Copyright (c) 2004, 2015 IBM Corporation 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:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2004, 2015 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.internal.runtime;

import java.io.*;
import java.net.URL;
import java.net.UnknownServiceException;
import org.eclipse.core.internal.boot.PlatformURLConnection;
import org.eclipse.core.internal.boot.PlatformURLHandler;
import org.eclipse.osgi.service.datalocation.Location;
import org.eclipse.osgi.util.NLS;

public class PlatformURLConfigConnection extends PlatformURLConnection {
	private static final String FILE_PROTOCOL = "file"; //$NON-NLS-1$
	private static boolean isRegistered = false;
	public static final String CONFIG = "config"; //$NON-NLS-1$

	private boolean parentConfiguration = false;

	/*
	 * Constructor for the class.
	 */
	public PlatformURLConfigConnection(URL url) {
		super(url);
	}

	@Override
	protected URL resolve() throws IOException {
		String spec = url.getFile().trim();
		if (spec.startsWith("/")) //$NON-NLS-1$
			spec = spec.substring(1);
		if (!spec.startsWith(CONFIG))
			throw new IOException(NLS.bind(CommonMessages.url_badVariant, url.toString()));
		String path = spec.substring(CONFIG.length() + 1);
		// resolution takes parent configuration into account (if it exists)
		Activator activator = Activator.getDefault();
		if (activator == null)
			throw new IOException(CommonMessages.activator_not_available);
		Location localConfig = activator.getConfigurationLocation();
		Location parentConfig = localConfig.getParentLocation();
		// assume we will find the file locally
		URL localURL = new URL(localConfig.getURL(), path);
		if (!FILE_PROTOCOL.equals(localURL.getProtocol()) || parentConfig == null)
			// we only support cascaded file: URLs
			return localURL;
		File localFile = new File(localURL.getPath());
		if (localFile.exists())
			// file exists in local configuration
			return localURL;
		// try to find in the parent configuration
		URL parentURL = new URL(parentConfig.getURL(), path);
		if (FILE_PROTOCOL.equals(parentURL.getProtocol())) {
			// we only support cascaded file: URLs			
			File parentFile = new File(parentURL.getPath());
			if (parentFile.exists()) {
				// parent has the location
				parentConfiguration = true;
				return parentURL;
			}
		}
		return localURL;
	}

	public static void startup() {
		// register connection type for platform:/config handling
		if (isRegistered)
			return;
		PlatformURLHandler.register(CONFIG, PlatformURLConfigConnection.class);
		isRegistered = true;
	}

	@Override
	public OutputStream getOutputStream() throws IOException {
		if (parentConfiguration || Activator.getDefault() == null || Activator.getDefault().getConfigurationLocation().isReadOnly())
			throw new UnknownServiceException(NLS.bind(CommonMessages.url_noOutput, url));
		//This is not optimal but connection is a private instance variable in the super-class.
		URL resolved = getResolvedURL();
		if (resolved != null) {
			String fileString = resolved.getFile();
			if (fileString != null) {
				File file = new File(fileString);
				String parent = file.getParent();
				if (parent != null)
					new File(parent).mkdirs();
				return new FileOutputStream(file);
			}
		}
		return null;
	}
}