using UnityEngine;
using UnityEngine.UI;
using System;
using System.Collections.Generic;
using System.IO;

namespace GeneralTools
{
    /// <summary>
    /// 序列帧动画播放器
    /// 支持UGUI的Image和Unity2D的SpriteRenderer
    /// </summary>
    public class FrameAnimator : MonoBehaviour
    {

        //目标Image组件
        private RawImage image;
        /// <summary>
        /// 序列帧
        /// </summary>
        private List<Texture> frames = null;
        /// <summary>
        /// 帧率
        /// </summary>
        private float framerate = 24.0f;
        /// <summary>
        /// 是否忽略timeScale
        /// </summary>
        private bool ignoreTimeScale = true;
        /// <summary>
        /// 是否循环
        /// </summary>
        private bool loop = true;
        /// <summary>
        /// 是否允许播放
        /// </summary>
        private bool isAllowPlay = false;
        /// <summary>
        /// 结束事件
        /// 在每次播放完一个周期时触发
        /// 在循环模式下触发此事件时，当前帧不一定为结束帧
        /// </summary>
        public event Action OnFinishEvent;

        //当前帧索引
        private int currentFrameIndex = 0;
        //下一次更新时间
        private float timer = 0.0f;

        public FrameAnimator Init(List<Texture> _frames, bool _loop, float _framerate = 24)
        {
            Stop();
            image = GetComponent<RawImage>();
            if (image == null)
            {
                Debug.LogError("未找到RawImage", gameObject);
            }
            frames = _frames;
            loop = _loop;
            framerate = _framerate;
            image.texture = _frames[0];
            OnFinishEvent = null;
            return this;
        }
        public void Play()
        {
            isAllowPlay = true;
            gameObject.SetActive(true);
        }
        public void Pause()
        {
            isAllowPlay = false;
        }
        public void Stop()
        {
            isAllowPlay = false;
            ResetIndex();
        }
        public void Hide()
        {
            Stop();
            gameObject.SetActive(false);
        }
        public void RePlay()
        {
            isAllowPlay = false;
            ResetIndex();
            if (frames.Count > 0)
            {
                image.texture = frames[currentFrameIndex];
            }
            Play();
        }
        public void SetLoop(bool _loop)
        {
            loop = _loop;
        }
        /// <summary>
        /// 重设动画索引
        /// </summary>
        private int ResetIndex()
        {
            currentFrameIndex = framerate > 0 ? 0 : frames.Count - 1;
            return currentFrameIndex;
        }
        void FixedUpdate()
        {
            //帧数据无效，禁用脚本
            if (frames == null || frames.Count == 0 || image == null || frames.Count == 1 || framerate == 0)
            {
                return;
            }
            else
            {
                //是否允许播放
                if (!isAllowPlay) return;
                //获取当前时间
                float time = ignoreTimeScale ? Time.unscaledTime : Time.time;
                //计算帧间隔时间
                float interval = Mathf.Abs(1.0f / framerate);
                //满足更新条件，执行更新操作
                if (time - timer > interval)
                {
                    //执行更新操作
                    DoUpdate();
                }
            }
        }
        //具体更新操作
        private void DoUpdate()
        {
            //计算新的索引
            int nextIndex = currentFrameIndex + (framerate > 0 ? 1 : -1);
            //索引越界，表示已经到结束帧
            if (nextIndex < 0 || nextIndex >= frames.Count)
            {
                //非循环,模式结束
                if (loop == false)
                {
                    isAllowPlay = false;
                    //播放结束事件
                    OnFinishEvent?.Invoke();
                    nextIndex = frames.Count - 1;
                }
                else
                {
                    nextIndex = ResetIndex();
                }
            }
            //钳制索引
            currentFrameIndex = Mathf.Clamp(nextIndex, 0, frames.Count - 1);
            //更新图片
            RefreshTexture(currentFrameIndex);
            //设置计时器为当前时间
            timer = ignoreTimeScale ? Time.unscaledTime : Time.time;
        }
        private void RefreshTexture(int index)
        {
            image.texture = frames[index];
        }
        //正向手动刷新
        public void ManualUpdatePositive()
        {
            DoUpdate();
        }
        //反向手动刷新
        public void ManualUpdateReverse()
        {
            framerate *= -1;
            DoUpdate();
            framerate *= -1;
        }
    }
}