using UnityEngine;
using UnityEngine.UI;

public class UIImageSheetAnimation : MonoBehaviour
{
    public enum AnimationType
    {
        WholeSheet,
        SingleRow,
    }

    public enum TimeType
    {
        LifeTime,
        FPS,
    }

    public enum StartFrameType
    {
        Constant,
        RandomBetweenTwoConstants,
    }

    [HideInInspector]
    public float lifeTime = 5f;
    [HideInInspector]
    public bool loop = true;
    [HideInInspector]
    public int sizeX = 1;
    [HideInInspector]
    public int sizeY = 1;
    [HideInInspector]
    public StartFrameType startFrameMode = StartFrameType.Constant;
    [HideInInspector]
    public float startFrameMin = 0;//默认使用下面的
    [HideInInspector]
    public float startFrame = 0;
    [HideInInspector]
    public AnimationType animationMode = AnimationType.WholeSheet;
    [HideInInspector]
    public bool randomRow = true;
    private bool initRandomRow = false;

    private int cacheRow;//用于处理random row
    [HideInInspector]
    public int row = 0;

    [HideInInspector]
    public TimeType timeMode = TimeType.LifeTime;
    public ParticleSystem.MinMaxCurve frameOverTime;//因为CustomEditor中不好实现 所以这个暴露出来
    [HideInInspector]
    public float cycles = 1;
    [HideInInspector]
    public float FPS = 30;

    private Image mainImg;
    private bool imgEnable = true;
    private Material mat;
    private Material matInstance;//copy的实例

    private float totalTime;//总运行时间
    private float totalDis;//总偏移值

    private const string UV_PROPERTY = "_MainTex_ST";
    private int UV_ID;

    private float cacheUV_X;
    private float cacheUV_Y;

    // Start is called before the first frame update
    void Start()
    {
        //check param 
        if (sizeX <= 0 || sizeY <= 0)
        {
            Debug.LogError("SizeX和SizeY需要不小于0");
            return;
        }

        mainImg = GetComponent<Image>();

        imgEnable = mainImg.enabled;
        mat = mainImg.material;

        //Create material instance
        matInstance = new Material(mat);
        //Init
        mainImg.material = matInstance;

        UV_ID = Shader.PropertyToID(UV_PROPERTY);

        //add offset
        if (startFrameMode == StartFrameType.Constant)
            totalDis += startFrame;
        else
            totalDis += Random.Range(startFrameMin, startFrame);
    }

    // Update is called once per frame
    void Update()
    {
        if (sizeX > 0 && sizeY > 0)
        {
            bool updateUV = true;

            //全序列 or 特定row
            bool wholeSheet = animationMode == AnimationType.WholeSheet;
            if (wholeSheet)
            {
                //无需修改
            }
            else
            {
                if (randomRow)
                {
                    //初始一个随机row
                    if (!initRandomRow)
                    {
                        row = Random.Range(0, sizeY);
                        initRandomRow = true;
                    }
                }
                else
                {
                    //无需修改
                }

                //对row做范围修订
                if (row < 0) row = 0;
                if (row >= sizeY) row = (sizeY - 1);
            }

            //根据loop和lifeTime控制Image的Enable属性
            if (!loop && totalTime >= lifeTime && imgEnable)
            {
                mainImg.enabled = false;
                imgEnable = false;

                //重置
                totalTime = 0;
                totalDis = 0;

                updateUV = false;
            }
            if (loop && !imgEnable)
            {
                mainImg.enabled = true;
                imgEnable = true;

                updateUV = true;
            }

            if (updateUV)
            {
                if (loop && totalTime >= lifeTime)
                {
                    totalTime %= lifeTime;
                }

                //TimeLife Mode
                if (timeMode == TimeType.LifeTime)
                {
                    if (frameOverTime.mode == ParticleSystemCurveMode.Constant)
                    {
                        totalDis = frameOverTime.constantMax % (sizeX * sizeY);
                    }
                    else if (frameOverTime.mode == ParticleSystemCurveMode.Curve)
                    {
                        var curve = frameOverTime.curveMax;

                        totalDis = (sizeX * sizeY) * curve.Evaluate((totalTime / lifeTime * cycles) % 1);
                    }
                    else if (frameOverTime.mode == ParticleSystemCurveMode.TwoConstants)
                    {
                        totalDis = Random.Range(frameOverTime.constantMin, frameOverTime.constantMax) % (sizeX * sizeY);
                    }
                    else if (frameOverTime.mode == ParticleSystemCurveMode.TwoCurves)
                    {
                        var curve = frameOverTime.curveMin;
                        var curveMax = frameOverTime.curveMax;

                        float cTime = (totalTime / lifeTime * cycles) % 1;

                        totalDis = (sizeX * sizeY) * Random.Range(curve.Evaluate(cTime), curveMax.Evaluate(cTime));
                    }
                }
                //FPS Mode
                if (timeMode == TimeType.FPS)
                {
                    totalDis = (FPS * totalTime) % (sizeX * sizeY);
                }

                //random row update
                if (animationMode == AnimationType.SingleRow && randomRow)
                {
                    if (sizeY - Mathf.FloorToInt(totalDis) / sizeX - 1 != cacheRow)
                    {
                        row = Random.Range(0, sizeY);
                    }
                }

                float dTime = Time.deltaTime;
                totalTime += dTime;

                int index = Mathf.FloorToInt(totalDis);
                if (loop)
                    index %= (sizeX * sizeY);
                else
                    index = Mathf.Min(sizeX * sizeY - 1, index);

                float uv_x = index % sizeX;
                float uv_y = wholeSheet ? (sizeY - index / sizeX - 1) : sizeY - row - 1;

                cacheRow = sizeY - index / sizeX - 1;//走whole sheet模式下本次的row值

                uv_x /= sizeX;
                uv_y /= sizeY;

                //优化每帧调用
                if (cacheUV_X != uv_x || cacheUV_Y != uv_y)
                {
                    cacheUV_X = uv_x;
                    cacheUV_Y = uv_y;

                    matInstance.SetVector(UV_ID, new Vector4(1f / sizeX, 1f / sizeY, uv_x, uv_y));
                }

            }
        }
    }

    void Reset()
    {
        //用于首次添加脚本和调用Reset时重置数据
        frameOverTime.mode = ParticleSystemCurveMode.Curve;
        
        frameOverTime.constantMin = 0;
        frameOverTime.constantMax = 0;

        frameOverTime.curveMin = AnimationCurve.EaseInOut(0, 0, 1, 1);
        frameOverTime.curveMax = AnimationCurve.EaseInOut(0, 0, 1, 1);

        frameOverTime.curveMultiplier = sizeX * sizeY;//Force Update
    }

    void OnDestroy()
    {
        if (matInstance)
            DestroyImmediate(matInstance);
    }
}