/*******************************************************************************
 * Copyright (c) 2000, 2008 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
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.jface.text.DefaultIndentLineAutoEditStrategy;

import dwt.dwthelper.utils;


/**
 * This strategy always copies the indentation of the previous line.
 * <p>
 * This class is not intended to be subclassed.</p>
 *
 * @since 3.1
 */
public class DefaultIndentLineAutoEditStrategy : IAutoEditStrategy {

    /**
     * Creates a new indent line auto edit strategy which can be installed on
     * text viewers.
     */
    public DefaultIndentLineAutoEditStrategy() {
    }

    /**
     * Returns the first offset greater than <code>offset</code> and smaller than
     * <code>end</code> whose character is not a space or tab character. If no such
     * offset is found, <code>end</code> is returned.
     *
     * @param document the document to search in
     * @param offset the offset at which searching start
     * @param end the offset at which searching stops
     * @return the offset in the specified range whose character is not a space or tab
     * @exception BadLocationException if position is an invalid range in the given document
     */
    protected int findEndOfWhiteSpace(IDocument document, int offset, int end) throws BadLocationException {
        while (offset < end) {
            char c= document.getChar(offset);
            if (c !is ' ' && c !is '\t') {
                return offset;
            }
            offset++;
        }
        return end;
    }

    /**
     * Copies the indentation of the previous line.
     *
     * @param d the document to work on
     * @param c the command to deal with
     */
    private void autoIndentAfterNewLine(IDocument d, DocumentCommand c) {

        if (c.offset is -1 || d.getLength() is 0)
            return;

        try {
            // find start of line
            int p= (c.offset is d.getLength() ? c.offset  - 1 : c.offset);
            IRegion info= d.getLineInformationOfOffset(p);
            int start= info.getOffset();

            // find white spaces
            int end= findEndOfWhiteSpace(d, start, c.offset);

            StringBuffer buf= new StringBuffer(c.text);
            if (end > start) {
                // append to input
                buf.append(d.get(start, end - start));
            }

            c.text= buf.toString();

        } catch (BadLocationException excp) {
            // stop work
        }
    }

    /*
     * @see dwtx.jface.text.IAutoEditStrategy#customizeDocumentCommand(dwtx.jface.text.IDocument, dwtx.jface.text.DocumentCommand)
     */
    public void customizeDocumentCommand(IDocument d, DocumentCommand c) {
        if (c.length is 0 && c.text !is null && TextUtilities.endsWith(d.getLegalLineDelimiters(), c.text) !is -1)
            autoIndentAfterNewLine(d, c);
    }
}