/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012-2015 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 2 of the License.

 *

 * This program 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 for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.aot;

import java.io.IOException;

import java.io.InputStream;

import java.util.Arrays;

import java.util.HashMap;

import java.util.Map;

import net.orfjackal.retrolambda.LambdaClassBackporter;

import net.orfjackal.retrolambda.LambdaClassDumper;

import net.orfjackal.retrolambda.LambdaClassSaver;

import net.orfjackal.retrolambda.LambdaReifier;

import net.orfjackal.retrolambda.LambdaUsageBackporter;

import net.orfjackal.retrolambda.asm.Opcodes;

import org.apidesign.bck2brwsr.core.ExtraJavaScript;

import org.apidesign.vm4brwsr.Bck2Brwsr;

/**

 *

 * @author Jaroslav Tulach

 */

@ExtraJavaScript(processByteCode = false, resource="")

final class RetroLambda extends LambdaClassSaver implements BytecodeProcessor {

    private Map<String,byte[]> converted;

    public RetroLambda() {

        super(null, Opcodes.V1_7);

    }

    @Override

    public void saveIfLambda(String className, byte[] bytecode) {

        if (LambdaReifier.isLambdaClassToReify(className)) {

            try {

                byte[] backportedBytecode = LambdaClassBackporter.transform(bytecode, Opcodes.V1_7);

                putBytecode(className + ".class", backportedBytecode);

            } catch (Throwable t) {

                // print to stdout to keep in sync with other log output

                throw new IllegalStateException("ERROR: Failed to backport lambda class: " + className);

            }

        }

    }

    private void putBytecode(String className, byte[] backportedBytecode) {

        assert className.endsWith(".class") : "Full resource: " + className;

        if (converted == null) {

            converted = new HashMap<>();

        }

        converted.put(className, backportedBytecode);

    }

    @Override

    public Map<String, byte[]> process(

        String className, byte[] byteCode, Bck2Brwsr.Resources resources

    ) throws IOException {

        int minor = byteCode[4] << 8 | byteCode[5];

        int major = byteCode[6] << 8 | byteCode[7];

        if (major <= 51) {

            return null;

        }

        ClassLoader prev = Thread.currentThread().getContextClassLoader();

        try (LambdaClassDumper dumper = new LambdaClassDumper(this)) {

            Thread.currentThread().setContextClassLoader(new ResLdr(resources));

            dumper.install();

            byte[] newB = LambdaUsageBackporter.transform(byteCode, Opcodes.V1_7);

            if (!Arrays.equals(newB, byteCode)) {

                putBytecode(className, newB);

            }

        } catch (Throwable t) {

            t.printStackTrace();

        } finally {

            Thread.currentThread().setContextClassLoader(prev);

        }

        Map<String, byte[]> ret = converted;

        converted = null;

        return ret;

    }

    private static final class ResLdr extends ClassLoader {

        private final Bck2Brwsr.Resources res;

        public ResLdr(Bck2Brwsr.Resources res) {

            this.res = res;

        }

        @Override

        public Class<?> loadClass(String name) throws ClassNotFoundException {

            Class<?> c = findLoadedClass(name);

            if (c != null) {

                return c;

            }

            if (name.startsWith("java.")) {

                return super.loadClass(name);

            }

            String r = name.replace('.', '/') + ".class";

            try (InputStream is = res.get(r)) {

                if (is == null) {

                    throw new ClassNotFoundException(name);

                }

                byte[] arr = Bck2BrwsrJars.readFrom(is);

                return defineClass(name, arr, 0, arr.length);

            } catch (IOException e) {

                return super.loadClass(name);

            }

        }

    }    

}