/*******************************************************************************
 * Copyright (c) 2012-2015 Codenvy, S.A.
 * 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:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.ext.java.worker;

import org.eclipse.che.ide.api.text.BadLocationException;
import org.eclipse.che.ide.ext.java.jdt.text.AbstractDocument;
import org.eclipse.che.ide.ext.java.jdt.text.ConfigurableLineTracker;
import org.eclipse.che.ide.ext.java.jdt.text.CopyOnWriteTextStore;
import org.eclipse.che.ide.ext.java.jdt.text.GapTextStore;

/**
 * Default document implementation. Uses a {@link CopyOnWriteTextStore} as text store.
 * <p>
 * The used line tracker considers the following strings as line delimiters: "\n", "\r", "\r\n". In case of a text replacement
 * across line delimiter boundaries and with different line delimiters, the line tracker might have to be repaired. Use
 * {@link #isLineInformationRepairNeeded(int, int, String)} before doing the text replace if you have the need to discover such a
 * situation.
 * </p>
 * <p>
 * The document is ready to use. It has a default position category for which a default position updater is installed.
 * </p>
 * <p>
 * <strong>Performance:</strong> The implementation should perform reasonably well for typical source code documents. It is not
 * designed for very large documents of a size of several megabytes. Space-saving implementations are initially used for both the
 * text store and the line tracker; the first modification after a {@link #set(String) set} incurs the cost to transform the
 * document structures to efficiently handle updates.
 * </p>
 * <p>
 * See {@link org.eclipse.che.ide.ext.java.jdt.text.GapTextStore} and <code>TreeLineTracker</code> for algorithmic behavior of the used document structures.
 * </p>
 */
public class WorkerDocument extends AbstractDocument {

    private static final String[] delimeters = {"\n"};

    /** Creates a new empty document. */
    public WorkerDocument() {
        super();
        ConfigurableLineTracker lineTracker = new ConfigurableLineTracker(delimeters);
        setTextStore(new CopyOnWriteTextStore(new GapTextStore()));
        setLineTracker(lineTracker);
        completeInitialization();
    }

    /**
     * Creates a new document with the given initial content.
     *
     * @param initialContent
     *         the document's initial content
     */
    public WorkerDocument(String initialContent) {
        super();
        ConfigurableLineTracker lineTracker = new ConfigurableLineTracker(delimeters);
        setTextStore(new CopyOnWriteTextStore(new GapTextStore()));
        setLineTracker(lineTracker);
        getStore().set(initialContent);
        getTracker().set(initialContent);
        completeInitialization();
    }

    /*
     * @see org.eclipse.jface.text.IRepairableDocumentExtension# isLineInformationRepairNeeded(int, int, java.lang.String)
     * @since 3.4
     */
    public boolean isLineInformationRepairNeeded(int offset, int length, String text) throws BadLocationException {
        if ((0 > offset) || (0 > length) || (offset + length > getLength()))
            throw new BadLocationException();

        return isLineInformationRepairNeeded(text) || isLineInformationRepairNeeded(get(offset, length));
    }

    /**
     * Checks whether the line information needs to be repaired.
     *
     * @param text
     *         the text to check
     * @return <code>true</code> if the line information must be repaired
     * @since 3.4
     */
    private boolean isLineInformationRepairNeeded(String text) {
        if (text == null)
            return false;

        int length = text.length();
        if (length == 0)
            return false;

        int rIndex = text.indexOf('\r');
        int nIndex = text.indexOf('\n');
        if (rIndex == -1 && nIndex == -1)
            return false;

        if (rIndex > 0 && rIndex < length - 1 && nIndex > 1 && rIndex < length - 2)
            return false;

        String defaultLD = null;
        try {
            defaultLD = getLineDelimiter(0);
        } catch (BadLocationException x) {
            return true;
        }

        if (defaultLD == null)
            return false;

        defaultLD = getDefaultLineDelimiter();

        if (defaultLD.length() == 1) {
            if (rIndex != -1 && !"\r".equals(defaultLD)) //$NON-NLS-1$
                return true;
            if (nIndex != -1 && !"\n".equals(defaultLD)) //$NON-NLS-1$
                return true;
        } else if (defaultLD.length() == 2)
            return rIndex == -1 || nIndex - rIndex != 1;

        return false;
    }

}