using UnityEngine;

/// <summary>
/// 用 UI 虚拟摇杆（移动轮盘）驱动角色移动，替代原来的点击地面移动。
///
/// 用法：挂在带 CharacterController 的角色上，把场景里的 <see cref="VirtualJoystick"/>
/// 拖到 joystick 字段（在 Inspector / 预制体里接线，代码里不查找节点）。
/// 摇杆方向默认按摄像机朝向换算成世界方向，推杆越满速度越快；只做水平移动，y 不变。
/// </summary>
[RequireComponent(typeof(CharacterController))]
public class PlayerMoveController : MonoBehaviour
{
    [Header("输入")]
    [Tooltip("移动轮盘；必须在 Inspector / 预制体里指定，留空角色不会移动")]
    [SerializeField] private VirtualJoystick joystick;

    [Tooltip("是否按摄像机朝向移动（关掉则按世界坐标轴移动）")]
    [SerializeField] private bool cameraRelative = true;

    [Tooltip("朝向参考的摄像机，留空用 Camera.main")]
    [SerializeField] private Transform cameraTransform;

    [Header("移动")]
    [Tooltip("满杆时的移动速度（单位/秒）")]
    [SerializeField] private float speed = 5f;

    [Tooltip("转向平滑速度，越大转得越快")]
    [SerializeField] private float turnSpeed = 12f;

    [Tooltip("输入平滑时间（0 = 立刻响应）")]
    [SerializeField] private float inputSmoothing = 0.05f;

    private CharacterController _controller;
    private Vector2 _smoothedInput;
    private Vector2 _smoothingVelocity;

    private void Awake()
    {
        _controller = GetComponent<CharacterController>();

        if (joystick == null)
            Debug.LogError("[PlayerMoveController] 没有指定移动轮盘（joystick），请在 Inspector / 预制体里拖入。", this);
    }

    private void Update()
    {
        Vector2 input = joystick != null ? joystick.Value : Vector2.zero;

        if (inputSmoothing > 0f)
            input = Vector2.SmoothDamp(_smoothedInput, input, ref _smoothingVelocity, inputSmoothing);
        _smoothedInput = input;

        if (input.sqrMagnitude <= 0.0001f)
            return;

        Vector3 direction = ToWorldDirection(input);
        if (direction.sqrMagnitude <= 0.0001f)
            return;

        _controller.Move(direction * (speed * input.magnitude * Time.deltaTime));

        transform.rotation = Quaternion.Slerp(
            transform.rotation,
            Quaternion.LookRotation(direction),
            Time.deltaTime * turnSpeed);
    }

    /// <summary>把摇杆的二维输入换算成世界方向（水平面内，已归一化）。</summary>
    private Vector3 ToWorldDirection(Vector2 input)
    {
        Vector3 forward = Vector3.forward;
        Vector3 right = Vector3.right;

        if (cameraRelative)
        {
            Transform cam = cameraTransform != null
                ? cameraTransform
                : (Camera.main != null ? Camera.main.transform : null);

            if (cam != null)
            {
                forward = cam.forward;
                forward.y = 0f;
                right = cam.right;
                right.y = 0f;

                if (forward.sqrMagnitude > 0.0001f) forward.Normalize();
                else forward = Vector3.forward;

                if (right.sqrMagnitude > 0.0001f) right.Normalize();
                else right = Vector3.right;
            }
        }

        Vector3 dir = right * input.x + forward * input.y;
        if (dir.sqrMagnitude > 1f)
            dir.Normalize();
        return dir;
    }
}