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

public class LoadImage : MonoBehaviour
{
    private int _current;

    public int Current
    {
        get => _current;
        set
        {
            if (value >= 0 && value < 4)
            {
                _current = value;
                return;
            }
            _current = 0;
        }
    }

    private void Start()
    {
        Load("/");
        Image image = GameObject.Find("Image").GetComponent<Image>();
        Current = 0;
        image.sprite = images[Current];
        Button button = GameObject.Find("Button").GetComponent<Button>();
        button.onClick.AddListener(() =>
        {
            Current++;
            image.sprite = images[Current];
        });
    }

    // 储存获取到的图片  
    List<Texture2D> allTex2d = new List<Texture2D>();
    public Sprite[] images;

    /// <summary>
    /// 读取StremingAssets文件夹指定的文件夹目录下的所有图片进行加载
    /// </summary>
    /// <param name="path"> StremingAssets文件夹下的文件夹名字 </param>
    void Load(string path)
    {
        List<string> filePaths = new List<string>();
        string[] dirs = null;
        string imgtype = "*.BMP|*.JPG|*.GIF|*.PNG";
        string[] ImageType = imgtype.Split('|');
        for (int i = 0; i < ImageType.Length; i++)
        {
            //获取Application.dataPath文件夹下所有的图片路径  
            dirs = Directory.GetFiles((Application.streamingAssetsPath + "/" + path), ImageType[i]);
            for (int j = 0; j < dirs.Length; j++)
            {
                filePaths.Add(dirs[j]);
            }
        }


        for (int i = 0; i < filePaths.Count; i++)
        {
            Texture2D tx = new Texture2D(187, 287);
            tx.LoadImage(GetImageByte(filePaths[i]));
            //获取图片名字，并去除.png 后缀
            tx.name = filePaths[i].Substring(filePaths[i].LastIndexOf(@"\") + 1,
                filePaths[i].LastIndexOf('.') - filePaths[i].LastIndexOf('\\') - 1);
            allTex2d.Add(tx);
        }

        images = new Sprite[allTex2d.Count];
        for (int i = 0; i < allTex2d.Count; i++)
        {
            images[i] = TextureToSprite(allTex2d[i]);
        }
    }


    /// <summary>  
    /// 根据图片路径返回图片的字节流byte[]  
    /// </summary>  
    /// <param name="imagePath">图片路径</param>  
    /// <returns>返回的字节流</returns>  
    public static byte[] GetImageByte(string imagePath)
    {
        FileStream files = new FileStream(imagePath, FileMode.Open);
        byte[] imgByte = new byte[files.Length];
        files.Read(imgByte, 0, imgByte.Length);
        files.Close();
        return imgByte;
    }

    /// <summary>
    /// 将Texture2d转换为Sprite
    /// </summary>
    /// <param name="tex">参数是texture2d纹理</param>
    /// <returns></returns>
    private Sprite TextureToSprite(Texture2D tex)
    {
        Sprite sprite = Sprite.Create(tex, new Rect(0, 0, tex.width, tex.height), new Vector2(0.5f, 0.5f));
        return sprite;
    }
}