import static com.sun.tools.jdeps.Module.trace;

import static java.util.stream.Collectors.*;

import com.sun.tools.classfile.Dependency;

import java.io.BufferedInputStream;

import java.io.InputStream;

import java.lang.module.ModuleReader;

import java.nio.file.DirectoryStream;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedHashMap;

import java.util.LinkedHashSet;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.Optional;

import java.util.Set;

import java.util.function.Function;

import java.util.function.Supplier;

import java.util.stream.Stream;

public class JdepsConfiguration {

    private static final String MODULE_INFO = "module-info.class";

    private final SystemModuleFinder system;

    private final ModuleFinder finder;

    private final Map<String, Module> nameToModule = new LinkedHashMap<>();

    private final Map<String, Module> packageToModule = new HashMap<>();

    private final Map<String, List<Archive>> packageToUnnamedModule = new HashMap<>();

    private final List<Archive> classpathArchives = new ArrayList<>();

    private final List<Archive> initialArchives = new ArrayList<>();

    private final Set<Module> rootModules = new HashSet<>();

    private final Configuration configuration;

    private JdepsConfiguration(SystemModuleFinder systemModulePath,

                               ModuleFinder finder,

                               Set<String> roots,

                               List<Path> classpaths,

                               List<Archive> initialArchives)

        throws IOException

    {

        trace("root: %s%n", roots);

        this.system = systemModulePath;

        this.finder = finder;

        // build root set

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

        if (initialArchives.isEmpty() && classpaths.isEmpty() && !roots.isEmpty()) {

            // named module as root. No initial unnamed module

            mods.addAll(roots);

        } else {

            // unnamed module

            mods.addAll(roots);

            mods.addAll(systemModulePath.defaultSystemRoots());

        }

        this.configuration = Configuration.empty()

                .resolveRequires(finder, ModuleFinder.of(), mods);

        this.configuration.modules().stream()

                .map(ResolvedModule::reference)

                .forEach(this::addModuleReference);

        // packages in unnamed module

        initialArchives.forEach(archive -> {

            addPackagesInUnnamedModule(archive);

            this.initialArchives.add(archive);

        });

        // classpath archives

        for (Path p : classpaths) {

            if (Files.exists(p)) {

                Archive archive = Archive.getInstance(p);

                addPackagesInUnnamedModule(archive);

                classpathArchives.add(archive);

            }

        }

        // all roots specified in -addmods or -m are included

        // as the initial set for analysis.

        roots.stream()

             .map(nameToModule::get)

             .forEach(this.rootModules::add);

        initProfiles();

        trace("resolved modules: %s%n", nameToModule.keySet().stream()

                .sorted().collect(joining("\n", "\n", "")));

    private void initProfiles() {

        // other system modules are not observed and not added in nameToModule map

        Map<String, Module> systemModules =

            system.moduleNames()

                .collect(toMap(Function.identity(), (mn) -> {

                    Module m = nameToModule.get(mn);

                    if (m == null) {

                        ModuleReference mref = finder.find(mn).get();

                        m = toModule(mref);

                    }

                    return m;

                }));

        Profile.init(systemModules);

    }

    private void addModuleReference(ModuleReference mref) {

        Module module = toModule(mref);

        nameToModule.put(mref.descriptor().name(), module);

        mref.descriptor().packages()

            .forEach(pn -> packageToModule.putIfAbsent(pn, module));

    }

    private void addPackagesInUnnamedModule(Archive archive) {

        archive.reader().entries().stream()

               .filter(e -> e.endsWith(".class") && !e.equals(MODULE_INFO))

               .map(this::toPackageName)

               .distinct()

               .forEach(pn -> packageToUnnamedModule

                   .computeIfAbsent(pn, _n -> new ArrayList<>()).add(archive));

    }

    private String toPackageName(String name) {

        int i = name.lastIndexOf('/');

        return i > 0 ? name.replace('/', '.').substring(0, i) : "";

    }

    public Optional<Module> findModule(String name) {

        Objects.requireNonNull(name);

        Module m = nameToModule.get(name);

        return m!= null ? Optional.of(m) : Optional.empty();

    }

    public Optional<ModuleDescriptor> findModuleDescriptor(String name) {

        Objects.requireNonNull(name);

        Module m = nameToModule.get(name);

        return m!= null ? Optional.of(m.descriptor()) : Optional.empty();

    }

    boolean isSystem(Module m) {

        return system.find(m.name()).isPresent();

    }

    /**

     * Returns the modules that the given module can read

     */

    public Stream<Module> reads(Module module) {

        return configuration.findModule(module.name()).get()

            .reads().stream()

            .map(ResolvedModule::name)

            .map(nameToModule::get);

    }

    /**

     * Returns the list of packages that split between resolved module and

     * unnamed module

     */

    public Map<String, Set<String>> splitPackages() {

        Set<String> splitPkgs = packageToModule.keySet().stream()

                                       .filter(packageToUnnamedModule::containsKey)

                                       .collect(toSet());

        if (splitPkgs.isEmpty())

            return Collections.emptyMap();

        return splitPkgs.stream().collect(toMap(Function.identity(), (pn) -> {

            Set<String> sources = new LinkedHashSet<>();

            sources.add(packageToModule.get(pn).getModule().location().toString());

            packageToUnnamedModule.get(pn).stream()

                .map(Archive::getPathName)

                .forEach(sources::add);

            return sources;

        }));

    }

    /**

     * Returns an optional archive containing the given Location

     */

    public Optional<Archive> findClass(Dependency.Location location) {

        String name = location.getName();

        int i = name.lastIndexOf('/');

        String pn = i > 0 ? name.substring(0, i).replace('/', '.') : "";

        Archive archive = packageToModule.get(pn);

        if (archive != null) {

            return archive.contains(name + ".class")

                        ? Optional.of(archive)

                        : Optional.empty();

        if (packageToUnnamedModule.containsKey(pn)) {

            return packageToUnnamedModule.get(pn).stream()

                    .filter(a -> a.contains(name + ".class"))

                    .findFirst();

        return Optional.empty();

    public Map<String, Module> getModules() {

        return nameToModule;

    public Stream<Module> resolve(Set<String> roots) {

        if (roots.isEmpty()) {

            return nameToModule.values().stream();

            return Configuration.empty()

                    .resolveRequires(finder, ModuleFinder.of(), roots)

                    .modules().stream()

                    .map(ResolvedModule::name)

                    .map(nameToModule::get);

    public List<Archive> classPathArchives() {

        return classpathArchives;

    }

    public List<Archive> initialArchives() {

        return initialArchives;

    }

    public Set<Module> rootModules() {

        return rootModules;

    public Module toModule(ModuleReference mref) {

        try {

            String mn = mref.descriptor().name();

            URI location = mref.location().orElseThrow(FileNotFoundException::new);

            ModuleDescriptor md = mref.descriptor();

            Module.Builder builder = new Module.Builder(md, system.find(mn).isPresent());

            final ClassFileReader reader;

            if (location.getScheme().equals("jrt")) {

                reader = system.getClassReader(mn);

            } else {

                reader = ClassFileReader.newInstance(Paths.get(location));

            }

            builder.classes(reader);

            return builder.build();

    static class SystemModuleFinder implements ModuleFinder {

        private static final String JAVA_SE = "java.se";

        private final FileSystem fileSystem;

        private final Path root;

        private final Map<String, ModuleReference> systemModules;

        SystemModuleFinder() {

            this(System.getProperty("java.home"));

        }

        SystemModuleFinder(String javaHome) {

            final FileSystem fs;

            final Path root;

            final Map<String, ModuleReference> systemModules;

            if (javaHome != null) {

                if (Files.isRegularFile(Paths.get(javaHome, "lib", "modules"))) {

                    try {

                        // jrt file system

                        fs = FileSystems.getFileSystem(URI.create("jrt:/"));

                        root = fs.getPath("/modules");

                        systemModules = Files.walk(root, 1)

                            .filter(path -> !path.equals(root))

                            .map(this::toModuleReference)

                            .collect(toMap(mref -> mref.descriptor().name(),

                                           Function.identity()));

                    } catch (IOException e) {

                        throw new UncheckedIOException(e);

                    }

                } else {

                    // exploded image

                    fs = FileSystems.getDefault();

                    root = Paths.get(javaHome, "modules");

                    systemModules = ModuleFinder.ofSystem().findAll().stream()

                        .collect(toMap(mref -> mref.descriptor().name(), Function.identity()));

                }

                fs = null;

                root = null;

                systemModules = Collections.emptyMap();

            this.fileSystem = fs;

            this.root = root;

            this.systemModules = systemModules;

        private ModuleReference toModuleReference(Path path) {

            Path minfo = path.resolve(MODULE_INFO);

            try (InputStream in = Files.newInputStream(minfo);

                 BufferedInputStream bin = new BufferedInputStream(in)) {

                ModuleDescriptor descriptor = dropHashes(ModuleDescriptor.read(bin));

                String mn = descriptor.name();

                URI uri = URI.create("jrt:/" + path.getFileName().toString());

                Supplier<ModuleReader> readerSupplier = new Supplier<>() {

                    @Override

                    public ModuleReader get() {

                        return new ModuleReader() {

                            @Override

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

                                return name.equals(mn)

                                    ? Optional.of(uri) : Optional.empty();

                            }

                            @Override

                            public void close() throws IOException {

                            }

                        };

                    }

                };

                return new ModuleReference(descriptor, uri, readerSupplier);

            } catch (IOException e) {

                throw new UncheckedIOException(e);

        private ModuleDescriptor dropHashes(ModuleDescriptor md) {

            ModuleDescriptor.Builder builder = new ModuleDescriptor.Builder(md.name());

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

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

            md.provides().values().stream().forEach(builder::provides);

            md.uses().stream().forEach(builder::uses);

            builder.conceals(md.conceals());

            return builder.build();

        }

        @Override

        public Set<ModuleReference> findAll() {

            return systemModules.values().stream().collect(toSet());

        @Override

        public Optional<ModuleReference> find(String mn) {

            return systemModules.containsKey(mn)

                    ? Optional.of(systemModules.get(mn)) : Optional.empty();

        public Stream<String> moduleNames() {

            return systemModules.values().stream()

                .map(mref -> mref.descriptor().name());

        }

        public ClassFileReader getClassReader(String modulename) throws IOException {

                return ClassFileReader.newInstance(fileSystem, mp);

        public Set<String> defaultSystemRoots() {

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

            boolean hasJava = false;

            if (systemModules.containsKey(JAVA_SE)) {

                // java.se is a system module

                hasJava = true;

                roots.add(JAVA_SE);

            }

            for (ModuleReference mref : systemModules.values()) {

                String mn = mref.descriptor().name();

                if (hasJava && mn.startsWith("java."))

                    continue;

                // add as root if observable and exports at least one package

                ModuleDescriptor descriptor = mref.descriptor();

                for (ModuleDescriptor.Exports e : descriptor.exports()) {

                    if (!e.isQualified()) {

                        roots.add(mn);

                        break;

                    }

                }

            }

            return roots;

        }

    public static class Builder {

        // the token for "all modules on the module path"

        private static final String ALL_MODULE_PATH = "ALL-MODULE-PATH";

        final SystemModuleFinder systemModulePath;

        final Set<String> rootModules = new HashSet<>();

        final List<Archive> initialArchives = new ArrayList<>();

        final List<Path> paths = new ArrayList<>();

        final List<Path> classPaths = new ArrayList<>();

        ModuleFinder upgradeModulePath;

        ModuleFinder appModulePath;

        boolean addAllApplicationModules;

        public Builder() {

            this(System.getProperty("java.home"));

        }

        public Builder(String systemModulePath) {

            this.systemModulePath = new SystemModuleFinder(systemModulePath);;

        }

        public Builder upgradeModulePath(String upgradeModulePath) {

            this.upgradeModulePath = createModulePathFinder(upgradeModulePath);

            return this;

        }

        public Builder appModulePath(String modulePath) {

            this.appModulePath = createModulePathFinder(modulePath);

            return this;

        }

        public Builder addmods(Set<String> addmods) {

            for (String mn : addmods) {

                switch (mn) {

                    case ALL_MODULE_PATH:

                        this.addAllApplicationModules = true;

                        break;

                    default:

                        this.rootModules.add(mn);

                }

            }

            return this;

        }

        /*

         * This method is for -check option to find all target modules specified

         * in qualified exports.

         *

         * Include all system modules and modules found on modulepath

         */

        public Builder allModules() {

            systemModulePath.moduleNames()

                            .forEach(this.rootModules::add);

            this.addAllApplicationModules = true;

            return this;

        }

        public Builder addRoot(Path path) {