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	/*
	* Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package jdk.internal.jimage;

	import java.io.IOException;
	import java.io.InputStream;
	import java.io.UncheckedIOException;
	import java.nio.ByteBuffer;
	import java.nio.ByteOrder;
	import java.nio.IntBuffer;
	import java.nio.file.Files;
	import java.nio.file.attribute.BasicFileAttributes;
	import java.nio.file.attribute.FileTime;
	import java.nio.file.Path;
	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Map;
	import java.util.Objects;
	import java.util.Set;
	import java.util.function.Consumer;

	/**
	* @implNote This class needs to maintain JDK 8 source compatibility.
	*
	* It is used internally in the JDK to implement jimage/jrtfs access,
	* but also compiled and delivered as part of the jrtfs.jar to support access
	* to the jimage file provided by the shipped JDK by tools running on JDK 8.
	*/
	public final class ImageReader implements AutoCloseable {
	private final SharedImageReader reader;

	private volatile boolean closed;

	private ImageReader(SharedImageReader reader) {
	this.reader = reader;
	}

	public static ImageReader open(Path imagePath, ByteOrder byteOrder) throws IOException {
	Objects.requireNonNull(imagePath);
	Objects.requireNonNull(byteOrder);

	return SharedImageReader.open(imagePath, byteOrder);
	}

	public static ImageReader open(Path imagePath) throws IOException {
	return open(imagePath, ByteOrder.nativeOrder());
	}

	@Override
	public void close() throws IOException {
	if (closed) {
	throw new IOException("image file already closed");
	}
	reader.close(this);
	closed = true;
	}

	private void ensureOpen() throws IOException {
	if (closed) {
	throw new IOException("image file closed");
	}
	}

	private void requireOpen() {
	if (closed) {
	throw new IllegalStateException("image file closed");
	}
	}

	// directory management interface
	public Directory getRootDirectory() throws IOException {
	ensureOpen();
	return reader.getRootDirectory();
	}


	public Node findNode(String name) throws IOException {
	ensureOpen();
	return reader.findNode(name);
	}

	public byte[] getResource(Node node) throws IOException {
	ensureOpen();
	return reader.getResource(node);
	}

	public byte[] getResource(Resource rs) throws IOException {
	ensureOpen();
	return reader.getResource(rs);
	}

	public ImageHeader getHeader() {
	requireOpen();
	return reader.getHeader();
	}

	public static void releaseByteBuffer(ByteBuffer buffer) {
	BasicImageReader.releaseByteBuffer(buffer);
	}

	public String getName() {
	requireOpen();
	return reader.getName();
	}

	public ByteOrder getByteOrder() {
	requireOpen();
	return reader.getByteOrder();
	}

	public Path getImagePath() {
	requireOpen();
	return reader.getImagePath();
	}

	public ImageStringsReader getStrings() {
	requireOpen();
	return reader.getStrings();
	}

	public ImageLocation findLocation(String mn, String rn) {
	requireOpen();
	return reader.findLocation(mn, rn);
	}

	public ImageLocation findLocation(String name) {
	requireOpen();
	return reader.findLocation(name);
	}

	public String[] getEntryNames() {
	requireOpen();
	return reader.getEntryNames();
	}

	public String[] getModuleNames() {
	requireOpen();
	int off = "/modules/".length();
	return reader.findNode("/modules")
	.getChildren()
	.stream()
	.map(Node::getNameString)
	.map(s -> s.substring(off, s.length()))
	.toArray(String[]::new);
	}

	public long[] getAttributes(int offset) {
	requireOpen();
	return reader.getAttributes(offset);
	}

	public String getString(int offset) {
	requireOpen();
	return reader.getString(offset);
	}

	public byte[] getResource(String name) {
	requireOpen();
	return reader.getResource(name);
	}

	public byte[] getResource(ImageLocation loc) {
	requireOpen();
	return reader.getResource(loc);
	}

	public ByteBuffer getResourceBuffer(ImageLocation loc) {
	requireOpen();
	return reader.getResourceBuffer(loc);
	}

	public InputStream getResourceStream(ImageLocation loc) {
	requireOpen();
	return reader.getResourceStream(loc);
	}

	private final static class SharedImageReader extends BasicImageReader {
	static final int SIZE_OF_OFFSET = Integer.BYTES;

	static final Map<Path, SharedImageReader> OPEN_FILES = new HashMap<>();

	// List of openers for this shared image.
	final Set<ImageReader> openers;

	// attributes of the .jimage file. jimage file does not contain
	// attributes for the individual resources (yet). We use attributes
	// of the jimage file itself (creation, modification, access times).
	// Iniitalized lazily, see {@link #imageFileAttributes()}.
	BasicFileAttributes imageFileAttributes;

	// directory management implementation
	final HashMap<String, Node> nodes;
	volatile Directory rootDir;

	Directory packagesDir;
	Directory modulesDir;

	private SharedImageReader(Path imagePath, ByteOrder byteOrder) throws IOException {
	super(imagePath, byteOrder);
	this.openers = new HashSet<>();
	this.nodes = new HashMap<>();
	}

	public static ImageReader open(Path imagePath, ByteOrder byteOrder) throws IOException {
	Objects.requireNonNull(imagePath);
	Objects.requireNonNull(byteOrder);

	synchronized (OPEN_FILES) {
	SharedImageReader reader = OPEN_FILES.get(imagePath);

	if (reader == null) {
	// Will fail with an IOException if wrong byteOrder.
	reader = new SharedImageReader(imagePath, byteOrder);
	OPEN_FILES.put(imagePath, reader);
	} else if (reader.getByteOrder() != byteOrder) {
	throw new IOException("\"" + reader.getName() + "\" is not an image file");
	}

	ImageReader image = new ImageReader(reader);
	reader.openers.add(image);

	return image;
	}
	}

	public void close(ImageReader image) throws IOException {
	Objects.requireNonNull(image);

	synchronized (OPEN_FILES) {
	if (!openers.remove(image)) {
	throw new IOException("image file already closed");
	}

	if (openers.isEmpty()) {
	close();
	nodes.clear();
	rootDir = null;

	if (!OPEN_FILES.remove(this.getImagePath(), this)) {
	throw new IOException("image file not found in open list");
	}
	}
	}
	}

	void addOpener(ImageReader reader) {
	synchronized (OPEN_FILES) {
	openers.add(reader);
	}
	}

	boolean removeOpener(ImageReader reader) {
	synchronized (OPEN_FILES) {
	return openers.remove(reader);
	}
	}

	// directory management interface
	Directory getRootDirectory() {
	return buildRootDirectory();
	}

	/**
	* Lazily build a node from a name.
	*/
	synchronized Node buildNode(String name) {
	Node n;
	boolean isPackages = name.startsWith("/packages");
	boolean isModules = !isPackages && name.startsWith("/modules");

	if (!(isModules \|\| isPackages)) {
	return null;
	}

	ImageLocation loc = findLocation(name);

	if (loc != null) { // A sub tree node
	if (isPackages) {
	n = handlePackages(name, loc);
	} else { // modules sub tree
	n = handleModulesSubTree(name, loc);
	}
	} else { // Asking for a resource? /modules/java.base/java/lang/Object.class
	if (isModules) {
	n = handleResource(name);
	} else {
	// Possibly ask for /packages/java.lang/java.base
	// although /packages/java.base not created
	n = handleModuleLink(name);
	}
	}
	return n;
	}

	synchronized Directory buildRootDirectory() {
	Directory root = rootDir; // volatile read
	if (root != null) {
	return root;
	}

	root = newDirectory(null, "/");
	root.setIsRootDir();

	// /packages dir
	packagesDir = newDirectory(root, "/packages");
	packagesDir.setIsPackagesDir();

	// /modules dir
	modulesDir = newDirectory(root, "/modules");
	modulesDir.setIsModulesDir();

	root.setCompleted(true);
	return rootDir = root;
	}

	/**
	* To visit sub tree resources.
	*/
	interface LocationVisitor {
	void visit(ImageLocation loc);
	}

	void visitLocation(ImageLocation loc, LocationVisitor visitor) {
	byte[] offsets = getResource(loc);
	ByteBuffer buffer = ByteBuffer.wrap(offsets);
	buffer.order(getByteOrder());
	IntBuffer intBuffer = buffer.asIntBuffer();
	for (int i = 0; i < offsets.length / SIZE_OF_OFFSET; i++) {
	int offset = intBuffer.get(i);
	ImageLocation pkgLoc = getLocation(offset);
	visitor.visit(pkgLoc);
	}
	}

	void visitPackageLocation(ImageLocation loc) {
	// Retrieve package name
	String pkgName = getBaseExt(loc);
	// Content is array of offsets in Strings table
	byte[] stringsOffsets = getResource(loc);
	ByteBuffer buffer = ByteBuffer.wrap(stringsOffsets);
	buffer.order(getByteOrder());
	IntBuffer intBuffer = buffer.asIntBuffer();
	// For each module, create a link node.
	for (int i = 0; i < stringsOffsets.length / SIZE_OF_OFFSET; i++) {
	// skip empty state, useless.
	intBuffer.get(i);
	i++;
	int offset = intBuffer.get(i);
	String moduleName = getString(offset);
	Node targetNode = findNode("/modules/" + moduleName);
	if (targetNode != null) {
	String pkgDirName = packagesDir.getName() + "/" + pkgName;
	Directory pkgDir = (Directory) nodes.get(pkgDirName);
	newLinkNode(pkgDir, pkgDir.getName() + "/" + moduleName, targetNode);
	}
	}
	}

	Node handlePackages(String name, ImageLocation loc) {
	long size = loc.getUncompressedSize();
	Node n = null;
	// Only possiblities are /packages, /packages/package/module
	if (name.equals("/packages")) {
	visitLocation(loc, (childloc) -> {
	findNode(childloc.getFullName());
	});
	packagesDir.setCompleted(true);
	n = packagesDir;
	} else {
	if (size != 0) { // children are offsets to module in StringsTable
	String pkgName = getBaseExt(loc);
	Directory pkgDir = newDirectory(packagesDir, packagesDir.getName() + "/" + pkgName);
	visitPackageLocation(loc);
	pkgDir.setCompleted(true);
	n = pkgDir;
	} else { // Link to module
	String pkgName = loc.getParent();
	String modName = getBaseExt(loc);
	Node targetNode = findNode("/modules/" + modName);
	if (targetNode != null) {
	String pkgDirName = packagesDir.getName() + "/" + pkgName;
	Directory pkgDir = (Directory) nodes.get(pkgDirName);
	Node linkNode = newLinkNode(pkgDir, pkgDir.getName() + "/" + modName, targetNode);
	n = linkNode;
	}
	}
	}
	return n;
	}

	// Asking for /packages/package/module although
	// /packages/<pkg>/ not yet created, need to create it
	// prior to return the link to module node.
	Node handleModuleLink(String name) {
	// eg: unresolved /packages/package/module
	// Build /packages/package node
	Node ret = null;
	String radical = "/packages/";
	String path = name;
	if (path.startsWith(radical)) {
	int start = radical.length();
	int pkgEnd = path.indexOf('/', start);
	if (pkgEnd != -1) {
	String pkg = path.substring(start, pkgEnd);
	String pkgPath = radical + pkg;
	Node n = findNode(pkgPath);
	// If not found means that this is a symbolic link such as:
	// /packages/java.util/java.base/java/util/Vector.class
	// and will be done by a retry of the filesystem
	for (Node child : n.getChildren()) {
	if (child.name.equals(name)) {
	ret = child;
	break;
	}
	}
	}
	}
	return ret;
	}

	Node handleModulesSubTree(String name, ImageLocation loc) {
	Node n;
	assert (name.equals(loc.getFullName()));
	Directory dir = makeDirectories(name);
	visitLocation(loc, (childloc) -> {
	String path = childloc.getFullName();
	if (path.startsWith("/modules")) { // a package
	makeDirectories(path);
	} else { // a resource
	makeDirectories(childloc.buildName(true, true, false));
	newResource(dir, childloc);
	}
	});
	dir.setCompleted(true);
	n = dir;
	return n;
	}

	Node handleResource(String name) {
	Node n = null;
	String locationPath = name.substring("/modules".length());
	ImageLocation resourceLoc = findLocation(locationPath);
	if (resourceLoc != null) {
	Directory dir = makeDirectories(resourceLoc.buildName(true, true, false));
	Resource res = newResource(dir, resourceLoc);
	n = res;
	}
	return n;
	}

	String getBaseExt(ImageLocation loc) {
	String base = loc.getBase();
	String ext = loc.getExtension();
	if (ext != null && !ext.isEmpty()) {
	base = base + "." + ext;
	}
	return base;
	}

	synchronized Node findNode(String name) {
	buildRootDirectory();
	Node n = nodes.get(name);
	if (n == null \|\| !n.isCompleted()) {
	n = buildNode(name);
	}
	return n;
	}

	/**
	* Returns the file attributes of the image file.
	*/
	BasicFileAttributes imageFileAttributes() {
	BasicFileAttributes attrs = imageFileAttributes;
	if (attrs == null) {
	try {
	Path file = getImagePath();
	attrs = Files.readAttributes(file, BasicFileAttributes.class);
	} catch (IOException ioe) {
	throw new UncheckedIOException(ioe);
	}
	imageFileAttributes = attrs;
	}
	return attrs;
	}

	Directory newDirectory(Directory parent, String name) {
	Directory dir = Directory.create(parent, name, imageFileAttributes());
	nodes.put(dir.getName(), dir);
	return dir;
	}

	Resource newResource(Directory parent, ImageLocation loc) {
	Resource res = Resource.create(parent, loc, imageFileAttributes());
	nodes.put(res.getName(), res);
	return res;
	}

	LinkNode newLinkNode(Directory dir, String name, Node link) {
	LinkNode linkNode = LinkNode.create(dir, name, link);
	nodes.put(linkNode.getName(), linkNode);
	return linkNode;
	}

	Directory makeDirectories(String parent) {
	Directory last = rootDir;
	for (int offset = parent.indexOf('/', 1);
	offset != -1;
	offset = parent.indexOf('/', offset + 1)) {
	String dir = parent.substring(0, offset);
	last = makeDirectory(dir, last);
	}
	return makeDirectory(parent, last);

	}

	Directory makeDirectory(String dir, Directory last) {
	Directory nextDir = (Directory) nodes.get(dir);
	if (nextDir == null) {
	nextDir = newDirectory(last, dir);
	}
	return nextDir;
	}

	byte[] getResource(Node node) throws IOException {
	if (node.isResource()) {
	return super.getResource(node.getLocation());
	}
	throw new IOException("Not a resource: " + node);
	}

	byte[] getResource(Resource rs) throws IOException {
	return super.getResource(rs.getLocation());
	}
	}

	// jimage file does not store directory structure. We build nodes
	// using the "path" strings found in the jimage file.
	// Node can be a directory or a resource
	public abstract static class Node {
	private static final int ROOT_DIR = 0b0000_0000_0000_0001;
	private static final int PACKAGES_DIR = 0b0000_0000_0000_0010;
	private static final int MODULES_DIR = 0b0000_0000_0000_0100;

	private int flags;
	private final String name;
	private final BasicFileAttributes fileAttrs;
	private boolean completed;

	protected Node(String name, BasicFileAttributes fileAttrs) {
	this.name = Objects.requireNonNull(name);
	this.fileAttrs = Objects.requireNonNull(fileAttrs);
	}

	/**
	* A node is completed when all its direct children have been built.
	*
	* @return
	*/
	public boolean isCompleted() {
	return completed;
	}

	public void setCompleted(boolean completed) {
	this.completed = completed;
	}

	public final void setIsRootDir() {
	flags \|= ROOT_DIR;
	}

	public final boolean isRootDir() {
	return (flags & ROOT_DIR) != 0;
	}

	public final void setIsPackagesDir() {
	flags \|= PACKAGES_DIR;
	}

	public final boolean isPackagesDir() {
	return (flags & PACKAGES_DIR) != 0;
	}

	public final void setIsModulesDir() {
	flags \|= MODULES_DIR;
	}

	public final boolean isModulesDir() {
	return (flags & MODULES_DIR) != 0;
	}

	public final String getName() {
	return name;
	}

	public final BasicFileAttributes getFileAttributes() {
	return fileAttrs;
	}

	// resolve this Node (if this is a soft link, get underlying Node)
	public final Node resolveLink() {
	return resolveLink(false);
	}

	public Node resolveLink(boolean recursive) {
	return this;
	}

	// is this a soft link Node?
	public boolean isLink() {
	return false;
	}

	public boolean isDirectory() {
	return false;
	}

	public List<Node> getChildren() {
	throw new IllegalArgumentException("not a directory: " + getNameString());
	}

	public boolean isResource() {
	return false;
	}

	public ImageLocation getLocation() {
	throw new IllegalArgumentException("not a resource: " + getNameString());
	}

	public long size() {
	return 0L;
	}

	public long compressedSize() {
	return 0L;
	}

	public String extension() {
	return null;
	}

	public long contentOffset() {
	return 0L;
	}

	public final FileTime creationTime() {
	return fileAttrs.creationTime();
	}

	public final FileTime lastAccessTime() {
	return fileAttrs.lastAccessTime();
	}

	public final FileTime lastModifiedTime() {
	return fileAttrs.lastModifiedTime();
	}

	public final String getNameString() {
	return name;
	}

	@Override
	public final String toString() {
	return getNameString();
	}

	@Override
	public final int hashCode() {
	return name.hashCode();
	}

	@Override
	public final boolean equals(Object other) {
	if (this == other) {
	return true;
	}

	if (other instanceof Node) {
	return name.equals(((Node) other).name);
	}

	return false;
	}
	}

	// directory node - directory has full path name without '/' at end.
	static final class Directory extends Node {
	private final List<Node> children;

	private Directory(String name, BasicFileAttributes fileAttrs) {
	super(name, fileAttrs);
	children = new ArrayList<>();
	}

	static Directory create(Directory parent, String name, BasicFileAttributes fileAttrs) {
	Directory d = new Directory(name, fileAttrs);
	if (parent != null) {
	parent.addChild(d);
	}
	return d;
	}

	@Override
	public boolean isDirectory() {
	return true;
	}

	@Override
	public List<Node> getChildren() {
	return Collections.unmodifiableList(children);
	}

	void addChild(Node node) {
	children.add(node);
	}

	public void walk(Consumer<? super Node> consumer) {
	consumer.accept(this);
	for ( Node child : children ) {
	if (child.isDirectory()) {
	((Directory)child).walk(consumer);
	} else {
	consumer.accept(child);
	}
	}
	}
	}

	// "resource" is .class or any other resource (compressed/uncompressed) in a jimage.
	// full path of the resource is the "name" of the resource.
	static class Resource extends Node {
	private final ImageLocation loc;

	private Resource(ImageLocation loc, BasicFileAttributes fileAttrs) {
	super(loc.getFullName(true), fileAttrs);
	this.loc = loc;
	}

	static Resource create(Directory parent, ImageLocation loc, BasicFileAttributes fileAttrs) {
	Resource rs = new Resource(loc, fileAttrs);
	parent.addChild(rs);
	return rs;
	}

	@Override
	public boolean isCompleted() {
	return true;
	}

	@Override
	public boolean isResource() {
	return true;
	}

	@Override
	public ImageLocation getLocation() {
	return loc;
	}

	@Override
	public long size() {
	return loc.getUncompressedSize();
	}

	@Override
	public long compressedSize() {
	return loc.getCompressedSize();
	}

	@Override
	public String extension() {
	return loc.getExtension();
	}

	@Override
	public long contentOffset() {
	return loc.getContentOffset();
	}
	}

	// represents a soft link to another Node
	static class LinkNode extends Node {
	private final Node link;

	private LinkNode(String name, Node link) {
	super(name, link.getFileAttributes());
	this.link = link;
	}

	static LinkNode create(Directory parent, String name, Node link) {
	LinkNode ln = new LinkNode(name, link);
	parent.addChild(ln);
	return ln;
	}

	@Override
	public boolean isCompleted() {
	return true;
	}

	@Override
	public Node resolveLink(boolean recursive) {
	return (recursive && link instanceof LinkNode) ? ((LinkNode)link).resolveLink(true) : link;
	}

	@Override
	public boolean isLink() {
	return true;
	}
	}
	}

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