------------------------------------

		/**
		 *  @private
         *  Array of events that we should listen for from the master component.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override protected function get eventsToHandle():Array {
			return super.eventsToHandle.concat([ "change" ]);
		}
		
		//--------------------------------------------------------------------------
		//  Overridden methods: AccessibilityImplementation
		//--------------------------------------------------------------------------

		/**
		 *  @private
		 *  Gets the role for the component.
		 *
		 *  @param childID The child id.
		 * 
         *  @return Role.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accRole(childID:uint):uint {
			if (childID == 0) {
				return role;
			}
			return ROLE_SYSTEM_LISTITEM;
		}

		/**
		 *  @private
		 *  must be overridden in student_ar_fl_accessibility_SelectableListAccImpl subclasses.
		 *
		 *  @param childID The child id.
         *  @return Value.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accValue(childID:uint):String {
			return "";
		}

		/**
		 *  @private
		 *  IAccessible method for returning the state of the ListItem.
		 *  States are predefined for all the components in MSAA.
		 *  Values are assigned to each state.
		 *  Depending upon the listItem being Selected, Selectable,
		 *  Invisible, Offscreen, a value is returned.
		 *
		 *  @param childID The child id.
		 *
         *  @return State.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accState(childID:uint):uint {
			var accState:uint = getState(childID);
			if (childID > 0) {
				var list:SelectableList = SelectableList(master);
				var index:uint = childID - 1;
				// For returning states (OffScreen and Invisible)
				// when the list Item is not in the displayed rows.
				if (index < list.verticalScrollPosition || index >= list.verticalScrollPosition + list.rowCount) {
					accState |= (STATE_SYSTEM_OFFSCREEN | STATE_SYSTEM_INVISIBLE);
				} else {
					accState |= STATE_SYSTEM_SELECTABLE;
					var item:Object = list.getItemAt(index);
					var selItems:Array = list.selectedIndices;
					for(var i:int = 0; i < selItems.length; i++) {
						if(selItems[i] == index) {
							accState |= STATE_SYSTEM_SELECTED | STATE_SYSTEM_FOCUSED;
							break;
						}
					}
				}
			}
			return accState;
		}

		/**
		 *  @private
		 *  IAccessible method for returning the Default Action.
		 *
		 *  @param childID The child id.
		 *
         *  @return DefaultAction.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accDefaultAction(childID:uint):String {
			if (childID == 0) {
				return null;
			}
			return "Double Click";
		}

		/**
		 *  @private
		 *  IAccessible method for executing the Default Action.
		 *
         *  @param childID The child id.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function accDoDefaultAction(childID:uint):void {
			if (childID > 0) {
				SelectableList(master).selectedIndex = childID - 1;
			}
		}

		/**
		 *  @private
		 *  Method to return an array of childIDs.
		 *
         *  @return Array child ids
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function getChildIDArray():Array {
			var childIDs:Array = [];
			var list:SelectableList = SelectableList(master);
			if (list.dataProvider) {
				var n:uint = list.dataProvider.length;
				for (var i:int = 0; i < n; i++) {
					childIDs[i] = i + 1;
				}
			}
			return childIDs;
		}

		/**
		 *  @private
		 *  IAccessible method for returning the bounding box of the ListItem.
		 *
		 *  @param childID The child id
		 *
         *  @return Object Location 
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function accLocation(childID:uint):* {
			var list:SelectableList = SelectableList(master);
			if(childID > 0) {
				var index:uint = childID - 1;
				if (index < list.verticalScrollPosition || index >= list.verticalScrollPosition + list.rowCount) {
					return null;
				}
				var item:Object = list.getItemAt(index);
				return list.itemToCellRenderer(item);
			}
			return list;
		}

		/**
		 *  @private
		 *  IAccessible method for returning the child Selections in the List.
		 *
		 *  @param childID The child id
		 *
         *  @return Array child ids.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accSelection():Array {
			var accSelection:Array = [];
			var selectedIndices:Array = SelectableList(master).selectedIndices;
			var n:int = selectedIndices.length;
			for (var i:int = 0; i < n; i++) {
				accSelection[i] = selectedIndices[i] + 1;
			}
			return accSelection;
		}

		/**
		 *  @private
		 *  IAccessible method for returning the childFocus of the List.
		 *
		 *  @param childID The child id
		 *
         *  @return uint focused child id.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function get_accFocus():uint {
			var index:uint = SelectableList(master).selectedIndex;
			return (index >= 0) ? index + 1 : 0;
		}

		/**
		 *  @private
		 *  IAccessible method for selecting an item.
		 *
         *  @param childID The child id
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override public function accSelect(selFlag:uint, childID:uint):void {
			var list:SelectableList = SelectableList(master);
			var index:uint = childID - 1;
			if(list.dataProvider) {
				if (index >= 0 && index < list.dataProvider.length) {
					list.selectedIndex = index;
				}
			}
		}

		//--------------------------------------------------------------------------
		//  Overridden methods: AccImpl
		//--------------------------------------------------------------------------

		/**
		 *  @private
		 *  must be overridden in student_ar_fl_accessibility_SelectableListAccImpl subclasses
		 *
		 *  @param childID The child id.
         *  @return Name.
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override protected function getName(childID:uint):String {
			return "";
		}

		//--------------------------------------------------------------------------
		//  Overridden event handlers: AccImpl
		//--------------------------------------------------------------------------

		/**
		 *  @private
		 *  Override the generic event handler.
		 *  All AccImpl must implement this
		 *  to listen for events from its master component. 
		 * 
         *  @param event The event object
         *
         * @langversion 3.0
         * @playerversion Flash 9.0.28.0
		 */
		override protected function eventHandler(event:Event):void {
			switch (event.type) {
				case "change":
					var index:uint = SelectableList(master).selectedIndex;
					if (index >= 0) {
						if(Accessibility.active) {
							var childID:uint = index + 1;
							Accessibility.sendEvent(master, childID, EVENT_OBJECT_FOCUS);
							Accessibility.sendEvent(master, childID, EVENT_OBJECT_SELECTION);
						}
					}
					break;
			}
		}
	}
}