// nip44.ts
import { chacha20 } from "@noble/ciphers/chacha";
import { ensureBytes, equalBytes } from "@noble/ciphers/utils";
import { secp256k1 } from "@noble/curves/secp256k1";
import { hkdf } from "@noble/hashes/hkdf";
import { hmac } from "@noble/hashes/hmac";
import { sha256 } from "@noble/hashes/sha256";
import { concatBytes, randomBytes } from "@noble/hashes/utils";
import { base64 } from "@scure/base";

// utils.ts
var utf8Decoder = new TextDecoder("utf-8");
var utf8Encoder = new TextEncoder();

// nip44.ts
var utils = {
  v2: {
    maxPlaintextSize: 65536 - 128,
    minCiphertextSize: 100,
    maxCiphertextSize: 102400,
    getConversationKey(privkeyA, pubkeyB) {
      const key = secp256k1.getSharedSecret(privkeyA, "02" + pubkeyB);
      return key.subarray(1, 33);
    },
    getMessageKeys(conversationKey, salt) {
      const keys = hkdf(sha256, conversationKey, salt, "nip44-v2", 76);
      return {
        encryption: keys.subarray(0, 32),
        nonce: keys.subarray(32, 44),
        auth: keys.subarray(44, 76)
      };
    },
    calcPadding(len) {
      if (!Number.isSafeInteger(len) || len < 0)
        throw new Error("expected positive integer");
      if (len <= 32)
        return 32;
      const nextpower = 1 << Math.floor(Math.log2(len - 1)) + 1;
      const chunk = nextpower <= 256 ? 32 : nextpower / 8;
      return chunk * (Math.floor((len - 1) / chunk) + 1);
    },
    pad(unpadded) {
      const unpaddedB = utf8Encoder.encode(unpadded);
      const len = unpaddedB.length;
      if (len < 1 || len >= utils.v2.maxPlaintextSize)
        throw new Error("invalid plaintext length: must be between 1b and 64KB");
      const paddedLen = utils.v2.calcPadding(len);
      const zeros = new Uint8Array(paddedLen - len);
      const lenBuf = new Uint8Array(2);
      new DataView(lenBuf.buffer).setUint16(0, len);
      return concatBytes(lenBuf, unpaddedB, zeros);
    },
    unpad(padded) {
      const unpaddedLen = new DataView(padded.buffer).getUint16(0);
      const unpadded = padded.subarray(2, 2 + unpaddedLen);
      if (unpaddedLen === 0 || unpadded.length !== unpaddedLen || padded.length !== 2 + utils.v2.calcPadding(unpaddedLen))
        throw new Error("invalid padding");
      return utf8Decoder.decode(unpadded);
    }
  }
};
function encrypt(key, plaintext, options = {}) {
  const version = options.version ?? 2;
  if (version !== 2)
    throw new Error("unknown encryption version " + version);
  const salt = options.salt ?? randomBytes(32);
  ensureBytes(salt, 32);
  const keys = utils.v2.getMessageKeys(key, salt);
  const padded = utils.v2.pad(plaintext);
  const ciphertext = chacha20(keys.encryption, keys.nonce, padded);
  const mac = hmac(sha256, keys.auth, ciphertext);
  return base64.encode(concatBytes(new Uint8Array([version]), salt, ciphertext, mac));
}
function decrypt(key, ciphertext) {
  const u = utils.v2;
  ensureBytes(key, 32);
  const clen = ciphertext.length;
  if (clen < u.minCiphertextSize || clen >= u.maxCiphertextSize)
    throw new Error("invalid ciphertext length: " + clen);
  if (ciphertext[0] === "#")
    throw new Error("unknown encryption version");
  let data;
  try {
    data = base64.decode(ciphertext);
  } catch (error) {
    throw new Error("invalid base64: " + error.message);
  }
  const vers = data.subarray(0, 1)[0];
  if (vers !== 2)
    throw new Error("unknown encryption version " + vers);
  const salt = data.subarray(1, 33);
  const ciphertext_ = data.subarray(33, -32);
  const mac = data.subarray(-32);
  const keys = u.getMessageKeys(key, salt);
  const calculatedMac = hmac(sha256, keys.auth, ciphertext_);
  if (!equalBytes(calculatedMac, mac))
    throw new Error("invalid MAC");
  const padded = chacha20(keys.encryption, keys.nonce, ciphertext_);
  return u.unpad(padded);
}
export {
  decrypt,
  encrypt,
  utils
};