/// HD address derivation using bitcore-lib family.
/// Derives child addresses at m/0/{index} (external receive chain).

// @ts-ignore
import bitcore from "bitcore-lib";
import bs58check from "bs58check";
// @ts-ignore
import bitcoreCash from "bitcore-lib-cash";
// @ts-ignore
import bitcoreLtc from "bitcore-lib-ltc";
// @ts-ignore
import bitcoreDoge from "bitcore-lib-doge";
// @ts-ignore
import dashcore from "@dashevo/dashcore-lib";

function getXpub(coin: string): string {
  const key = `XPUB_${coin.toUpperCase()}`;
  const val = process.env[key];
  if (!val) throw new Error(`Missing env var: ${key}`);
  return val;
}

export function derive(coin: string, index: number): string {
  const xpub = getXpub(coin === "xec" ? "xec" : coin);

  if (coin === "btc") {
    const hd = new bitcore.HDPublicKey(xpub);
    return hd.deriveChild(0).deriveChild(index).publicKey.toAddress().toString();
  }
  if (coin === "bch") {
    const hd = new bitcoreCash.HDPublicKey(xpub);
    return hd.deriveChild(0).deriveChild(index).publicKey.toAddress().toCashAddress();
  }
  if (coin === "xec") {
    const hd = new bitcoreCash.HDPublicKey(xpub);
    const addr = hd.deriveChild(0).deriveChild(index).publicKey.toAddress().toCashAddress();
    return addr.replace(/^bitcoincash:/, "ecash:");
  }
  if (coin === "ltc") {
    // Remap zpub/Ltub/Mtub to standard xpub version bytes for bitcore-lib-ltc
    const decoded = Buffer.from(bs58check.decode(xpub));
    decoded[0] = 0x04; decoded[1] = 0x88; decoded[2] = 0xb2; decoded[3] = 0x1e;
    const normalized = bs58check.encode(decoded);
    const hd = new bitcoreLtc.HDPublicKey(normalized);
    const pubkey = hd.deriveChild(0).deriveChild(index).publicKey;
    return new bitcoreLtc.Address(pubkey, bitcoreLtc.Networks.mainnet, bitcoreLtc.Address.PayToWitnessPublicKeyHash).toString();
  }
  if (coin === "doge") {
    const hd = new bitcoreDoge.HDPublicKey(xpub);
    return hd.deriveChild(0).deriveChild(index).publicKey.toAddress().toString();
  }
  if (coin === "dash") {
    const hd = new dashcore.HDPublicKey(xpub);
    return hd.deriveChild(0).deriveChild(index).publicKey.toAddress().toString();
  }

  throw new Error(`Unsupported coin: ${coin}`);
}