/*******************************************************************************
 * Copyright (c) 2002, 2006 GEBIT Gesellschaft fuer EDV-Beratung
 * und Informatik-Technologien mbH, 
 * Berlin, Duesseldorf, Frankfurt (Germany) and others.
 *
 * This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 * 
 * Contributors:
 *     GEBIT Gesellschaft fuer EDV-Beratung und Informatik-Technologien mbH - initial API and implementation
 * 	   IBM Corporation - bug 24108, bug 111740
 *     John-Mason P. Shackelford - bug 51215
 *******************************************************************************/

package org.eclipse.ant.internal.ui.editor.text;

/*
 * This file originates from an internal package of Eclipse's 
 * Manifest Editor. It has been copied by GEBIT to here in order to
 * permanently use those features. It has been renamed and edited by GEBIT 
 * after copying.
 */

import org.eclipse.jface.text.rules.ICharacterScanner;
import org.eclipse.jface.text.rules.IToken;
import org.eclipse.jface.text.rules.MultiLineRule;

public class TagRule extends MultiLineRule {

	public TagRule(IToken token) {
		super("<", ">", token); //$NON-NLS-1$ //$NON-NLS-2$
	}

	@Override
	protected boolean sequenceDetected(ICharacterScanner scanner, char[] sequence, boolean eofAllowed) {
		int c = scanner.read();
		if (sequence[0] == '<') {
			if (c == '?') {
				// processing instruction - abort
				scanner.unread();
				return false;
			}
			if (c == '!') {
				scanner.unread();
				// comment - abort
				return false;
			}
		} else if (sequence[0] == '>') {
			scanner.unread();
		}

		return super.sequenceDetected(scanner, sequence, eofAllowed);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.text.rules.PatternRule#endSequenceDetected(org.eclipse.jface.text.rules.ICharacterScanner)
	 */
	@Override
	protected boolean endSequenceDetected(ICharacterScanner scanner) {
		int c;
		while ((c = scanner.read()) != ICharacterScanner.EOF) {
			if (c == fEscapeCharacter) {
				// Skip the escaped character.
				scanner.read();
			} else if (c == '>') {
				endOfTagDetected(scanner);
				return true;
			}
		}

		scanner.unread();
		return false;
	}

	private void endOfTagDetected(ICharacterScanner scanner) {
		int c;
		int scanAhead = 0;
		int endOfTagOffset = 0;
		while ((c = scanner.read()) != ICharacterScanner.EOF && c != '<') {
			scanAhead++;
			if (c == '>') {
				endOfTagOffset = scanAhead;
			}
		}

		if (c == '<') {
			int rewind = (scanAhead - endOfTagOffset) + 1;
			for (int i = 0; i < rewind; i++) {
				scanner.unread();
			}
		}
	}
}