using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;
using BrotliSharpLib;

namespace UnityStudio
{
    public class WebFile
    {
        public static byte[] gzipMagic = { 0x1f, 0x8b };
        public static byte[] brotliMagic = { 0x62, 0x72, 0x6F, 0x74, 0x6C, 0x69 };
        public List<MemoryFile> fileList = new List<MemoryFile>();


        public class WebData
        {
            public int dataOffset;
            public int dataLength;
            public string path;
        }


        public WebFile(EndianBinaryReader reader)
        {
            var magic = reader.ReadBytes(2);
            reader.Position = 0;
            if (gzipMagic.SequenceEqual(magic))
            {
                var stream = new MemoryStream();
                using (var gs = new GZipStream(reader.BaseStream, CompressionMode.Decompress))
                {
                    gs.CopyTo(stream);
                }
                stream.Position = 0;
                using (reader = new EndianBinaryReader(stream, EndianType.LittleEndian))
                {
                    ReadUnityWebData(reader);
                }
            }
            else
            {
                reader.Position = 0x20;
                magic = reader.ReadBytes(6);
                reader.Position = 0;
                if (brotliMagic.SequenceEqual(magic))
                {
                    var buff = reader.ReadBytes((int)reader.BaseStream.Length);
                    var uncompressedData = Brotli.DecompressBuffer(buff, 0, buff.Length);
                    var stream = new MemoryStream(uncompressedData);
                    using (reader = new EndianBinaryReader(stream, EndianType.LittleEndian))
                    {
                        ReadUnityWebData(reader);
                    }
                }
                else
                {
                    reader.endian = EndianType.LittleEndian;
                    ReadUnityWebData(reader);
                }
            }
        }

        private void ReadUnityWebData(EndianBinaryReader reader)
        {
            var signature = reader.ReadStringToNull();
            if (signature != "UnityWebData1.0")
                return;
            var headLength = reader.ReadInt32();
            var dataList = new List<WebData>();
            while (reader.Position < headLength)
            {
                var data = new WebData();
                data.dataOffset = reader.ReadInt32();
                data.dataLength = reader.ReadInt32();
                var pathLength = reader.ReadInt32();
                data.path = Encoding.UTF8.GetString(reader.ReadBytes(pathLength));
                dataList.Add(data);
            }

            foreach (var data in dataList)
            {
                var file = new MemoryFile();
                file.fileName = Path.GetFileName(data.path);
                reader.Position = data.dataOffset;
                file.stream = new MemoryStream(reader.ReadBytes(data.dataLength));
                fileList.Add(file);
            }
        }
    }
}