dojo.provide("dijit._KeyNavContainer");
dojo.require("dijit._Container");

dojo.declare("dijit._KeyNavContainer",
	dijit._Container,
	{

		// summary:
		//		A _Container with keyboard navigation of its children.
		// description:
		//		To use this mixin, call connectKeyNavHandlers() in
		//		postCreate() and call startupKeyNavChildren() in startup().
		//		It provides normalized keyboard and focusing code for Container
		//		widgets.
/*=====
		// focusedChild: [protected] Widget
		//		The currently focused child widget, or null if there isn't one
		focusedChild: null,
=====*/

		// tabIndex: Integer
		//		Tab index of the container; same as HTML tabIndex attribute.
		//		Note then when user tabs into the container, focus is immediately
		//		moved to the first item in the container.
		tabIndex: "0",

		_keyNavCodes: {},

		connectKeyNavHandlers: function(/*dojo.keys[]*/ prevKeyCodes, /*dojo.keys[]*/ nextKeyCodes){
			// summary:
			//		Call in postCreate() to attach the keyboard handlers
			//		to the container.
			// preKeyCodes: dojo.keys[]
			//		Key codes for navigating to the previous child.
			// nextKeyCodes: dojo.keys[]
			//		Key codes for navigating to the next child.
			// tags:
			//		protected

			var keyCodes = (this._keyNavCodes = {});
			var prev = dojo.hitch(this, this.focusPrev);
			var next = dojo.hitch(this, this.focusNext);
			dojo.forEach(prevKeyCodes, function(code){ keyCodes[code] = prev; });
			dojo.forEach(nextKeyCodes, function(code){ keyCodes[code] = next; });
			this.connect(this.domNode, "onkeypress", "_onContainerKeypress");
			this.connect(this.domNode, "onfocus", "_onContainerFocus");
		},

		startupKeyNavChildren: function(){
			// summary:
			//		Call in startup() to set child tabindexes to -1
			// tags:
			//		protected
			dojo.forEach(this.getChildren(), dojo.hitch(this, "_startupChild"));
		},

		addChild: function(/*dijit._Widget*/ widget, /*int?*/ insertIndex){
			// summary:
			//		Add a child to our _Container
			dijit._KeyNavContainer.superclass.addChild.apply(this, arguments);
			this._startupChild(widget);
		},

		focus: function(){
			// summary:
			//		Default focus() implementation: focus the first child.
			this.focusFirstChild();
		},

		focusFirstChild: function(){
			// summary:
			//		Focus the first focusable child in the container.
			// tags:
			//		protected
			var child = this._getFirstFocusableChild();
			if(child){ // edge case: Menu could be empty or hidden
				this.focusChild(child);
			}
		},

		focusNext: function(){
			// summary:
			//		Focus the next widget
			// tags:
			//		protected
			var child = this._getNextFocusableChild(this.focusedChild, 1);
			this.focusChild(child);
		},

		focusPrev: function(){
			// summary:
			//		Focus the last focusable node in the previous widget
			//		(ex: go to the ComboButton icon section rather than button section)
			// tags:
			//		protected
			var child = this._getNextFocusableChild(this.focusedChild, -1);
			this.focusChild(child, true);
		},

		focusChild: function(/*dijit._Widget*/ widget, /*Boolean*/ last){
			// summary:
			//		Focus widget.
			// widget:
			//		Reference to container's child widget
			// last:
			//		If true and if widget has multiple focusable nodes, focus the
			//		last one instead of the first one
			// tags:
			//		protected
			
			if(this.focusedChild && widget !== this.focusedChild){
				this._onChildBlur(this.focusedChild);
			}
			widget.focus(last ? "end" : "start");
			this.focusedChild = widget;
		},

		_startupChild: function(/*dijit._Widget*/ widget){
			// summary:
			//		Setup for each child widget
			// description:
			//		Sets tabIndex=-1 on each child, so that the tab key will 
			//		leave the container rather than visiting each child.
			// tags:
			//		private
			
			widget.set("tabIndex", "-1");
			
			this.connect(widget, "_onFocus", function(){
				// Set valid tabIndex so tabbing away from widget goes to right place, see #10272
				widget.set("tabIndex", this.tabIndex);
			});
			this.connect(widget, "_onBlur", function(){
				widget.set("tabIndex", "-1");
			});
		},

		_onContainerFocus: function(evt){
			// summary:
			//		Handler for when the container gets focus
			// description:
			//		Initially the container itself has a tabIndex, but when it gets
			//		focus, switch focus to first child...
			// tags:
			//		private

			// Note that we can't use _onFocus() because switching focus from the
			// _onFocus() handler confuses the focus.js code
			// (because it causes _onFocusNode() to be called recursively)

			// focus bubbles on Firefox,
			// so just make sure that focus has really gone to the container
			if(evt.target !== this.domNode){ return; }

			this.focusFirstChild();

			// and then set the container's tabIndex to -1,
			// (don't remove as that breaks Safari 4)
			// so that tab or shift-tab will go to the fields after/before
			// the container, rather than the container itself
			dojo.attr(this.domNode, "tabIndex", "-1");
		},

		_onBlur: function(evt){
			// When focus is moved away the container, and its descendant (popup) widgets,
			// then restore the container's tabIndex so that user can tab to it again.
			// Note that using _onBlur() so that this doesn't happen when focus is shifted
			// to one of my child widgets (typically a popup)
			if(this.tabIndex){
				dojo.attr(this.domNode, "tabIndex", this.tabIndex);
			}
			this.inherited(arguments);
		},

		_onContainerKeypress: function(evt){
			// summary:
			//		When a key is pressed, if it's an arrow key etc. then
			//		it's handled here.
			// tags:
			//		private
			if(evt.ctrlKey || evt.altKey){ return; }
			var func = this._keyNavCodes[evt.charOrCode];
			if(func){
				func();
				dojo.stopEvent(evt);
			}
		},

		_onChildBlur: function(/*dijit._Widget*/ widget){
			// summary:
			//		Called when focus leaves a child widget to go
			//		to a sibling widget.
			// tags:
			//		protected
		},

		_getFirstFocusableChild: function(){
			// summary:
			//		Returns first child that can be focused
			return this._getNextFocusableChild(null, 1);	// dijit._Widget
		},

		_getNextFocusableChild: function(child, dir){
			// summary:
			//		Returns the next or previous focusable child, compared
			//		to "child"
			// child: Widget
			//		The current widget
			// dir: Integer
			//		* 1 = after
			//		* -1 = before
			if(child){
				child = this._getSiblingOfChild(child, dir);
			}
			var children = this.getChildren();
			for(var i=0; i < children.length; i++){
				if(!child){
					child = children[(dir>0) ? 0 : (children.length-1)];
				}
				if(child.isFocusable()){
					return child;	// dijit._Widget
				}
				child = this._getSiblingOfChild(child, dir);
			}
			// no focusable child found
			return null;	// dijit._Widget
		}
	}
);
