/*

 * 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.tools.jlink.internal.plugins;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.lang.module.Configuration;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleDescriptor.Exports;

import java.lang.module.ModuleDescriptor.Opens;

import java.lang.module.ModuleDescriptor.Provides;

import java.lang.module.ModuleDescriptor.Requires;

import java.lang.module.ModuleDescriptor.Version;

import java.lang.module.ModuleFinder;

import java.lang.module.ModuleReader;

import java.lang.module.ModuleReference;

import java.lang.module.ResolvedModule;

import java.net.URI;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.EnumSet;

import java.util.HashMap;

import java.util.HashSet;

import java.util.LinkedHashMap;

import java.util.List;

import java.util.Map;

import java.util.Objects;

import java.util.Optional;

import java.util.Set;

import java.util.TreeSet;

import java.util.function.IntSupplier;

import java.util.function.Supplier;

import java.util.stream.Collectors;

import jdk.internal.module.Checks;

import jdk.internal.module.DefaultRoots;

import jdk.internal.module.IllegalAccessMaps;

import jdk.internal.module.ModuleHashes;

import jdk.internal.module.ModuleInfo.Attributes;

import jdk.internal.module.ModuleInfoExtender;

import jdk.internal.module.ModuleReferenceImpl;

import jdk.internal.module.ModuleResolution;

import jdk.internal.module.ModuleTarget;

import jdk.internal.org.objectweb.asm.ClassReader;

import jdk.internal.org.objectweb.asm.ClassVisitor;

import jdk.internal.org.objectweb.asm.ClassWriter;

import jdk.internal.org.objectweb.asm.MethodVisitor;

import jdk.internal.org.objectweb.asm.Opcodes;

import static jdk.internal.org.objectweb.asm.Opcodes.*;

import jdk.tools.jlink.internal.ModuleSorter;

import jdk.tools.jlink.plugin.Plugin;

import jdk.tools.jlink.plugin.PluginException;

import jdk.tools.jlink.plugin.ResourcePool;

import jdk.tools.jlink.plugin.ResourcePoolBuilder;

import jdk.tools.jlink.plugin.ResourcePoolEntry;

/**

 * Jlink plugin to reconstitute module descriptors and other attributes for system

 * modules. The plugin generates implementations of SystemModules to avoid parsing

 * module-info.class files at startup. It also generates SystemModulesMap to return

 * the SystemModules implementation for a specific initial module.

 *

 * As a side effect, the plugin adds the ModulePackages class file attribute to the

 * module-info.class files that don't have the attribute.

 *

 * @see jdk.internal.module.SystemModuleFinders

 * @see jdk.internal.module.SystemModules

 */

public final class SystemModulesPlugin implements Plugin {

    private static final String NAME = "system-modules";

    private static final String DESCRIPTION =

            PluginsResourceBundle.getDescription(NAME);

    private static final String SYSTEM_MODULES_MAP_CLASS =

            "jdk/internal/module/SystemModulesMap";

    private static final String SYSTEM_MODULES_CLASS_PREFIX =

            "jdk/internal/module/SystemModules$";

    private static final String ALL_SYSTEM_MODULES_CLASS =

            SYSTEM_MODULES_CLASS_PREFIX + "all";

    private static final String DEFAULT_SYSTEM_MODULES_CLASS =

            SYSTEM_MODULES_CLASS_PREFIX + "default";

    private boolean enabled;

    public SystemModulesPlugin() {

        this.enabled = true;

    }

    @Override

    public String getName() {

        return NAME;

    }

    @Override

    public String getDescription() {

        return DESCRIPTION;

    }

    @Override

    public Set<State> getState() {

        return enabled ? EnumSet.of(State.AUTO_ENABLED, State.FUNCTIONAL)

                       : EnumSet.of(State.DISABLED);

    }

    @Override

    public boolean hasArguments() {

        return true;

    }

    @Override

    public String getArgumentsDescription() {

        return PluginsResourceBundle.getArgument(NAME);

    }

    @Override

    public void configure(Map<String, String> config) {

        String arg = config.get(NAME);

        if (arg != null) {

            throw new IllegalArgumentException(NAME + ": " + arg);

        }

    }

    @Override

    public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {

        if (!enabled) {

            throw new PluginException(NAME + " was set");

        }

        // validate, transform (if needed), and add the module-info.class files

        List<ModuleInfo> moduleInfos = transformModuleInfos(in, out);

        // generate and add the SystemModuleMap and SystemModules classes

        Set<String> generated = genSystemModulesClasses(moduleInfos, out);

        // pass through all other resources

        in.entries()

            .filter(data -> !data.path().endsWith("/module-info.class")

                    && !generated.contains(data.path()))

            .forEach(data -> out.add(data));

        return out.build();

    }

    /**

     * Validates and transforms the module-info.class files in the modules, adding

     * the ModulePackages class file attribute if needed.

     *

     * @return the list of ModuleInfo objects, the first element is java.base

     */

    List<ModuleInfo> transformModuleInfos(ResourcePool in, ResourcePoolBuilder out) {

        List<ModuleInfo> moduleInfos = new ArrayList<>();

        // Sort modules in the topological order so that java.base is always first.

        new ModuleSorter(in.moduleView()).sorted().forEach(module -> {

            ResourcePoolEntry data = module.findEntry("module-info.class").orElseThrow(

                // automatic modules not supported

                () ->  new PluginException("module-info.class not found for " +

                        module.name() + " module")

            );

            assert module.name().equals(data.moduleName());

            try {

                byte[] content = data.contentBytes();

                Set<String> packages = module.packages();

                ModuleInfo moduleInfo = new ModuleInfo(content, packages);

                // link-time validation

                moduleInfo.validateNames();

                // check if any exported or open package is not present

                moduleInfo.validatePackages();

                // module-info.class may be overridden to add ModulePackages

                if (moduleInfo.shouldRewrite()) {

                    data = data.copyWithContent(moduleInfo.getBytes());

                }

                moduleInfos.add(moduleInfo);

                // add resource pool entry

                out.add(data);

            } catch (IOException e) {

                throw new PluginException(e);

            }

        });

        return moduleInfos;

    }

    /**

     * Generates the SystemModules classes (at least one) and the SystemModulesMap

     * class to map initial modules to a SystemModules class.

     *

     * @return the resource names of the resources added to the pool

     */

    private Set<String> genSystemModulesClasses(List<ModuleInfo> moduleInfos,

                                                ResourcePoolBuilder out) {

        int moduleCount = moduleInfos.size();

        ModuleFinder finder = finderOf(moduleInfos);

        assert finder.findAll().size() == moduleCount;

        // map of initial module name to SystemModules class name

        Map<String, String> map = new LinkedHashMap<>();

        // the names of resources written to the pool

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

        // generate the SystemModules implementation to reconstitute all modules

        Set<String> allModuleNames = moduleInfos.stream()

                .map(ModuleInfo::moduleName)

                .collect(Collectors.toSet());

        String rn = genSystemModulesClass(moduleInfos,

                                          resolve(finder, allModuleNames),

                                          ALL_SYSTEM_MODULES_CLASS,

                                          out);

        generated.add(rn);

        // generate, if needed, a SystemModules class to reconstitute the modules

        // needed for the case that the initial module is the unnamed module.

        String defaultSystemModulesClassName;

        Configuration cf = resolve(finder, DefaultRoots.compute(finder));

        if (cf.modules().size() == moduleCount) {

            // all modules are resolved so no need to generate a class

            defaultSystemModulesClassName = ALL_SYSTEM_MODULES_CLASS;

        } else {

            defaultSystemModulesClassName = DEFAULT_SYSTEM_MODULES_CLASS;

            rn = genSystemModulesClass(sublist(moduleInfos, cf),

                                       cf,

                                       defaultSystemModulesClassName,

                                       out);

            generated.add(rn);

        }

        // Generate a SystemModules class for each module with a main class

        int suffix = 0;

        for (ModuleInfo mi : moduleInfos) {

            if (mi.descriptor().mainClass().isPresent()) {

                String moduleName = mi.moduleName();

                cf = resolve(finder, Set.of(moduleName));

                if (cf.modules().size() == moduleCount) {

                    // resolves all modules so no need to generate a class

                    map.put(moduleName, ALL_SYSTEM_MODULES_CLASS);

                } else {

                    String cn = SYSTEM_MODULES_CLASS_PREFIX + (suffix++);

                    rn = genSystemModulesClass(sublist(moduleInfos, cf), cf, cn, out);

                    map.put(moduleName, cn);

                    generated.add(rn);

                }

            }

        }

        // generate SystemModulesMap

        rn = genSystemModulesMapClass(ALL_SYSTEM_MODULES_CLASS,

                                      defaultSystemModulesClassName,

                                      map,

                                      out);

        generated.add(rn);

        // return the resource names of the generated classes

        return generated;

    }

    /**

     * Resolves a collection of root modules, with service binding, to create

     * configuration.

     */

    private Configuration resolve(ModuleFinder finder, Set<String> roots) {

        return Configuration.empty().resolveAndBind(finder, ModuleFinder.of(), roots);

    }

    /**

     * Returns the list of ModuleInfo objects that correspond to the modules in

     * the given configuration.

     */

    private List<ModuleInfo> sublist(List<ModuleInfo> moduleInfos, Configuration cf) {

        Set<String> names = cf.modules()

                .stream()

                .map(ResolvedModule::name)

                .collect(Collectors.toSet());

        return moduleInfos.stream()

                .filter(mi -> names.contains(mi.moduleName()))

                .collect(Collectors.toList());

    }

    /**

     * Generate a SystemModules implementation class and add it as a resource.

     *

     * @return the name of the class resource added to the pool

     */

    private String genSystemModulesClass(List<ModuleInfo> moduleInfos,

                                         Configuration cf,

                                         String className,

                                         ResourcePoolBuilder out) {

        SystemModulesClassGenerator generator

            = new SystemModulesClassGenerator(className, moduleInfos);

        byte[] bytes = generator.getClassWriter(cf).toByteArray();

        String rn = "/java.base/" + className + ".class";

        ResourcePoolEntry e = ResourcePoolEntry.create(rn, bytes);

        out.add(e);

        return rn;

    }

    static class ModuleInfo {

        private final ByteArrayInputStream bais;

        private final Attributes attrs;

        private final Set<String> packages;

        private final boolean addModulePackages;

        private ModuleDescriptor descriptor;  // may be different that the original one

        ModuleInfo(byte[] bytes, Set<String> packages) throws IOException {

            this.bais = new ByteArrayInputStream(bytes);

            this.packages = packages;

            this.attrs = jdk.internal.module.ModuleInfo.read(bais, null);

            // If ModulePackages attribute is present, the packages from this

            // module descriptor returns the packages in that attribute.

            // If it's not present, ModuleDescriptor::packages only contains

            // the exported and open packages from module-info.class

            this.descriptor = attrs.descriptor();

            if (descriptor.isAutomatic()) {

                throw new InternalError("linking automatic module is not supported");

            }

            // add ModulePackages attribute if this module contains some packages

            // and ModulePackages is not present

            this.addModulePackages = packages.size() > 0 && !hasModulePackages();

        }

        String moduleName() {

            return attrs.descriptor().name();

        }

        ModuleDescriptor descriptor() {

            return descriptor;

        }

        Set<String> packages() {

            return packages;

        }

        ModuleTarget target() {

            return attrs.target();

        }

        ModuleHashes recordedHashes() {

            return attrs.recordedHashes();

        }

        ModuleResolution moduleResolution() {

            return attrs.moduleResolution();

        }

        /**

         * Validates names in ModuleDescriptor

         */

        void validateNames() {

            Checks.requireModuleName(descriptor.name());

            for (Requires req : descriptor.requires()) {

                Checks.requireModuleName(req.name());

            }

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

                Checks.requirePackageName(e.source());

                if (e.isQualified())

                    e.targets().forEach(Checks::requireModuleName);

            }

            for (Opens opens : descriptor.opens()) {

                Checks.requirePackageName(opens.source());

                if (opens.isQualified())

                    opens.targets().forEach(Checks::requireModuleName);

            }

            for (Provides provides : descriptor.provides()) {

                Checks.requireServiceTypeName(provides.service());

                provides.providers().forEach(Checks::requireServiceProviderName);

            }

            for (String service : descriptor.uses()) {

                Checks.requireServiceTypeName(service);

            }

            for (String pn : descriptor.packages()) {

                Checks.requirePackageName(pn);

            }

            for (String pn : packages) {

                Checks.requirePackageName(pn);

            }

        }

        /**

         * Validates if exported and open packages are present

         */

        void validatePackages() {

            Set<String> nonExistPackages = new TreeSet<>();

            descriptor.exports().stream()

                .map(Exports::source)

                .filter(pn -> !packages.contains(pn))

                .forEach(nonExistPackages::add);

            descriptor.opens().stream()

                .map(Opens::source)

                .filter(pn -> !packages.contains(pn))

                .forEach(nonExistPackages::add);

            if (!nonExistPackages.isEmpty()) {

                throw new PluginException("Packages that are exported or open in "

                    + descriptor.name() + " are not present: " + nonExistPackages);

            }

        }

        boolean hasModulePackages() throws IOException {

                @Override

                }

            };

            try (InputStream in = getInputStream()) {

                // parse module-info.class

                ClassReader cr = new ClassReader(in);

            }

        }

        /**

         * Returns true if module-info.class should be rewritten to add the

         * ModulePackages attribute.

         */

        boolean shouldRewrite() {

            return addModulePackages;

        }

        /**

         * Returns the bytes for the (possibly updated) module-info.class.

         */

        byte[] getBytes() throws IOException {

            try (InputStream in = getInputStream()) {

                if (shouldRewrite()) {

                    ModuleInfoRewriter rewriter = new ModuleInfoRewriter(in);

                    if (addModulePackages) {

                        rewriter.addModulePackages(packages);

                    }

                    // rewritten module descriptor

                    byte[] bytes = rewriter.getBytes();

                    try (ByteArrayInputStream bais = new ByteArrayInputStream(bytes)) {

                        this.descriptor = ModuleDescriptor.read(bais);

                    }

                    return bytes;

                } else {

                    return in.readAllBytes();

                }

            }

        }

        /*

         * Returns the input stream of the module-info.class

         */

        InputStream getInputStream() {

            bais.reset();

            return bais;

        }

        class ModuleInfoRewriter extends ByteArrayOutputStream {

            final ModuleInfoExtender extender;

            ModuleInfoRewriter(InputStream in) {

                this.extender = ModuleInfoExtender.newExtender(in);

            }