using UnityEngine;
using Unity.Cinemachine;

/// <summary>
/// 드론 카메라 자유비행(6DOF) 모드.
/// GamepadInputHandler의 입력을 받아 Cinemachine 카메라를 직접 이동/회전합니다.
/// 관성 기반 물리 모델로 자연스러운 드론 느낌을 구현합니다.
/// </summary>
public class DroneCameraMode : MonoBehaviour
{
    [Header("Movement Physics")]
    [SerializeField] private float acceleration = 5.0f;
    [SerializeField] private float drag = 3.0f;
    [SerializeField] private float maxSpeed = 10f;

    [Header("Rotation")]
    [SerializeField] private float yawSpeed = 90f;
    [SerializeField] private float pitchSpeed = 60f;
    [SerializeField] private float rotationSmoothing = 0.1f;

    [Header("FOV Control")]
    [SerializeField] private float fovSpeed = 30f;
    [SerializeField] private float minFOV = 10f;
    [SerializeField] private float maxFOV = 90f;

    [Header("Targeting")]
    [SerializeField] private float raycastDistance = 100f;
    [SerializeField] private float sphereCastRadius = 0.5f; // SphereCast 반경 (넓게 잡음)

    // 상태
    private bool isActive;
    private Vector3 velocity;
    private float currentYaw;
    private float currentPitch;
    private Quaternion targetRotation;

    // 타겟팅 (Head 본이 아닌 캐릭터 단위)
    private int currentTargetIndex = -1;
    private Transform currentTarget;
    public Transform CurrentTarget => currentTarget;

    // 참조
    private GamepadInputHandler gamepadInput;
    private CinemachineCamera targetCamera;

    // 드론 모드 진입 전 상태 저장
    private Transform savedFollow;
    private Transform savedLookAt;
    private Vector3 savedPosition;
    private Quaternion savedRotation;
    private float savedFOV;

    public bool IsActive => isActive;

    private void Awake()
    {
        gamepadInput = GetComponent<GamepadInputHandler>();
        if (gamepadInput == null)
            gamepadInput = gameObject.AddComponent<GamepadInputHandler>();
    }

    /// <summary>
    /// 드론 모드 활성화. 대상 Cinemachine 카메라의 Follow/LookAt을 해제하고 직접 제어를 시작합니다.
    /// </summary>
    public void Activate(CinemachineCamera camera)
    {
        if (camera == null || isActive) return;

        targetCamera = camera;

        // 현재 상태 저장
        savedFollow = camera.Follow;
        savedLookAt = camera.LookAt;
        savedPosition = camera.transform.position;
        savedRotation = camera.transform.rotation;
        savedFOV = camera.Lens.FieldOfView;

        // Cinemachine 추적 해제 → 직접 제어
        camera.Follow = null;
        camera.LookAt = null;

        // 현재 회전을 오일러로 분해
        Vector3 euler = camera.transform.eulerAngles;
        currentYaw = euler.y;
        currentPitch = euler.x;
        if (currentPitch > 180f) currentPitch -= 360f; // -180~180 범위로

        targetRotation = camera.transform.rotation;
        velocity = Vector3.zero;
        isActive = true;

        Debug.Log($"[DroneCameraMode] 활성화 - 카메라: {camera.name}");
    }

    /// <summary>
    /// 드론 모드 비활성화. Follow/LookAt을 복원합니다.
    /// </summary>
    public void Deactivate()
    {
        if (!isActive || targetCamera == null) return;

        // Follow/LookAt 복원
        targetCamera.Follow = savedFollow;
        targetCamera.LookAt = savedLookAt;

        velocity = Vector3.zero;
        isActive = false;

        Debug.Log("[DroneCameraMode] 비활성화");
    }

    /// <summary>
    /// 드론 모드 비활성화 + 원래 위치로 복귀
    /// </summary>
    public void DeactivateAndRestore()
    {
        if (!isActive || targetCamera == null) return;

        targetCamera.transform.position = savedPosition;
        targetCamera.transform.rotation = savedRotation;

        var lens = targetCamera.Lens;
        lens.FieldOfView = savedFOV;
        targetCamera.Lens = lens;

        Deactivate();
    }

    /// <summary>
    /// 현재 위치를 새 홈 포지션으로 저장
    /// </summary>
    public void SaveCurrentAsHome()
    {
        if (!isActive || targetCamera == null) return;

        savedPosition = targetCamera.transform.position;
        savedRotation = targetCamera.transform.rotation;
        savedFOV = targetCamera.Lens.FieldOfView;

        Debug.Log("[DroneCameraMode] 현재 위치를 홈으로 저장");
    }

    /// <summary>
    /// 홈 포지션으로 복귀 (드론 모드 유지)
    /// </summary>
    public void ReturnToHome()
    {
        if (!isActive || targetCamera == null) return;

        targetCamera.transform.position = savedPosition;
        targetCamera.transform.rotation = savedRotation;

        Vector3 euler = savedRotation.eulerAngles;
        currentYaw = euler.y;
        currentPitch = euler.x;
        if (currentPitch > 180f) currentPitch -= 360f;

        targetRotation = savedRotation;
        velocity = Vector3.zero;

        var lens = targetCamera.Lens;
        lens.FieldOfView = savedFOV;
        targetCamera.Lens = lens;

        Debug.Log("[DroneCameraMode] 홈 위치로 복귀");
    }

    /// <summary>
    /// 드론 상태를 직렬화 가능한 데이터로 반환
    /// </summary>
    public DroneStateData GetState()
    {
        return new DroneStateData
        {
            isActive = isActive,
            position = isActive && targetCamera != null ? targetCamera.transform.position : savedPosition,
            rotation = isActive && targetCamera != null ? targetCamera.transform.eulerAngles : savedRotation.eulerAngles,
            fov = isActive && targetCamera != null ? targetCamera.Lens.FieldOfView : savedFOV,
            speed = velocity.magnitude,
            targetName = currentTarget != null ? currentTarget.name : null
        };
    }

    private void LateUpdate()
    {
        if (!isActive || targetCamera == null || gamepadInput == null) return;

        float dt = Time.deltaTime;

        // === 회전 ===
        bool hasStickInput = gamepadInput.RightStick.sqrMagnitude > 0.01f;

        if (currentTarget != null && !hasStickInput)
        {
            // 타겟 자동 추적: 카메라가 타겟을 부드럽게 바라봄
            Vector3 dirToTarget = currentTarget.position - targetCamera.transform.position;
            if (dirToTarget.sqrMagnitude > 0.001f)
            {
                Quaternion lookRot = Quaternion.LookRotation(dirToTarget);
                targetCamera.transform.rotation = Quaternion.Slerp(
                    targetCamera.transform.rotation,
                    lookRot,
                    1f - Mathf.Exp(-dt / Mathf.Max(rotationSmoothing, 0.001f))
                );
                // yaw/pitch 동기화 (스틱 조작 시 이어서 진행되도록)
                Vector3 euler = targetCamera.transform.eulerAngles;
                currentYaw = euler.y;
                currentPitch = euler.x;
                if (currentPitch > 180f) currentPitch -= 360f;
            }
        }
        else
        {
            // 수동 회전: 우스틱으로 조작
            currentYaw += gamepadInput.RightStick.x * yawSpeed * dt;
            currentPitch -= gamepadInput.RightStick.y * pitchSpeed * dt;
            currentPitch = Mathf.Clamp(currentPitch, -85f, 85f);

            targetRotation = Quaternion.Euler(currentPitch, currentYaw, 0f);
            targetCamera.transform.rotation = Quaternion.Slerp(
                targetCamera.transform.rotation,
                targetRotation,
                1f - Mathf.Exp(-dt / Mathf.Max(rotationSmoothing, 0.001f))
            );
        }

        // === 이동 ===
        Vector3 inputDir = Vector3.zero;

        // 좌스틱 Y → 전진/후진
        inputDir += targetCamera.transform.forward * gamepadInput.LeftStick.y;

        // 좌스틱 X → 좌우 이동
        inputDir += targetCamera.transform.right * gamepadInput.LeftStick.x;

        // RT → 상승, LT → 하강
        float verticalInput = gamepadInput.RightTrigger - gamepadInput.LeftTrigger;
        inputDir += Vector3.up * verticalInput;

        // 물리: 가속 + 감쇠
        velocity += inputDir * (acceleration * dt);
        velocity -= velocity * (drag * dt);

        // 최대 속도 제한
        float currentMaxSpeed = maxSpeed;
        if (velocity.magnitude > currentMaxSpeed)
            velocity = velocity.normalized * currentMaxSpeed;

        targetCamera.transform.position += velocity * dt;

        // === FOV ===
        if (gamepadInput.LeftShoulderHeld || gamepadInput.RightShoulderHeld)
        {
            float fovDelta = 0f;
            if (gamepadInput.LeftShoulderHeld) fovDelta -= fovSpeed * dt;  // LB: 줌 인 (FOV 감소)
            if (gamepadInput.RightShoulderHeld) fovDelta += fovSpeed * dt; // RB: 줌 아웃 (FOV 증가)

            var lens = targetCamera.Lens;
            lens.FieldOfView = Mathf.Clamp(lens.FieldOfView + fovDelta, minFOV, maxFOV);
            targetCamera.Lens = lens;
        }

        // 타겟팅은 CameraController.HandleGamepadButtons()에서 처리
    }

    /// <summary>
    /// 외부에서 호출: 카메라 중앙 SphereCast로 타겟팅
    /// </summary>
    public void TryTargetFromCamera()
    {
        TryRaycastTarget();
    }

    /// <summary>
    /// 외부에서 호출: 캐릭터 목록 순환
    /// </summary>
    public void CycleTargetPublic(int direction)
    {
        CycleTarget(direction);
    }

    /// <summary>
    /// 카메라 중앙에서 SphereCast를 발사해 가장 가까운 캐릭터를 타겟팅합니다.
    /// </summary>
    private void TryRaycastTarget()
    {
        Camera mainCam = Camera.main;
        if (mainCam == null) return;

        var headTargets = GetHeadTargets();
        if (headTargets == null || headTargets.Count == 0)
        {
            // 타겟이 없으면 SystemController에서 새로고침 시도
            var sc = SystemController.Instance;
            if (sc != null)
            {
                sc.RefreshAvatarHeadColliders();
                headTargets = sc.GetAvatarHeadTargets();
                if (headTargets == null || headTargets.Count == 0) return;
            }
            else return;
        }

        Ray ray = mainCam.ViewportPointToRay(new Vector3(0.5f, 0.5f, 0f));
        RaycastHit[] hits = Physics.SphereCastAll(ray, sphereCastRadius, raycastDistance);

        Transform closestHead = null;
        float closestDist = float.MaxValue;
        int closestIndex = -1;

        foreach (var hit in hits)
        {
            // Head 타겟 목록에 있는지 확인 (콜라이더 종류 무관)
            int idx = headTargets.IndexOf(hit.transform);
            if (idx >= 0 && hit.distance < closestDist)
            {
                closestHead = hit.transform;
                closestDist = hit.distance;
                closestIndex = idx;
            }
        }

        if (closestHead != null)
        {
            currentTarget = closestHead;
            currentTargetIndex = closestIndex;
            Debug.Log($"[DroneCameraMode] 타겟 설정: {closestHead.name} (거리: {closestDist:F2}m)");
        }
        else
        {
            Debug.Log("[DroneCameraMode] 타겟을 찾지 못했습니다 - 가장 가까운 캐릭터로 설정합니다");
            // SphereCast가 안 맞으면 거리 기반으로 가장 가까운 캐릭터 선택
            SetClosestTarget();
        }
    }

    /// <summary>
    /// 카메라에서 가장 가까운 캐릭터를 타겟으로 설정합니다.
    /// </summary>
    private void SetClosestTarget()
    {
        var headTargets = GetHeadTargets();
        if (headTargets == null || headTargets.Count == 0 || targetCamera == null) return;

        Vector3 camPos = targetCamera.transform.position;
        float closestDist = float.MaxValue;
        int closestIndex = -1;

        for (int i = 0; i < headTargets.Count; i++)
        {
            if (headTargets[i] == null) continue;
            float dist = Vector3.Distance(camPos, headTargets[i].position);
            if (dist < closestDist)
            {
                closestDist = dist;
                closestIndex = i;
            }
        }

        if (closestIndex >= 0)
        {
            currentTargetIndex = closestIndex;
            currentTarget = headTargets[closestIndex];
            Debug.Log($"[DroneCameraMode] 가장 가까운 타겟: {currentTarget.name} (거리: {closestDist:F2}m)");
        }
    }

    /// <summary>
    /// 등록된 캐릭터 목록에서 다음/이전 캐릭터로 타겟을 전환합니다.
    /// </summary>
    private void CycleTarget(int direction)
    {
        var headTargets = GetHeadTargets();
        if (headTargets == null || headTargets.Count == 0) return;

        if (headTargets.Count == 1)
        {
            currentTargetIndex = 0;
            currentTarget = headTargets[0];
            Debug.Log($"[DroneCameraMode] 타겟 (유일): {currentTarget.name}");
            return;
        }

        currentTargetIndex += direction;

        // 순환
        if (currentTargetIndex >= headTargets.Count)
            currentTargetIndex = 0;
        else if (currentTargetIndex < 0)
            currentTargetIndex = headTargets.Count - 1;

        currentTarget = headTargets[currentTargetIndex];
        Debug.Log($"[DroneCameraMode] 타겟 전환 [{currentTargetIndex + 1}/{headTargets.Count}]: {currentTarget.name}");
    }

    /// <summary>
    /// 외부에서 타겟을 직접 설정합니다.
    /// </summary>
    public void SetTarget(Transform target)
    {
        currentTarget = target;
        var headTargets = GetHeadTargets();
        currentTargetIndex = headTargets != null ? headTargets.IndexOf(target) : -1;
    }

    /// <summary>
    /// 현재 타겟을 해제합니다.
    /// </summary>
    public void ClearTarget()
    {
        if (currentTarget != null)
        {
            Debug.Log($"[DroneCameraMode] 타겟 해제: {currentTarget.name}");
        }
        currentTarget = null;
        currentTargetIndex = -1;
    }

    private System.Collections.Generic.List<Transform> GetHeadTargets()
    {
        var systemController = SystemController.Instance;
        return systemController != null ? systemController.GetAvatarHeadTargets() : null;
    }

    [System.Serializable]
    public class DroneStateData
    {
        public bool isActive;
        public Vector3 position;
        public Vector3 rotation;
        public float fov;
        public float speed;
        public string targetName;
    }
}