/*******************************************************************************
 * 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 java.util.Arrays;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;


import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.IStructuredSelection;

import org.eclipse.jface.text.ITextSelection;

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

import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IMember;
import org.eclipse.jdt.core.JavaModelException;

import org.eclipse.jdt.internal.corext.refactoring.RefactoringAvailabilityTester;
import org.eclipse.jdt.internal.corext.refactoring.RefactoringExecutionStarter;
import org.eclipse.jdt.internal.corext.util.JavaModelUtil;

import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.actions.ActionUtil;
import org.eclipse.jdt.internal.ui.actions.SelectionConverter;
import org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor;
import org.eclipse.jdt.internal.ui.javaeditor.JavaTextSelection;
import org.eclipse.jdt.internal.ui.refactoring.RefactoringMessages;
import org.eclipse.jdt.internal.ui.util.ExceptionHandler;

/**
 * Action to push down methods and fields into subclasses.
 * <p>
 * Action is applicable to selections containing elements of
 * type <code>IField</code> and <code>IMethod</code>.
 * 
 * <p>
 * This class may be instantiated; it is not intended to be subclassed.
 * </p>
 * 
 * @since 2.1
 */
public class PushDownAction extends SelectionDispatchAction{

	private CompilationUnitEditor fEditor;
	
	/**
	 * Creates a new <code>PushDownAction</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 PushDownAction(IWorkbenchSite site) {
		super(site);
		setText(RefactoringMessages.PushDownAction_Push_Down); 
		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.PUSH_DOWN_ACTION);
	}

	/**
	 * Note: This constructor is for internal use only. Clients should not call this constructor.
	 * @param editor
	 */
	public PushDownAction(CompilationUnitEditor editor) {
		this(editor.getEditorSite());
		fEditor= editor;
		setEnabled(SelectionConverter.canOperateOn(fEditor));
	}

	//---- structured selection -----------------------------------------------

	/*
	 * @see SelectionDispatchAction#selectionChanged(IStructuredSelection)
	 */
	public void selectionChanged(IStructuredSelection selection) {
		try {
			setEnabled(RefactoringAvailabilityTester.isPushDownAvailable(selection));
		} catch (JavaModelException e) {
			// http://bugs.eclipse.org/bugs/show_bug.cgi?id=19253
			if (JavaModelUtil.isExceptionToBeLogged(e))
				JavaPlugin.log(e);
			setEnabled(false);//no UI
		}
	}

	/*
	 * @see SelectionDispatchAction#run(IStructuredSelection)
	 */
	public void run(IStructuredSelection selection) {
		try {
			IMember[] members= getSelectedMembers(selection);
			if (RefactoringAvailabilityTester.isPushDownAvailable(members))
				RefactoringExecutionStarter.startPushDownRefactoring(members, getShell());
		} catch (JavaModelException e) {
			ExceptionHandler.handle(e, RefactoringMessages.OpenRefactoringWizardAction_refactoring, RefactoringMessages.OpenRefactoringWizardAction_exception); 
		}
	}

	//---- text selection -----------------------------------------------------
	
	/*
	 * @see org.eclipse.jdt.ui.actions.SelectionDispatchAction#selectionChanged(ITextSelection)
	 */
	public void selectionChanged(ITextSelection selection) {
		setEnabled(true);
	}
	
	/**
	 * Note: This method is for internal use only. Clients should not call this method.
	 * @param selection
	 */
	public void selectionChanged(JavaTextSelection selection) {
		try {
			setEnabled(RefactoringAvailabilityTester.isPushDownAvailable(selection));
		} catch (JavaModelException e) {
			setEnabled(false);
		}
	}

	/*
	 * @see org.eclipse.jdt.ui.actions.SelectionDispatchAction#run(ITextSelection)
	 */
	public void run(ITextSelection selection) {
		try {
			if (!ActionUtil.isProcessable(getShell(), fEditor))
				return;
			IMember member= getSelectedMember();
			IMember[] array= new IMember[]{member};
			if (member != null && RefactoringAvailabilityTester.isPushDownAvailable(array)){
				RefactoringExecutionStarter.startPushDownRefactoring(array, getShell());	
			} else {
				MessageDialog.openInformation(getShell(), RefactoringMessages.OpenRefactoringWizardAction_unavailable, RefactoringMessages.PushDownAction_To_activate); 
			}
		} catch (JavaModelException e) {
			ExceptionHandler.handle(e, RefactoringMessages.OpenRefactoringWizardAction_refactoring, RefactoringMessages.OpenRefactoringWizardAction_exception); 
		}
	}
	
	//---- helper methods ---------------------------------------------------
		
	private static IMember[] getSelectedMembers(IStructuredSelection selection) {
		if (selection.isEmpty())
			return null;
		
		for  (Iterator iter= selection.iterator(); iter.hasNext(); ) {
			if (! (iter.next() instanceof IMember))
				return null;
		}
		Set memberSet= new HashSet();
		memberSet.addAll(Arrays.asList(selection.toArray()));
		return (IMember[]) memberSet.toArray(new IMember[memberSet.size()]);
	}
	
	private IMember getSelectedMember() throws JavaModelException{
		IJavaElement element= SelectionConverter.resolveEnclosingElement(
			fEditor, (ITextSelection)fEditor.getSelectionProvider().getSelection());
		if (element == null || ! (element instanceof IMember))
			return null;
		return (IMember)element;
	}	
}