dojo.provide("dijit._base.focus");

// summary:
//		These functions are used to query or set the focus and selection.
//
//		Also, they trace when widgets become actived/deactivated,
//		so that the widget can fire _onFocus/_onBlur events.
//		"Active" here means something similar to "focused", but
//		"focus" isn't quite the right word because we keep track of
//		a whole stack of "active" widgets.  Example:  Combobutton --> Menu -->
//		MenuItem.   The onBlur event for Combobutton doesn't fire due to focusing
//		on the Menu or a MenuItem, since they are considered part of the
//		Combobutton widget.  It only happens when focus is shifted
//		somewhere completely different.

dojo.mixin(dijit,
{
	// _curFocus: DomNode
	//		Currently focused item on screen
	_curFocus: null,

	// _prevFocus: DomNode
	//		Previously focused item on screen
	_prevFocus: null,

	isCollapsed: function(){
		// summary: tests whether the current selection is empty
		var _window = dojo.global;
		var _document = dojo.doc;
		if(_document.selection){ // IE
			return !_document.selection.createRange().text; // Boolean
		}else if(_window.getSelection){
			var selection = _window.getSelection();
			if(dojo.isString(selection)){ // Safari
				return !selection; // Boolean
			}else{ // Mozilla/W3
				return selection.isCollapsed || !selection.toString(); // Boolean
			}
		}
	},

	getBookmark: function(){
		// summary: Retrieves a bookmark that can be used with moveToBookmark to return to the same range
		var bookmark, selection = dojo.doc.selection;
		if(selection){ // IE
			var range = selection.createRange();
			if(selection.type.toUpperCase()=='CONTROL'){
				bookmark = range.length ? dojo._toArray(range) : null;
			}else{
				bookmark = range.getBookmark();
			}
		}else{
			if(dojo.global.getSelection){
				selection = dojo.global.getSelection();
				if(selection){
					var range = selection.getRangeAt(0);
					bookmark = range.cloneRange();
				}
			}else{
				console.debug("No idea how to store the current selection for this browser!");
			}
		}
		return bookmark; // Array
	},

	moveToBookmark: function(/*Object*/bookmark){
		// summary: Moves current selection to a bookmark
		// bookmark: this should be a returned object from dojo.html.selection.getBookmark()
		var _document = dojo.doc;
		if(_document.selection){ // IE
			var range;
			if(dojo.isArray(bookmark)){
				range = _document.body.createControlRange();
				dojo.forEach(bookmark, range.addElement);
			}else{
				range = _document.selection.createRange();
				range.moveToBookmark(bookmark);
			}
			range.select();
		}else{ //Moz/W3C
			var selection = dojo.global.getSelection && dojo.global.getSelection();
			if(selection && selection.removeAllRanges){
				selection.removeAllRanges();
				selection.addRange(bookmark);
			}else{
				console.debug("No idea how to restore selection for this browser!");
			}
		}
	},

	getFocus: function(/*Widget*/menu, /*Window*/ openedForWindow){
		// summary:
		//	Returns the current focus and selection.
		//	Called when a popup appears (either a top level menu or a dialog),
		//	or when a toolbar/menubar receives focus
		//
		// menu:
		//	the menu that's being opened
		//
		// openedForWindow:
		//	iframe in which menu was opened
		//
		// returns:
		//	a handle to restore focus/selection

		return {
			// Node to return focus to
			node: menu && dojo.isDescendant(dijit._curFocus, menu.domNode) ? dijit._prevFocus : dijit._curFocus,

			// Previously selected text
			bookmark:
				!dojo.withGlobal(openedForWindow||dojo.global, dijit.isCollapsed) ?
				dojo.withGlobal(openedForWindow||dojo.global, dijit.getBookmark) :
				null,

			openedForWindow: openedForWindow
		}; // Object
	},

	focus: function(/*Object || DomNode */ handle){
		// summary:
		//		Sets the focused node and the selection according to argument.
		//		To set focus to an iframe's content, pass in the iframe itself.
		// handle:
		//		object returned by get(), or a DomNode

		if(!handle){ return; }

		var node = "node" in handle ? handle.node : handle,		// because handle is either DomNode or a composite object
			bookmark = handle.bookmark,
			openedForWindow = handle.openedForWindow;

		// Set the focus
		// Note that for iframe's we need to use the <iframe> to follow the parentNode chain,
		// but we need to set focus to iframe.contentWindow
		if(node){
			var focusNode = (node.tagName.toLowerCase()=="iframe") ? node.contentWindow : node;
			if(focusNode && focusNode.focus){
				try{
					// Gecko throws sometimes if setting focus is impossible,
					// node not displayed or something like that
					focusNode.focus();
				}catch(e){/*quiet*/}
			}			
			dijit._onFocusNode(node);
		}

		// set the selection
		// do not need to restore if current selection is not empty
		// (use keyboard to select a menu item)
		if(bookmark && dojo.withGlobal(openedForWindow||dojo.global, dijit.isCollapsed)){
			if(openedForWindow){
				openedForWindow.focus();
			}
			try{
				dojo.withGlobal(openedForWindow||dojo.global, moveToBookmark, null, [bookmark]);
			}catch(e){
				/*squelch IE internal error, see http://trac.dojotoolkit.org/ticket/1984 */
			}
		}
	},

	// List of currently active widgets (focused widget and it's ancestors)
	_activeStack: [],

	registerWin: function(/*Window?*/targetWindow){
		// summary:
		//		Registers listeners on the specified window (either the main
		//		window or an iframe) to detect when the user has clicked somewhere.
		//		Anyone that creates an iframe should call this function.

		if(!targetWindow){
			targetWindow = window;
		}

		dojo.connect(targetWindow.document, "onmousedown", null, function(evt){
			dijit._justMouseDowned = true;
			setTimeout(function(){ dijit._justMouseDowned = false; }, 0);
			dijit._onTouchNode(evt.target||evt.srcElement);
		});
		//dojo.connect(targetWindow, "onscroll", ???);

		// Listen for blur and focus events on targetWindow's body
		var body = targetWindow.document.body || targetWindow.document.getElementsByTagName("body")[0];
		if(body){
			if(dojo.isIE){
				body.attachEvent('onactivate', function(evt){
					if(evt.srcElement.tagName.toLowerCase() != "body"){
						dijit._onFocusNode(evt.srcElement);
					}
				});
				body.attachEvent('ondeactivate', function(evt){ dijit._onBlurNode(evt.srcElement); });
			}else{
				body.addEventListener('focus', function(evt){ dijit._onFocusNode(evt.target); }, true);
				body.addEventListener('blur', function(evt){ dijit._onBlurNode(evt.target); }, true);
			}
		}
		body = null;	// prevent memory leak (apparent circular reference via closure)
	},

	_onBlurNode: function(/*DomNode*/ node){
		// summary:
		// 		Called when focus leaves a node.
		//		Usually ignored, _unless_ it *isn't* follwed by touching another node,
		//		which indicates that we tabbed off the last field on the page,
		//		in which case every widget is marked inactive
		dijit._prevFocus = dijit._curFocus;
		dijit._curFocus = null;

		var w = dijit.getEnclosingWidget(node);
		if (w && w._setStateClass){
			w._focused = false;
			w._setStateClass();
		}
		if(dijit._justMouseDowned){
			// the mouse down caused a new widget to be marked as active; this blur event
			// is coming late, so ignore it.
			return;
		}

		// if the blur event isn't followed by a focus event then mark all widgets as inactive.
		if(dijit._clearActiveWidgetsTimer){
			clearTimeout(dijit._clearActiveWidgetsTimer);
		}
		dijit._clearActiveWidgetsTimer = setTimeout(function(){
			delete dijit._clearActiveWidgetsTimer; dijit._setStack([]); }, 100);
	},

	_onTouchNode: function(/*DomNode*/ node){
		// summary
		//		Callback when node is focused or mouse-downed

		// ignore the recent blurNode event
		if(dijit._clearActiveWidgetsTimer){
			clearTimeout(dijit._clearActiveWidgetsTimer);
			delete dijit._clearActiveWidgetsTimer;
		}

		// compute stack of active widgets (ex: ComboButton --> Menu --> MenuItem)
		var newStack=[];
		try{
			while(node){
				if(node.dijitPopupParent){
					node=dijit.byId(node.dijitPopupParent).domNode;
				}else if(node.tagName && node.tagName.toLowerCase()=="body"){
					// is this the root of the document or just the root of an iframe?
					if(node===dojo.body()){
						// node is the root of the main document
						break;
					}
					// otherwise, find the iframe this node refers to (can't access it via parentNode,
					// need to do this trick instead) and continue tracing up the document
					node=dojo.query("iframe").filter(function(iframe){ return iframe.contentDocument.body===node; })[0];
				}else{
					var id = node.getAttribute && node.getAttribute("widgetId");
					if(id){
						newStack.unshift(id);
					}
					node=node.parentNode;
				}
			}
		}catch(e){ /* squelch */ }

		dijit._setStack(newStack);
	},

	_onFocusNode: function(/*DomNode*/ node){
		// summary
		//		Callback when node is focused
		if(node && node.tagName && node.tagName.toLowerCase() == "body"){
			return;
		}
		dijit._onTouchNode(node);
		if(node==dijit._curFocus){ return; }
		dijit._prevFocus = dijit._curFocus;
		dijit._curFocus = node;
		dojo.publish("focusNode", [node]);

		// handle focus/blur styling
		var w = dijit.getEnclosingWidget(node);
		if (w && w._setStateClass){
			w._focused = true;
			w._setStateClass();
		}
	},

	_setStack: function(newStack){
		// summary
		//	The stack of active widgets has changed.  Send out appropriate events and record new stack

		var oldStack = dijit._activeStack;		
		dijit._activeStack = newStack;

		// compare old stack to new stack to see how many elements they have in common
		for(var nCommon=0; nCommon<Math.min(oldStack.length, newStack.length); nCommon++){
			if(oldStack[nCommon] != newStack[nCommon]){
				break;
			}
		}

		// for all elements that have gone out of focus, send blur event
		for(var i=oldStack.length-1; i>=nCommon; i--){
			var widget = dijit.byId(oldStack[i]);
			if(widget){
				dojo.publish("widgetBlur", [widget]);
				if(widget._onBlur){
					widget._onBlur();
				}
			}
		}

		// for all element that have come into focus, send focus event
		for(var i=nCommon; i<newStack.length; i++){
			var widget = dijit.byId(newStack[i]);
			if(widget){
				dojo.publish("widgetFocus", [widget]);
				if(widget._onFocus){
					widget._onFocus();
				}
			}
		}
	}
});

// register top window and all the iframes it contains
dojo.addOnLoad(dijit.registerWin);
