using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using DG.Tweening;
using Ichni.RhythmGame.Beatmap;
using Ichni.UI;
using UniRx;
using UnityEngine;
using UnityEngine.Rendering.Universal;
using UnityEngine.Serialization;

namespace Ichni.RhythmGame
{
    public partial class GameCamera : GameElement, IHaveTransformSubmodule, IHaveTimeDurationSubmodule
    {
        #region [暴露属性字段] Camera View & Settings
        public Camera cam;
        //public Transform rotationPoint;
        //public Transform positionPoint;
        public Transform cameraTransform;

        public CameraViewType cameraViewType;
        public float perspectiveAngle;
        public float orthographicSize;

        public float perspectiveOffset;
        public float zoomOffset; // 用于效果（如CameraZoomEffect）的临时视野偏移

        public void RefreshFOV()
        {
            cam.fieldOfView = perspectiveAngle + perspectiveOffset + zoomOffset;
        }
        #endregion

        #region [子模块接口与关联引用] Submodules & References
        public TransformSubmodule transformSubmodule { get; set; }
        public TimeDurationSubmodule timeDurationSubmodule { get; set; }
        private static CameraManager cameraManager => GameManager.Instance.cameraManager;
        #endregion

        #region [生命周期] Lifecycle & Factory
        public static GameCamera GenerateElement(string elementName, Guid id,
            List<string> tags, bool isFirstGenerated, GameElement parentElement,
            CameraViewType cameraViewType, float perspectiveAngle, float orthographicSize)
        {
            GameCamera gameCamera = Instantiate(GameManager.Instance.basePrefabs.gameCamera).GetComponent<GameCamera>();

            gameCamera.Initialize(elementName, id, tags, isFirstGenerated, parentElement);

            cameraManager.gameCamera = gameCamera;
            
            gameCamera.parentElement = parentElement;
            gameCamera.cameraViewType = cameraViewType;
            gameCamera.cam.orthographic = cameraViewType == CameraViewType.Orthographic;
            gameCamera.perspectiveAngle = perspectiveAngle;
            gameCamera.orthographicSize = orthographicSize;
            gameCamera.cameraTransform = gameCamera.transform;

            float currentAspect = UIManager.GetScreenRatio();
            float targetAspect = UIManager.StandardRatio;
            
            if (currentAspect < targetAspect)
            {
                // 屏幕比较方 (如 4:3 平板)，需要增加垂直 FOV 以保持 16:9 标准下的水平绝对视野
                float hFovRad = 2.0f * Mathf.Atan(Mathf.Tan(perspectiveAngle * Mathf.Deg2Rad / 2.0f) * targetAspect);
                float newVFovRad = 2.0f * Mathf.Atan(Mathf.Tan(hFovRad / 2.0f) / currentAspect);
                
                // 设置 perspectiveOffset 以完美补足被裁切的空间
                gameCamera.perspectiveOffset = (newVFovRad * Mathf.Rad2Deg) - perspectiveAngle;
            }
            else
            {
                // 屏幕比较长 (如 20:9 手机)，维持原有垂直 FOV，左右延展屏幕用于渲染环境背景
                gameCamera.perspectiveOffset = 0f;
            }
            gameCamera.RefreshFOV();
            return gameCamera;
        }

        public override void AfterInitialize()
        {
            base.AfterInitialize();
            //gameCamera.GetComponent<UniversalAdditionalCameraData>().cameraStack.Add(cameraManager.uiCamera);
            GameManager.Instance.backgroundController.backgroundCanvas.worldCamera = cam;
        }

        public override void SetDefaultSubmodules()
        {
            transformSubmodule = new TransformSubmodule(this);
        }
        #endregion
    }

    #region [枚举类型] Enums
    public partial class GameCamera
    {
        public enum CameraViewType
        {
            Perspective = 0,
            Orthographic = 1
        }
    }
    #endregion

    #region [坐标变换逻辑更新] Transform Observe & Update Logics
    public partial class GameCamera
    {
        public void SetTransformObserver()
        {
            transformSubmodule.observer = Observable.EveryLateUpdate()
                .Where(_=>GameManager.Instance.songPlayer.isUpdating)
                .Subscribe(_ => UpdateTransform())
                .AddTo(transformSubmodule.attachedGameElement);
        }

        public void UpdateTransform(bool refreshAll = true)
        {
            bool willRefresh = false;

            if (!transformSubmodule.eulerAnglesOffsetLock && transformSubmodule.eulerAnglesDirtyMark)
            {
                transformSubmodule.currentEulerAngles = transformSubmodule.originalEulerAngles + transformSubmodule.eulerAnglesOffset;
                transform.localEulerAngles = transformSubmodule.currentEulerAngles;
                transformSubmodule.eulerAnglesDirtyMark = false;
                willRefresh = true;
                transformSubmodule.eulerAnglesOffset = Vector3.zero;
            }

            if (transformSubmodule.positionDirtyMark)
            {
                transformSubmodule.currentPosition = transformSubmodule.originalPosition + transformSubmodule.positionOffset;
                transform.localPosition = transformSubmodule.currentPosition;
                transformSubmodule.positionDirtyMark = false;
                willRefresh = true;
                transformSubmodule.positionOffset = Vector3.zero;
            }

            if (refreshAll && willRefresh)
            {
                Refresh();
            }
        }
    }
    #endregion

}