/*******************************************************************************
 * Copyright (c) 2001, 2009 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
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.sse.core.internal.text;

import java.util.Stack;

import org.eclipse.core.runtime.ISafeRunnable;
import org.eclipse.core.runtime.jobs.ILock;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentRewriteSession;
import org.eclipse.jface.text.DocumentRewriteSessionType;
import org.eclipse.wst.sse.core.internal.IExecutionDelegate;
import org.eclipse.wst.sse.core.internal.ILockable;
import org.eclipse.wst.sse.core.internal.ltk.parser.RegionParser;
import org.eclipse.wst.sse.core.internal.provisional.events.NoChangeEvent;
import org.eclipse.wst.sse.core.internal.provisional.events.StructuredDocumentEvent;

/**
 * An IStructuredDocument that performs most of its computation and event
 * notification through an IExecutionDelegate.
 * 
 * If the delegate has not been set, we execute on current thread, like
 * "normal". This is the case for normal non-editor use (which should still,
 * ultimately, be protected by a scheduling rule). For every operation, a
 * runnable is created, even if later (in the execution delegate instance) it
 * is decided nothing special is needed (that is, in fact being called from an
 * editor's display thread, in which case its just executed) in the UI.
 */
public class JobSafeStructuredDocument extends BasicStructuredDocument implements IExecutionDelegatable, ILockable {

	private static abstract class JobSafeRunnable implements ISafeRunnable {
		public void handleException(Throwable exception) {
			// logged in SafeRunner
		}
	}
	
	private Stack fExecutionDelegates = new Stack();
	private ILock fLockable = Job.getJobManager().newLock();

	public JobSafeStructuredDocument() {
		super();
	}


	public JobSafeStructuredDocument(RegionParser parser) {
		super(parser);
	}


	/**
	 * 
	 */
	protected final void acquireLock() {
		getLockObject().acquire();
	}

	private IExecutionDelegate getExecutionDelegate() {
		if (!fExecutionDelegates.isEmpty())
			return (IExecutionDelegate) fExecutionDelegates.peek();
		return null;
	}
	
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.wst.sse.core.ILockable#getLock()
	 */

	public ILock getLockObject() {
		return fLockable;
	}


	/**
	 * 
	 */
	protected final void releaseLock() {
		getLockObject().release();
	}
	
	/*
	 * @see org.eclipse.jface.text.IDocument.replace(int, int, String)
	 */
	public void replace(final int offset, final int length, final String text) throws BadLocationException {
		IExecutionDelegate delegate = getExecutionDelegate();
		if (delegate == null) {
			super.replace(offset, length, text);
		}
		else {
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					JobSafeStructuredDocument.super.replace(offset, length, text);
				}
			};
			delegate.execute(runnable);
		}
	}
	
	/*
	 * @see org.eclipse.jface.text.IDocumentExtension4.replace(int, int, String, long)
	 */
	public void replace(final int offset, final int length, final String text, final long modificationStamp) throws BadLocationException {
		IExecutionDelegate delegate = getExecutionDelegate();
		if (delegate == null) {
			super.replace(offset, length, text, modificationStamp);
		}
		else {
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					JobSafeStructuredDocument.super.replace(offset, length, text, modificationStamp);
				}
			};
			delegate.execute(runnable);
		}
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument#replaceText(java.lang.Object, int, int, java.lang.String)
	 */
	public StructuredDocumentEvent replaceText(final Object requester, final int start, final int replacementLength, final String changes) {
		StructuredDocumentEvent event = null;
		IExecutionDelegate delegate = getExecutionDelegate();
		if (delegate == null) {
			event = super.replaceText(requester, start, replacementLength, changes);
		}
		else {
			final Object[] resultSlot = new Object[1];
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					resultSlot[0] = JobSafeStructuredDocument.super.replaceText(requester, start, replacementLength, changes);
				}
			};
			delegate.execute(runnable);
			event = (StructuredDocumentEvent) resultSlot[0];
		}
		return event;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument#replaceText(java.lang.Object, int, int, java.lang.String, boolean)
	 */
	public StructuredDocumentEvent replaceText(final Object requester, final int start, final int replacementLength, final String changes, final boolean ignoreReadOnlySettings) {
		StructuredDocumentEvent event = null;
		IExecutionDelegate delegate = getExecutionDelegate();
		if (delegate == null) {
			event = super.replaceText(requester, start, replacementLength, changes, ignoreReadOnlySettings);
		}
		else {
			final Object[] resultSlot = new Object[1];
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					resultSlot[0] = JobSafeStructuredDocument.super.replaceText(requester, start, replacementLength, changes, ignoreReadOnlySettings);
				}

				public void handleException(Throwable exception) {
					resultSlot[0] = new NoChangeEvent(JobSafeStructuredDocument.this, requester, changes, start, replacementLength);
					super.handleException(exception);
				}
			};
			delegate.execute(runnable);
			event = (StructuredDocumentEvent) resultSlot[0];
		}
		return event;
	}

	public void setExecutionDelegate(IExecutionDelegate delegate) {
		if (delegate != null)
			fExecutionDelegates.push(delegate);
		else if (!fExecutionDelegates.isEmpty())
			fExecutionDelegates.pop();
	}

	public StructuredDocumentEvent setText(final Object requester, final String theString) {
		StructuredDocumentEvent event = null;
		IExecutionDelegate executionDelegate = getExecutionDelegate();
		if (executionDelegate == null) {
			event = super.setText(requester, theString);
		}
		else {
			final Object[] resultSlot = new Object[1];
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					resultSlot[0] = JobSafeStructuredDocument.super.setText(requester, theString);
				}
				public void handleException(Throwable exception) {
					resultSlot[0] = new NoChangeEvent(JobSafeStructuredDocument.this, requester, theString, 0, 0);
					super.handleException(exception);
				}
			};
			executionDelegate.execute(runnable);
			event = (StructuredDocumentEvent) resultSlot[0];
		}
		return event;
	}

	public DocumentRewriteSession startRewriteSession(DocumentRewriteSessionType sessionType) throws IllegalStateException {
		DocumentRewriteSession session = null;
		IExecutionDelegate executionDelegate = getExecutionDelegate();
		if (executionDelegate == null) {
			session = internalStartRewriteSession(sessionType);
		}
		else {
			final Object[] resultSlot = new Object[1];
			final DocumentRewriteSessionType finalSessionType = sessionType;
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					resultSlot[0] = internalStartRewriteSession(finalSessionType);
				}
			};
			executionDelegate.execute(runnable);
			if (resultSlot[0] instanceof Throwable) {
				throw new RuntimeException((Throwable) resultSlot[0]);
			}
			else {
				session = (DocumentRewriteSession) resultSlot[0];
			}
		}
		return session;
	}

	public void stopRewriteSession(DocumentRewriteSession session) {
		IExecutionDelegate executionDelegate = getExecutionDelegate();
		if (executionDelegate == null) {
			internalStopRewriteSession(session);
		}
		else {
			final DocumentRewriteSession finalSession = session;
			JobSafeRunnable runnable = new JobSafeRunnable() {
				public void run() throws Exception {
					internalStopRewriteSession(finalSession);
				}
			};
			executionDelegate.execute(runnable);
		}
	}


}