using UnityEngine;
using UnityEngine.InputSystem;

namespace Agame
{
    /// <summary>
    /// 第一人称视角控制:鼠标横移带动 body 偏航,纵移带动相机俯仰。
    ///
    /// 输入来自父节点(Player 根)上 PlayerInput 的 Look 动作。
    ///
    /// 网络侧前提(重要):本组件挂在 PlayerCamera 上,而 PlayerCamera 只会被
    /// <see cref="PlayerController"/> 为「本地拥有者」启用(见其 ApplyOwnership)。
    /// 非拥有者客户端的相机是 disabled 的,因此这里不会执行,天然不需要再判所有权。
    ///
    /// 反过来说:如果日后把 PlayerCamera 改成常驻启用,必须补上所有权判断,
    /// 否则每个客户端都会用自己的鼠标去转动别人玩家的视角。
    ///
    /// 关于光标:锁定/释放光标属于「窗口」层面,不是 gameplay 输入,
    /// 所以刻意没有做成 Action —— 那样的话玩家一旦切到别的输入上下文
    /// (比如打开菜单、禁用了 Player 这张 Map),连恢复光标的按键都收不到了。
    /// </summary>
    public class MouseLook : MonoBehaviour
    {
        [Header("Sensitivity")]
        [Tooltip("Degrees of rotation per pixel of mouse movement.")]
        [SerializeField] private float mouseSensitivity = 0.12f;

        [Header("Vertical Clamp")]
        [SerializeField] private float minLookAngle = -80f;
        [SerializeField] private float maxLookAngle = 80f;

        [Header("References")]
        [Tooltip("被偏航(Horizontal)的躯体 Transform,通常是玩家根节点。")]
        [SerializeField] private Transform characterBody;

        private InputAction _lookAction;
        private float _xRotation;
        private bool _warnedMissingBody;

        private void OnEnable()
        {
            // PlayerInput 挂在父节点(Player 根)上;相机自身可能是 disabled 的,
            // 所以要 includeInactive 才能取到。
            PlayerInput playerInput = GetComponentInParent<PlayerInput>(includeInactive: true);
            _lookAction = PlayerInputNames.Resolve(playerInput, PlayerInputNames.Look, this);

            // 跟随本对象的启用状态锁定光标:只有本地拥有者的相机会被启用,
            // 所以光标锁定/释放自然就只在拥有者这一侧发生。
            LockCursor(true);
        }

        private void OnDisable()
        {
            // 对象被禁用(非拥有者,或玩家已下线)时务必释放光标,否则会锁死在别人的机器上。
            LockCursor(false);
        }

        private void Update()
        {
            UpdateCursorLock();

            if (Cursor.lockState != CursorLockMode.Locked)
                return;

            if (_lookAction == null)
                return;

            // Look 绑定的是 <Mouse>/delta,读出来的就是这一帧的鼠标位移(单位:像素)。
            Vector2 delta = _lookAction.ReadValue<Vector2>();

            // 横移:转动躯体
            if (characterBody != null)
            {
                characterBody.Rotate(Vector3.up * (delta.x * mouseSensitivity));
            }
            else if (!_warnedMissingBody)
            {
                _warnedMissingBody = true;
                Debug.LogWarning(
                    $"[{nameof(MouseLook)}] 未指定 Character Body,水平视角不会生效。请指向玩家根节点的 Transform。",
                    this);
            }

            // 纵移:俯仰相机,并夹在上下限之间防止翻转
            _xRotation = Mathf.Clamp(_xRotation - (delta.y * mouseSensitivity), minLookAngle, maxLookAngle);
            transform.localRotation = Quaternion.Euler(_xRotation, 0f, 0f);
        }

        /// <summary>
        /// Esc 释放光标,左键重新抓取(方便编辑器里切出去)。
        /// </summary>
        private void UpdateCursorLock()
        {
            Keyboard keyboard = Keyboard.current;
            if (keyboard != null && keyboard.escapeKey.wasPressedThisFrame)
                LockCursor(false);

            Mouse mouse = Mouse.current;
            if (mouse != null && mouse.leftButton.wasPressedThisFrame && Cursor.lockState != CursorLockMode.Locked)
                LockCursor(true);
        }

        private void LockCursor(bool locked)
        {
            Cursor.lockState = locked ? CursorLockMode.Locked : CursorLockMode.None;
            Cursor.visible = !locked;
        }
    }
}