/*

 * Copyright (c) 2014, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.module;

import java.io.DataInput;

import java.io.DataInputStream;

import java.io.EOFException;

import java.io.IOException;

import java.io.InputStream;

import java.io.UncheckedIOException;

import java.lang.module.InvalidModuleDescriptorException;

import java.lang.module.ModuleDescriptor;

import java.lang.module.ModuleDescriptor.Builder;

import java.lang.module.ModuleDescriptor.Requires;

import java.lang.module.ModuleDescriptor.Exports;

import java.lang.module.ModuleDescriptor.Opens;

import java.nio.ByteBuffer;

import java.nio.BufferUnderflowException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.function.Supplier;

import static jdk.internal.module.ClassFileConstants.*;

/**

 * Read module information from a {@code module-info} class file.

 *

 * @implNote The rationale for the hand-coded reader is startup performance

 * and fine control over the throwing of InvalidModuleDescriptorException.

 */

public final class ModuleInfo {

    private final int JAVA_MIN_SUPPORTED_VERSION = 53;

    private final int JAVA_MAX_SUPPORTED_VERSION = 56;

    private static final JavaLangModuleAccess JLMA

        = SharedSecrets.getJavaLangModuleAccess();

    // supplies the set of packages when ModulePackages attribute not present

    private final Supplier<Set<String>> packageFinder;

    // indicates if the ModuleHashes attribute should be parsed

    private final boolean parseHashes;

    private ModuleInfo(Supplier<Set<String>> pf, boolean ph) {

        packageFinder = pf;

        parseHashes = ph;

    }

    private ModuleInfo(Supplier<Set<String>> pf) {

        this(pf, true);

    }

    /**

     * A holder class for the ModuleDescriptor that is created by reading the

     * Module and other standard class file attributes. It also holds the objects

     * that represent the non-standard class file attributes that are read from

     * the class file.

     */

    public static final class Attributes {

        private final ModuleDescriptor descriptor;

        private final ModuleTarget target;

        private final ModuleHashes recordedHashes;

        private final ModuleResolution moduleResolution;

        Attributes(ModuleDescriptor descriptor,

                   ModuleTarget target,

                   ModuleHashes recordedHashes,

                   ModuleResolution moduleResolution) {

            this.descriptor = descriptor;

            this.target = target;

            this.recordedHashes = recordedHashes;

            this.moduleResolution = moduleResolution;

        }

        public ModuleDescriptor descriptor() {

            return descriptor;

        }

        public ModuleTarget target() {

            return target;

        }

        public ModuleHashes recordedHashes() {

            return recordedHashes;

        }

        public ModuleResolution moduleResolution() {

            return moduleResolution;

        }

    }

    /**

     * Reads a {@code module-info.class} from the given input stream.

     *

     * @throws InvalidModuleDescriptorException

     * @throws IOException

     */

    public static Attributes read(InputStream in, Supplier<Set<String>> pf)

        throws IOException

    {

        try {

            return new ModuleInfo(pf).doRead(new DataInputStream(in));

        } catch (IllegalArgumentException | IllegalStateException e) {

            throw invalidModuleDescriptor(e.getMessage());

        } catch (EOFException x) {

            throw truncatedModuleDescriptor();

        }

    }

    /**

     * Reads a {@code module-info.class} from the given byte buffer.

     *

     * @throws InvalidModuleDescriptorException

     * @throws UncheckedIOException

     */

    public static Attributes read(ByteBuffer bb, Supplier<Set<String>> pf) {

        try {

            return new ModuleInfo(pf).doRead(new DataInputWrapper(bb));

        } catch (IllegalArgumentException | IllegalStateException e) {

            throw invalidModuleDescriptor(e.getMessage());

        } catch (EOFException x) {

            throw truncatedModuleDescriptor();

        } catch (IOException ioe) {

            throw new UncheckedIOException(ioe);

        }

    }

    /**

     * Reads a {@code module-info.class} from the given byte buffer

     * but ignore the {@code ModuleHashes} attribute.

     *

     * @throws InvalidModuleDescriptorException

     * @throws UncheckedIOException

     */

    public static Attributes readIgnoringHashes(ByteBuffer bb, Supplier<Set<String>> pf) {

        try {

            return new ModuleInfo(pf, false).doRead(new DataInputWrapper(bb));

        } catch (IllegalArgumentException | IllegalStateException e) {

            throw invalidModuleDescriptor(e.getMessage());

        } catch (EOFException x) {

            throw truncatedModuleDescriptor();

        } catch (IOException ioe) {

            throw new UncheckedIOException(ioe);

        }

    }

    /**

     * Reads the input as a module-info class file.

     *

     * @throws IOException

     * @throws InvalidModuleDescriptorException

     * @throws IllegalArgumentException if thrown by the ModuleDescriptor.Builder

     *         because an identifier is not a legal Java identifier, duplicate

     *         exports, and many other reasons

     */

    private Attributes doRead(DataInput in) throws IOException {

        int magic = in.readInt();

        if (magic != 0xCAFEBABE)

            throw invalidModuleDescriptor("Bad magic number");

        int minor_version = in.readUnsignedShort();

        int major_version = in.readUnsignedShort();

        if (major_version < JAVA_MIN_SUPPORTED_VERSION ||

                major_version > JAVA_MAX_SUPPORTED_VERSION) {

            throw invalidModuleDescriptor("Unsupported major.minor version "

                                          + major_version + "." + minor_version);

        }

        ConstantPool cpool = new ConstantPool(in);

        int access_flags = in.readUnsignedShort();

        if (access_flags != ACC_MODULE)

            throw invalidModuleDescriptor("access_flags should be ACC_MODULE");

        int this_class = in.readUnsignedShort();

        String mn = cpool.getClassName(this_class);

        if (!"module-info".equals(mn))

            throw invalidModuleDescriptor("this_class should be module-info");

        int super_class = in.readUnsignedShort();

        if (super_class > 0)

            throw invalidModuleDescriptor("bad #super_class");

        int interfaces_count = in.readUnsignedShort();

        if (interfaces_count > 0)

            throw invalidModuleDescriptor("Bad #interfaces");

        int fields_count = in.readUnsignedShort();

        if (fields_count > 0)

            throw invalidModuleDescriptor("Bad #fields");

        int methods_count = in.readUnsignedShort();

        if (methods_count > 0)

            throw invalidModuleDescriptor("Bad #methods");

        int attributes_count = in.readUnsignedShort();

        // the names of the attributes found in the class file

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

        Builder builder = null;

        Set<String> allPackages = null;

        String mainClass = null;

        ModuleTarget moduleTarget = null;

        ModuleHashes moduleHashes = null;

        ModuleResolution moduleResolution = null;

        for (int i = 0; i < attributes_count ; i++) {

            int name_index = in.readUnsignedShort();

            String attribute_name = cpool.getUtf8(name_index);

            int length = in.readInt();

            boolean added = attributes.add(attribute_name);

            if (!added && isAttributeAtMostOnce(attribute_name)) {

                throw invalidModuleDescriptor("More than one "

                                              + attribute_name + " attribute");

            }

            switch (attribute_name) {

                case MODULE :

                    builder = readModuleAttribute(in, cpool, major_version);

                    break;

                case MODULE_PACKAGES :

                    allPackages = readModulePackagesAttribute(in, cpool);

                    break;

                case MODULE_MAIN_CLASS :

                    mainClass = readModuleMainClassAttribute(in, cpool);

                    break;

                case MODULE_TARGET :

                    moduleTarget = readModuleTargetAttribute(in, cpool);

                    break;

                case MODULE_HASHES :

                    if (parseHashes) {

                        moduleHashes = readModuleHashesAttribute(in, cpool);

                    } else {

                        in.skipBytes(length);

                    }

                    break;

                case MODULE_RESOLUTION :

                    moduleResolution = readModuleResolution(in, cpool);

                    break;

                default:

                    if (isAttributeDisallowed(attribute_name)) {

                        throw invalidModuleDescriptor(attribute_name

                                                      + " attribute not allowed");

                    } else {

                        in.skipBytes(length);

                    }

            }

        }

        // the Module attribute is required

        if (builder == null) {

            throw invalidModuleDescriptor(MODULE + " attribute not found");

        }

        // ModuleMainClass  attribute

        if (mainClass != null) {

            builder.mainClass(mainClass);

        }

        // If the ModulePackages attribute is not present then the packageFinder

        // is used to find the set of packages

        boolean usedPackageFinder = false;

        if (allPackages == null && packageFinder != null) {

            try {

                allPackages = packageFinder.get();

            } catch (UncheckedIOException x) {

                throw x.getCause();

            }

            usedPackageFinder = true;

        }

        if (allPackages != null) {

            Set<String> knownPackages = JLMA.packages(builder);

            if (!allPackages.containsAll(knownPackages)) {

                Set<String> missingPackages = new HashSet<>(knownPackages);

                missingPackages.removeAll(allPackages);

                assert !missingPackages.isEmpty();

                String missingPackage = missingPackages.iterator().next();

                String tail;

                if (usedPackageFinder) {

                    tail = " not found in module";

                } else {

                    tail = " missing from ModulePackages class file attribute";

                }

                throw invalidModuleDescriptor("Package " + missingPackage + tail);

            }

            builder.packages(allPackages);

        }

        ModuleDescriptor descriptor = builder.build();

        return new Attributes(descriptor,

                              moduleTarget,

                              moduleHashes,

                              moduleResolution);

    }

    /**

     * Reads the Module attribute, returning the ModuleDescriptor.Builder to

     * build the corresponding ModuleDescriptor.

     */

    private Builder readModuleAttribute(DataInput in, ConstantPool cpool, int major)

        throws IOException

    {

        // module_name

        int module_name_index = in.readUnsignedShort();

        String mn = cpool.getModuleName(module_name_index);

        int module_flags = in.readUnsignedShort();

        Set<ModuleDescriptor.Modifier> modifiers = new HashSet<>();

        boolean open = ((module_flags & ACC_OPEN) != 0);

        if (open)

            modifiers.add(ModuleDescriptor.Modifier.OPEN);

        if ((module_flags & ACC_SYNTHETIC) != 0)

            modifiers.add(ModuleDescriptor.Modifier.SYNTHETIC);

        if ((module_flags & ACC_MANDATED) != 0)

            modifiers.add(ModuleDescriptor.Modifier.MANDATED);

        Builder builder = JLMA.newModuleBuilder(mn, false, modifiers);

        int module_version_index = in.readUnsignedShort();

        if (module_version_index != 0) {

            String vs = cpool.getUtf8(module_version_index);

            builder.version(vs);

        }

        int requires_count = in.readUnsignedShort();

        boolean requiresJavaBase = false;

        for (int i=0; i<requires_count; i++) {

            int requires_index = in.readUnsignedShort();

            String dn = cpool.getModuleName(requires_index);

            int requires_flags = in.readUnsignedShort();

            Set<Requires.Modifier> mods;

            if (requires_flags == 0) {

                mods = Set.of();

            } else {

                mods = new HashSet<>();

                if ((requires_flags & ACC_TRANSITIVE) != 0)

                    mods.add(Requires.Modifier.TRANSITIVE);

                if ((requires_flags & ACC_STATIC_PHASE) != 0)

                    mods.add(Requires.Modifier.STATIC);

                if ((requires_flags & ACC_SYNTHETIC) != 0)

                    mods.add(Requires.Modifier.SYNTHETIC);

                if ((requires_flags & ACC_MANDATED) != 0)

                    mods.add(Requires.Modifier.MANDATED);

            }

            int requires_version_index = in.readUnsignedShort();

            if (requires_version_index == 0) {

                builder.requires(mods, dn);

            } else {

                String vs = cpool.getUtf8(requires_version_index);

                JLMA.requires(builder, mods, dn, vs);

            }

            if (dn.equals("java.base")) {

                if (major >= 54

                    && (mods.contains(Requires.Modifier.TRANSITIVE)

                        || mods.contains(Requires.Modifier.STATIC))) {

                    String flagName;

                    if (mods.contains(Requires.Modifier.TRANSITIVE)) {

                        flagName = "ACC_TRANSITIVE";

                    } else {

                        flagName = "ACC_STATIC_PHASE";

                    }

                    throw invalidModuleDescriptor("The requires entry for java.base"

                                                  + " has " + flagName + " set");

                }

                requiresJavaBase = true;

            }

        }

        if (mn.equals("java.base")) {

            if (requires_count > 0) {

                throw invalidModuleDescriptor("The requires table for java.base"

                                              + " must be 0 length");

            }

        } else if (!requiresJavaBase) {

            throw invalidModuleDescriptor("The requires table must have"

                                          + " an entry for java.base");

        }

        int exports_count = in.readUnsignedShort();

        if (exports_count > 0) {

            for (int i=0; i<exports_count; i++) {

                int exports_index = in.readUnsignedShort();

                String pkg = cpool.getPackageName(exports_index);

                Set<Exports.Modifier> mods;

                int exports_flags = in.readUnsignedShort();

                if (exports_flags == 0) {

                    mods = Set.of();

                } else {

                    mods = new HashSet<>();

                    if ((exports_flags & ACC_SYNTHETIC) != 0)

                        mods.add(Exports.Modifier.SYNTHETIC);

                    if ((exports_flags & ACC_MANDATED) != 0)

                        mods.add(Exports.Modifier.MANDATED);

                }

                int exports_to_count = in.readUnsignedShort();

                if (exports_to_count > 0) {

                    Set<String> targets = new HashSet<>(exports_to_count);

                    for (int j=0; j<exports_to_count; j++) {

                        int exports_to_index = in.readUnsignedShort();

                        String target = cpool.getModuleName(exports_to_index);

                        if (!targets.add(target)) {

                            throw invalidModuleDescriptor(pkg + " exported to "

                                                          + target + " more than once");

                        }

                    }

                    builder.exports(mods, pkg, targets);

                } else {

                    builder.exports(mods, pkg);

                }

            }

        }

        int opens_count = in.readUnsignedShort();

        if (opens_count > 0) {

            if (open) {

                throw invalidModuleDescriptor("The opens table for an open"

                                              + " module must be 0 length");

            }

            for (int i=0; i<opens_count; i++) {

                int opens_index = in.readUnsignedShort();

                String pkg = cpool.getPackageName(opens_index);

                Set<Opens.Modifier> mods;

                int opens_flags = in.readUnsignedShort();

                if (opens_flags == 0) {

                    mods = Set.of();

                } else {

                    mods = new HashSet<>();

                    if ((opens_flags & ACC_SYNTHETIC) != 0)

                        mods.add(Opens.Modifier.SYNTHETIC);

                    if ((opens_flags & ACC_MANDATED) != 0)

                        mods.add(Opens.Modifier.MANDATED);

                }

                int open_to_count = in.readUnsignedShort();

                if (open_to_count > 0) {

                    Set<String> targets = new HashSet<>(open_to_count);

                    for (int j=0; j<open_to_count; j++) {

                        int opens_to_index = in.readUnsignedShort();

                        String target = cpool.getModuleName(opens_to_index);

                        if (!targets.add(target)) {

                            throw invalidModuleDescriptor(pkg + " opened to "

                                                          + target + " more than once");

                        }

                    }

                    builder.opens(mods, pkg, targets);

                } else {

                    builder.opens(mods, pkg);

                }

            }

        }

        int uses_count = in.readUnsignedShort();

        if (uses_count > 0) {

            for (int i=0; i<uses_count; i++) {

                int index = in.readUnsignedShort();

                String sn = cpool.getClassName(index);

                builder.uses(sn);

            }

        }

        int provides_count = in.readUnsignedShort();

        if (provides_count > 0) {

            for (int i=0; i<provides_count; i++) {

                int index = in.readUnsignedShort();

                String sn = cpool.getClassName(index);

                int with_count = in.readUnsignedShort();

                List<String> providers = new ArrayList<>(with_count);

                for (int j=0; j<with_count; j++) {

                    index = in.readUnsignedShort();

                    String pn = cpool.getClassName(index);