/*******************************************************************************
 * Copyright (c) 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
 *     Zend Technologies
 *******************************************************************************/
package org.eclipse.php.internal.ui.editor.configuration;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.*;
import org.eclipse.jface.text.rules.DefaultDamagerRepairer;
import org.eclipse.jface.text.rules.RuleBasedScanner;
import org.eclipse.php.internal.core.documentModel.parser.PHPRegionContext;
import org.eclipse.php.internal.core.documentModel.parser.regions.IPHPScriptRegion;
import org.eclipse.php.internal.ui.editor.highlighter.LineStyleProviderForPHP;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocument;
import org.eclipse.wst.sse.core.internal.provisional.text.IStructuredDocumentRegion;
import org.eclipse.wst.sse.core.internal.provisional.text.ITextRegion;
import org.eclipse.wst.sse.ui.internal.provisional.style.AbstractLineStyleProvider;
import org.eclipse.wst.sse.ui.internal.provisional.style.LineStyleProvider;

public class StructuredDocumentDamagerRepairer extends DefaultDamagerRepairer {

	private LineStyleProvider fProvider = null;

	public StructuredDocumentDamagerRepairer(LineStyleProvider provider) {
		super(new RuleBasedScanner());
		Assert.isNotNull(provider);
		fProvider = provider;
	}

	/**
	 * Returns presentation which covers only updated php tokens in case when
	 * the damage covers whole PHP region and this regions has not been fully
	 * reparsed.
	 * 
	 * @param region
	 * @param damage
	 * @return presentation or null - if region has been fully reparsed
	 */
	public TextPresentation getPresentation(ITypedRegion region, IRegion damage) {
		if (fProvider instanceof LineStyleProviderForPHP) {
			IStructuredDocumentRegion structuredDocumentRegion = ((LineStyleProviderForPHP) fProvider)
					.getDamagedRegion(region);
			ITextRegion textReg = structuredDocumentRegion.getRegionAtCharacterOffset(region.getOffset());
			if (textReg != null && textReg.getType() == PHPRegionContext.PHP_CONTENT
					&& damageCoversWholeRegion(region, textReg, damage)) {
				IPHPScriptRegion phpScriptRegion = (IPHPScriptRegion) textReg;
				if (!phpScriptRegion.isFullReparsed()) {
					Region r = new Region(phpScriptRegion.getUpdatedTokensStart() + region.getOffset(),
							phpScriptRegion.getUpdatedTokensLength());
					return new TextPresentation((IRegion) r, 1000);
				}
			}
		}
		return null;
	}

	private boolean damageCoversWholeRegion(ITypedRegion originalRegion, ITextRegion textRegion, IRegion damage) {
		// if php content region is bigger than actual damaged
		// region
		if ((textRegion.getLength() == originalRegion.getLength())
				&& (textRegion.getStart() < originalRegion.getOffset())) {
			if ((originalRegion.getOffset() == damage.getOffset())
					&& (originalRegion.getLength() == damage.getLength())) {
				return true;
			}
		} else if ((textRegion.getStart() == damage.getOffset()) && (textRegion.getLength() == damage.getLength())) {
			return true;
		}
		return false;
	}

	@Override
	public void createPresentation(TextPresentation presentation, ITypedRegion region) {

		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=491328
		// Workaround for bug 491328:
		// Method
		// PHPStructuredTextViewerConfiguration.getPresentationReconciler(ISourceViewer)
		// returns a *new* PHPStructuredPresentationReconciler object
		// containing a list of *new* StructuredDocumentDamagerRepairer
		// objects for each *shared* LineStyleProvider object retrieved by
		// method ReconcilerHighlighter.getProvider(String) and method
		// PHPStructuredTextViewerConfiguration.getConfiguredContentTypes(ISourceViewer).
		// Every thread initialized with
		// PHPStructuredTextViewerConfiguration.getPresentationReconciler(ISourceViewer)
		// will then work with their own instances of
		// PHPStructuredPresentationReconciler and
		// StructuredDocumentDamagerRepairer objects BUT will share same
		// LineStyleProvider instance per content type, which can be
		// problematic when multiple threads have simultaneous access to those
		// shared LineStyleProvider objects.
		// Since class LineStyleProvider isn't designed to be thread-safe for
		// now, we protect at least concurrent access to
		// main method LineStyleProvider.prepareRegions(...).
		// Of course, it doesn't protect places where
		// LineStyleProvider.prepareRegions(...) is called directly, like in
		// Highlighter.prepareStyleRangesArray(...).
		synchronized (fProvider) {
			PresentationCollector collector = new PresentationCollector(presentation);
			fProvider.prepareRegions(region, region.getOffset(), region.getLength(), collector);
		}
	}

	public void setProvider(LineStyleProvider provider) {
		fProvider = provider;
	}

	@Override
	public void setDocument(IDocument document) {
		super.setDocument(document);
		if (fProvider instanceof AbstractLineStyleProvider)
			((AbstractLineStyleProvider) fProvider).setDocument((IStructuredDocument) document);
	}

}