/*

 * Copyright (c) 2015, 2017, 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.module;

import java.io.Closeable;

import java.io.File;

import java.io.IOError;

import java.io.IOException;

import java.io.InputStream;

import java.io.UncheckedIOException;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleDescriptor.Builder;

import java.lang.module.ModuleReader;

import java.lang.module.ModuleReference;

import java.net.MalformedURLException;

import java.net.URI;

import java.net.URL;

import java.nio.ByteBuffer;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

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.Optional;

import java.util.Set;

import java.util.jar.JarEntry;

import java.util.jar.JarFile;

import java.util.stream.Collectors;

import java.util.stream.Stream;

import jdk.internal.loader.Resource;

import jdk.internal.misc.JavaLangModuleAccess;

import jdk.internal.misc.SharedSecrets;

import sun.net.www.ParseUtil;

/**

 * Provides support for patching modules, mostly the boot layer.

 */

public final class ModulePatcher {

    private static final JavaLangModuleAccess JLMA

        = SharedSecrets.getJavaLangModuleAccess();

    // module name -> sequence of patches (directories or JAR files)

    private final Map<String, List<Path>> map;

    /**

     * Initialize the module patcher with the given map. The map key is

     * the module name, the value is a list of path strings.

     */

    public ModulePatcher(Map<String, List<String>> input) {

        if (input.isEmpty()) {

            this.map = Collections.emptyMap();

        } else {

            Map<String, List<Path>> map = new HashMap<>();

            for (Map.Entry<String, List<String>> e : input.entrySet()) {

                String mn = e.getKey();

                List<Path> paths = e.getValue().stream()

                        .map(Paths::get)

                        .collect(Collectors.toList());

                map.put(mn, paths);

            }

            this.map = map;

        }

    }

    /**

     * Returns a module reference that interposes on the given module if

     * needed. If there are no patches for the given module then the module

     * reference is simply returned. Otherwise the patches for the module

     * are scanned (to find any new packages) and a new module reference is

     * returned.

     *

     * @throws UncheckedIOException if an I/O error is detected

     */

    public ModuleReference patchIfNeeded(ModuleReference mref) {

        // if there are no patches for the module then nothing to do

        ModuleDescriptor descriptor = mref.descriptor();

        String mn = descriptor.name();

        List<Path> paths = map.get(mn);

        if (paths == null)

            return mref;

        // Scan the JAR file or directory tree to get the set of packages.

        // For automatic modules then packages that do not contain class files

        // must be ignored.

        Set<String> packages = new HashSet<>();

        boolean isAutomatic = descriptor.isAutomatic();

        try {

            for (Path file : paths) {

                if (Files.isRegularFile(file)) {

                    // JAR file - do not open as a multi-release JAR as this

                    // is not supported by the boot class loader

                        jf.stream()

                          .filter(e -> !e.isDirectory()

                                  && (!isAutomatic || e.getName().endsWith(".class")))

                          .map(e -> toPackageName(file, e))

                          .filter(Checks::isPackageName)

                          .forEach(packages::add);

                    }

                } else if (Files.isDirectory(file)) {

                    // exploded directory without following sym links

                    Path top = file;

                    Files.find(top, Integer.MAX_VALUE,

                               ((path, attrs) -> attrs.isRegularFile()))

                            .filter(path -> (!isAutomatic

                                    || path.toString().endsWith(".class"))

                                    && !isHidden(path))

                            .map(path -> toPackageName(top, path))

                            .filter(Checks::isPackageName)

                            .forEach(packages::add);

                }

            }

        } catch (IOException ioe) {

            throw new UncheckedIOException(ioe);

        }

        // if there are new packages then we need a new ModuleDescriptor

        packages.removeAll(descriptor.packages());

        if (!packages.isEmpty()) {

            Builder builder = JLMA.newModuleBuilder(descriptor.name(),

                                                    /*strict*/ false,

                                                    descriptor.modifiers());

            if (!descriptor.isAutomatic()) {

                descriptor.requires().forEach(builder::requires);

                descriptor.exports().forEach(builder::exports);

                descriptor.opens().forEach(builder::opens);

                descriptor.uses().forEach(builder::uses);

            }

            descriptor.provides().forEach(builder::provides);

            descriptor.version().ifPresent(builder::version);

            descriptor.mainClass().ifPresent(builder::mainClass);

            // original + new packages

            builder.packages(descriptor.packages());

            builder.packages(packages);

            descriptor = builder.build();

        }

        // return a module reference to the patched module

        URI location = mref.location().orElse(null);

        ModuleTarget target = null;

        ModuleHashes recordedHashes = null;

        ModuleHashes.HashSupplier hasher = null;

        ModuleResolution mres = null;

        if (mref instanceof ModuleReferenceImpl) {

            ModuleReferenceImpl impl = (ModuleReferenceImpl)mref;

            target = impl.moduleTarget();

            recordedHashes = impl.recordedHashes();

            hasher = impl.hasher();

            mres = impl.moduleResolution();

        }

        return new ModuleReferenceImpl(descriptor,

                                       location,

                                       () -> new PatchedModuleReader(paths, mref),

                                       this,

                                       target,

                                       recordedHashes,

                                       hasher,

                                       mres);

    }

    /**

     * Returns true is this module patcher has no patches.

     */

    public boolean isEmpty() {

        return map.isEmpty();

    }

    /*

     * Returns the names of the patched modules.

     */

    Set<String> patchedModules() {

        return map.keySet();

    }

    /**

     * A ModuleReader that reads resources from a patched module.

     *

     * This class is public so as to expose the findResource method to the

     * built-in class loaders and avoid locating the resource twice during

     * class loading (once to locate the resource, the second to gets the

     * URL for the CodeSource).

     */

    public static class PatchedModuleReader implements ModuleReader {

        private final List<ResourceFinder> finders;

        private final ModuleReference mref;

        private final URL delegateCodeSourceURL;

        private volatile ModuleReader delegate;

        /**

         * Creates the ModuleReader to reads resources in a patched module.

         */

        PatchedModuleReader(List<Path> patches, ModuleReference mref) {

            List<ResourceFinder> finders = new ArrayList<>();

            boolean initialized = false;

            try {

                for (Path file : patches) {

                    if (Files.isRegularFile(file)) {

                        finders.add(new JarResourceFinder(file));

                    } else {

                        finders.add(new ExplodedResourceFinder(file));

                    }

                }

                initialized = true;

            } catch (IOException ioe) {

                throw new UncheckedIOException(ioe);

            } finally {

                // close all ResourceFinder in the event of an error

                if (!initialized) closeAll(finders);

            }

            this.finders = finders;

            this.mref = mref;

            this.delegateCodeSourceURL = codeSourceURL(mref);

        }

        /**

         * Closes all resource finders.

         */

        private static void closeAll(List<ResourceFinder> finders) {

            for (ResourceFinder finder : finders) {

                try { finder.close(); } catch (IOException ioe) { }

            }

        }

        /**

         * Returns the code source URL for the given module.

         */

        private static URL codeSourceURL(ModuleReference mref) {

            try {

                Optional<URI> ouri = mref.location();

                if (ouri.isPresent())

                    return ouri.get().toURL();

            } catch (MalformedURLException e) { }

            return null;

        }

        /**

         * Returns the ModuleReader to delegate to when the resource is not

         * found in a patch location.

         */

        private ModuleReader delegate() throws IOException {

            ModuleReader r = delegate;

            if (r == null) {

                synchronized (this) {

                    r = delegate;

                    if (r == null) {

                        delegate = r = mref.open();

                    }

                }

            }

            return r;

        }

        /**

         * Finds a resources in the patch locations. Returns null if not found

         * or the name is "module-info.class" as that cannot be overridden.

         */

        private Resource findResourceInPatch(String name) throws IOException {

            if (!name.equals("module-info.class")) {

                for (ResourceFinder finder : finders) {

                    Resource r = finder.find(name);

                    if (r != null)

                        return r;

                }

            }

            return null;

        }

        /**

         * Finds a resource of the given name in the patched module.

         */

        public Resource findResource(String name) throws IOException {

            // patch locations

            Resource r = findResourceInPatch(name);

            if (r != null)

                return r;

            // original module

            ByteBuffer bb = delegate().read(name).orElse(null);

            if (bb == null)

                return null;

            return new Resource() {

                private <T> T shouldNotGetHere(Class<T> type) {

                    throw new InternalError("should not get here");

                }

                @Override

                public String getName() {

                    return shouldNotGetHere(String.class);

                }

                @Override

                public URL getURL() {

                    return shouldNotGetHere(URL.class);

                }

                @Override

                public URL getCodeSourceURL() {

                    return delegateCodeSourceURL;

                }

                @Override

                public ByteBuffer getByteBuffer() throws IOException {

                    return bb;

                }

                @Override

                public InputStream getInputStream() throws IOException {

                    return shouldNotGetHere(InputStream.class);

                }

                @Override

                public int getContentLength() throws IOException {

                    return shouldNotGetHere(int.class);

                }

            };

        }

        @Override

        public Optional<URI> find(String name) throws IOException {

            Resource r = findResourceInPatch(name);

            if (r != null) {

                URI uri = URI.create(r.getURL().toString());

                return Optional.of(uri);

            } else {

                return delegate().find(name);

            }

        }

        @Override

        public Optional<InputStream> open(String name) throws IOException {

            Resource r = findResourceInPatch(name);

            if (r != null) {

                return Optional.of(r.getInputStream());

            } else {

                return delegate().open(name);

            }

        }

        @Override

        public Optional<ByteBuffer> read(String name) throws IOException {

            Resource r = findResourceInPatch(name);

            if (r != null) {

                ByteBuffer bb = r.getByteBuffer();

                assert !bb.isDirect();

                return Optional.of(bb);

            } else {

                return delegate().read(name);

            }

        }

        @Override

        public void release(ByteBuffer bb) {

            if (bb.isDirect()) {

                try {

                    delegate().release(bb);

                } catch (IOException ioe) {

                    throw new InternalError(ioe);

                }

            }

        }

        @Override

        public Stream<String> list() throws IOException {

            Stream<String> s = delegate().list();

            for (ResourceFinder finder : finders) {

                s = Stream.concat(s, finder.list());

            }

            return s.distinct();

        }

        @Override

        public void close() throws IOException {

            closeAll(finders);

            delegate().close();

        }

    }

    /**

     * A resource finder that find resources in a patch location.

     */

    private static interface ResourceFinder extends Closeable {

        Resource find(String name) throws IOException;

        Stream<String> list() throws IOException;

    }

    /**

     * A ResourceFinder that finds resources in a JAR file.

     */

    private static class JarResourceFinder implements ResourceFinder {

        private final JarFile jf;

        private final URL csURL;

        JarResourceFinder(Path path) throws IOException {

            this.csURL = path.toUri().toURL();

        }

        @Override

        public void close() throws IOException {

            jf.close();

        }

        @Override

        public Resource find(String name) throws IOException {

            JarEntry entry = jf.getJarEntry(name);

            if (entry == null)

                return null;

            return new Resource() {

                @Override

                public String getName() {

                    return name;

                }

                @Override

                public URL getURL() {

                    String encodedPath = ParseUtil.encodePath(name, false);

                    try {

                        return new URL("jar:" + csURL + "!/" + encodedPath);

                    } catch (MalformedURLException e) {

                        return null;

                    }

                }

                @Override

                public URL getCodeSourceURL() {

                    return csURL;

                }

                @Override

                public ByteBuffer getByteBuffer() throws IOException {

                    byte[] bytes = getInputStream().readAllBytes();

                    return ByteBuffer.wrap(bytes);

                }

                @Override

                public InputStream getInputStream() throws IOException {

                    return jf.getInputStream(entry);

                }

                @Override

                public int getContentLength() throws IOException {

                    long size = entry.getSize();

                    return (size > Integer.MAX_VALUE) ? -1 : (int) size;

                }

            };

        }

        @Override

        public Stream<String> list() throws IOException {

            return jf.stream().map(JarEntry::getName);

        }

    }

    /**

     * A ResourceFinder that finds resources on the file system.

     */

    private static class ExplodedResourceFinder implements ResourceFinder {

        private final Path dir;

        ExplodedResourceFinder(Path dir) {

            this.dir = dir;

        }

        @Override

        public void close() { }

        @Override

        public Resource find(String name) throws IOException {

            Path file = Resources.toFilePath(dir, name);

            if (file != null) {

            } else {

                return null;

            }

        }

        private Resource newResource(String name, Path top, Path file) {