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 * Copyright (c) 2015, 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.tools.jlink.internal.plugins;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.UncheckedIOException;

import java.nio.charset.StandardCharsets;

import java.util.Comparator;

import java.util.List;

import java.util.Map;

import java.util.TreeSet;

import java.util.function.Predicate;

import java.util.stream.Collectors;

import jdk.tools.jlink.plugin.TransformerPlugin;

import jdk.tools.jlink.plugin.ModulePool;

import jdk.tools.jlink.plugin.ModuleEntry;

import jdk.tools.jlink.plugin.PluginException;

/**

 *

 * Exclude VM plugin

 */

public final class ExcludeVMPlugin implements TransformerPlugin {

    private static final class JvmComparator implements Comparator<Jvm> {

        @Override

        public int compare(Jvm o1, Jvm o2) {

            return o1.getEfficience() - o2.getEfficience();

        }

    }

    private enum Jvm {

        // The efficience order server - client - minimal.

        SERVER("server", 3), CLIENT("client", 2), MINIMAL("minimal", 1);

        private final String name;

        private final int efficience;

        Jvm(String name, int efficience) {

            this.name = name;

            this.efficience = efficience;

        }

        private String getName() {

            return name;

        }

        private int getEfficience() {

            return efficience;

        }

    }

    private static final String JVM_CFG = "jvm.cfg";

    public static final String NAME = "vm";

    private static final String ALL = "all";

    private static final String CLIENT = "client";

    private static final String SERVER = "server";

    private static final String MINIMAL = "minimal";

    private Predicate<String> predicate;

    private Jvm target;

    private boolean keepAll;

    @Override

    public String getName() {

        return NAME;

    }

    /**

     * VM paths:

     * /java.base/native/{architecture}/{server|client|minimal}/{shared lib}

     * e.g.: /java.base/native/amd64/server/libjvm.so

     * /java.base/native/server/libjvm.dylib

     */

    private List<ModuleEntry> getVMs(ModulePool in) {

        String jvmlib = jvmlib();

        List<ModuleEntry> ret = in.findModule("java.base").get().entries().filter((t) -> {

            return t.getPath().endsWith("/" + jvmlib);

        }).collect(Collectors.toList());

        return ret;

    }

    @Override

    public void visit(ModulePool in, ModulePool out) {

        String jvmlib = jvmlib();

        TreeSet<Jvm> existing = new TreeSet<>(new JvmComparator());

        TreeSet<Jvm> removed = new TreeSet<>(new JvmComparator());

        if (!keepAll) {

            // First retrieve all available VM names and removed VM

            List<ModuleEntry> jvms = getVMs(in);

            for (Jvm jvm : Jvm.values()) {

                for (ModuleEntry md : jvms) {

                    if (md.getPath().endsWith("/" + jvm.getName() + "/" + jvmlib)) {

                        existing.add(jvm);

                        if (isRemoved(md)) {

                            removed.add(jvm);

                        }

                    }

                }

            }

        }

        // Check that target exists

        if (!keepAll) {

            if (!existing.contains(target)) {

                throw new PluginException("Selected VM " + target.getName() + " doesn't exist.");

            }

        }

        // Rewrite the jvm.cfg file.

        in.transformAndCopy((file) -> {

            if (!keepAll) {

                if (file.getType().equals(ModuleEntry.Type.NATIVE_LIB)) {

                    if (file.getPath().endsWith(JVM_CFG)) {

                        try {

                            file = handleJvmCfgFile(file, existing, removed);

                        } catch (IOException ex) {

                            throw new UncheckedIOException(ex);

                        }

                    }

                }

                file = isRemoved(file) ? null : file;

            }

            return file;

        }, out);

    }

    private boolean isRemoved(ModuleEntry file) {

        return !predicate.test(file.getPath());

    }

    @Override

    public Category getType() {

        return Category.FILTER;

    }

    @Override

    public String getDescription() {

        return PluginsResourceBundle.getDescription(NAME);

    }

    @Override

    public boolean hasArguments() {

        return true;

    }

    @Override

    public String getArgumentsDescription() {

       return PluginsResourceBundle.getArgument(NAME);

    }

    @Override

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

        String value = config.get(NAME);

        String exclude = "";

        switch (value) {

            case ALL: {

                // no filter.

                keepAll = true;

                break;

            }

            case CLIENT: {

                target = Jvm.CLIENT;

                exclude = "/java.base/native**server/**,/java.base/native**minimal/**";

                break;

            }

            case SERVER: {

                target = Jvm.SERVER;

                exclude = "/java.base/native**client/**,/java.base/native**minimal/**";

                break;

            }

            case MINIMAL: {

                target = Jvm.MINIMAL;

                exclude = "/java.base/native**server/**,/java.base/native**client/**";

                break;

            }

            default: {

                throw new IllegalArgumentException("Unknown exclude VM option: " + value);

            }

        }

        predicate = ResourceFilter.excludeFilter(exclude);

    }

    private ModuleEntry handleJvmCfgFile(ModuleEntry orig,

            TreeSet<Jvm> existing,

            TreeSet<Jvm> removed) throws IOException {

        if (keepAll) {

            return orig;

        }

        StringBuilder builder = new StringBuilder();

        // Keep comments

        try (BufferedReader reader

                = new BufferedReader(new InputStreamReader(orig.stream(),

                        StandardCharsets.UTF_8))) {

            reader.lines().forEach((s) -> {

                if (s.startsWith("#")) {

                    builder.append(s).append("\n");

                }

            });

        }

        TreeSet<Jvm> remaining = new TreeSet<>(new JvmComparator());

        // Add entry in jvm.cfg file from the more efficient to less efficient.

        for (Jvm platform : existing) {

            if (!removed.contains(platform)) {

                remaining.add(platform);

                builder.append("-").append(platform.getName()).append(" KNOWN\n");

            }

        }

        // removed JVM are aliased to the most efficient remaining JVM (last one).

        // The order in the file is from most to less efficient platform

        for (Jvm platform : removed.descendingSet()) {

            builder.append("-").append(platform.getName()).

                    append(" ALIASED_TO -").

                    append(remaining.last().getName()).append("\n");

        }

        byte[] content = builder.toString().getBytes(StandardCharsets.UTF_8);

        return orig.create(content);

    }

    private static String jvmlib() {

        String lib = "libjvm.so";

        if (isWindows()) {

            lib = "jvm.dll";

        } else if (isMac()) {

            lib = "libjvm.dylib";

        }

        return lib;

    }

    private static boolean isWindows() {

        return System.getProperty("os.name").startsWith("Windows");

    }

    private static boolean isMac() {

        return System.getProperty("os.name").startsWith("Mac OS");

    }

}