/*=============================================================================#
 # Copyright (c) 2005, 2019 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.r.ui.text.rd;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextDoubleClickStrategy;
import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextUtilities;

import org.eclipse.statet.ecommons.text.PairMatcher;

import org.eclipse.statet.r.core.source.IRDocumentConstants;
import org.eclipse.statet.r.core.source.RdDocumentContentInfo;


/**
 * Double click strategy aware of R identifier syntax rules, Comments and String (all in one).
 * <p>
 * Select content inside matching brackets or, if matching pairs found,
 * a single identifier.
 */
public class RdDoubleClickStrategy implements ITextDoubleClickStrategy {
	
	private static final char[][] BRACKETS = { {'{', '}'} };
	
	protected PairMatcher fPairMatcher;
	
	public RdDoubleClickStrategy() {
		super();
		fPairMatcher= new PairMatcher(BRACKETS, RdDocumentContentInfo.INSTANCE,
				new String[] { IRDocumentConstants.RDOC_DEFAULT_CONTENT_TYPE }, '\\');
	}
	
	/**
	 * @see ITextDoubleClickStrategy#doubleClicked
	 */
	@Override
	public void doubleClicked(final ITextViewer textViewer) {
		final int offset = textViewer.getSelectedRange().x;
		
		if (offset < 0) {
			return;
		}
		
		final IDocument document = textViewer.getDocument();
		try {
			ITypedRegion partition = TextUtilities.getPartition(document, IRDocumentConstants.RDOC_PARTITIONING, offset, true);
			String type = partition.getType();
			
			// Bracket-Pair-Matching in Code-Partitions
			if (IRDocumentConstants.RDOC_DEFAULT_CONTENT_TYPE.equals(type)) {
				final IRegion region = fPairMatcher.match(document, offset);
				if (region != null && region.getLength() >= 2) {
					textViewer.setSelectedRange(region.getOffset() + 1, region.getLength() - 2);
					return;
				}
			}
			
			// For other partitions, use prefere new partitions (instead opend)
			partition = TextUtilities.getPartition(document, IRDocumentConstants.RDOC_PARTITIONING, offset, false);
			type = partition.getType();
			// Start in Comment-Partitions
			if (IRDocumentConstants.RDOC_COMMENT_CONTENT_TYPE.equals(type) || IRDocumentConstants.RDOC_PLATFORM_SPECIF.equals(type)) {
				final int partitionOffset = partition.getOffset();
				if (offset == partitionOffset || offset == partitionOffset+1) {
					textViewer.setSelectedRange(partitionOffset, partition.getLength());
					return;
				}
			}
		} catch (final BadLocationException e) {
		} catch (final NullPointerException e) {
		}
		// else
		final IRegion region = getDefaultWordSelection(document, offset);
		textViewer.setSelectedRange(region.getOffset(), region.getLength());
	}
	
	protected IRegion getDefaultWordSelection(final IDocument document, final int anchor) {
		try {
			int offset = anchor;
			char c;
			
			while (offset >= 0) {
				c = document.getChar(offset);
				if (!Character.isLetterOrDigit(c)) {
					break;
				}
				--offset;
			}
			
			final int start = offset;
			
			offset = anchor;
			final int length = document.getLength();
			
			while (offset < length) {
				c = document.getChar(offset);
				if (!Character.isLetterOrDigit(c)) {
					break;
				}
				++offset;
			}
			
			final int end = offset;
			
			if (start < end) {
				return new Region (start + 1, end - start - 1);
			}
			
		} catch (final BadLocationException x) {
		}
		return new Region(anchor, 0);
	}
	
}