using UnityEngine;
using UnityEngine.InputSystem;

/// <summary>
/// 게임패드 입력을 처리하여 드론 카메라 제어에 필요한 값을 제공합니다.
/// Unity Input System의 Gamepad.current를 사용합니다.
/// </summary>
public class GamepadInputHandler : MonoBehaviour
{
    [Header("Deadzone Settings")]
    [SerializeField] private float stickDeadzone = 0.15f;

    [Header("Response Curve")]
    [SerializeField] private float stickExponent = 2.0f; // 비선형 응답 곡선 (2 = 제곱)

    [Header("Speed Multipliers")]
    [SerializeField] private float slowMultiplier = 0.3f;  // LT 누를 때
    [SerializeField] private float boostMultiplier = 3.0f;  // RT 누를 때

    // 스틱 값 (데드존 + 커브 적용 후)
    public Vector2 LeftStick { get; private set; }
    public Vector2 RightStick { get; private set; }

    // 트리거 값 (0~1)
    public float LeftTrigger { get; private set; }
    public float RightTrigger { get; private set; }

    // 속도 배율 (LT/RT 기반)
    public float SpeedMultiplier { get; private set; } = 1f;

    // 버튼 상태 (이번 프레임에 눌렸는지)
    public bool ButtonSouthPressed { get; private set; }  // A (Xbox) / Cross (PS)
    public bool ButtonEastPressed { get; private set; }   // B (Xbox) / Circle (PS)
    public bool ButtonNorthPressed { get; private set; }  // Y (Xbox) / Triangle (PS)
    public bool ButtonWestPressed { get; private set; }   // X (Xbox) / Square (PS)
    public bool LeftShoulderPressed { get; private set; } // LB
    public bool RightShoulderPressed { get; private set; }// RB
    public bool LeftShoulderHeld { get; private set; }
    public bool RightShoulderHeld { get; private set; }
    public bool StartPressed { get; private set; }
    // D-pad는 소비형 플래그 (LateUpdate에서 읽은 뒤 자동 리셋)
    private bool _dpadUp, _dpadDown, _dpadLeft, _dpadRight;
    // D-pad 이전 프레임 상태 (엣지 감지용)
    private bool _dpadUpHeld, _dpadDownHeld, _dpadLeftHeld, _dpadRightHeld;
    public bool DpadUpPressed => _dpadUp;
    public bool DpadDownPressed => _dpadDown;
    public bool DpadLeftPressed => _dpadLeft;
    public bool DpadRightPressed => _dpadRight;

    // 게임패드 연결 상태
    public bool IsGamepadConnected => Gamepad.current != null;

    private bool wasConnected = false;

    private void Update()
    {
        var gamepad = Gamepad.current;
        if (gamepad == null)
        {
            if (wasConnected)
            {
                Debug.Log("[GamepadInputHandler] 게임패드 연결 해제됨");
                wasConnected = false;
            }
            ResetAll();
            return;
        }

        if (!wasConnected)
        {
            Debug.Log($"[GamepadInputHandler] 게임패드 연결됨: {gamepad.displayName}");
            wasConnected = true;
        }

        // 스틱
        LeftStick = ApplyDeadzoneAndCurve(gamepad.leftStick.ReadValue());
        RightStick = ApplyDeadzoneAndCurve(gamepad.rightStick.ReadValue());

        // 트리거
        LeftTrigger = gamepad.leftTrigger.ReadValue();
        RightTrigger = gamepad.rightTrigger.ReadValue();

        // 속도 배율 계산
        SpeedMultiplier = CalculateSpeedMultiplier();

        // 버튼 (이번 프레임 pressed)
        ButtonSouthPressed = gamepad.buttonSouth.wasPressedThisFrame;
        ButtonEastPressed = gamepad.buttonEast.wasPressedThisFrame;
        ButtonNorthPressed = gamepad.buttonNorth.wasPressedThisFrame;
        ButtonWestPressed = gamepad.buttonWest.wasPressedThisFrame;
        LeftShoulderPressed = gamepad.leftShoulder.wasPressedThisFrame;
        RightShoulderPressed = gamepad.rightShoulder.wasPressedThisFrame;
        LeftShoulderHeld = gamepad.leftShoulder.isPressed;
        RightShoulderHeld = gamepad.rightShoulder.isPressed;
        StartPressed = gamepad.startButton.wasPressedThisFrame;
        // D-pad: ReadValue()로 방향 판별 (일부 게임패드에서 wasPressedThisFrame이 안 먹는 경우 대응)
        Vector2 dpadValue = gamepad.dpad.ReadValue();
        bool dpadUpNow = dpadValue.y > 0.5f;
        bool dpadDownNow = dpadValue.y < -0.5f;
        bool dpadLeftNow = dpadValue.x < -0.5f;
        bool dpadRightNow = dpadValue.x > 0.5f;

        // 엣지 감지: 이전 프레임에 안 눌려있다가 이번에 눌린 경우만 플래그 세움
        if (dpadUpNow && !_dpadUpHeld) _dpadUp = true;
        if (dpadDownNow && !_dpadDownHeld) _dpadDown = true;
        if (dpadLeftNow && !_dpadLeftHeld) _dpadLeft = true;
        if (dpadRightNow && !_dpadRightHeld) _dpadRight = true;

        _dpadUpHeld = dpadUpNow;
        _dpadDownHeld = dpadDownNow;
        _dpadLeftHeld = dpadLeftNow;
        _dpadRightHeld = dpadRightNow;
    }

    private Vector2 ApplyDeadzoneAndCurve(Vector2 raw)
    {
        float magnitude = raw.magnitude;
        if (magnitude < stickDeadzone)
            return Vector2.zero;

        // 데드존 이후 0~1로 리매핑
        float normalized = (magnitude - stickDeadzone) / (1f - stickDeadzone);
        normalized = Mathf.Clamp01(normalized);

        // 응답 곡선 적용
        float curved = Mathf.Pow(normalized, stickExponent);

        return raw.normalized * curved;
    }

    private float CalculateSpeedMultiplier()
    {
        // LT와 RT가 동시에 눌리면 기본 속도
        if (LeftTrigger > 0.1f && RightTrigger > 0.1f)
            return 1f;

        if (LeftTrigger > 0.1f)
            return Mathf.Lerp(1f, slowMultiplier, LeftTrigger);

        if (RightTrigger > 0.1f)
            return Mathf.Lerp(1f, boostMultiplier, RightTrigger);

        return 1f;
    }

    /// <summary>
    /// D-pad 플래그를 소비합니다. LateUpdate에서 읽은 후 호출해주세요.
    /// </summary>
    public void ConsumeDpad()
    {
        _dpadUp = false;
        _dpadDown = false;
        _dpadLeft = false;
        _dpadRight = false;
    }

    private void ResetAll()
    {
        LeftStick = Vector2.zero;
        RightStick = Vector2.zero;
        LeftTrigger = 0f;
        RightTrigger = 0f;
        SpeedMultiplier = 1f;
        ButtonSouthPressed = false;
        ButtonEastPressed = false;
        ButtonNorthPressed = false;
        ButtonWestPressed = false;
        LeftShoulderPressed = false;
        RightShoulderPressed = false;
        LeftShoulderHeld = false;
        RightShoulderHeld = false;
        StartPressed = false;
        _dpadUp = false;
        _dpadDown = false;
        _dpadLeft = false;
        _dpadRight = false;
    }
}