/*******************************************************************************
 * Copyright (c) 2002 International Business Machines Corp. and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v0.5 
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v05.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/
package net.sourceforge.phpdt.ui.actions;

import org.eclipse.jface.action.Action;
import org.eclipse.jface.text.ITextSelection;
import org.eclipse.jface.util.Assert;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.IWorkbenchSite;

/**
 * Action that dispatches the <code>IAction#run()</code> and the
 * <code>ISelectionChangedListener#selectionChanged</code> according to the
 * type of the selection.
 * 
 * <ul>
 * <li>if selection is of type <code>ITextSelection</code> then
 * <code>run(ITextSelection)</code> and
 * <code>selectionChanged(ITextSelection)</code> is called.</li>
 * <li>if selection is of type <code>IStructuredSelection</code> then
 * <code>run(IStructuredSelection)</code> and <code>
 * 	selectionChanged(IStructuredSelection)</code>
 * is called.</li>
 * <li>default is to call <code>run(ISelection)</code> and <code>
 * 	selectionChanged(ISelection)</code>.</li>
 * </ul>
 * 
 * <p>
 * Note: This class is not intended to be subclassed outside the JDT UI plugin.
 * </p>
 * 
 * @since 2.0
 */
public abstract class SelectionDispatchAction extends Action implements
		ISelectionChangedListener {

	private IWorkbenchSite fSite;

	/**
	 * Creates a new action with no text and no image.
	 * <p>
	 * Configure the action later using the set methods.
	 * </p>
	 * 
	 * @param site
	 *            the site this action is working on
	 */
	protected SelectionDispatchAction(IWorkbenchSite site) {
		Assert.isNotNull(site);
		fSite = site;
	}

	/**
	 * Returns the site owning this action.
	 * 
	 * @return the site owning this action
	 */
	public IWorkbenchSite getSite() {
		return fSite;
	}

	/**
	 * Returns the selection provided by the site owning this action.
	 * 
	 * @return the site's selection
	 */
	public ISelection getSelection() {
		return getSelectionProvider().getSelection();
	}

	/**
	 * Returns the shell provided by the site owning this action.
	 * 
	 * @return the site's shell
	 */
	public Shell getShell() {
		return fSite.getShell();
	}

	/**
	 * Returns the selection provider managed by the site owning this action.
	 * 
	 * @return the site's selection provider
	 */
	public ISelectionProvider getSelectionProvider() {
		return fSite.getSelectionProvider();
	}

	/**
	 * Updates the action's enablement state according to the given selection.
	 * This default implementation calls one of the
	 * <code>selectionChanged</code> methods depending on the type of the
	 * passed selection.
	 * 
	 * @param selection
	 *            the selection this action is working on
	 */
	public void update(ISelection selection) {
		dispatchSelectionChanged(selection);
	}

	/**
	 * Notifies this action that the given structured selection has changed.
	 * This default implementation calls
	 * <code>selectionChanged(ISelection selection)</code>.
	 * 
	 * @param selection
	 *            the new selection
	 */
	protected void selectionChanged(IStructuredSelection selection) {
		selectionChanged((ISelection) selection);
	}

	/**
	 * Executes this actions with the given structured selection. This default
	 * implementation calls <code>run(ISelection selection)</code>.
	 */
	protected void run(IStructuredSelection selection) {
		run((ISelection) selection);
	}

	/**
	 * Notifies this action that the given text selection has changed. This
	 * default implementation calls
	 * <code>selectionChanged(ISelection selection)</code>.
	 * 
	 * @param selection
	 *            the new selection
	 */
	protected void selectionChanged(ITextSelection selection) {
		selectionChanged((ISelection) selection);
	}

	/**
	 * Executes this actions with the given text selection. This default
	 * implementation calls <code>run(ISelection selection)</code>.
	 */
	protected void run(ITextSelection selection) {
		run((ISelection) selection);
	}

	/**
	 * Notifies this action that the given selection has changed. This default
	 * implementation sets the action's enablement state to <code>false</code>.
	 * 
	 * @param selection
	 *            the new selection
	 */
	protected void selectionChanged(ISelection selection) {
		setEnabled(false);
	}

	/**
	 * Executes this actions with the given selection. This default
	 * implementation does nothing.
	 */
	protected void run(ISelection selection) {
	}

	/*
	 * (non-Javadoc) Method declared on IAction.
	 */
	public void run() {
		dispatchRun(getSelection());
	}

	/*
	 * (non-Javadoc) Method declared on ISelectionChangedListener.
	 */
	public void selectionChanged(SelectionChangedEvent event) {
		dispatchSelectionChanged(event.getSelection());
	}

	private void dispatchSelectionChanged(ISelection selection) {
		if (selection instanceof IStructuredSelection) {
			selectionChanged((IStructuredSelection) selection);
		} else if (selection instanceof ITextSelection) {
			selectionChanged((ITextSelection) selection);
		} else {
			selectionChanged(selection);
		}
	}

	private void dispatchRun(ISelection selection) {
		if (selection instanceof IStructuredSelection) {
			run((IStructuredSelection) selection);
		} else if (selection instanceof ITextSelection) {
			run((ITextSelection) selection);
		} else {
			run(selection);
		}
	}
}