<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" 
    width="439" creationComplete="init()" height="271">
    <mx:HTTPService id="dir" url="{SERVER_URL}dir.php" resultFormat="e4x" />
    <mx:Tree id="leftTree" x="10" y="10" height="250" width="204" 
        dataProvider="{dir.lastResult}" labelField="@name" showRoot="false" 
        dragEnabled="true" dropEnabled="false" allowMultipleSelection="true" 
        click="showThumb(event)"/>
    <mx:List id="downloadList" x="222" y="10" height="135" width="207" 
        allowMultipleSelection="true" dataProvider="{fileListProvider}" 
        dragEnter="handleDragEnter(event)" dragOver="handleDragOver(event)" 
        dragDrop="handleDragDrop(event)" dragExit="handleDragExit(event)" 
        click="showThumb(event)" keyUp="handleKeyUp(event)"/>
    <mx:Button id="downloadButton" x="347" y="153" label="Download" 
        enabled="false" click="initializeDownload(event)" />
    <mx:Button id="refreshButton" x="347" y="239" label="Refresh" 
        click="refresh(event)"  width="82"/>
    <mx:Canvas id="imageHolder" x="222" y="153" width="117" height="108">
        <mx:Image id="imageThumb" x="0" y="0" width="117" height="108" 
            source="{currentPhotoPath}"/>
    </mx:Canvas>
    <mx:Script>
        <![CDATA[
            import mx.messaging.channels.StreamingAMFChannel;
            /* File downloading application
               Drag and drop between two different controlers: tree and list */
 
            import mx.rpc.events.ResultEvent;
            import mx.collections.ArrayCollection;
            import mx.controls.listClasses.ListBase;
            import mx.core.UIComponent;
            import mx.managers.DragManager;
            import mx.core.DragSource;
            import mx.controls.List;
            import mx.events.DragEvent;
 
            // internet - on flexer
            public const SERVER_URL:String = "http://www.flexer.info/wp-content/uploads/2008/05/";
 
            // bindable variable used for the list
            [Bindable]
            public var fileListProvider:ArrayCollection = new ArrayCollection();
 
            // bindable variable used for thumbnail
            [Bindable]
            public var currentPhotoPath:String = "";
 
            public var fRef:FileReference = new FileReference();
 
            public function init():void
            {
                /* initialization function */
 
                // file reference events - used for debug purposes
                fRef.addEventListener(Event.CANCEL, doEvent);
                fRef.addEventListener(Event.COMPLETE, doEvent);
                fRef.addEventListener(Event.OPEN, doEvent);
                fRef.addEventListener(Event.SELECT, doEvent);
                fRef.addEventListener(HTTPStatusEvent.HTTP_STATUS, doEvent);
                fRef.addEventListener(IOErrorEvent.IO_ERROR, doEvent);
                fRef.addEventListener(ProgressEvent.PROGRESS, doEvent);
                fRef.addEventListener(SecurityErrorEvent.SECURITY_ERROR, doEvent);				
 
                // getting folder content
                dir.send();
            }

            private function handleDragEnter(event:DragEvent):void
            {
                /* this function validates the drop */
 
                if (event.dragInitiator is Tree) {
                    var ds:DragSource = event.dragSource;
                    // check if the format is what we need - treeItems
                    if (!ds.hasFormat("treeItems")) 
                        return;
                    var items:Array = ds.dataForFormat("treeItems") as Array;
                    for (var i:Number=0; i < items.length; i++) {
                        var item:XML = XML(items[i]);
                        // we want only files to be dragable
                        if (item.@type != "file") 
                            return; 
                    }   
 
                    // check for the item to be unique
                    var paths:ArrayCollection = downloadList.dataProvider as ArrayCollection;
                    for (var j:Number=0; j < paths.length; j++)
                    {
                        if (item.@path == paths[j].path.toString()) return;
                    }
                }
 
                // accept the drop
                DragManager.acceptDragDrop(UIComponent(event.currentTarget));
            }

            private function handleDragOver(event:DragEvent):void
            {
                /* this function shows feedback to the user */
 
                // show feedback icon
                DragManager.showFeedback(DragManager.COPY);
            }
 
            private function handleDragDrop(event:DragEvent):void
            {
                /* this function adds new items to the list */
 
                // getting source
                var ds:DragSource = event.dragSource;
                // getting target
                var dropTarget:List = List(event.currentTarget);
                // tempoaray array used to add items to list
                var arr:Array;
 
                // getting the nodes dragged 
                // multiple selection is allowed so we have arrays
                if (ds.hasFormat("items")) {
                    arr = ds.dataForFormat("items") as Array;
                } else if (ds.hasFormat("treeItems")) {
                    arr = ds.dataForFormat("treeItems") as Array;
                }
 
                // adding the dragged nodes to list
                for (var i:Number=0; i < arr.length; i++) {
                    // getting node
                    var node:XML = XML(arr[i]);
                    // creating new list item
                    var item:Object = new Object();
                    // setting item's properties
                    item.label = node.@name;
                    // we set path also which is needed for download
                    item.path = node.@path;
                    // add to data provider
                    fileListProvider.addItem(item);
                }
                // finish drag
                handleDragExit(event);
            }			
 
            private function handleDragExit(event:DragEvent):void
            {
                /* this function finishes the drag and drop */
 
                // we hide the feedback
                var dropTarget:ListBase=ListBase(event.currentTarget);
                dropTarget.hideDropFeedback(event);
                // we check the data provider to enable the download button
                if (dropTarget.dataProvider.length > 0)
                    downloadButton.enabled = true;
            }
 
            private function showThumb(event:MouseEvent):void
            {
                /* this function shows the thumbnail 
                   used for both tree and list click events */
 
                // if click is on the tree
                if (event.currentTarget.name == "leftTree") {
                    // folders cannot show thumbnail
                    // other file types than images are automatically not shown 
                    if (leftTree.selectedItem.@type == "file")
                        currentPhotoPath = SERVER_URL + leftTree.selectedItem.@path;
                    else
                        currentPhotoPath = "";
                // if click is on the list
                } else if (event.currentTarget.name == "downloadList") {
                    currentPhotoPath = (downloadList.selectedItem ? SERVER_URL + 
                                        downloadList.selectedItem.path : "");
                }
            }
 
            private function handleKeyUp(event:KeyboardEvent):void
            {
                /* this function is used for deleting items from the list */
 
                // if we have pressed the DELETE key and 
                // also there is at least one item selected
                if (event.keyCode == Keyboard.DELETE && downloadList.selectedIndex > -1) {
                    var removeItems:Array = downloadList.selectedIndices;
                    // remove selected items
                    for (var i:Number = 0; i < removeItems.length; i++) {
                        downloadList.dataProvider.removeItemAt(removeItems[i]);
                    }
                    currentPhotoPath = "";
                    // if the list is empty we disable the download button
                    if (downloadList.dataProvider.length <= 0)
                        downloadButton.enabled = false;
                }
            }
 
            private function initializeDownload(event:MouseEvent):void
            {
                /* this function starts the download 
                   we use FileReference to download */
 
                // get the items dragged in the list
                var paths:ArrayCollection = downloadList.dataProvider as ArrayCollection;
                // initialize the query/url string
                var qStr:String = "";
                // compose the query/url string
                // we are sending an array to the server
                for (var i:int = 0; i < paths.length; i++)
                    qStr += "&name[]="+escape(paths[i].path.toString());
                // get the file
                // the file download.php on the server gets the array
                // and in the memory creates an tgz archive
                // and sends it back as being a file (using http headers)
                // we are using FileReference for this
                fRef.download(new URLRequest(SERVER_URL + "download.php?" + qStr),"archive.tgz");
            }
 
            private function doEvent(evt:Event):void {
                /* Function is displaying events reached when downloading 
                   For debug purposes */
 
                var fr:FileReference = evt.currentTarget as FileReference;   
                // for debug purposes */
                //trace("type:"+evt.type+", eventString:"+evt.toString()); 
                //trace(fr.creationDate);
                //trace(fr.creator);
                //trace(fr.modificationDate);
                //trace(fr.name);
                //trace(fr.size);
                //trace(fr.type);
            } 		
 
            private function refresh(evt:Event):void {
                /* Function is refresing both the tree and the list and 
                   disables the download button */
 
                // empty the list
                downloadList.dataProvider = new ArrayCollection();
                // disable the download button
                downloadButton.enabled = false;
                // refresh the tree
                dir.send();
            }
        ]]>
    </mx:Script>
</mx:Application>