// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "kudu/util/hash_util.h"

#include <array>
#include <cstdint>

#include <gtest/gtest.h>

#include "kudu/util/hash.pb.h"
#include "kudu/util/slice.h"
#include "kudu/util/test_macros.h"

namespace kudu {

// Test Murmur2 Hash64 returns the expected values for inputs. These tests are
// duplicated on the Java side to ensure that hash computations are stable
// across both platforms.
TEST(HashUtilTest, TestMurmur2Hash64) {
  uint64_t hash;

  hash = HashUtil::MurmurHash2_64("ab", 2, 0);
  ASSERT_EQ(7115271465109541368, hash);

  hash = HashUtil::MurmurHash2_64("abcdefg", 7, 0);
  ASSERT_EQ(2601573339036254301, hash);

  hash = HashUtil::MurmurHash2_64("quick brown fox", 15, 42);
  ASSERT_EQ(3575930248840144026, hash);
}

// Test FastHash64/32 returns the expected values for inputs. These tests are
// duplicated on the Java side to ensure that hash computations are stable
// across both platforms.
TEST(HashUtilTest, TestFastHash64) {
  uint64_t hash;

  hash = HashUtil::FastHash64("ab", 2, 0);
  ASSERT_EQ(17293172613997361769UL, hash);

  hash = HashUtil::FastHash64("abcdefg", 7, 0);
  ASSERT_EQ(10206404559164245992UL, hash);

  hash = HashUtil::FastHash64("quick brown fox", 15, 42);
  ASSERT_EQ(3757424404558187042UL, hash);

  hash = HashUtil::FastHash64(nullptr, 0, 0);
  ASSERT_EQ(12680076593665652444UL, hash);

  hash = HashUtil::FastHash64("", 0, 0);
  ASSERT_EQ(4144680785095980158UL, hash);

  hash = HashUtil::FastHash64("", 0, 1234);
  ASSERT_EQ(3296774803014270295UL, hash);

  // 15 byte buffer with negative and positive numbers help test the 8 byte loop iteration
  // and the remainder of 7 bytes in the fast hash implementation.
  std::array<char, 15> buffer;
  for (int i = 0; i < buffer.size(); i++) {
    buffer[i] = static_cast<char>(i - 8);
  }
  hash = HashUtil::FastHash64(buffer.data(), buffer.size(), 0);
  ASSERT_EQ(7308577902719593318, hash);
}

TEST(HashUtilTest, TestFastHash32) {
  uint64_t hash;

  hash = HashUtil::FastHash32("ab", 2, 0);
  ASSERT_EQ(2564147595U, hash);

  hash = HashUtil::FastHash32("abcdefg", 7, 0);
  ASSERT_EQ(1497700618U, hash);

  hash = HashUtil::FastHash32("quick brown fox", 15, 42);
  ASSERT_EQ(1676541068U, hash);

  hash = HashUtil::FastHash32(nullptr, 0, 0);
  ASSERT_EQ(842467426U, hash);

  hash = HashUtil::FastHash32("", 0, 0);
  ASSERT_EQ(3045300040U, hash);

  hash = HashUtil::FastHash32("", 0, 1234);
  ASSERT_EQ(811548192U, hash);

  std::array<char, 15> buffer;
  for (int i = 0; i < buffer.size(); i++) {
    buffer[i] = static_cast<char>(i - 8);
  }
  hash = HashUtil::FastHash32(buffer.data(), buffer.size(), 0);
  ASSERT_EQ(3815875205, hash);
}

TEST(HashUtilTest, TestComputeHash32Available) {
  Slice data("abcd");
  for (int h = HashAlgorithm_MIN; h <= HashAlgorithm_MAX; h++) {
    const auto hash_algorithm = static_cast<HashAlgorithm>(h);
    if (HashUtil::IsComputeHash32Available(hash_algorithm)) {
      NO_FATALS(HashUtil::ComputeHash32(data, hash_algorithm, 0));
    }
  }
}

} // namespace kudu