/*******************************************************************************
 * Copyright (c) 2000, 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
 *******************************************************************************/
package org.eclipse.jface.text.rules;


import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyleRange;

import org.eclipse.core.runtime.Assert;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextAttribute;
import org.eclipse.jface.text.TextPresentation;
import org.eclipse.jface.text.presentation.IPresentationDamager;
import org.eclipse.jface.text.presentation.IPresentationRepairer;


/**
 * A standard implementation of a syntax driven presentation damager
 * and presentation repairer. It uses a token scanner to scan
 * the document and to determine its damage and new text presentation.
 * The tokens returned by the scanner are supposed to return text attributes
 * as their data.
 *
 * @see ITokenScanner
 * @since 2.0
 */
public class DefaultDamagerRepairer implements IPresentationDamager, IPresentationRepairer {


	/** The document this object works on */
	protected IDocument fDocument;
	/** The scanner it uses */
	protected ITokenScanner fScanner;
	/** The default text attribute if non is returned as data by the current token */
	protected TextAttribute fDefaultTextAttribute;

	/**
	 * Creates a damager/repairer that uses the given scanner and returns the given default
	 * text attribute if the current token does not carry a text attribute.
	 *
	 * @param scanner the token scanner to be used
	 * @param defaultTextAttribute the text attribute to be returned if non is specified by the current token,
	 * 			may not be <code>null</code>
	 *
	 * @deprecated use DefaultDamagerRepairer(ITokenScanner) instead
	 */
	@Deprecated
	public DefaultDamagerRepairer(ITokenScanner scanner, TextAttribute defaultTextAttribute) {

		Assert.isNotNull(defaultTextAttribute);

		fScanner= scanner;
		fDefaultTextAttribute= defaultTextAttribute;
	}

	/**
	 * Creates a damager/repairer that uses the given scanner. The scanner may not be <code>null</code>
	 * and is assumed to return only token that carry text attributes.
	 *
	 * @param scanner the token scanner to be used, may not be <code>null</code>
	 */
	public DefaultDamagerRepairer(ITokenScanner scanner) {

		Assert.isNotNull(scanner);

		fScanner= scanner;
		fDefaultTextAttribute= new TextAttribute(null);
	}

	/*
	 * @see IPresentationDamager#setDocument(IDocument)
	 * @see IPresentationRepairer#setDocument(IDocument)
	 */
	@Override
	public void setDocument(IDocument document) {
		fDocument= document;
	}


	//---- IPresentationDamager

	/**
	 * Returns the end offset of the line that contains the specified offset or
	 * if the offset is inside a line delimiter, the end offset of the next line.
	 *
	 * @param offset the offset whose line end offset must be computed
	 * @return the line end offset for the given offset
	 * @exception BadLocationException if offset is invalid in the current document
	 */
	protected int endOfLineOf(int offset) throws BadLocationException {

		IRegion info= fDocument.getLineInformationOfOffset(offset);
		if (offset <= info.getOffset() + info.getLength())
			return info.getOffset() + info.getLength();

		int line= fDocument.getLineOfOffset(offset);
		try {
			info= fDocument.getLineInformation(line + 1);
			return info.getOffset() + info.getLength();
		} catch (BadLocationException x) {
			return fDocument.getLength();
		}
	}

	/**
	 * {@inheritDoc}
	 * <p>
	 * This implementation damages entire lines unless clipped by the given partition.
	 * </p>
	 *
	 * @return the full lines containing the document changes described by the document event,
	 *         clipped by the given partition. If there was a partitioning change then the whole
	 *         partition is returned.
	 */
	@Override
	public IRegion getDamageRegion(ITypedRegion partition, DocumentEvent e, boolean documentPartitioningChanged) {

		if (!documentPartitioningChanged) {
			try {

				IRegion info= fDocument.getLineInformationOfOffset(e.getOffset());
				int start= Math.max(partition.getOffset(), info.getOffset());

				int end= e.getOffset() + (e.getText() == null ? e.getLength() : e.getText().length());

				if (info.getOffset() <= end && end <= info.getOffset() + info.getLength()) {
					// optimize the case of the same line
					end= info.getOffset() + info.getLength();
				} else
					end= endOfLineOf(end);

				end= Math.min(partition.getOffset() + partition.getLength(), end);
				return new Region(start, end - start);

			} catch (BadLocationException x) {
			}
		}

		return partition;
	}

	//---- IPresentationRepairer

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

		if (fScanner == null) {
			// will be removed if deprecated constructor will be removed
			addRange(presentation, region.getOffset(), region.getLength(), fDefaultTextAttribute);
			return;
		}

		int lastStart= region.getOffset();
		int length= 0;
		boolean firstToken= true;
		IToken lastToken= Token.UNDEFINED;
		TextAttribute lastAttribute= getTokenTextAttribute(lastToken);

		fScanner.setRange(fDocument, lastStart, region.getLength());

		while (true) {
			IToken token= fScanner.nextToken();
			if (token.isEOF())
				break;

			TextAttribute attribute= getTokenTextAttribute(token);
			if (lastAttribute != null && lastAttribute.equals(attribute)) {
				length += fScanner.getTokenLength();
				firstToken= false;
			} else {
				if (!firstToken)
					addRange(presentation, lastStart, length, lastAttribute);
				firstToken= false;
				lastToken= token;
				lastAttribute= attribute;
				lastStart= fScanner.getTokenOffset();
				length= fScanner.getTokenLength();
			}
		}

		addRange(presentation, lastStart, length, lastAttribute);
	}

	/**
	 * Returns a text attribute encoded in the given token. If the token's
	 * data is not <code>null</code> and a text attribute it is assumed that
	 * it is the encoded text attribute. It returns the default text attribute
	 * if there is no encoded text attribute found.
	 *
	 * @param token the token whose text attribute is to be determined
	 * @return the token's text attribute
	 */
	protected TextAttribute getTokenTextAttribute(IToken token) {
		Object data= token.getData();
		if (data instanceof TextAttribute)
			return (TextAttribute) data;
		return fDefaultTextAttribute;
	}

	/**
	 * Adds style information to the given text presentation.
	 *
	 * @param presentation the text presentation to be extended
	 * @param offset the offset of the range to be styled
	 * @param length the length of the range to be styled
	 * @param attr the attribute describing the style of the range to be styled
	 */
	protected void addRange(TextPresentation presentation, int offset, int length, TextAttribute attr) {
		if (attr != null) {
			int style= attr.getStyle();
			int fontStyle= style & (SWT.ITALIC | SWT.BOLD | SWT.NORMAL);
			StyleRange styleRange= new StyleRange(offset, length, attr.getForeground(), attr.getBackground(), fontStyle);
			styleRange.strikeout= (style & TextAttribute.STRIKETHROUGH) != 0;
			styleRange.underline= (style & TextAttribute.UNDERLINE) != 0;
			styleRange.font= attr.getFont();
			presentation.addStyleRange(styleRange);
		}
	}
}