// by chai
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

namespace TweenAnimation
{
    // tween播放过程中产生事件
    [Serializable]
    public class TweenEvent
    {
        public string name; // 事件名
        public float time; // 事件触发时间
        public UnityEvent eventHandler; // 回调函数
#if UNITY_EDITOR
        [NonSerialized]
        public bool unfold = false;
#endif
        [NonSerialized]
        public bool trigged = false;
        public TweenEvent()
        {
            name = "New Event";
            time = 0;
            eventHandler = null;
        }
    }

    public class TweenAnimation : MonoBehaviour
    {
        public enum EventTriggeredDirection
        {
            None = 0, 
            Forward = 1, 
            Backward = 2,
        }

        public enum PlaybackStyle
        {
            Once, 
            Loop, 
            PingPong,
        }

        public new string name = "New Animation";

        [SerializeReference]
        public List<TweenModule> modules;

        public float duration;

        public PlaybackStyle playbackStyle;

        public EventTriggeredDirection eventTriggeredDirection;

        // 回放次数，0是不限制，默认是0
        public int playbackLimit;

        // 是否触发事件
        public bool triggerEvents;

        // 只触发一次事件
        public bool triggerOnce;

        // 脚本中处理 ITweenEventHandler
        public bool scriptHandler;

        public List<TweenEvent> eventList;

        // 默认的事件回调函数
        public UnityEvent onStart;
        public UnityEvent onTurnStart;
        public UnityEvent onTurnEnd;
        public UnityEvent onEnd;

        // 上次更新时的时间（一个turn内的）
        private float m_LastPlaybackTurnTime;

        public TweenAnimation()
        {
            this.playbackStyle = PlaybackStyle.Loop;
            this.playbackLimit = 0;
            this.duration = 1;
            this.modules = new List<TweenModule>();
            this.triggerOnce = false;
            m_LastPlaybackTurnTime = -0.001f;
        }

        public void AddModule(TweenModule module)
        {
            if (modules == null)
                modules = new List<TweenModule>();
            modules.Add(module);
        }

        public void RemoveModule(TweenModule module)
        {
            if (modules == null)
                return;
            if (modules.Contains(module))
                modules.Remove(module);
        }

        public void AddEvent(TweenEvent e)
        {
            if (eventList == null)
                eventList = new List<TweenEvent>();
            eventList.Add(e);
        }

        public void RemoveEvent(TweenEvent e)
        {
            if (eventList == null)
                return;
            eventList.Remove(e);
        }

        public void BeforePlay()
        {
            m_LastPlaybackTurnTime = -0.001f;
            ResetEventTriggerFlag();
        }

        private void ResetEventTriggerFlag()
        {
            for(int i = 0; i < eventList.Count; ++i)
            {
                var e = eventList[i];
                if (e == null)
                    continue;
                e.trigged = false;
            }
        }

        /// <summary>
        /// 根据时间执行tween, time是从播放开始的真实时间
        /// </summary>
        /// <param name="time">real time</param>
        public void Process(float time)
        {
            if (modules == null)
                return;

            float limitTime = ApplyLimit(time); // 转换为playback limit后的逻辑时间
            float logicTime = HandleTime(limitTime); // 转换为1个turn内的逻辑时间

            // 处理事件
            if(triggerEvents)
            {
                if (limitTime >= 0 && m_LastPlaybackTurnTime < 0)
                    onStart.Invoke();
                bool isPingpong = playbackStyle == PlaybackStyle.PingPong;
                for (int i = 0; i < eventList.Count; ++i)
                {
                    var e = eventList[i];
                    if (e == null)
                        continue;
                    if (triggerOnce && e.trigged)
                        continue;
                    float t = e.time;
                    bool bTrigger = false;
                    bool isOdd = (((int)(limitTime / duration)) & 1) == 1;
                    if (isPingpong && isOdd && (eventTriggeredDirection & EventTriggeredDirection.Backward) == 0)
                        continue;
                    if (isPingpong && !isOdd && (eventTriggeredDirection & EventTriggeredDirection.Forward) == 0)
                        continue;
                    if (isPingpong && isOdd)
                        bTrigger = logicTime <= t && m_LastPlaybackTurnTime > t;
                    else
                        bTrigger = logicTime >= t && m_LastPlaybackTurnTime < t;
                    if(bTrigger && e.eventHandler != null)
                    {
                        e.eventHandler.Invoke();
                        if (triggerOnce)
                            e.trigged = true;
                    }
                }
                m_LastPlaybackTurnTime = logicTime;
            }

            // 更新动画
            for (int i = 0; i < modules.Count; i ++)
            {
                TweenModule module = modules[i];
                if (!module.enabled)
                    continue;
                module.OnUpdate(logicTime);
            }
        }

        float HandleOnce(float time)
        {
            time = Mathf.Clamp(time, 0, duration);
            return time;
        }

        float HandleLoop(float time)
        {
            time = time % duration;
            return time;
        }

        float HandlePingpong(float time)
        {
            if (time <= duration)
                return time;
            float remain = time % duration;
            int round = (int)(time / duration);
            bool bOdd = (round & 1) == 1;
            if (bOdd)
                time = duration - remain;
            else
                time = remain;

            return time;
        }

        // 返回[0,duration]范围内的逻辑时间
        public float HandleTime(float time)
        {
            float logicTime = time;
            if (this.playbackStyle == PlaybackStyle.Once)
                logicTime = HandleOnce(time);
            else if (this.playbackStyle == PlaybackStyle.Loop)
                logicTime = HandleLoop(time);
            else if (this.playbackStyle == PlaybackStyle.PingPong)
                logicTime = HandlePingpong(time);
            return logicTime;
        }

        // 返回真实时间对应的逻辑时间
        public float ApplyLimit(float time)
        {
            if (playbackLimit <= 0)
                return time;
            if (playbackStyle == PlaybackStyle.Loop)
                time = Mathf.Clamp(time, 0, playbackLimit * duration - 0.001f); // 0.001是为了防止HandleTime的mod等于0
            else if(playbackStyle == PlaybackStyle.PingPong)
                time = Mathf.Clamp(time, 0, playbackLimit * duration);
            return time;
        }

#if UNITY_EDITOR
        public void UpdateEditor(float time)
        {
            Process(time);
        }

        // 返回0-duration内的时间，用负数代表从右往左
        public float GetIdentifiedTime(float t)
        {
            int round = (int)(t / duration);
            float time = HandleTime(t);
            if(playbackStyle == PlaybackStyle.PingPong)
            {
                bool bOdd = (round & 1) == 1;
                if(bOdd)
                    time = -time;
            }
            return time;
        }

#endif

    }

}