// nip44.ts
import { chacha20 } from "@noble/ciphers/chacha";
import { equalBytes } from "@noble/ciphers/utils";
import { secp256k1 } from "@noble/curves/secp256k1";
import { extract as hkdf_extract, expand as hkdf_expand } 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
import { bytesToHex, hexToBytes } from "@noble/hashes/utils";
var utf8Decoder = new TextDecoder("utf-8");
var utf8Encoder = new TextEncoder();

// nip44.ts
var minPlaintextSize = 1;
var maxPlaintextSize = 65535;
function getConversationKey(privkeyA, pubkeyB) {
  const sharedX = secp256k1.getSharedSecret(privkeyA, "02" + pubkeyB).subarray(1, 33);
  return hkdf_extract(sha256, sharedX, "nip44-v2");
}
function getMessageKeys(conversationKey, nonce) {
  const keys = hkdf_expand(sha256, conversationKey, nonce, 76);
  return {
    chacha_key: keys.subarray(0, 32),
    chacha_nonce: keys.subarray(32, 44),
    hmac_key: keys.subarray(44, 76)
  };
}
function calcPaddedLen(len) {
  if (!Number.isSafeInteger(len) || len < 1)
    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);
}
function writeU16BE(num) {
  if (!Number.isSafeInteger(num) || num < minPlaintextSize || num > maxPlaintextSize)
    throw new Error("invalid plaintext size: must be between 1 and 65535 bytes");
  const arr = new Uint8Array(2);
  new DataView(arr.buffer).setUint16(0, num, false);
  return arr;
}
function pad(plaintext) {
  const unpadded = utf8Encoder.encode(plaintext);
  const unpaddedLen = unpadded.length;
  const prefix = writeU16BE(unpaddedLen);
  const suffix = new Uint8Array(calcPaddedLen(unpaddedLen) - unpaddedLen);
  return concatBytes(prefix, unpadded, suffix);
}
function unpad(padded) {
  const unpaddedLen = new DataView(padded.buffer).getUint16(0);
  const unpadded = padded.subarray(2, 2 + unpaddedLen);
  if (unpaddedLen < minPlaintextSize || unpaddedLen > maxPlaintextSize || unpadded.length !== unpaddedLen || padded.length !== 2 + calcPaddedLen(unpaddedLen))
    throw new Error("invalid padding");
  return utf8Decoder.decode(unpadded);
}
function hmacAad(key, message, aad) {
  if (aad.length !== 32)
    throw new Error("AAD associated data must be 32 bytes");
  const combined = concatBytes(aad, message);
  return hmac(sha256, key, combined);
}
function decodePayload(payload) {
  if (typeof payload !== "string")
    throw new Error("payload must be a valid string");
  const plen = payload.length;
  if (plen < 132 || plen > 87472)
    throw new Error("invalid payload length: " + plen);
  if (payload[0] === "#")
    throw new Error("unknown encryption version");
  let data;
  try {
    data = base64.decode(payload);
  } catch (error) {
    throw new Error("invalid base64: " + error.message);
  }
  const dlen = data.length;
  if (dlen < 99 || dlen > 65603)
    throw new Error("invalid data length: " + dlen);
  const vers = data[0];
  if (vers !== 2)
    throw new Error("unknown encryption version " + vers);
  return {
    nonce: data.subarray(1, 33),
    ciphertext: data.subarray(33, -32),
    mac: data.subarray(-32)
  };
}
function encrypt(plaintext, conversationKey, nonce = randomBytes(32)) {
  const { chacha_key, chacha_nonce, hmac_key } = getMessageKeys(conversationKey, nonce);
  const padded = pad(plaintext);
  const ciphertext = chacha20(chacha_key, chacha_nonce, padded);
  const mac = hmacAad(hmac_key, ciphertext, nonce);
  return base64.encode(concatBytes(new Uint8Array([2]), nonce, ciphertext, mac));
}
function decrypt(payload, conversationKey) {
  const { nonce, ciphertext, mac } = decodePayload(payload);
  const { chacha_key, chacha_nonce, hmac_key } = getMessageKeys(conversationKey, nonce);
  const calculatedMac = hmacAad(hmac_key, ciphertext, nonce);
  if (!equalBytes(calculatedMac, mac))
    throw new Error("invalid MAC");
  const padded = chacha20(chacha_key, chacha_nonce, ciphertext);
  return unpad(padded);
}
var v2 = {
  utils: {
    getConversationKey,
    calcPaddedLen
  },
  encrypt,
  decrypt
};
export {
  decrypt,
  encrypt,
  getConversationKey,
  v2
};