import {
  createECDHEECDSAKeyExchange,
  createECDHEPSKKeyExchange,
  createECDHERSAKeyExchange,
  createPSKKeyExchange,
  createRSAKeyExchange,
  KeyExchange,
} from "./key-exchange";
import AEADCipher from "./suites/aead";

const cipherSuites = {
  TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: 0xc02b,
  TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384: 0xc02c,
  TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256: 0xc02f,
  TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384: 0xc030,
  TLS_RSA_WITH_AES_128_GCM_SHA256: 0x009c,
  TLS_RSA_WITH_AES_256_GCM_SHA384: 0x009d,
  TLS_PSK_WITH_AES_128_GCM_SHA256: 0x00a8,
  TLS_PSK_WITH_AES_256_GCM_SHA384: 0x00a9,
  TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256: 0xd001,
  TLS_ECDHE_PSK_WITH_AES_256_GCM_SHA384: 0xd002,
  TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256: 0xccac,
  TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256: 0xcca9,
  TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256: 0xcca8,
  TLS_PSK_WITH_CHACHA20_POLY1305_SHA256: 0xccab,
};

const AEAD_AES_128_GCM = {
  K_LEN: 16, // Length of a key.
  N_MIN: 12, // Min nonce length.
  N_MAX: 12, // Max nonce length.
  P_MAX: 2 ** 36 - 31, // Max length of a plaintext.

  // Max safe int in js is 2 ** 53. So, use this value
  // instead of 2 ** 61 as described in rfc5116.
  A_MAX: 2 ** 53 - 1, // Max length of an additional data.
  C_MAX: 2 ** 36 - 15, // Cipher text length.
};

const AEAD_AES_256_GCM = {
  K_LEN: 32, // Length of a key.
  N_MIN: 12, // Min nonce length.
  N_MAX: 12, // Max nonce length.
  P_MAX: 2 ** 36 - 31, // Max length of a plaintext.

  // Note: see above.
  A_MAX: 2 ** 53 - 1, // Max length of an additional data.
  C_MAX: 2 ** 36 - 15, // Cipher text length.
};

const RSA_KEY_EXCHANGE = createRSAKeyExchange();
const ECDHE_RSA_KEY_EXCHANGE = createECDHERSAKeyExchange();
const ECDHE_ECDSA_KEY_EXCHANGE = createECDHEECDSAKeyExchange();
const PSK_KEY_EXCHANGE = createPSKKeyExchange();
const ECDHE_PSK_KEY_EXCHANGE = createECDHEPSKKeyExchange();

/**
 * Convert cipher value to cipher instance.
 * @param {number} cipher
 */
export function createCipher(cipher: number) {
  switch (cipher) {
    case cipherSuites.TLS_RSA_WITH_AES_128_GCM_SHA256:
      return createAEADCipher(
        cipherSuites.TLS_RSA_WITH_AES_128_GCM_SHA256,
        "TLS_RSA_WITH_AES_128_GCM_SHA256",
        "aes-128-gcm",
        RSA_KEY_EXCHANGE,
        AEAD_AES_128_GCM
      );
    case cipherSuites.TLS_RSA_WITH_AES_256_GCM_SHA384:
      return createAEADCipher(
        cipherSuites.TLS_RSA_WITH_AES_256_GCM_SHA384,
        "TLS_RSA_WITH_AES_256_GCM_SHA384",
        "aes-256-gcm",
        RSA_KEY_EXCHANGE,
        AEAD_AES_256_GCM,
        "sha384"
      );
    case cipherSuites.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
        "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
        "aes-128-gcm",
        ECDHE_RSA_KEY_EXCHANGE,
        AEAD_AES_128_GCM
      );
    case cipherSuites.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
        "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
        "aes-256-gcm",
        ECDHE_RSA_KEY_EXCHANGE,
        AEAD_AES_256_GCM,
        "sha384"
      );
    case cipherSuites.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
        "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
        "aes-128-gcm",
        ECDHE_ECDSA_KEY_EXCHANGE,
        AEAD_AES_128_GCM
      );
    case cipherSuites.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
        "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
        "aes-256-gcm",
        ECDHE_ECDSA_KEY_EXCHANGE,
        AEAD_AES_256_GCM,
        "sha384"
      );
    case cipherSuites.TLS_PSK_WITH_AES_128_GCM_SHA256:
      return createAEADCipher(
        cipherSuites.TLS_PSK_WITH_AES_128_GCM_SHA256,
        "TLS_PSK_WITH_AES_128_GCM_SHA256",
        "aes-128-gcm",
        PSK_KEY_EXCHANGE,
        AEAD_AES_128_GCM,
        "sha256"
      );
    case cipherSuites.TLS_PSK_WITH_AES_256_GCM_SHA384:
      return createAEADCipher(
        cipherSuites.TLS_PSK_WITH_AES_256_GCM_SHA384,
        "TLS_PSK_WITH_AES_256_GCM_SHA384",
        "aes-256-gcm",
        PSK_KEY_EXCHANGE,
        AEAD_AES_256_GCM,
        "sha384"
      );
    case cipherSuites.TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256,
        "TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256",
        "aes-128-gcm",
        ECDHE_PSK_KEY_EXCHANGE,
        AEAD_AES_128_GCM,
        "sha256"
      );
    case cipherSuites.TLS_ECDHE_PSK_WITH_AES_256_GCM_SHA384:
      return createAEADCipher(
        cipherSuites.TLS_ECDHE_PSK_WITH_AES_256_GCM_SHA384,
        "TLS_ECDHE_PSK_WITH_AES_256_GCM_SHA384",
        "aes-256-gcm",
        ECDHE_PSK_KEY_EXCHANGE,
        AEAD_AES_256_GCM,
        "sha384"
      );
    default:
      break;
  }

  return (null as any) as AEADCipher;
}

/**
 * @param {number} id An internal id of cipher suite.
 * @param {string} name A valid cipher suite name.
 * @param {string} block A valid nodejs cipher name.
 * @param {KeyExchange} kx Key exchange type.
 * @param {Object} constants Cipher specific constants.
 * @param {string} hash
 * @returns {AEADCipher}
 */
function createAEADCipher(
  id: number,
  name: string,
  block: string,
  kx: KeyExchange,
  constants: { K_LEN: number; N_MAX: number },
  hash = "sha256"
) {
  const cipher = new AEADCipher();

  cipher.id = id;
  cipher.name = name;
  cipher.blockAlgorithm = block;
  cipher.kx = kx;
  cipher.hash = hash;

  cipher.keyLength = constants.K_LEN;
  cipher.nonceLength = constants.N_MAX;

  // RFC5288, sec. 3
  cipher.nonceImplicitLength = 4;
  cipher.nonceExplicitLength = 8;

  cipher.ivLength = cipher.nonceImplicitLength;

  cipher.authTagLength = 16;

  return cipher;
}