using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Wabbajack.Compression.BSA.Interfaces;
using Wabbajack.DTOs.BSA.ArchiveStates;
using Wabbajack.DTOs.Streams;
using Wabbajack.Paths;

namespace Wabbajack.Compression.BSA.TES3Archive
{
    public class Reader : IReader
    {
        public static string TES3_MAGIC = Encoding.ASCII.GetString(new byte[] { 0, 1, 0, 0 });
        internal long _dataOffset;
        private uint _fileCount;
        private TES3FileEntry[] _files;
        private uint _hashTableOffset;
        public IStreamFactory _streamFactory;
        private uint _versionNumber;

        public IEnumerable<IFile> Files => _files;

        public IArchive State =>
            new TES3State
            {
                FileCount = _fileCount,
                DataOffset = _dataOffset,
                HashOffset = _hashTableOffset,
                VersionNumber = _versionNumber
            };

        public static async ValueTask<Reader> Load(IStreamFactory factory)
        {
            await using var fs = await factory.GetStream();
            using var br = new BinaryReader(fs);
            var rdr = new Reader
            {
                _streamFactory = factory,
                _versionNumber = br.ReadUInt32(),
                _hashTableOffset = br.ReadUInt32(),
                _fileCount = br.ReadUInt32()
            };

            rdr._files = new TES3FileEntry[rdr._fileCount];
            for (var i = 0; i < rdr._fileCount; i++)
            {
                var file = new TES3FileEntry
                {
                    Index = i,
                    Archive = rdr,
                    Size = br.ReadUInt32(),
                    Offset = br.ReadUInt32()
                };
                rdr._files[i] = file;
            }

            for (var i = 0; i < rdr._fileCount; i++) rdr._files[i].NameOffset = br.ReadUInt32();

            var origPos = br.BaseStream.Position;
            for (var i = 0; i < rdr._fileCount; i++)
            {
                br.BaseStream.Position = origPos + rdr._files[i].NameOffset;
                rdr._files[i].Path = br.ReadStringTerm(VersionType.TES3).ToRelativePath();
            }

            br.BaseStream.Position = rdr._hashTableOffset + 12;
            for (var i = 0; i < rdr._fileCount; i++)
            {
                rdr._files[i].Hash1 = br.ReadUInt32();
                rdr._files[i].Hash2 = br.ReadUInt32();
            }

            rdr._dataOffset = br.BaseStream.Position;
            return rdr;
        }

        public async ValueTask DisposeAsync()
        {
        }

        public void Dump(Action<string> print)
        {
            throw new NotImplementedException();
        }
    }
}