/*
 * Minecraft Forge
 * Copyright (c) 2016-2018.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation version 2.1
 * of the License.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

package net.minecraftforge.fml.common.patcher;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import net.minecraftforge.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper;
import net.minecraftforge.fml.repackage.com.nothome.delta.Delta;

import org.apache.logging.log4j.LogManager;

import com.google.common.hash.Hashing;
import com.google.common.io.ByteArrayDataOutput;
import com.google.common.io.ByteStreams;
import com.google.common.io.Files;
import org.apache.logging.log4j.Logger;

import javax.annotation.Nullable;

public class GenDiffSet {

    private static final List<String> RESERVED_NAMES = Arrays.asList("CON", "PRN", "AUX", "NUL", "COM1", "COM2", "COM3", "COM4", "COM5", "COM6", "COM7", "COM8", "COM9", "LPT1", "LPT2", "LPT3", "LPT4", "LPT5", "LPT6", "LPT7", "LPT8", "LPT9");

    public static void main(String[] args) throws IOException
    {
        String sourceJar = args[0]; //Clean Vanilla jar minecraft.jar or minecraft_server.jar
        String targetDir = args[1]; //Directory containing obfed output classes, typically mcp/reobf/minecraft
        String deobfData = args[2]; //Path to FML's deobfusication_data.lzma
        String outputDir = args[3]; //Path to place generated .binpatch
        String killTarget = args[4]; //"true" if we should destroy the target file if it generated a successful .binpatch

        Logger logger = LogManager.getLogger("FML.GENDIFF");
        logger.info("Creating patches at {} for {} from {}", outputDir, sourceJar, targetDir);
        Delta delta = new Delta();
        FMLDeobfuscatingRemapper remapper = FMLDeobfuscatingRemapper.INSTANCE;
        remapper.setupLoadOnly(deobfData, false);
        JarFile sourceZip = new JarFile(sourceJar);
        boolean kill = killTarget.equalsIgnoreCase("true");

        File f = new File(outputDir);
        f.mkdirs();

        for (String name : remapper.getObfedClasses())
        {
//            Logger.getLogger("GENDIFF").info(String.format("Evaluating path for data :%s",name));
            String fileName = name;
            String jarName = name;
            if (RESERVED_NAMES.contains(name.toUpperCase(Locale.ENGLISH)))
            {
                fileName = "_"+name;
            }
            File targetFile = new File(targetDir, fileName.replace('/', File.separatorChar) + ".class");
            jarName = jarName+".class";
            if (targetFile.exists())
            {
                String sourceClassName = name.replace('/', '.');
                String targetClassName = remapper.map(name).replace('/', '.');
                JarEntry entry = sourceZip.getJarEntry(jarName);
                byte[] vanillaBytes = toByteArray(sourceZip, entry);
                byte[] patchedBytes = Files.toByteArray(targetFile);

                byte[] diff = delta.compute(vanillaBytes, patchedBytes);


                ByteArrayDataOutput diffOut = ByteStreams.newDataOutput(diff.length + 50);
                // Original name
                diffOut.writeUTF(name);
                // Source name
                diffOut.writeUTF(sourceClassName);
                // Target name
                diffOut.writeUTF(targetClassName);
                // exists at original
                diffOut.writeBoolean(entry != null);
                if (entry != null)
                {
                    diffOut.writeInt(Hashing.adler32().hashBytes(vanillaBytes).asInt());
                }
                // length of patch
                diffOut.writeInt(diff.length);
                // patch
                diffOut.write(diff);

                File target = new File(outputDir, targetClassName+".binpatch");
                target.getParentFile().mkdirs();
                Files.write(diffOut.toByteArray(), target);
                logger.info("Wrote patch for {} ({}) at {}", name, targetClassName, target.getAbsolutePath());
                if (kill)
                {
                    targetFile.delete();
                    logger.info("  Deleted target: {}", targetFile);
                }
            }
        }
        sourceZip.close();
    }

    private static byte[] toByteArray(JarFile sourceZip, @Nullable JarEntry entry) throws IOException
    {
        if (entry == null)
        {
            return new byte[0];
        }

        try (InputStream sourceZipInputStream = sourceZip.getInputStream(entry))
        {
            return ByteStreams.toByteArray(sourceZipInputStream);
        }
    }
}