// source: https://github.com/sindresorhus/fnv1a
// FNV_PRIMES and FNV_OFFSETS from
// http://www.isthe.com/chongo/tech/comp/fnv/index.html#FNV-param
/* eslint-disable @typescript-eslint/no-loss-of-precision */

const FNV_PRIMES = {
  32: BigInt(16_777_619),
  64: BigInt(1_099_511_628_211),
  128: BigInt(309_485_009_821_345_068_724_781_371),
  256: BigInt(
    374_144_419_156_711_147_060_143_317_175_368_453_031_918_731_002_211
  ),
  512: BigInt(
    35_835_915_874_844_867_368_919_076_489_095_108_449_946_327_955_754_392_558_399_825_615_420_669_938_882_575_126_094_039_892_345_713_852_759
  ),
  1024: BigInt(
    5_016_456_510_113_118_655_434_598_811_035_278_955_030_765_345_404_790_744_303_017_523_831_112_055_108_147_451_509_157_692_220_295_382_716_162_651_878_526_895_249_385_292_291_816_524_375_083_746_691_371_804_094_271_873_160_484_737_966_720_260_389_217_684_476_157_468_082_573
  ),
} as const

const FNV_OFFSETS = {
  32: BigInt(2_166_136_261),
  64: BigInt(14_695_981_039_346_656_037),
  128: BigInt(144_066_263_297_769_815_596_495_629_667_062_367_629),
  256: BigInt(
    100_029_257_958_052_580_907_070_968_620_625_704_837_092_796_014_241_193_945_225_284_501_741_471_925_557
  ),
  512: BigInt(
    9_659_303_129_496_669_498_009_435_400_716_310_466_090_418_745_672_637_896_108_374_329_434_462_657_994_582_932_197_716_438_449_813_051_892_206_539_805_784_495_328_239_340_083_876_191_928_701_583_869_517_785
  ),
  1024: BigInt(
    14_197_795_064_947_621_068_722_070_641_403_218_320_880_622_795_441_933_960_878_474_914_617_582_723_252_296_732_303_717_722_150_864_096_521_202_355_549_365_628_174_669_108_571_814_760_471_015_076_148_029_755_969_804_077_320_157_692_458_563_003_215_304_957_150_157_403_644_460_363_550_505_412_711_285_966_361_610_267_868_082_893_823_963_790_439_336_411_086_884_584_107_735_010_676_915
  ),
} as const

export default function fnv1a(
  inputString: string,
  {
    size = 32,
    seed = 0,
  }: {
    size?: keyof typeof FNV_PRIMES
    seed?: number
  } = {}
) {
  if (!FNV_PRIMES[size]) {
    throw new Error(
      'The `size` option must be one of 32, 64, 128, 256, 512, or 1024'
    )
  }

  let hash: bigint = FNV_OFFSETS[size] ^ BigInt(seed)
  const fnvPrime = FNV_PRIMES[size]

  // Handle Unicode code points > 0x7f
  let isUnicoded = false

  for (let index = 0; index < inputString.length; index++) {
    let characterCode = inputString.charCodeAt(index)

    // Non-ASCII characters trigger the Unicode escape logic
    if (characterCode > 0x7f && !isUnicoded) {
      inputString = unescape(encodeURIComponent(inputString))
      characterCode = inputString.charCodeAt(index)
      isUnicoded = true
    }

    hash ^= BigInt(characterCode)
    hash = BigInt.asUintN(size, hash * fnvPrime)
  }

  return hash
}