package me.bill.fakePlayerPlugin.fakeplayer;

import me.bill.fakePlayerPlugin.util.FppLogger;
import org.bukkit.Bukkit;
import org.bukkit.World;
import org.bukkit.entity.Player;

import java.lang.reflect.Method;

public final class NmsHelper {

  private NmsHelper() {
  }

  public static ClassLoader findNmsClassLoader() {

    try {
      Class<?> craftServerClass = getCraftClass("CraftServer");
      Method getServer = craftServerClass.getMethod("getServer");
      Object mcServer = getServer.invoke(craftServerClass.cast(Bukkit.getServer()));
      Class<?> c = mcServer.getClass();
      while (c != null && c != Object.class) {
        ClassLoader cl = c.getClassLoader();
        if (cl != null && canLoadNms(cl)) return cl;
        c = c.getSuperclass();
      }
    } catch (Exception ignored) {
    }

    try {
      Class<?> craftPlayerClass = getCraftClass("entity.CraftPlayer");
      Method getHandle = craftPlayerClass.getMethod("getHandle");
      for (Player p : Bukkit.getOnlinePlayers()) {
        try {
          Object nmsPlayer = getHandle.invoke(craftPlayerClass.cast(p));
          Class<?> c = nmsPlayer.getClass();
          while (c != null && c != Object.class) {
            ClassLoader cl = c.getClassLoader();
            if (cl != null && canLoadNms(cl)) return cl;
            c = c.getSuperclass();
          }
        } catch (Exception ignored) {
        }
      }
    } catch (Exception ignored) {
    }

    ClassLoader cl = Thread.currentThread().getContextClassLoader();
    while (cl != null) {
      if (canLoadNms(cl)) return cl;
      cl = cl.getParent();
    }

    return null;
  }

  private static boolean canLoadNms(ClassLoader cl) {
    for (String probe :
        new String[]{
            "net.minecraft.server.players.PlayerList",
            "net.minecraft.server.MinecraftServer",
            "net.minecraft.network.protocol.game.ClientboundPlayerInfoUpdatePacket"
        }) {
      try {
        cl.loadClass(probe);
        return true;
      } catch (ClassNotFoundException ignored) {
      }
    }
    return false;
  }

  public static Object getServerLevel(World world) {
    try {
      Class<?> craftWorldClass = getCraftClass("CraftWorld");
      Method getHandle = craftWorldClass.getMethod("getHandle");
      return getHandle.invoke(craftWorldClass.cast(world));
    } catch (Exception e) {
      FppLogger.warn("NmsHelper.getServerLevel failed: " + e.getMessage());
      return null;
    }
  }

  static Class<?> getCraftClass(String suffix) throws ClassNotFoundException {
    try {
      return Class.forName("org.bukkit.craftbukkit." + suffix);
    } catch (ClassNotFoundException ignored) {
    }
    String[] parts = Bukkit.getServer().getClass().getPackage().getName().split("\\.");
    if (parts.length >= 4)
      return Class.forName("org.bukkit.craftbukkit." + parts[3] + "." + suffix);
    throw new ClassNotFoundException("Cannot resolve CraftBukkit class: " + suffix);
  }
}