using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.UI;
using DG.Tweening;
using static UnityEngine.Rendering.DebugUI;

/// <summary>
/// 图片加载器
/// </summary>
public class ImageLoader<T> : MonoBehaviour
{
    public static Dictionary<string, Texture2D> dicTextures;

    static List<string> removeKeys;
    static Image progress;

    static ImageLoader()
    {
        dicTextures = new Dictionary<string, Texture2D>();
        removeKeys = new List<string>();
        if(progress==null) progress = GameObject.Find("progress").GetComponent<Image>();
    }

    public static void RemoveTexture()
    {
        if (removeKeys.Count > 0)
        {
            if (dicTextures.ContainsKey(removeKeys[0]))
            {
                Destroy(dicTextures[removeKeys[0]]);
                dicTextures.Remove(removeKeys[0]);
                Resources.UnloadUnusedAssets();
            }
            Debug.Log("Removed:" + removeKeys[0]);
            removeKeys.RemoveAt(0);
        }
    }

    #region 本地文件加载
    ///// <summary>
    ///// 从外部指定文件中加载图片
    ///// </summary>
    ///// <param name="imgFullName">文件路径</param>
    ///// <returns></returns>
    //public static Texture2D LoadTextureByIO(string imgFullName)
    //{
    //    FileStream fs = new FileStream(imgFullName, FileMode.Open, FileAccess.Read);
    //    fs.Seek(0, SeekOrigin.Begin);//游标的操作，可有可无
    //    byte[] bytes = new byte[fs.Length];//生命字节，用来存储读取到的图片字节
    //    try
    //    {
    //        fs.Read(bytes, 0, bytes.Length);//开始读取，这里最好用trycatch语句，防止读取失败报错

    //    }
    //    catch (System.Exception e)
    //    {
    //        Debug.Log(e);
    //    }
    //    fs.Close();//切记关闭

    //    int width = 2048;//图片的宽（这里两个参数可以提到方法参数中）
    //    int height = 2048;//图片的高（这里说个题外话，pico相关的开发，这里不能大于4k×4k不然会显示异常，当时开发pico的时候应为这个问题找了大半天原因，因为美术给的图是6000*3600，导致出现切几张图后就黑屏了。。。
    //    Texture2D texture = new Texture2D(width, height);
    //    if (texture.LoadImage(bytes))
    //    {
    //        //print("图片加载完毕 ");
    //        return texture;
    //    }
    //    else
    //    {
    //        //print("图片尚未加载");
    //        return null;
    //    }
    //}
    #endregion

    /// <summary>
    /// 协程加载图像
    /// </summary>
    /// <param name="imgFullName">图像名</param>
    /// <param name="mat">材质对象</param>
 public static IEnumerator LoadImage(string imgFullName, T mat, ImageLoadedEventHandler<T> ImageLoaded = null)
    {
        // Debug.Log(imgFullName);
        //progress.gameObject.SetActive(true);
        DOTween.KillAll();
        progress.fillAmount = 0;
        Texture2D tex = null;
        if (dicTextures.ContainsKey(imgFullName))
        {
            tex = dicTextures[imgFullName];
        }
        else
        {
            UnityWebRequest www = UnityWebRequestTexture.GetTexture(imgFullName);
            yield return www.SendWebRequest();
            // Debug.Log($"下载{imgFullName}进度：{www.downloadProgress}");
            //while (!www.isDone)
            //{
            //    yield return null;
            //    //GameObject.Find("progress").GetComponent<LoadProgress>().loadWebRequest = www;
            //    DOTween.To(() => progress.fillAmount, x => progress.fillAmount = x, www.downloadProgress, Time.deltaTime).OnComplete(() =>
            //    {
            //        if (progress.fillAmount >= 0.99)
            //        {
            //            DOTween.KillAll();
            //            progress.fillAmount = 0;
            //        }
            //    });
            //    //Tweener tweener = DOTween.To(() => progress.fillAmount, x=> progress.fillAmount, www.downloadProgress,Time.deltaTime);
            //    //progress.fillAmount = www.downloadProgress;
            //    //progress.fillAmount = Mathf.Lerp(progress.fillAmount, www.downloadProgress,Time.deltaTime);
            //    Debug.Log(www.downloadProgress);
            //}
            //DOTween.KillAll(); progress.fillAmount = 0;
            //DOTween.To(() => progress.fillAmount, x => progress.fillAmount = x, 0, 0);
            if (www.result == UnityWebRequest.Result.ConnectionError)
            {
                Debug.Log(www.error);
            }
            else
            {
                //progress.gameObject.SetActive(false);
                try
                {
                    tex = ((DownloadHandlerTexture)www.downloadHandler).texture;
                    if (!dicTextures.ContainsKey(imgFullName))
                    {
                        dicTextures.Add(imgFullName, tex);
                    }
                }
                catch
                {
                    Debug.Log("图片加载失败：" + imgFullName);
                }
            }

            www.Dispose();
        }

        if (ImageLoaded == null)
        {
            ImageLoaded = DefaultImageLoaded;
        }

        ImageLoaded(tex, mat);
    }

    public static void DefaultImageLoaded(Texture2D tex, T mat)
    {
        if (mat != null)
        {
            if (mat is Material)
            {
                Material matTmp = mat as Material;
                // 更新材质
                matTmp.mainTexture = tex;
                if (matTmp.IsKeywordEnabled("_EMISSION"))
                {
                    matTmp.SetTexture("_EmissionMap", tex);
                }
            }
            else if (mat is RawImage)
            {
                RawImage matTmp = mat as RawImage;
                matTmp.texture = tex;
            }
            else if (mat is Image)
            {
                Image matTmp = mat as Image;
                matTmp.sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), Vector2.zero);
            }

            // ClearImage();
        }
    }

    public static void RemoveImage(string imageName)
    {
        // removeKeys.Add(imageName);
        // Debug.Log("Remove:" + imageName);

        if (dicTextures.ContainsKey(imageName))
        {
            Destroy(dicTextures[imageName]);
            dicTextures.Remove(imageName);
        }
        // Resources.UnloadUnusedAssets();
    }

    public static void ClearImage()
    {
        foreach (string key in dicTextures.Keys)
        {
            Destroy(dicTextures[key]);
        }
        dicTextures.Clear();
    }

    //回收内存的协程
    IEnumerator ToDestoryThis(Texture2D thisSprite)
    {
        yield return new WaitForSeconds(0.1f);
        //Destroy(thisSprite);
        Resources.UnloadUnusedAssets();//卸载未占用的asset资源
        System.GC.Collect();//回收内存
    }
}

/// <summary>
/// 图片加载结束事件委托
/// </summary>
/// <param name="tex">图片对象</param>
public delegate void ImageLoadedEventHandler<T>(Texture2D tex, T mat);