// Copyright 2021 The Tint Authors.
//
// Licensed 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 "src/tint/utils/transform.h"

#include <string>
#include <type_traits>

#include "gmock/gmock.h"

#define CHECK_ELEMENT_TYPE(vector, expected)                                 \
  static_assert(std::is_same<decltype(vector)::value_type, expected>::value, \
                "unexpected result vector element type")

namespace tint {
namespace utils {
namespace {

TEST(TransformTest, Empty) {
  const std::vector<int> empty{};
  {
    auto transformed = Transform(empty, [](int) -> int {
      [] { FAIL() << "Transform should not be called for empty vector"; }();
      return 0;
    });
    CHECK_ELEMENT_TYPE(transformed, int);
    EXPECT_EQ(transformed.size(), 0u);
  }
  {
    auto transformed = Transform(empty, [](int, size_t) -> int {
      [] { FAIL() << "Transform should not be called for empty vector"; }();
      return 0;
    });
    CHECK_ELEMENT_TYPE(transformed, int);
    EXPECT_EQ(transformed.size(), 0u);
  }
}

TEST(TransformTest, Identity) {
  const std::vector<int> input{1, 2, 3, 4};
  {
    auto transformed = Transform(input, [](int i) { return i; });
    CHECK_ELEMENT_TYPE(transformed, int);
    EXPECT_THAT(transformed, testing::ElementsAre(1, 2, 3, 4));
  }
  {
    auto transformed = Transform(input, [](int i, size_t) { return i; });
    CHECK_ELEMENT_TYPE(transformed, int);
    EXPECT_THAT(transformed, testing::ElementsAre(1, 2, 3, 4));
  }
}

TEST(TransformTest, Index) {
  const std::vector<int> input{10, 20, 30, 40};
  {
    auto transformed = Transform(input, [](int, size_t idx) { return idx; });
    CHECK_ELEMENT_TYPE(transformed, size_t);
    EXPECT_THAT(transformed, testing::ElementsAre(0u, 1u, 2u, 3u));
  }
}

TEST(TransformTest, TransformSameType) {
  const std::vector<int> input{1, 2, 3, 4};
  {
    auto transformed = Transform(input, [](int i) { return i * 10; });
    CHECK_ELEMENT_TYPE(transformed, int);
    EXPECT_THAT(transformed, testing::ElementsAre(10, 20, 30, 40));
  }
}

TEST(TransformTest, TransformDifferentType) {
  const std::vector<int> input{1, 2, 3, 4};
  {
    auto transformed =
        Transform(input, [](int i) { return std::to_string(i); });
    CHECK_ELEMENT_TYPE(transformed, std::string);
    EXPECT_THAT(transformed, testing::ElementsAre("1", "2", "3", "4"));
  }
}

}  // namespace
}  // namespace utils
}  // namespace tint