// 核心代码

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using UnityEngine;
using System.Threading.Tasks;
using Aspose.Slides;

namespace FancyScrollView.PPT
{
    public class PPTDManager : MonoBehaviour
    {
        private static PPTDManager instance;

        public static PPTDManager Instance
        {
            get
            {
                if (instance == null)
                {
                    instance = new GameObject().AddComponent<PPTDManager>();

                    // instance = new PPTDManager();
                }

                return instance;
            }
        }

        public Presentation LoadPPT(string path)
        {
            if (File.Exists(path) == false) return null;

            return new Presentation(path);
        }

        private Dictionary<string, Sprite> itemDatasCash = new Dictionary<string, Sprite>();

        public void LoadPPTByIndex(ItemData itemData, Action<Sprite> completion)
        {
            Sprite sprite;

            var key = itemData.path + itemData.pageIndex;

            if (itemDatasCash.TryGetValue(key, out sprite))
            {
                completion?.Invoke(sprite);
            }
            else
            {
                Presentation presentation = itemData.presentation;
                int index = itemData.pageIndex;
                var slide = presentation.Slides[index];
                var bitmap = slide.GetThumbnail(1, 1);

                Bitmap2Byte(bitmap, (bytes) =>
                {
                    // PPT的尺寸
                    // int width = 960;
                    // int height = 540;
                    int width = Convert.ToInt16(presentation.SlideSize.Size.Width);
                    int height = Convert.ToUInt16(presentation.SlideSize.Size.Height);

                    Texture2D texture2D = new Texture2D(width, height);
                    texture2D.LoadImage(bytes);
                    sprite = Sprite.Create(texture2D, new Rect(0, 0, width, height), Vector2.zero);
                    if (itemDatasCash.ContainsKey(key) == false)
                    {
                        itemDatasCash.Add(key, sprite);
                    }

                    completion?.Invoke(sprite);
                });
            }
        }


        private async Task Bitmap2Byte(Bitmap bitmap, Action<byte[]> completion)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                bitmap.Save(stream, ImageFormat.Png);
                byte[] data = new byte[stream.Length];
                stream.Seek(0, SeekOrigin.Begin);
                await stream.ReadAsync(data, 0, Convert.ToInt32(stream.Length));
                completion?.Invoke(data);
            }
        }
    }
}