/*----------------------------------------------------------------------------*/
/* Copyright (c) 2014-2020 FIRST. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

#include "frc/controller/PIDController.h"
#include "gtest/gtest.h"

class PIDInputOutputTest : public testing::Test {
 protected:
  frc2::PIDController* controller;

  void SetUp() override { controller = new frc2::PIDController(0, 0, 0); }

  void TearDown() override { delete controller; }
};

TEST_F(PIDInputOutputTest, ContinuousInputTest) {
  controller->SetP(1);
  controller->EnableContinuousInput(-180, 180);

  EXPECT_LT(controller->Calculate(-179, 179), 0);
}

TEST_F(PIDInputOutputTest, ProportionalGainOutputTest) {
  controller->SetP(4);

  EXPECT_DOUBLE_EQ(-0.1, controller->Calculate(0.025, 0));
}

TEST_F(PIDInputOutputTest, IntegralGainOutputTest) {
  controller->SetI(4);

  double out = 0;

  for (int i = 0; i < 5; i++) {
    out = controller->Calculate(0.025, 0);
  }

  EXPECT_DOUBLE_EQ(-0.5 * controller->GetPeriod().to<double>(), out);
}

TEST_F(PIDInputOutputTest, DerivativeGainOutputTest) {
  controller->SetD(4);

  controller->Calculate(0, 0);

  EXPECT_DOUBLE_EQ(-10_ms / controller->GetPeriod(),
                   controller->Calculate(0.0025, 0));
}