Copyright (c) 2008, 2014 Freescale Semiconductor 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:
    Freescale Semiconductor - initial API and implementation
    IBM Corporation - ongoing development
/*******************************************************************************
 * Copyright (c) 2008, 2014 Freescale Semiconductor 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:
 *     Freescale Semiconductor - initial API and implementation
 *     IBM Corporation - ongoing development
 *******************************************************************************/
package org.eclipse.core.internal.resources.projectvariables;

import java.net.URI;
import org.eclipse.core.filesystem.URIUtil;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.variableresolvers.PathVariableResolver;

Path Variable representing the parent directory of the variable provided
in argument, following the syntax:
"${PARENT-COUNT-MyVariable}"
/**
 * Path Variable representing the parent directory of the variable provided
 * in argument, following the syntax:
 *
 * "${PARENT-COUNT-MyVariable}"
 *
 */
public class ParentVariableResolver extends PathVariableResolver {

	final public static String NAME = "PARENT"; //$NON-NLS-1$

	public ParentVariableResolver() {
		// nothing
	}

	@Override
	public String getValue(String variable, IResource resource) {
		int index = variable.indexOf('-');
		if (index == -1 || index == (variable.length() - 1))
			return null;

		String countRemaining = variable.substring(index + 1);
		index = countRemaining.indexOf('-');
		if (index == -1 || index == (variable.length() - 1))
			return null;

		String countString = countRemaining.substring(0, index);
		int count = 0;
		try {
			count = Integer.parseInt(countString);
			if (count < 0)
				return null;
		} catch (NumberFormatException e) {
			return null;
		}
		String argument = countRemaining.substring(index + 1);

		URI value = resource.getPathVariableManager().getURIValue(argument);
		if (value == null)
			return null;
		value = resource.getPathVariableManager().resolveURI(value);
		value = URIUtil.toURI(URIUtil.toPath(value).removeLastSegments(count));

		return value.toASCIIString();
	}
}