/*

 * Copyright (c) 2016, 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.lang.reflect.Method;

import java.util.Arrays;

import java.util.Collections;

import java.util.EnumSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.stream.Collectors;

import jdk.tools.jlink.plugin.PluginException;

import jdk.tools.jlink.plugin.Pool;

import jdk.tools.jlink.plugin.TransformerPlugin;

/**

 * Plugin to generate java.lang.invoke classes.

 */

public final class GenerateJLIClassesPlugin implements TransformerPlugin {

    private static final String NAME = "generate-jli-classes";

    private static final String BMH_PARAM = "bmh";

    private static final String BMH_SPECIES_PARAM = "bmh-species";

    private static final String DESCRIPTION = PluginsResourceBundle.getDescription(NAME);

    private static final String BMH = "java/lang/invoke/BoundMethodHandle";

    private static final Method FACTORY_METHOD;

    List<String> speciesTypes;

    public GenerateJLIClassesPlugin() {

    }

    @Override

    public Set<PluginType> getType() {

        return Collections.singleton(CATEGORY.TRANSFORMER);

    }

    @Override

    public String getName() {

        return NAME;

    }

    @Override

    public String getDescription() {

        return DESCRIPTION;

    }

    @Override

    public Set<STATE> getState() {

        return EnumSet.of(STATE.AUTO_ENABLED, STATE.FUNCTIONAL);

    }

    @Override

    public boolean hasArguments() {

        return true;

    }

    @Override

    public String getArgumentsDescription() {

       return PluginsResourceBundle.getArgument(NAME);

    }

    /**

     * @return the default Species forms to generate.

     *

     * This list was derived from running a Java concatenating strings

     * with -Djava.lang.invoke.stringConcat=MH_INLINE_SIZED_EXACT set

     * plus a subset of octane. A better long-term solution is to define

     * and run a set of quick generators and extracting this list as a

     * step in the build process.

     */

    public static List<String> defaultSpecies() {

        return List.of("LL", "L3", "L4", "L5", "L6", "L7", "L7I",

                "L7II", "L7IIL", "L8", "L9", "L10", "L11", "L11I", "L11II",

                "L12", "L13", "LI", "D", "L3I", "LIL", "LLI", "LLIL",

                "LILL", "I", "LLILL");

    }

    @Override

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

        String mainArgument = config.get(NAME);

        // Enable by default

        boolean bmhEnabled = true;

        if (mainArgument != null) {

            Set<String> args = Arrays.stream(mainArgument.split(","))

                    .collect(Collectors.toSet());

            if (!args.contains(BMH_PARAM)) {

                bmhEnabled = false;

            }

        }

        if (!bmhEnabled) {

            speciesTypes = List.of();

        } else {

            String args = config.get(BMH_SPECIES_PARAM);

            List<String> bmhSpecies;

            if (args != null && !args.isEmpty()) {

                bmhSpecies = Arrays.stream(args.split(","))

                    .map(String::trim)

                    .filter(s -> !s.isEmpty())

                    .collect(Collectors.toList());

            } else {

                bmhSpecies = defaultSpecies();

            }

            // Expand BMH species signatures

            speciesTypes = bmhSpecies.stream()

                    .map(type -> expandSignature(type))

                    .collect(Collectors.toList());

            // Validation check

            for (String type : speciesTypes) {

                for (char c : type.toCharArray()) {

                    if ("LIJFD".indexOf(c) < 0) {

                        throw new PluginException("All characters must "

                                + "correspond to a basic field type: LIJFD");

                    }

                }

            }

        }

    }

    @Override

    public void visit(Pool in, Pool out) {

        for (Pool.ModuleData data : in.getContent()) {

            if (("/java.base/" + BMH + ".class").equals(data.getPath())) {

                // Add BoundMethodHandle unchanged

                out.add(data);

                speciesTypes.forEach(types -> generateConcreteClass(types, data, out));

            } else {

            }

        }

    }

    @SuppressWarnings("unchecked")

    private void generateConcreteClass(String types, Pool.ModuleData data, Pool out) {

        try {

            // Generate class

            Map.Entry<String, byte[]> result = (Map.Entry<String, byte[]>)

                    FACTORY_METHOD.invoke(null, types);

            String className = result.getKey();

            byte[] bytes = result.getValue();

            // Add class to pool

            Pool.ModuleData ndata = new Pool.ModuleData(data.getModule(),

                    "/java.base/" + className + ".class",

                    Pool.ModuleDataType.CLASS_OR_RESOURCE,

                    new ByteArrayInputStream(bytes), bytes.length);

        } catch (Exception ex) {

            throw new PluginException(ex);

        }

    }

    static {

        try {

            Class<?> BMHFactory = Class.forName("java.lang.invoke.BoundMethodHandle$Factory");

            Method genClassMethod = BMHFactory.getDeclaredMethod("generateConcreteBMHClassBytes",

                    String.class);

            genClassMethod.setAccessible(true);

            FACTORY_METHOD = genClassMethod;

        } catch (Exception e) {

            throw new PluginException(e);

        }

    }

    // Convert LL -> LL, L3 -> LLL

    private static String expandSignature(String signature) {

        StringBuilder sb = new StringBuilder();

        char last = 'X';

        int count = 0;

        for (int i = 0; i < signature.length(); i++) {

            char c = signature.charAt(i);

            if (c >= '0' && c <= '9') {

                count *= 10;

                count += (c - '0');

            } else {

                for (int j = 1; j < count; j++) {

                    sb.append(last);

                }

                sb.append(c);

                last = c;

                count = 0;

            }

        }

        for (int j = 1; j < count; j++) {

            sb.append(last);

        }

        return sb.toString();

    }

}