// RUN: %target-run-stdlib-swift
// REQUIRES: executable_test

import StdlibUnittest

let SipHashTests = TestSuite("SipHashTests")

extension Hasher {
  typealias HashValue = Int
}

struct SipHashTest {
  let input: [UInt8]
  let seed: (UInt64, UInt64)
  let output: UInt64

  /// Test vector from the reference C implementation.
  ///
  /// SipHash output with
  ///
  ///     seed = 00 01 02 ...
  ///
  /// and
  ///
  ///     input = (empty string)
  ///     input = 00 (1 byte)
  ///     input = 00 01 (2 bytes)
  ///     input = 00 01 02 (3 bytes)
  ///     ...
  ///     input = 00 01 02 ... 3e (63 bytes)
  init(referenceVectorIndex i: Int, output: UInt64) {
    self.input = Array(0..<UInt8(i))
    self.seed = (0x07060504_03020100, 0x0F0E0D0C_0B0A0908)
    self.output = output
  }

  init(input: [UInt8], seed: (UInt64, UInt64), output: UInt64) {
    self.input = input
    self.seed = seed
    self.output = output
  }
}

let sipHash13Tests: [SipHashTest] = [
  SipHashTest(referenceVectorIndex: 0, output: 0xabac0158050fc4dc),
  SipHashTest(referenceVectorIndex: 1, output: 0xc9f49bf37d57ca93),
  SipHashTest(referenceVectorIndex: 2, output: 0x82cb9b024dc7d44d),
  SipHashTest(referenceVectorIndex: 3, output: 0x8bf80ab8e7ddf7fb),
  SipHashTest(referenceVectorIndex: 4, output: 0xcf75576088d38328),
  SipHashTest(referenceVectorIndex: 5, output: 0xdef9d52f49533b67),
  SipHashTest(referenceVectorIndex: 6, output: 0xc50d2b50c59f22a7),
  SipHashTest(referenceVectorIndex: 7, output: 0xd3927d989bb11140),
  SipHashTest(referenceVectorIndex: 8, output: 0x369095118d299a8e),
  SipHashTest(referenceVectorIndex: 9, output: 0x25a48eb36c063de4),
  SipHashTest(referenceVectorIndex: 10, output: 0x79de85ee92ff097f),
  SipHashTest(referenceVectorIndex: 11, output: 0x70c118c1f94dc352),
  SipHashTest(referenceVectorIndex: 12, output: 0x78a384b157b4d9a2),
  SipHashTest(referenceVectorIndex: 13, output: 0x306f760c1229ffa7),
  SipHashTest(referenceVectorIndex: 14, output: 0x605aa111c0f95d34),
  SipHashTest(referenceVectorIndex: 15, output: 0xd320d86d2a519956),
  SipHashTest(referenceVectorIndex: 16, output: 0xcc4fdd1a7d908b66),
  SipHashTest(referenceVectorIndex: 17, output: 0x9cf2689063dbd80c),
  SipHashTest(referenceVectorIndex: 18, output: 0x8ffc389cb473e63e),
  SipHashTest(referenceVectorIndex: 19, output: 0xf21f9de58d297d1c),
  SipHashTest(referenceVectorIndex: 20, output: 0xc0dc2f46a6cce040),
  SipHashTest(referenceVectorIndex: 21, output: 0xb992abfe2b45f844),
  SipHashTest(referenceVectorIndex: 22, output: 0x7ffe7b9ba320872e),
  SipHashTest(referenceVectorIndex: 23, output: 0x525a0e7fdae6c123),
  SipHashTest(referenceVectorIndex: 24, output: 0xf464aeb267349c8c),
  SipHashTest(referenceVectorIndex: 25, output: 0x45cd5928705b0979),
  SipHashTest(referenceVectorIndex: 26, output: 0x3a3e35e3ca9913a5),
  SipHashTest(referenceVectorIndex: 27, output: 0xa91dc74e4ade3b35),
  SipHashTest(referenceVectorIndex: 28, output: 0xfb0bed02ef6cd00d),
  SipHashTest(referenceVectorIndex: 29, output: 0x88d93cb44ab1e1f4),
  SipHashTest(referenceVectorIndex: 30, output: 0x540f11d643c5e663),
  SipHashTest(referenceVectorIndex: 31, output: 0x2370dd1f8c21d1bc),
  SipHashTest(referenceVectorIndex: 32, output: 0x81157b6c16a7b60d),
  SipHashTest(referenceVectorIndex: 33, output: 0x4d54b9e57a8ff9bf),
  SipHashTest(referenceVectorIndex: 34, output: 0x759f12781f2a753e),
  SipHashTest(referenceVectorIndex: 35, output: 0xcea1a3bebf186b91),
  SipHashTest(referenceVectorIndex: 36, output: 0x2cf508d3ada26206),
  SipHashTest(referenceVectorIndex: 37, output: 0xb6101c2da3c33057),
  SipHashTest(referenceVectorIndex: 38, output: 0xb3f47496ae3a36a1),
  SipHashTest(referenceVectorIndex: 39, output: 0x626b57547b108392),
  SipHashTest(referenceVectorIndex: 40, output: 0xc1d2363299e41531),
  SipHashTest(referenceVectorIndex: 41, output: 0x667cc1923f1ad944),
  SipHashTest(referenceVectorIndex: 42, output: 0x65704ffec8138825),
  SipHashTest(referenceVectorIndex: 43, output: 0x24f280d1c28949a6),
  SipHashTest(referenceVectorIndex: 44, output: 0xc2ca1cedfaf8876b),
  SipHashTest(referenceVectorIndex: 45, output: 0xc2164bfc9f042196),
  SipHashTest(referenceVectorIndex: 46, output: 0xa16e9c9368b1d623),
  SipHashTest(referenceVectorIndex: 47, output: 0x49fb169c8b5114fd),
  SipHashTest(referenceVectorIndex: 48, output: 0x9f3143f8df074c46),
  SipHashTest(referenceVectorIndex: 49, output: 0xc6fdaf2412cc86b3),
  SipHashTest(referenceVectorIndex: 50, output: 0x7eaf49d10a52098f),
  SipHashTest(referenceVectorIndex: 51, output: 0x1cf313559d292f9a),
  SipHashTest(referenceVectorIndex: 52, output: 0xc44a30dda2f41f12),
  SipHashTest(referenceVectorIndex: 53, output: 0x36fae98943a71ed0),
  SipHashTest(referenceVectorIndex: 54, output: 0x318fb34c73f0bce6),
  SipHashTest(referenceVectorIndex: 55, output: 0xa27abf3670a7e980),
  SipHashTest(referenceVectorIndex: 56, output: 0xb4bcc0db243c6d75),
  SipHashTest(referenceVectorIndex: 57, output: 0x23f8d852fdb71513),
  SipHashTest(referenceVectorIndex: 58, output: 0x8f035f4da67d8a08),
  SipHashTest(referenceVectorIndex: 59, output: 0xd89cd0e5b7e8f148),
  SipHashTest(referenceVectorIndex: 60, output: 0xf6f4e6bcf7a644ee),
  SipHashTest(referenceVectorIndex: 61, output: 0xaec59ad80f1837f2),
  SipHashTest(referenceVectorIndex: 62, output: 0xc3b2f6154b6694e0),
  SipHashTest(referenceVectorIndex: 63, output: 0x9d199062b7bbb3a8),

  SipHashTest(
    input: [
      0x72, 0xdc, 0xde, 0xd4, 0x6d, 0xb4, 0xc8, 0xa1,
      0xcf, 0x22, 0xe2, 0x7f, 0xe3, 0xf6, 0xe5, 0x6d,
      0x8b, 0x66, 0x0b, 0xaf, 0xba, 0x16, 0x25, 0xf3,
      0x63, 0x8e, 0x69, 0x80, 0xf3, 0x7e, 0xd6, 0xe3,
    ],
    seed: (0xa3432fc680796c34, 0x1173946a79aeaae5),
    output: 0x4d457d818f46941d),
]

let incrementalPatterns: [[Int]] = [
  [1], [2], [3], [4], [5], [6], [7], [8], [9],
  [15], [16], [17],
  [31], [32], [33],
  [0, 1],
  [1, 2],
  [1, 3, 5],
  [1, 7],
  [1, 9],
  [7, 9],
]

struct Loop<C: Collection>: Sequence, IteratorProtocol {
  var base: C
  var iterator: C.Iterator

  init(_ base: C) {
    self.base = base
    self.iterator = base.makeIterator()
  }

  mutating func next() -> C.Element? {
    if let element = iterator.next() {
      return element
    }
    iterator = base.makeIterator()
    return iterator.next()
  }
}

SipHashTests.test("Hasher/combine(UnsafeRawBufferPointer)")
  .forEach(in: sipHash13Tests) { test in
  var hasher = Hasher(_rawSeed: test.seed)
  test.input.withUnsafeBytes { hasher.combine(bytes: $0) }
  let hash = hasher.finalize()
  expectEqual(Hasher.HashValue(truncatingIfNeeded: test.output), hash)
}

SipHashTests.test("Hasher/combine(UnsafeRawBufferPointer)/pattern")
  .forEach(in: cartesianProduct(sipHash13Tests, incrementalPatterns)) { test_ in
  let (test, pattern) = test_

  var hasher = Hasher(_rawSeed: test.seed)
  var chunkSizes = Loop(pattern).makeIterator()
  var startIndex = 0
  while startIndex != test.input.endIndex {
    let chunkSize = min(
      chunkSizes.next()!,
      test.input.endIndex - startIndex)
    let slice = test.input[startIndex..<(startIndex+chunkSize)]
    slice.withUnsafeBytes { hasher.combine(bytes: $0) }
    startIndex += chunkSize
  }
  let hash = hasher.finalize()
  expectEqual(Hasher.HashValue(truncatingIfNeeded: test.output), hash)
}


func testIntegerType<I: FixedWidthInteger>(
  _ type: I.Type,
  combiner: @escaping (inout Hasher, I) -> Void) {
  SipHashTests.test("Hasher._combine(\(type.self))")
    .forEach(in: sipHash13Tests) { test in

    var hasher = Hasher(_rawSeed: test.seed)

    // Load little-endian chunks and combine them into the hasher.
    let bitWidth = I.bitWidth
    var i = 0
    var count = 0
    var chunk: I = 0
    while i < test.input.count {
      chunk |= I(test.input[i]) << (8 * count)
      i += 1
      count += 1
      if 8 * count == bitWidth {
        combiner(&hasher, chunk)
        count = 0
        chunk = 0
      }
    }
    // Combine tail bytes.
    if count > 0 {
      hasher._combine(bytes: UInt64(truncatingIfNeeded: chunk), count: count)
    }

    let hash = hasher.finalize()
    expectEqual(Hasher.HashValue(truncatingIfNeeded: test.output), hash)
  }
}

testIntegerType(UInt.self) { $0._combine($1) }
testIntegerType(UInt64.self) { $0._combine($1) }
testIntegerType(UInt32.self) { $0._combine($1) }
testIntegerType(UInt16.self) { $0._combine($1) }
testIntegerType(UInt8.self) { $0._combine($1) }

SipHashTests.test("Hasher/OperationsAfterFinalize") {
  // Verify that finalize is nonmutating.
  var hasher1 = Hasher(_rawSeed: (0, 0))
  hasher1._combine(1 as UInt8)
  _ = hasher1.finalize()
  // Hasher is now consumed. The operations below are illegal, but this isn't
  // currently enforced. Check that the behavior matches that of a nonmutating
  // function.
  hasher1._combine(2 as UInt16)
  let hash1a = hasher1.finalize()
  let hash1b = hasher1.finalize()
  expectEqual(hash1a, hash1b)

  var hasher2 = Hasher(_rawSeed: (0, 0))
  hasher2._combine(1 as UInt8)
  hasher2._combine(2 as UInt16)
  let hash2 = hasher2.finalize()
  expectEqual(hash1a, hash2)
}

runAllTests()