/*
    * Copyright (C) 2007-2012 Argeo GmbH
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *         http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.argeo.eclipse.ui.dialogs;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.argeo.eclipse.ui.EclipseUiException;
  import org.eclipse.swt.SWT;
  import org.eclipse.swt.events.FocusEvent;
  import org.eclipse.swt.events.FocusListener;
  import org.eclipse.swt.events.ShellAdapter;
  import org.eclipse.swt.events.ShellEvent;
  import org.eclipse.swt.graphics.Point;
  import org.eclipse.swt.graphics.Rectangle;
  import org.eclipse.swt.layout.GridData;
  import org.eclipse.swt.layout.GridLayout;
  import org.eclipse.swt.widgets.Composite;
  import org.eclipse.swt.widgets.Control;
  import org.eclipse.swt.widgets.Display;
  import org.eclipse.swt.widgets.Shell;
  
  /** Generic lightweight dialog, not based on JFace. */
  public class LightweightDialog {
  	private final static Log log = LogFactory.getLog(LightweightDialog.class);
  
  	// must be the same value as org.eclipse.jface.window.Window#OK
  	public final static int OK = 0;
  	// must be the same value as org.eclipse.jface.window.Window#CANCEL
  	public final static int CANCEL = 1;
  
  	private Shell parentShell;
  	private Shell backgroundShell;
  	private Shell foregoundShell;
  
  	private Integer returnCode = null;
  	private boolean block = true;
  
  	private String title;
  
  	/** Tries to find a display */
  	private static Display getDisplay() {
  		try {
  			Display display = Display.getCurrent();
  			if (display != null)
  				return display;
  			else
  				return Display.getDefault();
  		} catch (Exception e) {
  			return Display.getCurrent();
  		}
  	}
  
  	public LightweightDialog(Shell parentShell) {
  		this.parentShell = parentShell;
  	}
  
  	public int open() {
  		if (foregoundShell != null)
  			throw new EclipseUiException("There is already a shell");
  		backgroundShell = new Shell(parentShell, SWT.ON_TOP);
  		backgroundShell.setFullScreen(true);
  		// if (parentShell != null) {
  		// backgroundShell.setBounds(parentShell.getBounds());
  		// } else
  		// backgroundShell.setMaximized(true);
  		backgroundShell.setAlpha(128);
  		backgroundShell.setBackground(getDisplay().getSystemColor(SWT.COLOR_BLACK));
  		foregoundShell = new Shell(backgroundShell, SWT.NO_TRIM | SWT.ON_TOP);
  		if (title != null)
  			setTitle(title);
  		foregoundShell.setLayout(new GridLayout());
  		foregoundShell.setSize(getInitialSize());
  		createDialogArea(foregoundShell);
  		// shell.pack();
  		// shell.layout();
  
  		Rectangle shellBounds = parentShell != null ? parentShell.getBounds() : Display.getCurrent().getBounds();// RAP
  		Point dialogSize = foregoundShell.getSize();
  		int x = shellBounds.x + (shellBounds.width - dialogSize.x) / 2;
  		int y = shellBounds.y + (shellBounds.height - dialogSize.y) / 2;
  		foregoundShell.setLocation(x, y);
  
  		foregoundShell.addShellListener(new ShellAdapter() {
  			private static final long serialVersionUID = -2701270481953688763L;
  
  			@Override
 			public void shellDeactivated(ShellEvent e) {
 				if (hasChildShells())
 					return;
 				if (returnCode == null)// not yet closed
 					closeShell(CANCEL);
 			}
 
 			@Override
 			public void shellClosed(ShellEvent e) {
 				notifyClose();
 			}
 
 		});
 
 		backgroundShell.open();
 		foregoundShell.open();
 		// after the foreground shell has been opened
 		backgroundShell.addFocusListener(new FocusListener() {
 			private static final long serialVersionUID = 3137408447474661070L;
 
 			@Override
 			public void focusLost(FocusEvent event) {
 			}
 
 			@Override
 			public void focusGained(FocusEvent event) {
 				if (hasChildShells())
 					return;
 				if (returnCode == null)// not yet closed
 					closeShell(CANCEL);
 			}
 		});
 
 		if (block) {
 			try {
 				runEventLoop(foregoundShell);
 			} catch (ThreadDeath t) {
 				returnCode = CANCEL;
 				if (log.isTraceEnabled())
 					log.error("Thread death, canceling dialog", t);
 			} catch (Throwable t) {
 				returnCode = CANCEL;
 				log.error("Cannot open blocking lightweight dialog", t);
 			}
 		}
 		if (returnCode == null)
 			returnCode = OK;
 		return returnCode;
 	}
 
 	private boolean hasChildShells() {
 		if (foregoundShell == null)
 			return false;
 		return foregoundShell.getShells().length != 0;
 	}
 
 	// public synchronized int openAndWait() {
 	// open();
 	// while (returnCode == null)
 	// try {
 	// wait(100);
 	// } catch (InterruptedException e) {
 	// // silent
 	// }
 	// return returnCode;
 	// }
 
 	private synchronized void notifyClose() {
 		if (returnCode == null)
 			returnCode = CANCEL;
 		notifyAll();
 	}
 
 	protected void closeShell(int returnCode) {
 		this.returnCode = returnCode;
 		if (CANCEL == returnCode)
 			onCancel();
 		if (foregoundShell != null && !foregoundShell.isDisposed()) {
 			foregoundShell.close();
 			foregoundShell.dispose();
 			foregoundShell = null;
 		}
 
 		if (backgroundShell != null && !backgroundShell.isDisposed()) {
 			backgroundShell.close();
 			backgroundShell.dispose();
 		}
 	}
 
 	protected Point getInitialSize() {
 		// if (exception != null)
 		// return new Point(800, 600);
 		// else
 		return new Point(600, 400);
 	}
 
 	protected Control createDialogArea(Composite parent) {
 		Composite dialogarea = new Composite(parent, SWT.NONE);
 		dialogarea.setLayout(new GridLayout());
 		dialogarea.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
 		return dialogarea;
 	}
 
 	protected Shell getBackgroundShell() {
 		return backgroundShell;
 	}
 
 	protected Shell getForegoundShell() {
 		return foregoundShell;
 	}
 
 	public void setBlockOnOpen(boolean shouldBlock) {
 		block = shouldBlock;
 	}
 
 	public void pack() {
 		foregoundShell.pack();
 	}
 
 	private void runEventLoop(Shell loopShell) {
 		Display display;
 		if (foregoundShell == null) {
 			display = Display.getCurrent();
 		} else {
 			display = loopShell.getDisplay();
 		}
 
 		while (loopShell != null && !loopShell.isDisposed()) {
 			try {
 				if (!display.readAndDispatch()) {
 					display.sleep();
 				}
 			} catch (Throwable e) {
 				handleException(e);
 			}
 		}
 		if (!display.isDisposed())
 			display.update();
 	}
 
 	protected void handleException(Throwable t) {
 		if (t instanceof ThreadDeath) {
 			// Don't catch ThreadDeath as this is a normal occurrence when
 			// the thread dies
 			throw (ThreadDeath) t;
 		}
 		// Try to keep running.
 		t.printStackTrace();
 	}
 
 	/** @return false, if the dialog should not be closed. */
 	protected boolean onCancel() {
 		return true;
 	}
 
 	public void setTitle(String title) {
 		this.title = title;
 		if (title != null && getForegoundShell() != null)
 			getForegoundShell().setText(title);
 	}
 
 	public Integer getReturnCode() {
 		return returnCode;
 	}
 
 }