/*******************************************************************************
 * Copyright (c) 2000, 2005 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.jdt.ui.actions;

import org.eclipse.ui.IWorkbenchSite;
import org.eclipse.ui.PlatformUI;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.search.IJavaSearchConstants;

import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.JavaPluginImages;
import org.eclipse.jdt.internal.ui.javaeditor.JavaEditor;
import org.eclipse.jdt.internal.ui.search.SearchMessages;
import org.eclipse.jdt.internal.ui.util.ExceptionHandler;

/**
 * Finds implementors of the selected element in the workspace.
 * The action is applicable to selections representing a Java interface.
 * 
 * <p>
 * This class may be instantiated; it is not intended to be subclassed.
 * </p>
 * 
 * @since 2.0
 */
public class FindImplementorsAction extends FindAction {

	/**
	 * Creates a new <code>FindImplementorsAction</code>. The action 
	 * requires that the selection provided by the site's selection provider is of type 
	 * <code>org.eclipse.jface.viewers.IStructuredSelection</code>.
	 * 
	 * @param site the site providing context information for this action
	 */
	public FindImplementorsAction(IWorkbenchSite site) {
		super(site); 
	}

	/**
	 * Note: This constructor is for internal use only. Clients should not call this constructor.
	 * @param editor the Java editor
	 */
	public FindImplementorsAction(JavaEditor editor) {
		super(editor); 
	}

	void init() {
		setText(SearchMessages.Search_FindImplementorsAction_label); 
		setToolTipText(SearchMessages.Search_FindImplementorsAction_tooltip); 
		setImageDescriptor(JavaPluginImages.DESC_OBJS_SEARCH_DECL);
		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.FIND_IMPLEMENTORS_IN_WORKSPACE_ACTION);
	}
	
	Class[] getValidTypes() {
		return new Class[] { ICompilationUnit.class, IType.class};
	}

	boolean canOperateOn(IJavaElement element) {
		if (!super.canOperateOn(element))
			return false;

		if (element.getElementType() == IJavaElement.TYPE)
			try {
				return ((IType) element).isInterface();
			} catch (JavaModelException ex) {
				ExceptionHandler.log(ex, SearchMessages.Search_Error_javaElementAccess_message); 
				return false;
			}
		// should not happen: handled by super.canOperateOn
		return false;
	}

	int getLimitTo() {
		return IJavaSearchConstants.IMPLEMENTORS;
	}

	String getOperationUnavailableMessage() {
		return SearchMessages.JavaElementAction_operationUnavailable_interface; 
	}
}