// Copyright 2021 Google LLC
//
// 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 <cmath>

#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include "tensorflow/lite/kernels/custom_ops_register.h"
#include "tensorflow/lite/kernels/test_util.h"
#include "tensorflow/lite/schema/schema_generated.h"
#include "tensorflow/lite/testing/util.h"

namespace tflite {
namespace {

template <typename T>
tflite::TensorType GetTTEnum();

template <>
tflite::TensorType GetTTEnum<float>() {
  return tflite::TensorType_FLOAT32;
}

template <>
tflite::TensorType GetTTEnum<double>() {
  return tflite::TensorType_FLOAT64;
}

class Atan2Model : public tflite::SingleOpModel {
 public:
  Atan2Model(tflite::TensorData y, tflite::TensorData x,
             tflite::TensorData output) {
    y_ = AddInput(y);
    x_ = AddInput(x);
    output_ = AddOutput(output);
    SetCustomOp("atan2", {}, ops::custom::Register_ATAN2);
    BuildInterpreter({GetShape(y_), GetShape(x_)});
  }

  int y_;
  int x_;
  int output_;

  template <typename T>
  std::vector<T> GetOutput(const std::vector<T>& y, const std::vector<T>& x) {
    PopulateTensor<T>(y_, y);
    PopulateTensor<T>(x_, x);
    Invoke();
    return ExtractVector<T>(output_);
  }
};

template <typename Float>
class Atan2CustomTest : public ::testing::Test {
 public:
  using FloatType = Float;
};

using TestTypes = ::testing::Types<float, double>;

TYPED_TEST_SUITE(Atan2CustomTest, TestTypes);

TYPED_TEST(Atan2CustomTest, TestScalar) {
  using Float = typename TestFixture::FloatType;
  tflite::TensorData y = {GetTTEnum<Float>(), {}};
  tflite::TensorData x = {GetTTEnum<Float>(), {}};
  tflite::TensorData output = {GetTTEnum<Float>(), {}};
  Atan2Model m(y, x, output);
  auto got = m.GetOutput<Float>({0.0}, {0.0});
  ASSERT_EQ(got.size(), 1);
  EXPECT_FLOAT_EQ(got[0], 0.0);

  ASSERT_FLOAT_EQ(m.GetOutput<Float>({1.0}, {0.0})[0], M_PI / 2);
  ASSERT_FLOAT_EQ(m.GetOutput<Float>({0.0}, {1.0})[0], 0.0);
  ASSERT_FLOAT_EQ(m.GetOutput<Float>({-1.0}, {0.0})[0], -M_PI / 2);
}

TYPED_TEST(Atan2CustomTest, TestBatch) {
  using Float = typename TestFixture::FloatType;
  tflite::TensorData y = {GetTTEnum<Float>(), {4, 2, 1}};
  tflite::TensorData x = {GetTTEnum<Float>(), {4, 2, 1}};
  tflite::TensorData output = {GetTTEnum<Float>(), {4, 2, 1}};
  Atan2Model m(y, x, output);

  std::vector<Float> y_data = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8};
  std::vector<Float> x_data = {0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1};

  auto got = m.GetOutput<Float>(y_data, x_data);

  ASSERT_EQ(got.size(), 8);
  for (int i = 0; i < 8; ++i) {
    EXPECT_FLOAT_EQ(got[i], std::atan2(y_data[i], x_data[i]));
  }
}

}  // namespace
}  // namespace tflite