package keccak

import (
  "encoding/hex"
  "testing"
)

func TestKeccak256KnownAnswers(t *testing.T) {
  cases := []struct {
    name string
    in   string
    want string
  }{
    {"empty", "", "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470"},
    {
      "abc",
      "abc",
      "4e03657aea45a94fc7d47ba826c8d667c0d1e6e33a64a036ec44f58fa12d6c45",
    },
    {
      "longer",
      "The quick brown fox jumps over the lazy dog",
      "4d741b6f1eb29cb2a9b9911c82f56fa8d73b04959d3d9d222895df6c0b28aa15",
    },
  }
  for _, tc := range cases {
    t.Run(tc.name, func(t *testing.T) {
      sum := Hash256([]byte(tc.in))
      got := hex.EncodeToString(sum[:])
      if got != tc.want {
        t.Fatalf("Hash256(%q) = %s, want %s", tc.in, got, tc.want)
      }
    })
  }
}

func TestStreamingMatchesOneShot(t *testing.T) {
  data := make([]byte, 0, 500)
  for i := 0; i < 500; i++ {
    data = append(data, byte(i))
  }
  oneShot := Hash256(data)

  h := New()
  for i := 0; i < len(data); i += 7 {
    end := i + 7
    if end > len(data) {
      end = len(data)
    }
    h.Write(data[i:end])
  }
  if got := h.Sum256(); got != oneShot {
    t.Fatalf("streaming digest differs from one-shot")
  }
}

// TestSum256DoesNotDisturbState ensures Sum256 clones the state (hash.Hash
// semantics) so repeated calls are stable.
func TestSum256DoesNotDisturbState(t *testing.T) {
  h := New()
  h.Write([]byte("abc"))
  first := h.Sum256()
  second := h.Sum256()
  if first != second {
    t.Fatalf("Sum256 mutated state")
  }
  if first != Hash256([]byte("abc")) {
    t.Fatalf("Sum256 mismatch with Hash256")
  }
}