Copyright (c) 2003, 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
    Sergey Prigogin (Google) - use parameterized types (bug 442021)
/*******************************************************************************
 * Copyright (c) 2003, 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
 *     Sergey Prigogin (Google) - use parameterized types (bug 442021)
 *******************************************************************************/
package org.eclipse.core.internal.runtime;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Map;
import org.eclipse.core.runtime.*;
import org.osgi.framework.Bundle;

// This class provides implements the find* methods exposed on Platform.
// It does the lookup in bundles and fragments and does the variable replacement.
// Can only be used if OSGi is available.
public class FindSupport {
	// OSGI system properties
	public static final String PROP_NL = "osgi.nl"; //$NON-NLS-1$
	public static final String PROP_OS = "osgi.os"; //$NON-NLS-1$
	public static final String PROP_WS = "osgi.ws"; //$NON-NLS-1$
	public static final String PROP_ARCH = "osgi.arch"; //$NON-NLS-1$

	private static String[] NL_JAR_VARIANTS = buildNLVariants(Activator.getContext() == null ? System.getProperty(PROP_NL) : Activator.getContext().getProperty(PROP_NL));

	private static String[] buildNLVariants(String nl) {
		ArrayList<String> result = new ArrayList<>();
		IPath base = new Path("nl"); //$NON-NLS-1$

		IPath path = new Path(nl.replace('_', '/'));
		while (path.segmentCount() > 0) {
			result.add(base.append(path).toString());
			// for backwards compatibility only, don't replace the slashes
			if (path.segmentCount() > 1)
				result.add(base.append(path.toString().replace('/', '_')).toString());
			path = path.removeLastSegments(1);
		}

		return result.toArray(new String[result.size()]);
	}

	
See doc on FileLocator.find(Bundle, IPath, Map) /**
	 * See doc on {@link FileLocator#find(Bundle, IPath, Map)} 
	 */
	public static URL find(Bundle bundle, IPath path) {
		return find(bundle, path, null);
	}

	
See doc on FileLocator.find(Bundle, IPath, Map) /**
	 * See doc on {@link FileLocator#find(Bundle, IPath, Map)} 
	 */
	public static URL find(Bundle b, IPath path, Map<String, String> override) {
		return find(b, path, override, null);
	}

	
See doc on FileLocator.findEntries(Bundle, IPath) /**
	 * See doc on {@link FileLocator#findEntries(Bundle, IPath)}
	 */
	public static URL[] findEntries(Bundle bundle, IPath path) {
		return findEntries(bundle, path, null);
	}

	
See doc on FileLocator.findEntries(Bundle, IPath, Map) /**
	 * See doc on {@link FileLocator#findEntries(Bundle, IPath, Map)}
	 */
	public static URL[] findEntries(Bundle bundle, IPath path, Map<String, String> override) {
		ArrayList<URL> results = new ArrayList<>(1);
		find(bundle, path, override, results);
		return results.toArray(new URL[results.size()]);
	}

	private static URL find(Bundle b, IPath path, Map<String, String> override, ArrayList<URL> multiple) {
		if (path == null)
			return null;

		URL result = null;

		// Check for the empty or root case first
		if (path.isEmpty() || path.isRoot()) {
			// Watch for the root case.  It will produce a new
			// URL which is only the root directory (and not the
			// root of this plugin).	
			result = findInPlugin(b, Path.EMPTY, multiple);
			if (result == null || multiple != null)
				result = findInFragments(b, Path.EMPTY, multiple);
			return result;
		}

		// Now check for paths without variable substitution
		String first = path.segment(0);
		if (first.charAt(0) != '$') {
			result = findInPlugin(b, path, multiple);
			if (result == null || multiple != null)
				result = findInFragments(b, path, multiple);
			return result;
		}

		// Worry about variable substitution
		IPath rest = path.removeFirstSegments(1);
		if (first.equalsIgnoreCase("$nl$")) //$NON-NLS-1$
			return findNL(b, rest, override, multiple);
		if (first.equalsIgnoreCase("$os$")) //$NON-NLS-1$
			return findOS(b, rest, override, multiple);
		if (first.equalsIgnoreCase("$ws$")) //$NON-NLS-1$
			return findWS(b, rest, override, multiple);
		if (first.equalsIgnoreCase("$files$")) //$NON-NLS-1$
			return null;

		return null;
	}

	private static URL findOS(Bundle b, IPath path, Map<String, String> override, ArrayList<URL> multiple) {
		String os = null;
		if (override != null)
			try {
				// check for override
				os = override.get("$os$"); //$NON-NLS-1$
			} catch (ClassCastException e) {
				// just in case
			}
		if (os == null)
			// use default
			os = Activator.getContext().getProperty(PROP_OS);
		if (os.length() == 0)
			return null;

		// Now do the same for osarch
		String osArch = null;
		if (override != null)
			try {
				// check for override
				osArch = override.get("$arch$"); //$NON-NLS-1$
			} catch (ClassCastException e) {
				// just in case
			}
		if (osArch == null)
			// use default
			osArch = Activator.getContext().getProperty(PROP_ARCH);
		if (osArch.length() == 0)
			return null;

		URL result = null;
		IPath base = new Path("os").append(os).append(osArch); //$NON-NLS-1$
		// Keep doing this until all you have left is "os" as a path
		while (base.segmentCount() != 1) {
			IPath filePath = base.append(path);
			result = findInPlugin(b, filePath, multiple);
			if (result != null && multiple == null)
				return result;
			result = findInFragments(b, filePath, multiple);
			if (result != null && multiple == null)
				return result;
			base = base.removeLastSegments(1);
		}
		// If we get to this point, we haven't found it yet.
		// Look in the plugin and fragment root directories
		result = findInPlugin(b, path, multiple);
		if (result != null && multiple == null)
			return result;
		return findInFragments(b, path, multiple);
	}

	private static URL findWS(Bundle b, IPath path, Map<String, String> override, ArrayList<URL> multiple) {
		String ws = null;
		if (override != null)
			try {
				// check for override
				ws = override.get("$ws$"); //$NON-NLS-1$
			} catch (ClassCastException e) {
				// just in case
			}
		if (ws == null)
			// use default
			ws = Activator.getContext().getProperty(PROP_WS);
		IPath filePath = new Path("ws").append(ws).append(path); //$NON-NLS-1$
		// We know that there is only one segment to the ws path
		// e.g. ws/win32	
		URL result = findInPlugin(b, filePath, multiple);
		if (result != null && multiple == null)
			return result;
		result = findInFragments(b, filePath, multiple);
		if (result != null && multiple == null)
			return result;
		// If we get to this point, we haven't found it yet.
		// Look in the plugin and fragment root directories
		result = findInPlugin(b, path, multiple);
		if (result != null && multiple == null)
			return result;
		return findInFragments(b, path, multiple);
	}

	private static URL findNL(Bundle b, IPath path, Map<String, String> override, ArrayList<URL> multiple) {
		String nl = null;
		String[] nlVariants = null;
		if (override != null)
			try {
				// check for override
				nl = override.get("$nl$"); //$NON-NLS-1$
			} catch (ClassCastException e) {
				// just in case
			}
		nlVariants = nl == null ? NL_JAR_VARIANTS : buildNLVariants(nl);
		if (nl != null && nl.length() == 0)
			return null;

		URL result = null;
		for (String nlVariant : nlVariants) {
			IPath filePath = new Path(nlVariant).append(path);
			result = findInPlugin(b, filePath, multiple);
			if (result != null && multiple == null)
				return result;
			result = findInFragments(b, filePath, multiple);
			if (result != null && multiple == null)
				return result;
		}
		// If we get to this point, we haven't found it yet.
		// Look in the plugin and fragment root directories
		result = findInPlugin(b, path, multiple);
		if (result != null && multiple == null)
			return result;
		return findInFragments(b, path, multiple);
	}

	private static URL findInPlugin(Bundle b, IPath filePath, ArrayList<URL> multiple) {
		URL result = b.getEntry(filePath.toString());
		if (result != null && multiple != null)
			multiple.add(result);
		return result;
	}

	private static URL findInFragments(Bundle b, IPath filePath, ArrayList<URL> multiple) {
		Activator activator = Activator.getDefault();
		if (activator == null)
			return null;
		Bundle[] fragments = activator.getFragments(b);
		if (fragments == null)
			return null;

		if (multiple != null)
			multiple.ensureCapacity(fragments.length + 1);

		for (Bundle fragment : fragments) {
			URL fileURL = fragment.getEntry(filePath.toString());
			if (fileURL != null) {
				if (multiple == null)
					return fileURL;
				multiple.add(fileURL);
			}
		}
		return null;
	}

	
See doc on FileLocator.openStream(Bundle, IPath, boolean) /**
	 * See doc on {@link FileLocator#openStream(Bundle, IPath, boolean)} 
	 */
	public static final InputStream openStream(Bundle bundle, IPath file, boolean substituteArgs) throws IOException {
		URL url = null;
		if (!substituteArgs) {
			url = findInPlugin(bundle, file, null);
			if (url == null)
				url = findInFragments(bundle, file, null);
		} else {
			url = FindSupport.find(bundle, file);
		}
		if (url != null)
			return url.openStream();
		throw new IOException("Cannot find " + file.toString()); //$NON-NLS-1$
	}

	
See doc on FileLocator.find(URL) /**
	 * See doc on {@link FileLocator#find(URL)} 
	 */
	public static URL find(URL url) {
		// if !platform/plugin | fragment URL return
		if (!"platform".equalsIgnoreCase(url.getProtocol())) //$NON-NLS-1$
			return null;

		// call a helper method to get the bundle object and rest of the path
		String spec = url.getFile().trim();
		Object[] obj = null;
		try {
			obj = PlatformURLPluginConnection.parse(spec, url);
		} catch (IOException e) {
			RuntimeLog.log(new Status(IStatus.ERROR, IRuntimeConstants.PI_RUNTIME, "Invalid input url:" + url, e)); //$NON-NLS-1$
			return null;
		}
		Bundle bundle = (Bundle) obj[0];
		String path = (String) obj[1];

		// use FileLocator.find(bundle, path, null) to look for the file
		if ("/".equals(path)) //$NON-NLS-1$
			return bundle.getEntry(path);
		return find(bundle, new Path(path), null);
	}
}