using System;
using System.Collections;
using System.Collections.Generic;
using Ichni.RhythmGame.Beatmap;
using UniRx;
using UnityEngine;

namespace Ichni.RhythmGame
{
    /// <summary>
    /// 将物体的z轴指向目标物体，注意，LookAt的启用期间，物体的旋转将被锁定
    /// </summary>
    public partial class LookAt : AnimationBase
    {
        #region [暴露属性字段与关联] Exposed Fields & References
        public GameElement targetGameElement;
        public TransformSubmodule targetTransformSubmodule;
        public FlexibleBool enabling;
        #endregion

        #region [生命周期与工厂] Lifecycle & Factory
        public static LookAt GenerateElement(string elementName, Guid id,
            List<string> tags, bool isFirstGenerated, GameElement animatedObject,
            GameElement lookAtTarget, FlexibleBool enabling)
        {
            LookAt look = Instantiate(GameManager.Instance.basePrefabs.emptyObject).AddComponent<LookAt>();

            look.Initialize(elementName, id, tags, isFirstGenerated, animatedObject);

            look.animatedObject = animatedObject;
            look.enabling = enabling;
            look.animationReturnType = FlexibleReturnType.Before;

            look.targetGameElement = lookAtTarget;
            look.targetTransformSubmodule = (animatedObject as IHaveTransformSubmodule).transformSubmodule;
            
            //look.timeDurationSubmodule.SetDuration(-999f, 999f); //TODO: 换为(-delay, songLength)

            return look;
        }

        public override void SetDefaultSubmodules()
        {
            timeDurationSubmodule = new TimeDurationSubmodule(this);
        }
        #endregion
        
        #region [核心动画逻辑] Core Animation Logic
        void LateUpdate()
        {
            if (enabling.value)
            {
                (animatedObject as IHaveTransformSubmodule)?.UpdateLookAt(this);
            }
        }

        protected override void UpdateAnimation(float songTime)
        {
            if (targetGameElement is null) return;
            
            enabling.UpdateFlexibleBool(songTime);
            
            if (!targetTransformSubmodule.eulerAnglesOffsetLock || enabling.value)
            {
                targetTransformSubmodule.eulerAnglesOffsetLock = enabling.value;
            }

            if (enabling.value)
            {
                animationReturnType = FlexibleReturnType.MiddleExecuting;
                targetTransformSubmodule.eulerAnglesDirtyMark = true;
            }
            else if (animationReturnType != FlexibleReturnType.MiddleInterval)
            {
                animationReturnType = FlexibleReturnType.MiddleInterval;
                targetTransformSubmodule.eulerAnglesDirtyMark = true;
            }
        }
        
        public override void ApplyTimeOffset(float offset)
        {
            base.ApplyTimeOffset(offset);
            enabling.animations.ForEach(anim => anim.ApplyTimeOffset(offset));
        }
        #endregion
    }

}