import { MEMBER_MASK, NB_ROUNDS, TWEAK_LENGTH, PT, LFSR_8_TK2, LFSR_8_TK3, S8, C } from './constants'

/**
 * Create a tweakey based on the specified domain separation, nonce, key and current counter state.
 * @param counter The counter.
 * @param domainSeparation The domain separation.
 * @param nonce The nonce.
 * @param key The encryption key.
 * @returns The tweakey.
 */
export function tweakeyEncode (counter: number[], domainSeparation: number, nonce: number[], key: number[]): number[] {
  return counter.concat([domainSeparation ^ MEMBER_MASK], Array(8).fill(0), nonce, key)
}

/**
 * Perform a round of SKINNY-188/384+ encryption.
 * @param plaintext The plaintext to encrypt.
 * @param tweakey The tweakey to use for encryption.
 * @returns The ciphertext.
 */
export function skinnyEncrypt (plaintext: number[], tweakey: number[]): number[] {
  const tk = Array(NB_ROUNDS + 1).fill(Array(TWEAK_LENGTH).fill(0))

  tk[0] = [...Array(TWEAK_LENGTH).keys()].map(i => tweakey[i])

  for (let i = 0; i < NB_ROUNDS - 1; i++) {
    tk[i + 1] = [...tk[i]]

    for (let j = 0; j < TWEAK_LENGTH; j++) {
      tk[i + 1][j] = tk[i][j - j % 16 + PT[j % 16]]
    }

    for (let j = 0; j < 8; j++) {
      tk[i + 1][j + 16] = LFSR_8_TK2[tk[i + 1][j + 16]]
      tk[i + 1][j + 32] = LFSR_8_TK3[tk[i + 1][j + 32]]
    }
  }

  let s = [...Array(16).keys()].map(i => plaintext[i])
  for (let i = 0; i < NB_ROUNDS; i++) {
    for (let j = 0; j < 16; j++) {
      s[j] = S8[s[j]]
    }

    s[0] ^= (C[i] & 0xf)
    s[4] ^= (C[i] >> 4) & 0xf
    s[8] ^= 0x2

    for (let j = 0; j < 8; j++) {
      s[j] ^= tk[i][j] ^ tk[i][j + 16] ^ tk[i][j + 32]
    }

    s = [s[0], s[1], s[2], s[3], s[7], s[4], s[5], s[6], s[10], s[11], s[8], s[9], s[13], s[14], s[15], s[12]]

    for (let j = 0; j < 4; j++) {
      const tmp = [...s]
      s[j] = tmp[j] ^ tmp[8 + j] ^ tmp[12 + j]
      s[4 + j] = tmp[j]
      s[8 + j] = tmp[4 + j] ^ tmp[8 + j]
      s[12 + j] = tmp[0 + j] ^ tmp[8 + j]
    }
  }

  return [...Array(16).keys()].map(i => s[i])
}