/*----------------------------------------------------------------------------*/
/* Copyright (c) 2019-2020 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 <cmath>
#include <functional>
#include <initializer_list>
#include <memory>

#include <frc/controller/PIDController.h>
#include <frc/controller/ProfiledPIDController.h>
#include <frc/geometry/Pose2d.h>
#include <frc/kinematics/ChassisSpeeds.h>
#include <frc/kinematics/SwerveDriveKinematics.h>
#include <frc/kinematics/SwerveModuleState.h>
#include <frc/trajectory/Trajectory.h>
#include <units/length.h>
#include <units/time.h>
#include <units/voltage.h>
#include <wpi/ArrayRef.h>

#include "CommandBase.h"
#include "CommandHelper.h"
#include "frc2/Timer.h"

#pragma once

namespace frc2 {

/**
 * A command that uses two PID controllers ({@link PIDController}) and a
 * ProfiledPIDController ({@link ProfiledPIDController}) to follow a trajectory
 * {@link Trajectory} with a swerve drive.
 *
 * <p>The command handles trajectory-following, Velocity PID calculations, and
 * feedforwards internally. This is intended to be a more-or-less "complete
 * solution" that can be used by teams without a great deal of controls
 * expertise.
 *
 * <p>Advanced teams seeking more flexibility (for example, those who wish to
 * use the onboard PID functionality of a "smart" motor controller) may use the
 * secondary constructor that omits the PID and feedforward functionality,
 * returning only the raw module states from the position PID controllers.
 *
 * <p>The robot angle controller does not follow the angle given by
 * the trajectory but rather goes to the angle given in the final state of the
 * trajectory.
 */
template <size_t NumModules>
class SwerveControllerCommand
    : public CommandHelper<CommandBase, SwerveControllerCommand<NumModules>> {
  using voltsecondspermeter =
      units::compound_unit<units::voltage::volt, units::second,
                           units::inverse<units::meter>>;
  using voltsecondssquaredpermeter =
      units::compound_unit<units::voltage::volt, units::squared<units::second>,
                           units::inverse<units::meter>>;

 public:
  /**
   * Constructs a new SwerveControllerCommand that when executed will follow the
   * provided trajectory. This command will not return output voltages but
   * rather raw module states from the position controllers which need to be put
   * into a velocity PID.
   *
   * <p>Note: The controllers will *not* set the outputVolts to zero upon
   * completion of the path- this is left to the user, since it is not
   * appropriate for paths with nonstationary endstates.
   *
   * <p>Note 2: The rotation controller will calculate the rotation based on the
   * final pose in the trajectory, not the poses at each time step.
   *
   * @param trajectory      The trajectory to follow.
   * @param pose            A function that supplies the robot pose,
   *                        provided by the odometry class.
   * @param kinematics      The kinematics for the robot drivetrain.
   * @param xController     The Trajectory Tracker PID controller
   *                        for the robot's x position.
   * @param yController     The Trajectory Tracker PID controller
   *                        for the robot's y position.
   * @param thetaController The Trajectory Tracker PID controller
   *                        for angle for the robot.
   * @param output          The raw output module states from the
   *                        position controllers.
   * @param requirements    The subsystems to require.
   */
  SwerveControllerCommand(
      frc::Trajectory trajectory, std::function<frc::Pose2d()> pose,
      frc::SwerveDriveKinematics<NumModules> kinematics,
      frc2::PIDController xController, frc2::PIDController yController,
      frc::ProfiledPIDController<units::radians> thetaController,
      std::function<void(std::array<frc::SwerveModuleState, NumModules>)>
          output,
      std::initializer_list<Subsystem*> requirements);

  /**
   * Constructs a new SwerveControllerCommand that when executed will follow the
   * provided trajectory. This command will not return output voltages but
   * rather raw module states from the position controllers which need to be put
   * into a velocity PID.
   *
   * <p>Note: The controllers will *not* set the outputVolts to zero upon
   * completion of the path- this is left to the user, since it is not
   * appropriate for paths with nonstationary endstates.
   *
   * <p>Note 2: The rotation controller will calculate the rotation based on the
   * final pose in the trajectory, not the poses at each time step.
   *
   * @param trajectory      The trajectory to follow.
   * @param pose            A function that supplies the robot pose,
   *                        provided by the odometry class.
   * @param kinematics      The kinematics for the robot drivetrain.
   * @param xController     The Trajectory Tracker PID controller
   *                        for the robot's x position.
   * @param yController     The Trajectory Tracker PID controller
   *                        for the robot's y position.
   * @param thetaController The Trajectory Tracker PID controller
   *                        for angle for the robot.
   * @param output          The raw output module states from the
   *                        position controllers.
   * @param requirements    The subsystems to require.
   */
  SwerveControllerCommand(
      frc::Trajectory trajectory, std::function<frc::Pose2d()> pose,
      frc::SwerveDriveKinematics<NumModules> kinematics,
      frc2::PIDController xController, frc2::PIDController yController,
      frc::ProfiledPIDController<units::radians> thetaController,
      std::function<void(std::array<frc::SwerveModuleState, NumModules>)>
          output,
      wpi::ArrayRef<Subsystem*> requirements = {});

  void Initialize() override;

  void Execute() override;

  void End(bool interrupted) override;

  bool IsFinished() override;

 private:
  frc::Trajectory m_trajectory;
  std::function<frc::Pose2d()> m_pose;
  frc::SwerveDriveKinematics<NumModules> m_kinematics;
  std::unique_ptr<frc2::PIDController> m_xController;
  std::unique_ptr<frc2::PIDController> m_yController;
  std::unique_ptr<frc::ProfiledPIDController<units::radians>> m_thetaController;
  std::function<void(std::array<frc::SwerveModuleState, NumModules>)>
      m_outputStates;

  frc2::Timer m_timer;
  units::second_t m_prevTime;
  frc::Pose2d m_finalPose;
};
}  // namespace frc2

#include "SwerveControllerCommand.inc"
