package com.spineview.deobf;

import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.zip.ZipOutputStream;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.commons.ClassRemapper;
import org.objectweb.asm.commons.Remapper;

/**
 * 按"名字映射表"重命名载荷里的**成员**（字段/方法），产出一份新的载荷 zip，
 * 专门用来反编译 —— 这样反编译出来的代码里，声明和直接调用都带可识别的名字。
 *
 * ⚠️ 只改成员名，**不改类名**：载荷的 invokedynamic 是在运行时用加密串解出
 * "类名 + 方法名 + 描述符"再反射查找的，类名必须保持不变（成员名改了以后这份 zip
 * 只用于反编译，不能拿去运行）。
 *
 * 映射表（TSV，4 列，`#` 开头是注释）：
 *   owner<TAB>name<TAB>desc<TAB>newName
 *   - owner：内部类名，如 `et`、`com/badlogic/gdx/scenes/scene2d/ui/Tree`
 *   - name ：混淆成员名（字段或方法）
 *   - desc ：描述符；字段如 `F`（float）、`Ljava/lang/String;`；
 *            方法如 `(Ldl;)LdR;`。**写 `*` 表示"该 owner 下所有同名成员"**（仅在
 *            确定这一层不会撞车时用）
 *   - newName：要换成的新名字
 *
 * 用法：
 *   java -cp "asm.jar:asm-tree.jar:asm-commons.jar:build" com.spineview.deobf.Renamer <in.zip> <map.tsv> <out.zip>
 */
public final class Renamer {

  public static void main(String[] args) throws Exception {
    Path in = Paths.get(args[0]);
    Path map = Paths.get(args[1]);
    Path out = Paths.get(args[2]);

    Map<String, String> exact = new HashMap<String, String>();
    Map<String, String> wildcard = new HashMap<String, String>();
    int loaded = 0;
    for (String line : Files.readAllLines(map, StandardCharsets.UTF_8)) {
      if (line.isEmpty() || line.startsWith("#")) continue;
      String[] parts = line.split("\t");
      if (parts.length < 4 || parts[0].isEmpty() || parts[1].isEmpty()) continue;
      String owner = parts[0];
      String name = parts[1];
      String desc = parts[2];
      String renamed = parts[3];
      if (renamed.isEmpty()) continue;
      if (desc.equals("*")) {
        wildcard.put(owner + "#" + name, renamed);
      } else {
        exact.put(owner + "#" + name + "#" + desc, renamed);
      }
      loaded++;
    }
    System.err.println("映射条目 " + loaded + "（具体 " + exact.size() + "，通配 " + wildcard.size() + "）");

    int classes = 0;
    int renamedMembers = 0;
    try (ZipFile zip = new ZipFile(in.toFile());
        ZipOutputStream zipOut = new ZipOutputStream(Files.newOutputStream(out))) {
      Enumeration<? extends ZipEntry> entries = zip.entries();
      while (entries.hasMoreElements()) {
        ZipEntry entry = entries.nextElement();
        byte[] raw = readAll(zip.getInputStream(entry));
        if (!entry.getName().endsWith(".class")) {
          zipOut.putNextEntry(new ZipEntry(entry.getName()));
          zipOut.write(raw);
          zipOut.closeEntry();
          continue;
        }
        try {
          ClassReader reader = new ClassReader(raw);
          ClassWriter writer = new ClassWriter(0);
          final Map<String, String> exactMap = exact;
          final Map<String, String> wildcardMap = wildcard;
          final int[] counter = new int[1];
          Remapper remapper = new Remapper() {
            @Override
            public String mapFieldName(String owner, String name, String descriptor) {
              String renamed = lookup(owner, name, descriptor, exactMap, wildcardMap);
              if (renamed == null) return name;
              counter[0]++;
              return renamed;
            }

            @Override
            public String mapMethodName(String owner, String name, String descriptor) {
              String renamed = lookup(owner, name, descriptor, exactMap, wildcardMap);
              if (renamed == null) return name;
              counter[0]++;
              return renamed;
            }
          };
          reader.accept(new ClassRemapper(writer, remapper), 0);
          byte[] rewritten = writer.toByteArray();
          zipOut.putNextEntry(new ZipEntry(entry.getName()));
          zipOut.write(rewritten);
          zipOut.closeEntry();
          classes++;
          renamedMembers += counter[0];
        } catch (Throwable error) {
          zipOut.putNextEntry(new ZipEntry(entry.getName()));
          zipOut.write(raw);
          zipOut.closeEntry();
        }
      }
    }
    System.err.println("处理 " + classes + " 个类，改名成员引用 " + renamedMembers + " 处 -> " + out);
  }

  private static String lookup(String owner, String name, String descriptor,
      Map<String, String> exact, Map<String, String> wildcard) {
    String found = exact.get(owner + "#" + name + "#" + descriptor);
    if (found != null) return found;
    return wildcard.get(owner + "#" + name);
  }

  private static byte[] readAll(InputStream in) throws java.io.IOException {
    ByteArrayOutputStream buffer = new ByteArrayOutputStream();
    byte[] chunk = new byte[65536];
    int n;
    while ((n = in.read(chunk)) > 0) buffer.write(chunk, 0, n);
    return buffer.toByteArray();
  }

  /** 生成"没被用到"的映射条目清单，方便发现写错的 owner/desc。 */
  static List<String> unused(Map<String, Integer> hits) {
    List<String> out = new java.util.ArrayList<String>();
    for (Map.Entry<String, Integer> entry : hits.entrySet()) {
      if (entry.getValue() == 0) out.add(entry.getKey());
    }
    return out;
  }

  static void writeReport(Path path, Map<String, Integer> hits) throws Exception {
    try (BufferedWriter writer = Files.newBufferedWriter(path, StandardCharsets.UTF_8)) {
      for (Map.Entry<String, Integer> entry : hits.entrySet()) {
        writer.write(entry.getValue() + "\t" + entry.getKey());
        writer.write('\n');
      }
    }
  }
}