/*
 * Copyright (c) 2015, 2018, 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
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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.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.access.JavaLangModuleAccess;
import jdk.internal.access.SharedSecrets;
import sun.net.www.ParseUtil;


Provides support for patching modules, mostly the boot layer.
/**
 * 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.
/**
     * 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 = Map.of();
        } 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/**
     * 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
                    try (JarFile jf = new JarFile(file.toString())) {
                        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*/ descriptor.isAutomatic(),
                                                    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 patches.
/**
     * Returns true is this module patcher has patches.
     */
    public boolean hasPatches() {
        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).
/**
     * 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.
/**
         * 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.
/**
         * 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.
/**
         * 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.
/**
         * 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.
/**
         * 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.
/**
         * 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.
/**
     * 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.
/**
     * 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.jf = new JarFile(path.toString());
            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.
/**
     * 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) {
                return newResource(name, dir, file);
            } else {
                return null;
            }
        }

        private Resource newResource(String name, Path top, Path file) {
            return new Resource() {
                @Override
                public String getName() {
                    return name;
                }
                @Override
                public URL getURL() {
                    try {
                        return file.toUri().toURL();
                    } catch (IOException | IOError e) {
                        return null;
                    }
                }
                @Override
                public URL getCodeSourceURL() {
                    try {
                        return top.toUri().toURL();
                    } catch (IOException | IOError e) {
                        return null;
                    }
                }
                @Override
                public ByteBuffer getByteBuffer() throws IOException {
                    return ByteBuffer.wrap(Files.readAllBytes(file));
                }
                @Override
                public InputStream getInputStream() throws IOException {
                    return Files.newInputStream(file);
                }
                @Override
                public int getContentLength() throws IOException {
                    long size = Files.size(file);
                    return (size > Integer.MAX_VALUE) ? -1 : (int)size;
                }
            };
        }

        @Override
        public Stream<String> list() throws IOException {
            return Files.walk(dir, Integer.MAX_VALUE)
                        .map(f -> Resources.toResourceName(dir, f))
                        .filter(s -> !s.isEmpty());
        }
    }


    
Derives a package name from the file path of an entry in an exploded patch
/**
     * Derives a package name from the file path of an entry in an exploded patch
     */
    private static String toPackageName(Path top, Path file) {
        Path entry = top.relativize(file);
        Path parent = entry.getParent();
        if (parent == null) {
            return warnIfModuleInfo(top, entry.toString());
        } else {
            return parent.toString().replace(File.separatorChar, '.');
        }
    }

    
Returns true if the given file exists and is a hidden file
/**
     * Returns true if the given file exists and is a hidden file
     */
    private boolean isHidden(Path file) {
        try {
            return Files.isHidden(file);
        } catch (IOException ioe) {
            return false;
        }
    }

    
Derives a package name from the name of an entry in a JAR file.
/**
     * Derives a package name from the name of an entry in a JAR file.
     */
    private static String toPackageName(Path file, JarEntry entry) {
        String name = entry.getName();
        int index = name.lastIndexOf("/");
        if (index == -1) {
            return warnIfModuleInfo(file, name);
        } else {
            return name.substring(0, index).replace('/', '.');
        }
    }

    private static String warnIfModuleInfo(Path file, String e) {
        if (e.equals("module-info.class"))
            System.err.println("WARNING: " + e + " ignored in patch: " + file);
        return "";
    }
}