using UnityEngine;

public class ModelViewerOrbitCamera : MonoBehaviour
{
    [Header("观察目标")]
    [SerializeField] private Transform target; // 要观察的模型
    
    [Header("旋转设置")]
    [SerializeField] private float rotationSpeed = 5.0f;
    [SerializeField] private float autoRotationSpeed = 0.5f;
    [SerializeField] private float rotationSmoothness = 5.0f;
    
    [Header("缩放设置")]
    [SerializeField] private float zoomSpeed = 5.0f;
    [SerializeField] private float minZoomDistance = 1.0f;
    [SerializeField] private float maxZoomDistance = 20.0f;
    [SerializeField] private float defaultZoomDistance = 5.0f;
    
    [Header("平移设置")]
    [SerializeField] private float panSpeed = 0.5f;
    
    [Header("自动旋转")]
    [SerializeField] private bool enableAutoRotation = false;
    
    [Header("鼠标控制")]
    [SerializeField] private MouseButton rotateButton = MouseButton.Left;
    [SerializeField] private MouseButton panButton = MouseButton.Middle;
    [SerializeField] private float mouseSensitivity = 1.0f;
    
    [Header("触摸屏控制")]
    [SerializeField] private float touchSensitivity = 0.5f;
    
    [Header("边界限制")]
    [SerializeField] private Vector2 verticalAngleLimit = new Vector2(10f, 80f);
    
    private Vector3 currentRotation = Vector3.zero;
    private Vector3 targetRotation = Vector3.zero;
    
    private float currentDistance = 5.0f;
    private float targetDistance = 5.0f;
    
    private Vector3 targetPositionOffset = Vector3.zero;
    private Vector3 currentTargetPositionOffset = Vector3.zero;
    
    private Vector3 lastMousePosition = Vector3.zero;
    private Vector3 lastPanPosition = Vector3.zero;
    
    private enum MouseButton
    {
        Left = 0,
        Right = 1,
        Middle = 2
    }
    
    void Start()
    {
        // 如果未指定目标，尝试查找
        if (target == null)
        {
            // 可以在这里添加自动查找模型的逻辑
            // 例如：target = GameObject.Find("Model").transform;
        }
        
        // 初始化距离
        currentDistance = defaultZoomDistance;
        targetDistance = defaultZoomDistance;
        
        // 初始化旋转
        Vector3 angles = transform.eulerAngles;
        currentRotation = new Vector3(angles.y, angles.x, 0);
        targetRotation = currentRotation;
        
        // 计算初始位置
        UpdateCameraPosition();
    }
    
    void LateUpdate()
    {
        if (target == null) return;
        
        HandleInput();
        UpdateCameraPosition();
    }
    
    private void HandleInput()
    {
        // 处理桌面端输入
        HandleDesktopInput();
        
        // 处理移动端输入
        HandleTouchInput();
    }
    
    private void HandleDesktopInput()
    {
        // 旋转控制
        if (Input.GetMouseButton((int)rotateButton))
        {
            float horizontal = Input.GetAxis("Mouse X") * rotationSpeed * mouseSensitivity;
            float vertical = -Input.GetAxis("Mouse Y") * rotationSpeed * mouseSensitivity;
            
            targetRotation.x += horizontal;
            targetRotation.y += vertical;
            
            // 限制垂直角度
            targetRotation.y = Mathf.Clamp(targetRotation.y, verticalAngleLimit.x, verticalAngleLimit.y);
            
            // 停止自动旋转
            enableAutoRotation = false;
        }
        
        // 平移控制
        if (Input.GetMouseButton((int)panButton))
        {
            if (Input.GetMouseButtonDown((int)panButton))
            {
                lastPanPosition = Input.mousePosition;
            }
            
            Vector3 delta = Input.mousePosition - lastPanPosition;
            
            // 计算平移方向（基于相机的右和上方向）
            Vector3 right = transform.right;
            Vector3 up = transform.up;
            right.y = 0; // 保持水平平移
            up.y = 0;
            
            targetPositionOffset -= (right * delta.x + up * delta.y) * panSpeed * 0.01f;
            
            lastPanPosition = Input.mousePosition;
        }
        
        // 缩放控制
        float scroll = Input.GetAxis("Mouse ScrollWheel");
        if (Mathf.Abs(scroll) > 0.01f)
        {
            targetDistance -= scroll * zoomSpeed;
            targetDistance = Mathf.Clamp(targetDistance, minZoomDistance, maxZoomDistance);
        }
        
        // 重置按钮
        if (Input.GetKeyDown(KeyCode.R))
        {
            ResetView();
        }
        
        // 自动旋转切换
        if (Input.GetKeyDown(KeyCode.A))
        {
            enableAutoRotation = !enableAutoRotation;
        }
    }
    
    private void HandleTouchInput()
    {
        #if UNITY_IOS || UNITY_ANDROID || UNITY_WEBGL
        if (Input.touchCount == 1)
        {
            Touch touch = Input.GetTouch(0);
            
            if (touch.phase == TouchPhase.Moved)
            {
                Vector2 delta = touch.deltaPosition;
                
                targetRotation.x += delta.x * rotationSpeed * touchSensitivity * 0.1f;
                targetRotation.y -= delta.y * rotationSpeed * touchSensitivity * 0.1f;
                
                // 限制垂直角度
                targetRotation.y = Mathf.Clamp(targetRotation.y, verticalAngleLimit.x, verticalAngleLimit.y);
            }
        }
        else if (Input.touchCount == 2)
        {
            Touch touchZero = Input.GetTouch(0);
            Touch touchOne = Input.GetTouch(1);
            
            Vector2 touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
            Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;
            
            float prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
            float touchDeltaMag = (touchZero.position - touchOne.position).magnitude;
            
            float deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;
            
            targetDistance += deltaMagnitudeDiff * zoomSpeed * 0.01f;
            targetDistance = Mathf.Clamp(targetDistance, minZoomDistance, maxZoomDistance);
        }
        #endif
    }
    
    private void UpdateCameraPosition()
    {
        // 自动旋转
        if (enableAutoRotation)
        {
            targetRotation.x += autoRotationSpeed;
        }
        
        // 应用旋转平滑
        currentRotation = Vector3.Lerp(currentRotation, targetRotation, rotationSmoothness * Time.deltaTime);
        
        // 应用距离平滑
        currentDistance = Mathf.Lerp(currentDistance, targetDistance, rotationSmoothness * Time.deltaTime);
        
        // 应用平移平滑
        currentTargetPositionOffset = Vector3.Lerp(currentTargetPositionOffset, targetPositionOffset, rotationSmoothness * Time.deltaTime);
        
        // 计算旋转
        Quaternion rotation = Quaternion.Euler(currentRotation.y, currentRotation.x, 0);
        
        // 计算位置
        Vector3 position = rotation * new Vector3(0, 0, -currentDistance) + target.position + currentTargetPositionOffset;
        
        // 应用变换
        transform.position = position;
        transform.LookAt(target.position + currentTargetPositionOffset);
        
        // 可选：使相机稍微向上看
        // transform.LookAt(target.position + currentTargetPositionOffset + Vector3.up * 0.5f);
    }
    
    // 公共方法
    
    /// <summary>
    /// 重置视角
    /// </summary>
    public void ResetView()
    {
        targetRotation = new Vector3(0, 45f, 0); // 默认视角
        targetDistance = defaultZoomDistance;
        targetPositionOffset = Vector3.zero;
        enableAutoRotation = false;
    }
    
    /// <summary>
    /// 聚焦到模型
    /// </summary>
    public void FocusOnModel()
    {
        if (target != null)
        {
            targetPositionOffset = Vector3.zero;
        }
    }
    
    /// <summary>
    /// 设置观察目标
    /// </summary>
    public void SetTarget(Transform newTarget)
    {
        target = newTarget;
        ResetView();
    }
    
    /// <summary>
    /// 设置观察目标
    /// </summary>
    public void SetTarget(GameObject newTarget)
    {
        if (newTarget != null)
        {
            target = newTarget.transform;
            ResetView();
        }
    }
    
    /// <summary>
    /// 设置观察目标的中心点
    /// </summary>
    public void SetTargetOffset(Vector3 offset)
    {
        targetPositionOffset = offset;
    }
    
    /// <summary>
    /// 设置缩放距离
    /// </summary>
    public void SetZoomDistance(float distance)
    {
        targetDistance = Mathf.Clamp(distance, minZoomDistance, maxZoomDistance);
    }
    
    /// <summary>
    /// 设置旋转角度
    /// </summary>
    public void SetRotation(float horizontal, float vertical)
    {
        targetRotation = new Vector3(horizontal, Mathf.Clamp(vertical, verticalAngleLimit.x, verticalAngleLimit.y), 0);
    }
    
    /// <summary>
    /// 切换自动旋转
    /// </summary>
    public void ToggleAutoRotation(bool enable)
    {
        enableAutoRotation = enable;
    }
    
    /// <summary>
    /// 设置自动旋转速度
    /// </summary>
    public void SetAutoRotationSpeed(float speed)
    {
        autoRotationSpeed = speed;
    }
    
    // 编辑器调试信息
    void OnGUI()
    {
        if (Application.isEditor)
        {
            GUI.Label(new Rect(10, 10, 300, 20), 
                $"上帝视角观察器 - 模型查看器");
            
            if (target != null)
            {
                GUI.Label(new Rect(10, 30, 300, 20), 
                    $"目标: {target.name}");
            }
            else
            {
                GUI.Label(new Rect(10, 30, 300, 20), 
                    "目标: 未设置 (请在Inspector中指定)");
            }
            
            GUI.Label(new Rect(10, 50, 300, 20), 
                $"旋转: ({currentRotation.x:F1}, {currentRotation.y:F1})");
            GUI.Label(new Rect(10, 70, 300, 20), 
                $"距离: {currentDistance:F1}");
            GUI.Label(new Rect(10, 90, 300, 20), 
                $"自动旋转: {(enableAutoRotation ? "开" : "关")}");
            
            GUI.Label(new Rect(10, 120, 400, 20), 
                "控制说明:");
            GUI.Label(new Rect(10, 140, 400, 20), 
                "左键拖拽: 旋转视角");
            GUI.Label(new Rect(10, 160, 400, 20), 
                "中键拖拽: 平移视角");
            GUI.Label(new Rect(10, 180, 400, 20), 
                "滚轮: 缩放");
            GUI.Label(new Rect(10, 200, 400, 20), 
                "R键: 重置视角");
            GUI.Label(new Rect(10, 220, 400, 20), 
                "A键: 切换自动旋转");
        }
    }
    
    // 在Scene视图中绘制辅助线
    void OnDrawGizmosSelected()
    {
        if (target != null)
        {
            Gizmos.color = Color.yellow;
            Gizmos.DrawWireSphere(target.position + currentTargetPositionOffset, 0.5f);
            Gizmos.DrawLine(target.position + currentTargetPositionOffset, transform.position);
        }
    }
}