///|
#cfg(target="native")
priv suberror Aes128Error {
  AesBadKeyLength
  AesBadBlockLength
  AesBadNonceLength
  AesBadTag
} derive(Debug, ToJson)

///|
#cfg(target="native")
#warnings("-unused_field")
priv struct AesGcmResult {
  ciphertext : Bytes
  tag : Bytes
}

///|
#cfg(target="native")
let aes_sbox : Array[Int] = [
  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7,
  0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf,
  0x9c, 0xa4, 0x72, 0xc0, 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5,
  0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
  0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e,
  0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed,
  0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 0xd0, 0xef,
  0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff,
  0xf3, 0xd2, 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d,
  0x64, 0x5d, 0x19, 0x73, 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee,
  0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
  0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5,
  0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, 0xba, 0x78, 0x25, 0x2e,
  0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 0x70, 0x3e,
  0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55,
  0x28, 0xdf, 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f,
  0xb0, 0x54, 0xbb, 0x16,
]

///|
#cfg(target="native")
let aes_rcon : Array[Int] = [
  0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
]

///|
#cfg(target="native")
fn aes_xtime(x : Int) -> Int {
  let x = x << 1
  if (x & 0x100) != 0 {
    (x ^ 0x11b) & 0xff
  } else {
    x & 0xff
  }
}

///|
#cfg(target="native")
fn aes_mul2(x : Int) -> Int {
  aes_xtime(x)
}

///|
#cfg(target="native")
fn aes_mul3(x : Int) -> Int {
  aes_xtime(x) ^ x
}

///|
#cfg(target="native")
fn aes_expand_key(key : Bytes) -> FixedArray[Int] raise {
  guard key.length() == 16 else { raise AesBadKeyLength }
  let expanded = FixedArray::make(176, 0)
  for i in 0..<16 {
    expanded[i] = key[i].to_int()
  }
  let temp = FixedArray::make(4, 0)
  for bytes_generated = 16; bytes_generated < 176; {
    for i in 0..<4 {
      temp[i] = expanded[bytes_generated - 4 + i]
    }
    if bytes_generated % 16 == 0 {
      let t = temp[0]
      temp[0] = aes_sbox[temp[1]] ^ aes_rcon[bytes_generated / 16]
      temp[1] = aes_sbox[temp[2]]
      temp[2] = aes_sbox[temp[3]]
      temp[3] = aes_sbox[t]
    }
    for i in 0..<4 {
      expanded[bytes_generated + i] = expanded[bytes_generated - 16 + i] ^
        temp[i]
    }
    continue bytes_generated + 4
  }
  expanded
}

///|
#cfg(target="native")
fn aes_add_round_key(
  state : FixedArray[Int],
  round_key : FixedArray[Int],
  round : Int,
) -> Unit {
  let start = round * 16
  for i in 0..<16 {
    state[i] = state[i] ^ round_key[start + i]
  }
}

///|
#cfg(target="native")
fn aes_sub_bytes(state : FixedArray[Int]) -> Unit {
  for i in 0..<16 {
    state[i] = aes_sbox[state[i]]
  }
}

///|
#cfg(target="native")
fn aes_shift_rows(state : FixedArray[Int]) -> Unit {
  let tmp = state.copy()
  state[0] = tmp[0]
  state[4] = tmp[4]
  state[8] = tmp[8]
  state[12] = tmp[12]
  state[1] = tmp[5]
  state[5] = tmp[9]
  state[9] = tmp[13]
  state[13] = tmp[1]
  state[2] = tmp[10]
  state[6] = tmp[14]
  state[10] = tmp[2]
  state[14] = tmp[6]
  state[3] = tmp[15]
  state[7] = tmp[3]
  state[11] = tmp[7]
  state[15] = tmp[11]
}

///|
#cfg(target="native")
fn aes_mix_columns(state : FixedArray[Int]) -> Unit {
  for col in 0..<4 {
    let i = col * 4
    let a0 = state[i]
    let a1 = state[i + 1]
    let a2 = state[i + 2]
    let a3 = state[i + 3]
    state[i] = aes_mul2(a0) ^ aes_mul3(a1) ^ a2 ^ a3
    state[i + 1] = a0 ^ aes_mul2(a1) ^ aes_mul3(a2) ^ a3
    state[i + 2] = a0 ^ a1 ^ aes_mul2(a2) ^ aes_mul3(a3)
    state[i + 3] = aes_mul3(a0) ^ a1 ^ a2 ^ aes_mul2(a3)
  }
}

///|
#cfg(target="native")
#warnings("-unused_value")
fn aes128_encrypt_block(key : Bytes, block : Bytes) -> Bytes raise {
  guard block.length() == 16 else { raise AesBadBlockLength }
  let round_key = aes_expand_key(key)
  let state = FixedArray::make(16, 0)
  for i in 0..<16 {
    state[i] = block[i].to_int()
  }
  aes_add_round_key(state, round_key, 0)
  for round in 1..<10 {
    aes_sub_bytes(state)
    aes_shift_rows(state)
    aes_mix_columns(state)
    aes_add_round_key(state, round_key, round)
  }
  aes_sub_bytes(state)
  aes_shift_rows(state)
  aes_add_round_key(state, round_key, 10)
  let out = @buffer.new()
  for i in 0..<16 {
    out.write_byte((state[i] & 0xff).to_byte())
  }
  out.contents()
}

///|
#cfg(target="native")
fn aes_u64_be(data : Bytes, offset : Int) -> UInt64 {
  let mut value = 0UL
  for i in 0..<8 {
    value = (value << 8) | data[offset + i].to_uint64()
  }
  value
}

///|
#cfg(target="native")
fn aes_block_pair(data : Bytes, offset : Int, len : Int) -> (UInt64, UInt64) {
  let block = FixedArray::make(16, b'\x00')
  for i in 0.. (UInt64, UInt64) {
  let mut z_hi = 0UL
  let mut z_lo = 0UL
  let mut v_hi = y_hi
  let mut v_lo = y_lo
  for i in 0..<128 {
    let bit = if i < 64 {
      (x_hi >> (63 - i)) & 1UL
    } else {
      (x_lo >> (127 - i)) & 1UL
    }
    if bit == 1UL {
      z_hi = z_hi ^ v_hi
      z_lo = z_lo ^ v_lo
    }
    let lsb = v_lo & 1UL
    v_lo = (v_lo >> 1) | (v_hi << 63)
    v_hi = v_hi >> 1
    if lsb == 1UL {
      v_hi = v_hi ^ 0xe100000000000000UL
    }
  }
  (z_hi, z_lo)
}

///|
#cfg(target="native")
fn aes_gcm_ghash(h : Bytes, aad : Bytes, ciphertext : Bytes) -> Bytes {
  let h_hi = aes_u64_be(h, 0)
  let h_lo = aes_u64_be(h, 8)
  let mut y_hi = 0UL
  let mut y_lo = 0UL
  for offset = 0; offset < aad.length(); offset = offset + 16 {
    let len = @cmp.minimum(16, aad.length() - offset)
    let (x_hi, x_lo) = aes_block_pair(aad, offset, len)
    let r = aes_gcm_mul(y_hi ^ x_hi, y_lo ^ x_lo, h_hi, h_lo)
    y_hi = r.0
    y_lo = r.1
  }
  for offset = 0; offset < ciphertext.length(); offset = offset + 16 {
    let len = @cmp.minimum(16, ciphertext.length() - offset)
    let (x_hi, x_lo) = aes_block_pair(ciphertext, offset, len)
    let r = aes_gcm_mul(y_hi ^ x_hi, y_lo ^ x_lo, h_hi, h_lo)
    y_hi = r.0
    y_lo = r.1
  }
  let len_block = @buffer.new()
  len_block.write_uint64_be(aad.length().to_uint64() * 8UL)
  len_block.write_uint64_be(ciphertext.length().to_uint64() * 8UL)
  let len_bytes = len_block.contents()
  let x_hi = aes_u64_be(len_bytes, 0)
  let x_lo = aes_u64_be(len_bytes, 8)
  let r = aes_gcm_mul(y_hi ^ x_hi, y_lo ^ x_lo, h_hi, h_lo)
  let out = @buffer.new()
  out.write_uint64_be(r.0)
  out.write_uint64_be(r.1)
  out.contents()
}

///|
#cfg(target="native")
fn aes_gcm_counter_block(iv : Bytes, counter : UInt) -> Bytes raise {
  guard iv.length() == 12 else { raise AesBadNonceLength }
  let out = @buffer.new()
  out.write_bytes(iv)
  out.write_byte(((counter >> 24) & 0xff).to_byte())
  out.write_byte(((counter >> 16) & 0xff).to_byte())
  out.write_byte(((counter >> 8) & 0xff).to_byte())
  out.write_byte((counter & 0xff).to_byte())
  out.contents()
}

///|
#cfg(target="native")
#warnings("-unused_value")
fn aes128_gcm_encrypt(
  key : Bytes,
  iv : Bytes,
  plaintext : Bytes,
  aad : Bytes,
) -> AesGcmResult raise {
  let h = aes128_encrypt_block(
    key, b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
  )
  let ciphertext = @buffer.new()
  for offset = 0, counter = 2U; offset < plaintext.length(); {
    let stream = aes128_encrypt_block(key, aes_gcm_counter_block(iv, counter))
    let len = @cmp.minimum(16, plaintext.length() - offset)
    for i in 0.. Bytes raise {
  guard tag.length() == 16 else { raise AesBadTag }
  let h = aes128_encrypt_block(
    key, b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
  )
  let s = aes_gcm_ghash(h, aad, ciphertext)
  let e = aes128_encrypt_block(key, aes_gcm_counter_block(iv, 1U))
  let mut good = true
  for i in 0..<16 {
    good = good && (e[i] ^ s[i]) == tag[i]
  }
  guard good else { raise AesBadTag }
  let plaintext = @buffer.new()
  for offset = 0, counter = 2U; offset < ciphertext.length(); {
    let stream = aes128_encrypt_block(key, aes_gcm_counter_block(iv, counter))
    let len = @cmp.minimum(16, ciphertext.length() - offset)
    for i in 0..