/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.dnd;

 
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.internal.Callback;
import org.eclipse.swt.internal.carbon.CGPoint;
import org.eclipse.swt.internal.carbon.EventRecord;
import org.eclipse.swt.internal.carbon.OS;
import org.eclipse.swt.internal.carbon.Point;

/**
 *
 * <code>DragSource</code> defines the source object for a drag and drop transfer.
 *
 * <p>IMPORTANT: This class is <em>not</em> intended to be subclassed.</p>
 *  
 * <p>A drag source is the object which originates a drag and drop operation. For the specified widget, 
 * it defines the type of data that is available for dragging and the set of operations that can 
 * be performed on that data.  The operations can be any bit-wise combination of DND.MOVE, DND.COPY or 
 * DND.LINK.  The type of data that can be transferred is specified by subclasses of Transfer such as 
 * TextTransfer or FileTransfer.  The type of data transferred can be a predefined system type or it 
 * can be a type defined by the application.  For instructions on how to define your own transfer type,
 * refer to <code>ByteArrayTransfer</code>.</p>
 *
 * <p>You may have several DragSources in an application but you can only have one DragSource 
 * per Control.  Data dragged from this DragSource can be dropped on a site within this application 
 * or it can be dropped on another application such as an external Text editor.</p>
 * 
 * <p>The application supplies the content of the data being transferred by implementing the
 * <code>DragSourceListener</code> and associating it with the DragSource via DragSource#addDragListener.</p>
 * 
 * <p>When a successful move operation occurs, the application is required to take the appropriate 
 * action to remove the data from its display and remove any associated operating system resources or
 * internal references.  Typically in a move operation, the drop target makes a copy of the data 
 * and the drag source deletes the original.  However, sometimes copying the data can take a long 
 * time (such as copying a large file).  Therefore, on some platforms, the drop target may actually 
 * move the data in the operating system rather than make a copy.  This is usually only done in 
 * file transfers.  In this case, the drag source is informed in the DragEnd event that a
 * DROP_TARGET_MOVE was performed.  It is the responsibility of the drag source at this point to clean 
 * up its displayed information.  No action needs to be taken on the operating system resources.</p>
 *
 * <p> The following example shows a Label widget that allows text to be dragged from it.</p>
 * 
 * <code><pre>
 *	// Enable a label as a Drag Source
 *	Label label = new Label(shell, SWT.NONE);
 *	// This example will allow text to be dragged
 *	Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
 *	// This example will allow the text to be copied or moved to the drop target
 *	int operations = DND.DROP_MOVE | DND.DROP_COPY;
 *	
 *	DragSource source = new DragSource(label, operations);
 *	source.setTransfer(types);
 *	source.addDragListener(new DragSourceListener() {
 *		public void dragStart(DragSourceEvent e) {
 *			// Only start the drag if there is actually text in the
 *			// label - this text will be what is dropped on the target.
 *			if (label.getText().length() == 0) {
 *				event.doit = false;
 *			}
 *		};
 *		public void dragSetData(DragSourceEvent event) {
 *			// A drop has been performed, so provide the data of the 
 *			// requested type.
 *			// (Checking the type of the requested data is only 
 *			// necessary if the drag source supports more than 
 *			// one data type but is shown here as an example).
 *			if (TextTransfer.getInstance().isSupportedType(event.dataType)){
 *				event.data = label.getText();
 *			}
 *		}
 *		public void dragFinished(DragSourceEvent event) {
 *			// A Move operation has been performed so remove the data
 *			// from the source
 *			if (event.detail == DND.DROP_MOVE)
 *				label.setText("");
 *		}
 *	});
 * </pre></code>
 *
 *
 * <dl>
 *	<dt><b>Styles</b></dt> <dd>DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK</dd>
 *	<dt><b>Events</b></dt> <dd>DND.DragStart, DND.DragSetData, DND.DragEnd</dd>
 * </dl>
 *
 * @see <a href="http://www.eclipse.org/swt/snippets/#dnd">Drag and Drop snippets</a>
 * @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: DNDExample</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 * @noextend This class is not intended to be subclassed by clients.
 */
public class DragSource extends Widget {

	// info for registering as a drag source
	Control control;
	Listener controlListener;
	Transfer[] transferAgents = new Transfer[0];
	DragSourceEffect dragEffect;

	static final String DEFAULT_DRAG_SOURCE_EFFECT = "DEFAULT_DRAG_SOURCE_EFFECT"; //$NON-NLS-1$
	static final String DRAG_STARTED = "org.eclipse.swt.internal.dragStarted";	//$NON-NLS-1$
	static Callback DragSendDataProc;
	
	static {
		DragSendDataProc = new Callback(DragSource.class, "DragSendDataProc", 4); //$NON-NLS-1$
		int dragSendDataProcAddress = DragSendDataProc.getAddress();
		if (dragSendDataProcAddress == 0) SWT.error(SWT.ERROR_NO_MORE_CALLBACKS);
	}

/**
 * Creates a new <code>DragSource</code> to handle dragging from the specified <code>Control</code>.
 * Creating an instance of a DragSource may cause system resources to be allocated depending on the platform.  
 * It is therefore mandatory that the DragSource instance be disposed when no longer required.
 *
 * @param control the <code>Control</code> that the user clicks on to initiate the drag
 * @param style the bitwise OR'ing of allowed operations; this may be a combination of any of 
 *					DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK
 * 
 * @exception SWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 * @exception SWTError <ul>
 *    <li>ERROR_CANNOT_INIT_DRAG - unable to initiate drag source; this will occur if more than one
 *        drag source is created for a control or if the operating system will not allow the creation
 *        of the drag source</li>
 * </ul>
 * 
 * <p>NOTE: ERROR_CANNOT_INIT_DRAG should be an SWTException, since it is a
 * recoverable error, but can not be changed due to backward compatibility.</p>
 * 
 * @see Widget#dispose
 * @see DragSource#checkSubclass
 * @see DND#DROP_NONE
 * @see DND#DROP_COPY
 * @see DND#DROP_MOVE
 * @see DND#DROP_LINK
 */
public DragSource(Control control, int style) {
	super (control, checkStyle(style));
	this.control = control;
	if (control.getData(DND.DRAG_SOURCE_KEY) != null) {
		DND.error(DND.ERROR_CANNOT_INIT_DRAG);
	}
	control.setData(DND.DRAG_SOURCE_KEY, this);
	
	controlListener = new Listener () {
		public void handleEvent (Event event) {
			if (event.type == SWT.Dispose) {
				if (!DragSource.this.isDisposed()) {
					DragSource.this.dispose();
				}
			}
			if (event.type == SWT.DragDetect) {
				if (!DragSource.this.isDisposed()) {
					DragSource.this.drag(event);
				}
			}
		}
	};
	control.addListener (SWT.Dispose, controlListener);
	control.addListener (SWT.DragDetect, controlListener);
	
	this.addListener(SWT.Dispose, new Listener() {
		public void handleEvent(Event e) {
			onDispose();
		}
	});
	
	Object effect = control.getData(DEFAULT_DRAG_SOURCE_EFFECT);
	if (effect instanceof DragSourceEffect) {
		dragEffect = (DragSourceEffect) effect;
	} else if (control instanceof Tree) {
		dragEffect = new TreeDragSourceEffect((Tree) control);
	} else if (control instanceof Table) {
		dragEffect = new TableDragSourceEffect((Table) control);
	}
}

static int checkStyle (int style) {
	if (style == SWT.NONE) return DND.DROP_MOVE;
	return style;
}

static int DragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
	DragSource source = FindDragSource(dragSendRefCon, theDrag);
	if (source == null) return OS.cantGetFlavorErr;
	return source.dragSendDataProc(theType, dragSendRefCon, theItemRef, theDrag);
}

static DragSource FindDragSource(int dragSendRefCon, int theDrag) {
	if (dragSendRefCon == 0) return null;
	Display display = Display.findDisplay(Thread.currentThread());
	if (display == null || display.isDisposed()) return null;
	Widget widget = display.findWidget(dragSendRefCon);
	if (widget == null) return null;
	return (DragSource)widget.getData(DND.DRAG_SOURCE_KEY); 
}

/**
 * Adds the listener to the collection of listeners who will
 * be notified when a drag and drop operation is in progress, by sending
 * it one of the messages defined in the <code>DragSourceListener</code>
 * interface.
 * 
 * <p><ul>
 * <li><code>dragStart</code> is called when the user has begun the actions required to drag the widget. 
 * This event gives the application the chance to decide if a drag should be started.
 * <li><code>dragSetData</code> is called when the data is required from the drag source.
 * <li><code>dragFinished</code> is called when the drop has successfully completed (mouse up 
 * over a valid target) or has been terminated (such as hitting the ESC key). Perform cleanup 
 * such as removing data from the source side on a successful move operation.
 * </ul></p>
 *
 * @param listener the listener which should be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DragSourceListener
 * @see #getDragListeners
 * @see #removeDragListener
 * @see DragSourceEvent
 */
public void addDragListener(DragSourceListener listener) {
	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
	DNDListener typedListener = new DNDListener (listener);
	typedListener.dndWidget = this;
	addListener (DND.DragStart, typedListener);
	addListener (DND.DragSetData, typedListener);
	addListener (DND.DragEnd, typedListener);
}

protected void checkSubclass () {
	String name = getClass().getName ();
	String validName = DragSource.class.getName();
	if (!validName.equals(name)) {
		DND.error (SWT.ERROR_INVALID_SUBCLASS);
	}
}

void drag(Event dragEvent) {
	DNDEvent event = new DNDEvent();
	event.widget = this;
	event.x = dragEvent.x;
	event.y = dragEvent.y;
	event.time = dragEvent.time;
	event.doit = true;
	notifyListeners(DND.DragStart, event);
	if (!event.doit || transferAgents == null || transferAgents.length == 0) return;
	
	int[] theDrag = new int[1];
	if (OS.NewDrag(theDrag) != OS.noErr) {
		event = new DNDEvent();
		event.widget = this;
		event.time = (int)System.currentTimeMillis();
		event.doit = false;
		event.detail = DND.DROP_NONE; 
		notifyListeners(DND.DragEnd, event);
		return;
	}
	
	Point pt = new Point();
	OS.GetGlobalMouse (pt);

	for (int i = 0; i < transferAgents.length; i++) {
		Transfer transfer = transferAgents[i];
		if (transfer != null) {
			int[] types = transfer.getTypeIds();
			for (int j = 0; j < types.length; j++) {
				OS.AddDragItemFlavor(theDrag[0], 1, types[j], null, 0, 0);
			}
		}
	}
	
	OS.SetDragSendProc(theDrag[0], DragSendDataProc.getAddress(), control.handle);
	
	int theRegion = 0;
	Image newImage = null;
	try {	
		theRegion = OS.NewRgn();
		OS.SetRectRgn(theRegion, (short)(pt.h), (short)(pt.v), (short)(pt.h+20), (short)(pt.v+20));
		
		int operations = opToOsOp(getStyle());
		//set operations twice - local and not local
		OS.SetDragAllowableActions(theDrag[0], operations, true);
		OS.SetDragAllowableActions(theDrag[0], operations, false);
		
		Image image = event.image;
		if (image != null) {
			CGPoint imageOffsetPt = new CGPoint();
			imageOffsetPt.x = 0;
			imageOffsetPt.y = 0;
			/*
			* Bug in the Macintosh.  For  some reason, it seems that SetDragImageWithCGImage() 
			* expects an image with the alpha, otherwise the image does not draw.  The fix is
			* to make sure that the image has an alpha by creating a new image with alpha
			* when necessary.
			*/
			if (OS.CGImageGetAlphaInfo(image.handle) == OS.kCGImageAlphaNoneSkipFirst) {
				ImageData data = image.getImageData();
				data.alpha = 0xFF;
				newImage = new Image(image.getDevice(), data);
				image = newImage;
			}
			OS.SetDragImageWithCGImage(theDrag[0], image.handle, imageOffsetPt, 0);
		}
		EventRecord theEvent = new EventRecord();
		theEvent.message = OS.kEventMouseMoved;
		theEvent.modifiers = (short)OS.GetCurrentEventKeyModifiers();
		theEvent.what = (short)OS.osEvt;
		theEvent.where_h = pt.h;
		theEvent.where_v = pt.v;	
		control.setData(DRAG_STARTED, new Object());
		int result = OS.TrackDrag(theDrag[0], theEvent, theRegion);
		control.setData(DRAG_STARTED, null);
		int operation = DND.DROP_NONE;
		if (result == OS.noErr) { 
			int[] outAction = new int[1];
			OS.GetDragDropAction(theDrag[0], outAction);
			operation = osOpToOp(outAction[0]);
		}	
		event = new DNDEvent();
		event.widget = this;
		event.time = (int)System.currentTimeMillis();
		event.doit = result == OS.noErr;
		event.detail = operation; 
		notifyListeners(DND.DragEnd, event);
	} finally {	
		if (theRegion != 0) OS.DisposeRgn(theRegion);
		if (newImage != null) newImage.dispose();
	}
	OS.DisposeDrag(theDrag[0]);
}

int dragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
	control.setData(DRAG_STARTED, null);
	if (theType == 0) return OS.badDragFlavorErr;
	TransferData transferData = new TransferData();
	transferData.type = theType;
	DNDEvent event = new DNDEvent();
	event.widget = this;
	event.time = (int)System.currentTimeMillis(); 
	event.dataType = transferData; 
	notifyListeners(DND.DragSetData, event);
	if (!event.doit) return OS.dragNotAcceptedErr;
	Transfer transfer = null;
	for (int i = 0; i < transferAgents.length; i++) {
		Transfer transferAgent = transferAgents[i];
		if (transferAgent != null && transferAgent.isSupportedType(transferData)) {
			transfer = transferAgent;
			break;
		}
	}
	if (transfer == null) return OS.badDragFlavorErr;
	transfer.javaToNative(event.data, transferData);
	if (transferData.result != OS.noErr) return transferData.result;
	byte[] datum = transferData.data[0];
	if (datum == null) return OS.cantGetFlavorErr;
	int rc = OS.SetDragItemFlavorData(theDrag, theItemRef, theType, datum, datum.length, 0);
	if (rc == OS.noErr && transfer instanceof FileTransfer) {
		for (int i = 1; i < transferData.data.length; i++) {
			datum = transferData.data[i];
			if (datum == null) return OS.cantGetFlavorErr;
			rc = OS.AddDragItemFlavor(theDrag, 1 + i, theType, datum, datum.length, 0);
			if (rc != OS.noErr) break;
		}
	}
	return rc;
}

/**
 * Returns the Control which is registered for this DragSource.  This is the control that the 
 * user clicks in to initiate dragging.
 *
 * @return the Control which is registered for this DragSource
 */
public Control getControl () {
	return control;
}

/**
 * Returns an array of listeners who will be notified when a drag and drop 
 * operation is in progress, by sending it one of the messages defined in 
 * the <code>DragSourceListener</code> interface.
 *
 * @return the listeners who will be notified when a drag and drop
 * operation is in progress
 *
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DragSourceListener
 * @see #addDragListener
 * @see #removeDragListener
 * @see DragSourceEvent
 * 
 * @since 3.4
 */
public DragSourceListener[] getDragListeners() {
	Listener[] listeners = getListeners(DND.DragStart);
	int length = listeners.length;
	DragSourceListener[] dragListeners = new DragSourceListener[length];
	int count = 0;
	for (int i = 0; i < length; i++) {
		Listener listener = listeners[i];
		if (listener instanceof DNDListener) {
			dragListeners[count] = (DragSourceListener) ((DNDListener) listener).getEventListener();
			count++;
		}
	}
	if (count == length) return dragListeners;
	DragSourceListener[] result = new DragSourceListener[count];
	System.arraycopy(dragListeners, 0, result, 0, count);
	return result;
}

/**
 * Returns the drag effect that is registered for this DragSource.  This drag
 * effect will be used during a drag and drop operation.
 *
 * @return the drag effect that is registered for this DragSource
 * 
 * @since 3.3
 */
public DragSourceEffect getDragSourceEffect() {
	return dragEffect;
}

/**
 * Returns the list of data types that can be transferred by this DragSource.
 *
 * @return the list of data types that can be transferred by this DragSource
 */
public Transfer[] getTransfer(){
	return transferAgents;
}

void onDispose() {
	if (control == null)
		return;
	if (controlListener != null) {
		control.removeListener(SWT.Dispose, controlListener);
		control.removeListener(SWT.DragDetect, controlListener);
	}
	controlListener = null;
	control.setData(DND.DRAG_SOURCE_KEY, null);
	control = null;
	transferAgents = null;
}

int opToOsOp(int operation) {
	int osOperation = 0;
	if ((operation & DND.DROP_COPY) != 0){
		osOperation |= OS.kDragActionCopy;
	}
	if ((operation & DND.DROP_LINK) != 0) {
		osOperation |= OS.kDragActionAlias;
	}
	if ((operation & DND.DROP_MOVE) != 0) {
		osOperation |= OS.kDragActionMove;
	}
	if ((operation & DND.DROP_TARGET_MOVE) != 0) {
		osOperation |= OS.kDragActionDelete;
	}
	return osOperation;
}

int osOpToOp(int osOperation){
	int operation = 0;
	if ((osOperation & OS.kDragActionCopy) != 0){
		operation |= DND.DROP_COPY;
	}
	if ((osOperation & OS.kDragActionAlias) != 0) {
		operation |= DND.DROP_LINK;
	}
	if ((osOperation & OS.kDragActionDelete) != 0) {
		operation |= DND.DROP_TARGET_MOVE;
	}
	if ((osOperation & OS.kDragActionMove) != 0) {
		operation |= DND.DROP_MOVE;
	}
	if (osOperation == OS.kDragActionAll) {
		operation = DND.DROP_COPY | DND.DROP_MOVE | DND.DROP_LINK;
	}
	return operation;
}

/**
 * Removes the listener from the collection of listeners who will
 * be notified when a drag and drop operation is in progress.
 *
 * @param listener the listener which should no longer be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DragSourceListener
 * @see #addDragListener
 * @see #getDragListeners
 */
public void removeDragListener(DragSourceListener listener) {
	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
	removeListener (DND.DragStart, listener);
	removeListener (DND.DragSetData, listener);
	removeListener (DND.DragEnd, listener);
}

/**
 * Specifies the drag effect for this DragSource.  This drag effect will be 
 * used during a drag and drop operation.
 *
 * @param effect the drag effect that is registered for this DragSource
 * 
 * @since 3.3
 */
public void setDragSourceEffect(DragSourceEffect effect) {
	dragEffect = effect;
}
/**
 * Specifies the list of data types that can be transferred by this DragSource.
 * The application must be able to provide data to match each of these types when
 * a successful drop has occurred.
 * 
 * @param transferAgents a list of Transfer objects which define the types of data that can be
 * dragged from this source
 */
public void setTransfer(Transfer[] transferAgents){
	this.transferAgents = transferAgents;
}

}