Copyright (c) 2000, 2010 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ltk.core.refactoring;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;

import org.eclipse.core.filebuffers.FileBuffers;
import org.eclipse.core.filebuffers.ITextFileBuffer;
import org.eclipse.core.filebuffers.ITextFileBufferManager;

import org.eclipse.text.edits.MalformedTreeException;
import org.eclipse.text.edits.UndoEdit;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;

import org.eclipse.ltk.internal.core.refactoring.Lock;
import org.eclipse.ltk.internal.core.refactoring.TextChanges;
import org.eclipse.ltk.internal.core.refactoring.UndoDocumentChange;

A text change that operates directly on instances of IDocument. The document change uses a simple length compare to check if it is still valid. So as long as its length hasn't changed the text edits managed have a valid range and can be applied to the document. The same applies to the undo change returned from the perform method. 

Note: this class is not intended to be extended by clients.

Since:
3.0
@noextend
This class is not intended to be subclassed by clients./**
 * A text change that operates directly on instances of {@link IDocument}.
 * The document change uses a simple length compare to check if it
 * is still valid. So as long as its length hasn't changed the text edits
 * managed have a valid range and can be applied to the document. The
 * same applies to the undo change returned from the perform method.
 *
 * <p>
 * Note: this class is not intended to be extended by clients.
 * </p>
 *
 * @since 3.0
 *
 * @noextend This class is not intended to be subclassed by clients.
 */
public class DocumentChange extends TextChange {

	private IDocument fDocument;
	private int fLength;

	
Creates a new DocumentChange for the given IDocument. 
Params:
name – the change's name. Has to be a human readable name.
document – the document this change is working on/**
	 * Creates a new <code>DocumentChange</code> for the given
	 * {@link IDocument}.
	 *
	 * @param name the change's name. Has to be a human readable name.
	 * @param document the document this change is working on
	 */
	public DocumentChange(String name, IDocument document) {
		super(name);
		Assert.isNotNull(document);
		fDocument= document;
	}

	@Override
	public Object getModifiedElement(){
		return fDocument;
	}

	@Override
	public void initializeValidationData(IProgressMonitor pm) {
		// as long as we don't have modification stamps on documents
		// we can only remember its length.
		fLength= fDocument.getLength();
	}

	@Override
	public RefactoringStatus isValid(IProgressMonitor pm) throws CoreException {
		pm.beginTask("", 1); //$NON-NLS-1$
		RefactoringStatus result= TextChanges.isValid(fDocument, fLength);
		pm.worked(1);
		return result;
	}

	@Override
	protected IDocument acquireDocument(IProgressMonitor pm) throws CoreException {
		return fDocument;
	}

	@Override
	protected void commit(IDocument document, IProgressMonitor pm) throws CoreException {
		// do nothing
	}

	@Override
	protected void releaseDocument(IDocument document, IProgressMonitor pm) throws CoreException {
		//do nothing
	}

	/*
	 * @see org.eclipse.ltk.core.refactoring.TextChange#performEdits(org.eclipse.jface.text.IDocument)
	 * @since 3.6
	 */
	@Override
	protected UndoEdit performEdits(final IDocument document) throws BadLocationException, MalformedTreeException {
		ITextFileBufferManager fileBufferManager= FileBuffers.getTextFileBufferManager();
		
		ITextFileBuffer fileBuffer= fileBufferManager.getTextFileBuffer(document);
		if (fileBuffer == null || ! fileBuffer.isSynchronizationContextRequested()) {
			return super.performEdits(document);
		}
		
		/** The lock for waiting for computation in the UI thread to complete. */
		final Lock completionLock= new Lock();
		final UndoEdit[] result= new UndoEdit[1];
		final BadLocationException[] exception= new BadLocationException[1];
		Runnable runnable= new Runnable() {
			@Override
			public void run() {
				synchronized (completionLock) {
					try {
						result[0]= DocumentChange.super.performEdits(document);
					} catch (BadLocationException e) {
						exception[0]= e;
					} finally {
						completionLock.fDone= true;
						completionLock.notifyAll();
					}
				}
			}
		};
		
		synchronized (completionLock) {
			fileBufferManager.execute(runnable);
			while (! completionLock.fDone) {
				try {
					completionLock.wait(500);
				} catch (InterruptedException x) {
				}
			}
		}
		
		if (exception[0] != null) {
			throw exception[0];
		}
		
		return result[0];
	}
	
	@Override
	protected Change createUndoChange(UndoEdit edit) {
		return new UndoDocumentChange(getName(), fDocument, edit);
	}
}