/*******************************************************************************
 * 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.ui.parts;

import java.util.ArrayList;
import java.util.EventObject;
import java.util.Iterator;
import java.util.List;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.jface.action.IAction;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.IEditorSite;
import org.eclipse.ui.ISelectionListener;
import org.eclipse.ui.ISelectionService;
import org.eclipse.ui.IWorkbenchPart;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.actions.ActionFactory;
import org.eclipse.ui.part.EditorPart;

import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.IFigure;

import org.eclipse.gef.ContextMenuProvider;
import org.eclipse.gef.DefaultEditDomain;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.GraphicalViewer;
import org.eclipse.gef.commands.CommandStack;
import org.eclipse.gef.commands.CommandStackListener;
import org.eclipse.gef.ui.actions.ActionBarContributor;
import org.eclipse.gef.ui.actions.ActionRegistry;
import org.eclipse.gef.ui.actions.DeleteAction;
import org.eclipse.gef.ui.actions.PrintAction;
import org.eclipse.gef.ui.actions.RedoAction;
import org.eclipse.gef.ui.actions.SaveAction;
import org.eclipse.gef.ui.actions.SelectAllAction;
import org.eclipse.gef.ui.actions.UndoAction;
import org.eclipse.gef.ui.actions.UpdateAction;
import org.eclipse.gef.ui.properties.UndoablePropertySheetPage;

/**
 * This class serves as a quick starting point for clients who are new to GEF.
 * It will create an Editor containing a single GraphicalViewer as its control.
 * <P>
 * <EM>IMPORTANT</EM>This class should only be used as a reference for creating
 * your own EditorPart implementation. This class will not suit everyone's
 * needs, and may change in the future. Clients may copy the implementation.
 * 
 * @author hudsonr
 */
public abstract class GraphicalEditor extends EditorPart implements
		CommandStackListener, ISelectionListener {

	private static class ActionIDList extends ArrayList {
		public boolean add(Object o) {
			if (o instanceof IAction) {
				try {
					IAction action = (IAction) o;
					o = action.getId();
					throw new IllegalArgumentException(
							"Action IDs should be added to lists, not the action: " + action); //$NON-NLS-1$
				} catch (IllegalArgumentException exc) {
					exc.printStackTrace();
				}
			}
			return super.add(o);
		}
	}

	private DefaultEditDomain editDomain;
	private GraphicalViewer graphicalViewer;
	private ActionRegistry actionRegistry;
	private SelectionSynchronizer synchronizer;
	private List selectionActions = new ActionIDList();
	private List stackActions = new ActionIDList();
	private List propertyActions = new ActionIDList();

	/**
	 * Constructs the editor part
	 */
	public GraphicalEditor() {
	}

	/**
	 * When the command stack changes, the actions interested in the command
	 * stack are updated.
	 * 
	 * @param event
	 *            the change event
	 */
	public void commandStackChanged(EventObject event) {
		updateActions(stackActions);
	}

	/**
	 * Called to configure the graphical viewer before it receives its contents.
	 * This is where the root editpart should be configured. Subclasses should
	 * extend or override this method as needed.
	 */
	protected void configureGraphicalViewer() {
		getGraphicalViewer().getControl().setBackground(
				ColorConstants.listBackground);
	}

	/**
	 * Creates actions for this editor. Subclasses should override this method
	 * to create and register actions with the {@link ActionRegistry}.
	 */
	protected void createActions() {
		ActionRegistry registry = getActionRegistry();
		IAction action;

		action = new UndoAction(this);
		registry.registerAction(action);
		getStackActions().add(action.getId());

		action = new RedoAction(this);
		registry.registerAction(action);
		getStackActions().add(action.getId());

		action = new SelectAllAction(this);
		registry.registerAction(action);

		action = new DeleteAction((IWorkbenchPart) this);
		registry.registerAction(action);
		getSelectionActions().add(action.getId());

		action = new SaveAction(this);
		registry.registerAction(action);
		getPropertyActions().add(action.getId());

		registry.registerAction(new PrintAction(this));
	}

	/**
	 * Creates the GraphicalViewer on the specified <code>Composite</code>.
	 * 
	 * @param parent
	 *            the parent composite
	 */
	protected void createGraphicalViewer(Composite parent) {
		GraphicalViewer viewer = new ScrollingGraphicalViewer();
		viewer.createControl(parent);
		setGraphicalViewer(viewer);
		configureGraphicalViewer();
		hookGraphicalViewer();
		initializeGraphicalViewer();
	}

	/**
	 * Realizes the Editor by creating it's Control.
	 * <P>
	 * WARNING: This method may or may not be called by the workbench prior to
	 * {@link #dispose()}.
	 * 
	 * @param parent
	 *            the parent composite
	 */
	public void createPartControl(Composite parent) {
		createGraphicalViewer(parent);
	}

	/**
	 * @see org.eclipse.ui.IWorkbenchPart#dispose()
	 */
	public void dispose() {
		getCommandStack().removeCommandStackListener(this);
		getSite().getWorkbenchWindow().getSelectionService()
				.removeSelectionListener(this);
		getEditDomain().setActiveTool(null);
		getActionRegistry().dispose();
		super.dispose();
	}

	/**
	 * Does nothing be default. This method should be overridden if
	 * {@link #isSaveAsAllowed()} has been overridden to return
	 * <code>true</code>.
	 * 
	 * @see org.eclipse.ui.ISaveablePart#doSaveAs()
	 */
	public void doSaveAs() {
		throw new RuntimeException("doSaveAs must be overridden"); //$NON-NLS-1$
	}

	/**
	 * @see org.eclipse.ui.part.WorkbenchPart#firePropertyChange(int)
	 */
	protected void firePropertyChange(int property) {
		super.firePropertyChange(property);
		updateActions(propertyActions);
	}

	/**
	 * Lazily creates and returns the action registry.
	 * 
	 * @return the action registry
	 */
	protected ActionRegistry getActionRegistry() {
		if (actionRegistry == null)
			actionRegistry = new ActionRegistry();
		return actionRegistry;
	}

	/**
	 * Returns the adapter for the specified key.
	 * 
	 * <P>
	 * <EM>IMPORTANT</EM> certain requests, such as the property sheet, may be
	 * made before or after {@link #createPartControl(Composite)} is called. The
	 * order is unspecified by the Workbench.
	 * 
	 * @see org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class)
	 */
	public Object getAdapter(Class type) {
		if (type == org.eclipse.ui.views.properties.IPropertySheetPage.class) {
			return new UndoablePropertySheetPage(getCommandStack(),
					getActionRegistry().getAction(ActionFactory.UNDO.getId()),
					getActionRegistry().getAction(ActionFactory.REDO.getId()));
		}
		if (type == GraphicalViewer.class)
			return getGraphicalViewer();
		if (type == CommandStack.class)
			return getCommandStack();
		if (type == ActionRegistry.class)
			return getActionRegistry();
		if (type == EditPart.class && getGraphicalViewer() != null)
			return getGraphicalViewer().getRootEditPart();
		if (type == IFigure.class && getGraphicalViewer() != null)
			return ((GraphicalEditPart) getGraphicalViewer().getRootEditPart())
					.getFigure();
		return super.getAdapter(type);
	}

	/**
	 * Returns the command stack.
	 * 
	 * @return the command stack
	 */
	protected CommandStack getCommandStack() {
		return getEditDomain().getCommandStack();
	}

	/**
	 * Returns the edit domain.
	 * 
	 * @return the edit domain
	 */
	protected DefaultEditDomain getEditDomain() {
		return editDomain;
	}

	/**
	 * Returns the graphical viewer.
	 * 
	 * @return the graphical viewer
	 */
	protected GraphicalViewer getGraphicalViewer() {
		return graphicalViewer;
	}

	/**
	 * Returns the list of {@link IAction IActions} dependant on property
	 * changes in the Editor. These actions should implement the
	 * {@link UpdateAction} interface so that they can be updated in response to
	 * property changes. An example is the "Save" action.
	 * 
	 * @return the list of property-dependant actions
	 */
	protected List getPropertyActions() {
		return propertyActions;
	}

	/**
	 * Returns the list of <em>IDs</em> of Actions that are dependant on changes
	 * in the workbench's {@link ISelectionService}. The associated Actions can
	 * be found in the action registry. Such actions should implement the
	 * {@link UpdateAction} interface so that they can be updated in response to
	 * selection changes.
	 * 
	 * @see #updateActions(List)
	 * @return the list of selection-dependant action IDs
	 */
	protected List getSelectionActions() {
		return selectionActions;
	}

	/**
	 * Returns the selection syncronizer object. The synchronizer can be used to
	 * sync the selection of 2 or more EditPartViewers.
	 * 
	 * @return the syncrhonizer
	 */
	protected SelectionSynchronizer getSelectionSynchronizer() {
		if (synchronizer == null)
			synchronizer = new SelectionSynchronizer();
		return synchronizer;
	}

	/**
	 * Returns the list of <em>IDs</em> of Actions that are dependant on the
	 * CommmandStack's state. The associated Actions can be found in the action
	 * registry. These actions should implement the {@link UpdateAction}
	 * interface so that they can be updated in response to command stack
	 * changes. An example is the "undo" action.
	 * 
	 * @return the list of stack-dependant action IDs
	 */
	protected List getStackActions() {
		return stackActions;
	}

	/**
	 * Hooks the GraphicalViewer to the rest of the Editor. By default, the
	 * viewer is added to the SelectionSynchronizer, which can be used to keep 2
	 * or more EditPartViewers in sync. The viewer is also registered as the
	 * ISelectionProvider for the Editor's PartSite.
	 */
	protected void hookGraphicalViewer() {
		getSelectionSynchronizer().addViewer(getGraphicalViewer());
		getSite().setSelectionProvider(getGraphicalViewer());
	}

	/**
	 * Sets the site and input for this editor then creates and initializes the
	 * actions. Subclasses may extend this method, but should always call
	 * <code>super.init(site, input)
	 * </code>.
	 * 
	 * @see org.eclipse.ui.IEditorPart#init(IEditorSite, IEditorInput)
	 */
	public void init(IEditorSite site, IEditorInput input)
			throws PartInitException {
		setSite(site);
		setInput(input);
		getCommandStack().addCommandStackListener(this);
		getSite().getWorkbenchWindow().getSelectionService()
				.addSelectionListener(this);
		initializeActionRegistry();
	}

	/**
	 * Initializes the ActionRegistry. This registry may be used by
	 * {@link ActionBarContributor ActionBarContributors} and/or
	 * {@link ContextMenuProvider ContextMenuProviders}.
	 * <P>
	 * This method may be called on Editor creation, or lazily the first time
	 * {@link #getActionRegistry()} is called.
	 */
	protected void initializeActionRegistry() {
		createActions();
		updateActions(propertyActions);
		updateActions(stackActions);
	}

	/**
	 * Override to set the contents of the GraphicalViewer after it has been
	 * created.
	 * 
	 * @see #createGraphicalViewer(Composite)
	 */
	protected abstract void initializeGraphicalViewer();

	/**
	 * Returns <code>true</code> if the command stack is dirty
	 * 
	 * @see org.eclipse.ui.ISaveablePart#isDirty()
	 */
	public boolean isDirty() {
		return getCommandStack().isDirty();
	}

	/**
	 * Returns <code>false</code> by default. Subclasses must return
	 * <code>true</code> to allow {@link #doSaveAs()} to be called.
	 * 
	 * @see org.eclipse.ui.ISaveablePart#isSaveAsAllowed()
	 */
	public boolean isSaveAsAllowed() {
		return false;
	}

	/**
	 * @see org.eclipse.ui.ISelectionListener#selectionChanged(IWorkbenchPart,
	 *      ISelection)
	 */
	public void selectionChanged(IWorkbenchPart part, ISelection selection) {
		// If not the active editor, ignore selection changed.
		if (this.equals(getSite().getPage().getActiveEditor()))
			updateActions(selectionActions);
	}

	/**
	 * Sets the ActionRegistry for this EditorPart.
	 * 
	 * @param registry
	 *            the registry
	 */
	protected void setActionRegistry(ActionRegistry registry) {
		actionRegistry = registry;
	}

	/**
	 * Sets the EditDomain for this EditorPart.
	 * 
	 * @param ed
	 *            the domain
	 */
	protected void setEditDomain(DefaultEditDomain ed) {
		this.editDomain = ed;
	}

	/**
	 * @see org.eclipse.ui.IWorkbenchPart#setFocus()
	 */
	public void setFocus() {
		getGraphicalViewer().getControl().setFocus();
	}

	/**
	 * Sets the graphicalViewer for this EditorPart.
	 * 
	 * @param viewer
	 *            the graphical viewer
	 */
	protected void setGraphicalViewer(GraphicalViewer viewer) {
		getEditDomain().addViewer(viewer);
		this.graphicalViewer = viewer;
	}

	/**
	 * A convenience method for updating a set of actions defined by the given
	 * List of action IDs. The actions are found by looking up the ID in the
	 * {@link #getActionRegistry() action registry}. If the corresponding action
	 * is an {@link UpdateAction}, it will have its <code>update()</code> method
	 * called.
	 * 
	 * @param actionIds
	 *            the list of IDs to update
	 */
	protected void updateActions(List actionIds) {
		ActionRegistry registry = getActionRegistry();
		Iterator iter = actionIds.iterator();
		while (iter.hasNext()) {
			IAction action = registry.getAction(iter.next());
			if (action instanceof UpdateAction)
				((UpdateAction) action).update();
		}
	}

}