/*******************************************************************************
 * Copyright (c) 2000, 2010 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.gef;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.TraverseEvent;
import org.eclipse.swt.widgets.Event;

import org.eclipse.gef.commands.CommandStack;
import org.eclipse.gef.palette.PaletteListener;
import org.eclipse.gef.palette.PaletteRoot;
import org.eclipse.gef.palette.ToolEntry;
import org.eclipse.gef.tools.SelectionTool;
import org.eclipse.gef.ui.palette.PaletteViewer;

/**
 * The collective state of a GEF "application", loosely defined by a
 * CommandStack, one or more EditPartViewers, and the active Tool. An EditDomain
 * is usually tied with an Eclipse {@link org.eclipse.ui.IEditorPart
 * IEditorPart}). However, the distinction between EditorPart and EditDomain was
 * made to allow for much flexible use of the Graphical Editing Framework.
 */
public class EditDomain {

	private Tool defaultTool;
	private PaletteViewer paletteViewer;
	private PaletteRoot paletteRoot;
	private Tool activeTool;
	private List viewers = new ArrayList();
	private CommandStack commandStack = new CommandStack();

	/**
	 * Listens to the PaletteViewer for changes in selection, and sets the
	 * Domain's Tool accordingly.
	 */
	private PaletteListener paletteListener = new PaletteListener() {
		public void activeToolChanged(PaletteViewer viewer, ToolEntry tool) {
			handlePaletteToolChanged();
		}
	};

	/**
	 * Constructs an EditDomain and loads the default tool.
	 */
	public EditDomain() {
		loadDefaultTool();
	}

	/**
	 * Adds an EditPartViewer into the EditDomain. A viewer is most likely
	 * placed in a {@link org.eclipse.ui.IWorkbenchPart WorkbenchPart} of some
	 * form, such as the IEditorPart or an IViewPart.
	 * 
	 * @param viewer
	 *            The EditPartViewer
	 */
	public void addViewer(EditPartViewer viewer) {
		viewer.setEditDomain(this);
		if (!viewers.contains(viewer))
			viewers.add(viewer);
	}

	/**
	 * Called when one of the EditDomain's Viewers receives keyboard focus.
	 * 
	 * @param event
	 *            The SWT focus event
	 * @param viewer
	 *            the Viewer that received the event.
	 */
	public void focusGained(FocusEvent event, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.focusGained(event, viewer);
	}

	/**
	 * Called when one of the EditDomain's Viewers is losing keyboard focus.
	 * 
	 * @param event
	 *            The SWT focus event
	 * @param viewer
	 *            the Viewer that received the event.
	 */
	public void focusLost(FocusEvent event, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.focusLost(event, viewer);
	}

	/**
	 * Returns the active Tool
	 * 
	 * @return the active Tool
	 */
	public Tool getActiveTool() {
		return activeTool;
	}

	/**
	 * Returns the CommandStack. Command stacks could potentially be shared
	 * across domains depending on the application.
	 * 
	 * @return The command stack
	 */
	public CommandStack getCommandStack() {
		return commandStack;
	}

	/**
	 * Returns the default tool for this edit domain. This will be a
	 * {@link org.eclipse.gef.tools.SelectionTool} unless specifically replaced
	 * using {@link #setDefaultTool(Tool)}.
	 * 
	 * @return The default Tool for this domain
	 */
	public Tool getDefaultTool() {
		if (defaultTool == null)
			defaultTool = new SelectionTool();
		return defaultTool;
	}

	/**
	 * Returns the palette viewer currently associated with this domain.
	 * 
	 * @since 1.0
	 * @return The current palette viewer
	 */
	public PaletteViewer getPaletteViewer() {
		return paletteViewer;
	}

	private void handlePaletteToolChanged() {
		PaletteViewer paletteViewer = getPaletteViewer();
		if (paletteViewer != null) {
			ToolEntry entry = paletteViewer.getActiveTool();
			if (entry != null)
				setActiveTool(entry.createTool());
			else
				setActiveTool(getDefaultTool());
		}
	}

	/**
	 * Called when a key is <B>pressed</B> on a Viewer.
	 * 
	 * @param keyEvent
	 *            The SWT key event
	 * @param viewer
	 *            The source of the event.
	 */
	public void keyDown(KeyEvent keyEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.keyDown(keyEvent, viewer);
	}

	/**
	 * Called when a traversal occurs on a viewer.
	 * 
	 * @param traverseEvent
	 *            the SWT traverse event
	 * @param viewer
	 *            the source of the event
	 * @since 3.1
	 */
	public void keyTraversed(TraverseEvent traverseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.keyTraversed(traverseEvent, viewer);
	}

	/**
	 * Called when a key is <B>released</b> on a Viewer.
	 * 
	 * @param keyEvent
	 *            The SWT key event
	 * @param viewer
	 *            the source of the event.
	 */
	public void keyUp(KeyEvent keyEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.keyUp(keyEvent, viewer);
	}

	/**
	 * Loads the default Tool. If a palette has been provided and that palette
	 * has a default, then that tool is loaded. If not, the EditDomain's default
	 * tool is loaded. By default, this is the
	 * {@link org.eclipse.gef.tools.SelectionTool}.
	 */
	public void loadDefaultTool() {
		setActiveTool(null);
		PaletteViewer paletteViewer = getPaletteViewer();
		if (paletteRoot != null && paletteViewer != null) {
			if (paletteRoot.getDefaultEntry() != null) {
				paletteViewer.setActiveTool(paletteRoot.getDefaultEntry());
				return;
			} else
				paletteViewer.setActiveTool(null);
		}
		setActiveTool(getDefaultTool());
	}

	/**
	 * Called when the mouse button has been double-clicked on a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The source of the event.
	 */
	public void mouseDoubleClick(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseDoubleClick(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse button has been pressed on a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The source of the event.
	 */
	public void mouseDown(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseDown(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse has been dragged within a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The source of the event.
	 */
	public void mouseDrag(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseDrag(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse has hovered on a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The source of the event.
	 */
	public void mouseHover(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseHover(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse has been moved on a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The viewer that the mouse event is over.
	 */
	public void mouseMove(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseMove(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse button has been released on a Viewer.
	 * 
	 * @param mouseEvent
	 *            The SWT mouse event
	 * @param viewer
	 *            The source of the event.
	 */
	public void mouseUp(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseUp(mouseEvent, viewer);
	}

	/**
	 * Called by the DomainEventDispatcher when the mouse wheel has been
	 * scrolled.
	 * 
	 * @param event
	 *            The SWT event
	 * @param viewer
	 *            The source of the event
	 */
	public void mouseWheelScrolled(Event event, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.mouseWheelScrolled(event, viewer);
	}

	/**
	 * Called when a native drag has finished on a Viewer.
	 * 
	 * @param event
	 *            The DragSourceEvent
	 * @param viewer
	 *            The viewer where the drag finished
	 */
	public void nativeDragFinished(DragSourceEvent event, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.nativeDragFinished(event, viewer);
	}

	/**
	 * Called when a native drag has started on a Viewer.
	 * 
	 * @param event
	 *            The DragSourceEvent
	 * @param viewer
	 *            The viewer where the drag started
	 */
	public void nativeDragStarted(DragSourceEvent event, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.nativeDragStarted(event, viewer);
	}

	/**
	 * Removes a previously added viewer from the EditDomain. A Viewer that is
	 * removed from the EditDomain will no longer forward input to the domain
	 * and its active Tool.
	 * 
	 * @param viewer
	 *            the Viewer being removed
	 */
	public void removeViewer(EditPartViewer viewer) {
		if (viewers.remove(viewer))
			viewer.setEditDomain(null);
	}

	/**
	 * Sets the <code>CommandStack</code>.
	 * 
	 * @param stack
	 *            the CommandStack
	 */
	public void setCommandStack(CommandStack stack) {
		commandStack = stack;
	}

	/**
	 * Sets the default Tool, which is used if the Palette does not provide a
	 * default
	 * 
	 * @param tool
	 *            <code>null</code> or a Tool
	 */
	public void setDefaultTool(Tool tool) {
		defaultTool = tool;
	}

	/**
	 * Sets the PalatteRoot for this EditDomain. If the EditDomain already knows
	 * about a PaletteViewer, this root will be set into the palette viewer
	 * also. Loads the default Tool after the root has been set.
	 * <p>
	 * It is recommended that the palette root not be set multiple times. Some
	 * components (such as the PaletteCustomizerDialog for the PaletteViewer)
	 * might still hold on to the old root. If the input has changed or needs to
	 * be refreshed, just remove all the children from the root and add the new
	 * ones.
	 * 
	 * @param root
	 *            the palette's root
	 */
	public void setPaletteRoot(PaletteRoot root) {
		if (paletteRoot == root)
			return;
		paletteRoot = root;
		if (getPaletteViewer() != null) {
			getPaletteViewer().setPaletteRoot(paletteRoot);
			loadDefaultTool();
		}
	}

	/**
	 * Sets the <code>PaletteViewer</code> for this EditDomain
	 * 
	 * @param palette
	 *            the PaletteViewer
	 */
	public void setPaletteViewer(PaletteViewer palette) {
		if (palette == paletteViewer)
			return;
		if (paletteViewer != null)
			paletteViewer.removePaletteListener(paletteListener);
		paletteViewer = palette;
		if (paletteViewer != null) {
			palette.addPaletteListener(paletteListener);
			if (paletteRoot != null) {
				paletteViewer.setPaletteRoot(paletteRoot);
				loadDefaultTool();
			}
		}
	}

	/**
	 * Sets the active Tool for this EditDomain. If a current Tool is active, it
	 * is deactivated. The new Tool is told its EditDomain, and is activated.
	 * 
	 * @param tool
	 *            the Tool
	 */
	public void setActiveTool(Tool tool) {
		if (activeTool != null)
			activeTool.deactivate();
		activeTool = tool;
		if (activeTool != null) {
			activeTool.setEditDomain(this);
			activeTool.activate();
		}
	}

	/**
	 * Called when the mouse enters a Viewer.
	 * 
	 * @param mouseEvent
	 *            the SWT mouse event
	 * @param viewer
	 *            the Viewer being entered
	 */
	public void viewerEntered(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.viewerEntered(mouseEvent, viewer);
	}

	/**
	 * Called when the mouse exits a Viewer.
	 * 
	 * @param mouseEvent
	 *            the SWT mouse event
	 * @param viewer
	 *            the Viewer being exited
	 */
	public void viewerExited(MouseEvent mouseEvent, EditPartViewer viewer) {
		Tool tool = getActiveTool();
		if (tool != null)
			tool.viewerExited(mouseEvent, viewer);
	}

}