Copyright (c) 2005, 2018 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) 2005, 2018 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.osgi.storage.bundlefile;

import java.io.File;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;

A NestedDirBundleFile uses another BundleFile as its source but
accesses all of its resources relative to a nested directory within
the other BundleFile object.  This is used to support zipped bundles
that use a Bundle-ClassPath with an nested directory specified.

For Example:
Bundle-ClassPath: nested.jar,nesteddir/

/**
 * A NestedDirBundleFile uses another BundleFile as its source but
 * accesses all of its resources relative to a nested directory within
 * the other BundleFile object.  This is used to support zipped bundles
 * that use a Bundle-ClassPath with an nested directory specified.
 * <p>
 * For Example:
 * <pre>
 * Bundle-ClassPath: nested.jar,nesteddir/
 * </pre>
 */
public class NestedDirBundleFile extends BundleFile {
	private final BundleFile baseBundleFile;
	private final String nestedDirName;
	private final Collection<String> filterPrefixes;

	
Constructs a NestedDirBundleFile
Params:
baseBundlefile – the base bundle file
nestedDirName – /**
	 * Constructs a NestedDirBundleFile
	 * @param baseBundlefile the base bundle file
	 * @param nestedDirName
	 */
	public NestedDirBundleFile(BundleFile baseBundlefile, String nestedDirName) {
		this(baseBundlefile, nestedDirName, Collections.<String> emptyList());
	}

	
Constructs a NestedDirBundleFile
Params:
baseBundlefile – the base bundle file
nestedDirName – 
filterPrefixes – the prefixes to filter out for the bundle file/**
	 * Constructs a NestedDirBundleFile
	 * @param baseBundlefile the base bundle file
	 * @param nestedDirName
	 * @param filterPrefixes the prefixes to filter out for the bundle file
	 */
	public NestedDirBundleFile(BundleFile baseBundlefile, String nestedDirName, Collection<String> filterPrefixes) {
		super(baseBundlefile.getBaseFile());
		this.baseBundleFile = baseBundlefile;
		if (nestedDirName.charAt(nestedDirName.length() - 1) != '/') {
			nestedDirName = nestedDirName + '/';
		}
		this.nestedDirName = nestedDirName;
		this.filterPrefixes = filterPrefixes;
	}

	@Override
	public void close() {
		// do nothing.
	}

	private boolean filterPath(String path) {
		if (path.length() > 0 && path.charAt(0) == '/')
			path = path.substring(1);
		for (String prefix : filterPrefixes) {
			if (path.startsWith(prefix)) {
				return true;
			}
		}
		return false;
	}

	private boolean filterDir(String path) {
		if (filterPrefixes.isEmpty()) {
			return false;
		}
		if (path.length() > 0 && path.charAt(path.length() - 1) != '/') {
			path = path + '/';
		}
		return filterPath(path);
	}

	@Override
	public BundleEntry getEntry(String path) {
		if (filterPath(path)) {
			return null;
		}
		return baseBundleFile.getEntry(prependNestedDir(path));
	}

	@Override
	public boolean containsDir(String dir) {
		if (dir == null)
			return false;
		if (filterPath(dir)) {
			return false;
		}
		return baseBundleFile.containsDir(prependNestedDir(dir));
	}

	private String prependNestedDir(String path) {
		if (path.length() > 0 && path.charAt(0) == '/')
			path = path.substring(1);
		return new StringBuilder(nestedDirName).append(path).toString();
	}

	@Override
	public Enumeration<String> getEntryPaths(String path, boolean recurse) {
		if (filterDir(path)) {
			return null;
		}
		final Enumeration<String> basePaths = baseBundleFile.getEntryPaths(prependNestedDir(path), recurse);
		final int cpLength = nestedDirName.length();
		if (basePaths == null)
			return null;
		return new Enumeration<String>() {

		@Override
			public boolean hasMoreElements() {
				return basePaths.hasMoreElements();
			}

		@Override
			public String nextElement() {
				String next = basePaths.nextElement();
				return next.substring(cpLength);
			}
		};
	}

	@Override
	public File getFile(String entry, boolean nativeCode) {
		// getFile is only valid if this is a root bundle file.
		// TODO to catch bugs we probably should throw new UnsupportedOperationException()
		return null;
	}

	
Throws:
IOException – /**
	 * @throws IOException  
	 */
	@Override
	public void open() throws IOException {
		// do nothing
	}

	@Override
	public String toString() {
		return super.toString() + '[' + nestedDirName + ']';
	}

}