import { BN } from 'ethereumjs-util'
import { PrecompileInput } from './types'
import { OOGResult, ExecResult } from '../evm'
import { VmError, ERROR } from '../../exceptions'
const assert = require('assert')

// The following blake2 code has been taken from (license: Creative Commons CC0):
// https://github.com/dcposch/blakejs/blob/410c640d0f08d3b26904c6d1ab3d81df3619d282/blake2b.js
// The modifications include:
//  - Avoiding the use of context in F
//  - F accepts number of rounds as parameter
//  - Expect 2 64-byte t values, xor them both
//  - Take modulo 10 for indices of SIGMA
//  - Added type annotations
//  - Moved previously global `v` and `m` variables inside the F function

// 64-bit unsigned addition
// Sets v[a,a+1] += v[b,b+1]
// v should be a Uint32Array
function ADD64AA(v: Uint32Array, a: number, b: number) {
  const o0 = v[a] + v[b]
  let o1 = v[a + 1] + v[b + 1]
  if (o0 >= 0x100000000) {
    o1++
  }
  v[a] = o0
  v[a + 1] = o1
}

// 64-bit unsigned addition
// Sets v[a,a+1] += b
// b0 is the low 32 bits of b, b1 represents the high 32 bits
function ADD64AC(v: Uint32Array, a: number, b0: number, b1: number) {
  let o0 = v[a] + b0
  if (b0 < 0) {
    o0 += 0x100000000
  }
  let o1 = v[a + 1] + b1
  if (o0 >= 0x100000000) {
    o1++
  }
  v[a] = o0
  v[a + 1] = o1
}

// G Mixing function
// The ROTRs are inlined for speed
function B2B_G(
  v: Uint32Array,
  mw: Uint32Array,
  a: number,
  b: number,
  c: number,
  d: number,
  ix: number,
  iy: number
) {
  const x0 = mw[ix]
  const x1 = mw[ix + 1]
  const y0 = mw[iy]
  const y1 = mw[iy + 1]

  ADD64AA(v, a, b) // v[a,a+1] += v[b,b+1] ... in JS we must store a uint64 as two uint32s
  ADD64AC(v, a, x0, x1) // v[a, a+1] += x ... x0 is the low 32 bits of x, x1 is the high 32 bits

  // v[d,d+1] = (v[d,d+1] xor v[a,a+1]) rotated to the right by 32 bits
  let xor0 = v[d] ^ v[a]
  let xor1 = v[d + 1] ^ v[a + 1]
  v[d] = xor1
  v[d + 1] = xor0

  ADD64AA(v, c, d)

  // v[b,b+1] = (v[b,b+1] xor v[c,c+1]) rotated right by 24 bits
  xor0 = v[b] ^ v[c]
  xor1 = v[b + 1] ^ v[c + 1]
  v[b] = (xor0 >>> 24) ^ (xor1 << 8)
  v[b + 1] = (xor1 >>> 24) ^ (xor0 << 8)

  ADD64AA(v, a, b)
  ADD64AC(v, a, y0, y1)

  // v[d,d+1] = (v[d,d+1] xor v[a,a+1]) rotated right by 16 bits
  xor0 = v[d] ^ v[a]
  xor1 = v[d + 1] ^ v[a + 1]
  v[d] = (xor0 >>> 16) ^ (xor1 << 16)
  v[d + 1] = (xor1 >>> 16) ^ (xor0 << 16)

  ADD64AA(v, c, d)

  // v[b,b+1] = (v[b,b+1] xor v[c,c+1]) rotated right by 63 bits
  xor0 = v[b] ^ v[c]
  xor1 = v[b + 1] ^ v[c + 1]
  v[b] = (xor1 >>> 31) ^ (xor0 << 1)
  v[b + 1] = (xor0 >>> 31) ^ (xor1 << 1)
}

// Initialization Vector
// prettier-ignore
const BLAKE2B_IV32 = new Uint32Array([0xf3bcc908, 0x6a09e667, 0x84caa73b, 0xbb67ae85, 0xfe94f82b, 0x3c6ef372, 0x5f1d36f1, 0xa54ff53a, 0xade682d1, 0x510e527f, 0x2b3e6c1f, 0x9b05688c, 0xfb41bd6b, 0x1f83d9ab, 0x137e2179, 0x5be0cd19,])

// prettier-ignore
const SIGMA8 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3, 11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4, 7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8, 9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13, 2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9, 12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11, 13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10, 6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5, 10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3,]

// These are offsets into a uint64 buffer.
// Multiply them all by 2 to make them offsets into a uint32 buffer,
// because this is Javascript and we don't have uint64s
const SIGMA82 = new Uint8Array(
  SIGMA8.map(function (x) {
    return x * 2
  })
)

export function F(h: Uint32Array, m: Uint32Array, t: Uint32Array, f: boolean, rounds: number) {
  const v = new Uint32Array(32)
  let i = 0

  // init work variables
  for (i = 0; i < 16; i++) {
    v[i] = h[i]
    v[i + 16] = BLAKE2B_IV32[i]
  }

  // 128 bits of offset
  v[24] = v[24] ^ t[0]
  v[25] = v[25] ^ t[1]
  v[26] = v[26] ^ t[2]
  v[27] = v[27] ^ t[3]

  // last block flag set ?
  if (f) {
    v[28] = ~v[28]
    v[29] = ~v[29]
  }

  // twelve rounds of mixing
  // uncomment the DebugPrint calls to log the computation
  // and match the RFC sample documentation
  // util.debugPrint('          m[16]', m, 64)
  for (i = 0; i < rounds; i++) {
    // util.debugPrint('   (i=' + (i < 10 ? ' ' : '') + i + ') v[16]', v, 64)
    const ri = (i % 10) * 16
    B2B_G(v, m, 0, 8, 16, 24, SIGMA82[ri + 0], SIGMA82[ri + 1])
    B2B_G(v, m, 2, 10, 18, 26, SIGMA82[ri + 2], SIGMA82[ri + 3])
    B2B_G(v, m, 4, 12, 20, 28, SIGMA82[ri + 4], SIGMA82[ri + 5])
    B2B_G(v, m, 6, 14, 22, 30, SIGMA82[ri + 6], SIGMA82[ri + 7])
    B2B_G(v, m, 0, 10, 20, 30, SIGMA82[ri + 8], SIGMA82[ri + 9])
    B2B_G(v, m, 2, 12, 22, 24, SIGMA82[ri + 10], SIGMA82[ri + 11])
    B2B_G(v, m, 4, 14, 16, 26, SIGMA82[ri + 12], SIGMA82[ri + 13])
    B2B_G(v, m, 6, 8, 18, 28, SIGMA82[ri + 14], SIGMA82[ri + 15])
  }

  for (i = 0; i < 16; i++) {
    h[i] = h[i] ^ v[i] ^ v[i + 16]
  }
}

export default function (opts: PrecompileInput): ExecResult {
  assert(opts.data)

  const data = opts.data
  if (data.length !== 213) {
    return {
      returnValue: Buffer.alloc(0),
      gasUsed: opts.gasLimit,
      exceptionError: new VmError(ERROR.OUT_OF_RANGE),
    }
  }
  const lastByte = data.slice(212, 213)[0]
  if (lastByte !== 1 && lastByte !== 0) {
    return {
      returnValue: Buffer.alloc(0),
      gasUsed: opts.gasLimit,
      exceptionError: new VmError(ERROR.OUT_OF_RANGE),
    }
  }

  const rounds = data.slice(0, 4).readUInt32BE(0)
  const hRaw = data.slice(4, 68)
  const mRaw = data.slice(68, 196)
  const tRaw = data.slice(196, 212)
  // final
  const f = lastByte === 1

  const gasUsed = new BN(opts._common.param('gasPrices', 'blake2Round'))
  gasUsed.imul(new BN(rounds))
  if (opts.gasLimit.lt(gasUsed)) {
    return OOGResult(opts.gasLimit)
  }

  const h = new Uint32Array(16)
  for (let i = 0; i < 16; i++) {
    h[i] = hRaw.readUInt32LE(i * 4)
  }

  const m = new Uint32Array(32)
  for (let i = 0; i < 32; i++) {
    m[i] = mRaw.readUInt32LE(i * 4)
  }

  const t = new Uint32Array(4)
  for (let i = 0; i < 4; i++) {
    t[i] = tRaw.readUInt32LE(i * 4)
  }

  F(h, m, t, f, rounds)

  const output = Buffer.alloc(64)
  for (let i = 0; i < 16; i++) {
    output.writeUInt32LE(h[i], i * 4)
  }

  return {
    gasUsed,
    returnValue: output,
  }
}