// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.

#include <cmath>

#include "frc/geometry/Pose2d.h"
#include "frc/geometry/Rotation2d.h"
#include "frc/geometry/Transform2d.h"
#include "frc/geometry/Translation2d.h"
#include "gtest/gtest.h"

using namespace frc;

static constexpr double kEpsilon = 1E-9;

TEST(Transform2dTest, Inverse) {
  const Pose2d initial{1_m, 2_m, 45_deg};
  const Transform2d transform{{5_m, 0_m}, 5_deg};

  auto transformed = initial + transform;
  auto untransformed = transformed + transform.Inverse();

  EXPECT_NEAR(initial.X().to<double>(), untransformed.X().to<double>(),
              kEpsilon);
  EXPECT_NEAR(initial.Y().to<double>(), untransformed.Y().to<double>(),
              kEpsilon);
  EXPECT_NEAR(initial.Rotation().Degrees().to<double>(),
              untransformed.Rotation().Degrees().to<double>(), kEpsilon);
}

TEST(Transform2dTest, Composition) {
  const Pose2d initial{1_m, 2_m, 45_deg};
  const Transform2d transform1{{5_m, 0_m}, 5_deg};
  const Transform2d transform2{{0_m, 2_m}, 5_deg};

  auto transformedSeparate = initial + transform1 + transform2;
  auto transformedCombined = initial + (transform1 + transform2);

  EXPECT_NEAR(transformedSeparate.X().to<double>(),
              transformedCombined.X().to<double>(), kEpsilon);
  EXPECT_NEAR(transformedSeparate.Y().to<double>(),
              transformedCombined.Y().to<double>(), kEpsilon);
  EXPECT_NEAR(transformedSeparate.Rotation().Degrees().to<double>(),
              transformedCombined.Rotation().Degrees().to<double>(), kEpsilon);
}