using System.Collections.Generic;
using UnityEngine;
using Unity.Cinemachine;
using BaseGames.Core;

namespace BaseGames.Camera
{
    /// <summary>
    /// 相机状态单例控制器。管理房间相机切换、限位器更新与屏幕抖动。
    /// 须放置在持久化场景中。
    /// </summary>
    [DefaultExecutionOrder(-100)]
    public class CameraStateController : MonoBehaviour, ICameraService
    {
        [Header("引用")]
        [SerializeField] private CinemachineBrain          _brain;
        [SerializeField] private CinemachineImpulseSource  _impulseSource;

        [Header("默认混合配置")]
        [SerializeField] private CameraBlendProfileSO _defaultBlendProfile;

        // ── 注册表 ────────────────────────────────────────────────────────────
        private readonly HashSet<RoomCamera>  _registeredCameras = new HashSet<RoomCamera>();
        private RoomCamera _activeCamera;

        // ── Unity Lifecycle ───────────────────────────────────────────────────
        private void Awake()
        {
            if (ServiceLocator.GetOrDefault<ICameraService>() != null) { Destroy(gameObject); return; }
            ServiceLocator.Register<ICameraService>(this);
        }

        private void OnDestroy()
        {
            ServiceLocator.Unregister<ICameraService>(this);
        }

        // ── 公开 API ──────────────────────────────────────────────────────────

        /// <summary>向控制器注册一个房间相机（可选，也可由触发器直接调用 SwitchRoom）。</summary>
        public void RegisterRoomCamera(RoomCamera camera)
        {
            if (camera != null) _registeredCameras.Add(camera);
        }

        /// <summary>注销房间相机。</summary>
        public void UnregisterRoomCamera(RoomCamera camera)
        {
            if (camera != null) _registeredCameras.Remove(camera);
        }

        /// <summary>切换到目标房间相机，并应用对应的混合配置。</summary>
        public void SwitchRoom(RoomCamera targetCamera)
        {
            if (targetCamera == null || targetCamera == _activeCamera) return;

            // 应用混合配置到 Brain
            if (_brain != null)
            {
                var profile = targetCamera.BlendProfile ?? _defaultBlendProfile;
                if (profile != null)
                    _brain.DefaultBlend = profile.ToBlendDefinition();
            }

            // 禁用旧相机、启用新相机
            _activeCamera?.Deactivate();
            _activeCamera = targetCamera;
            _activeCamera.Activate();
        }

        /// <summary>触发屏幕抖动。</summary>
        public void TriggerImpulse(Vector3 velocity)
        {
            if (_impulseSource != null)
                _impulseSource.GenerateImpulse(velocity);
        }

        /// <summary>以默认强度触发屏幕抖动。</summary>
        public void TriggerImpulse(float strength = 0.3f)
            => TriggerImpulse(Vector3.down * strength);
    }
}