using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Threading;
using System.Threading.Tasks;
using Compression.BSA;
using Wabbajack.Common;
using Wabbajack.Common.FileSignatures;
using Wabbajack.VirtualFileSystem.SevenZipExtractor;

namespace Wabbajack.VirtualFileSystem
{
    public class GatheringExtractor<T> : IArchiveExtractCallback
    {
        private ArchiveFile _archive;
        private Predicate<RelativePath> _shouldExtract;
        private Func<RelativePath, IStreamFactory, ValueTask<T>> _mapFn;
        private Dictionary<RelativePath, T> _results;
        private Dictionary<uint, (RelativePath, ulong)> _indexes;
        private Stream _stream;
        private Definitions.FileType _sig;
        private Exception _killException;

        public GatheringExtractor(Stream stream, Definitions.FileType sig, Predicate<RelativePath> shouldExtract, Func<RelativePath,IStreamFactory, ValueTask<T>> mapfn)
        {
            
            _shouldExtract = shouldExtract;
            _mapFn = mapfn;
            _results = new Dictionary<RelativePath, T>();
            _stream = stream;
            _sig = sig;
        }

        public async Task<Dictionary<RelativePath, T>> Extract()
        {
            var source = new TaskCompletionSource<bool>();

            var th = new Thread(() =>
            {
                try
                {
                    _archive = ArchiveFile.Open(_stream, _sig).Result;
                    _indexes = _archive.Entries
                        .Select((entry, idx) => (entry, (uint)idx))
                        .Where(f => !f.entry.IsFolder)
                        .Select(t => ((RelativePath)t.entry.FileName, t.Item2, t.entry.Size))
                        .Where(t => _shouldExtract(t.Item1))
                        .ToDictionary(t => t.Item2, t => (t.Item1, t.Size));


                    _archive._archive.Extract(null, 0xFFFFFFFF, 0, this);
                    _archive.Dispose();
                    if (_killException != null)
                    {
                        source.SetException(_killException);
                    }
                    else
                    {
                        source.SetResult(true);
                    }
                }
                catch (Exception ex)
                {
                    source.SetException(ex);
                }
                
            }) {Priority = ThreadPriority.BelowNormal, Name = "7Zip Extraction Worker Thread"};
            th.Start();
            
            

            await source.Task;
            return _results;
        }

        public void SetTotal(ulong total)
        {
            
        }

        public void SetCompleted(ref ulong completeValue)
        {
            
        }

        public int GetStream(uint index, out ISequentialOutStream outStream, AskMode askExtractMode)
        {
            if (_indexes.ContainsKey(index))
            {
                outStream =  new GatheringExtractorStream<T>(this, index);
                return 0;
            }

            outStream = null;
            return 0;
        }

        public void PrepareOperation(AskMode askExtractMode)
        {
            
        }

        public void SetOperationResult(OperationResult resultEOperationResult)
        {
            
        }

        private class GatheringExtractorStream<T> : ISequentialOutStream, IOutStream
        {
            private GatheringExtractor<T> _extractor;
            private uint _index;
            private bool _written;
            private ulong _totalSize;
            private Stream _tmpStream;
            private TempFile _tmpFile;
            private IStreamFactory _factory;
            private bool _diskCached;

            public GatheringExtractorStream(GatheringExtractor<T> extractor, uint index)
            {
                _extractor = extractor;
                _index = index;
                _totalSize = extractor._indexes[index].Item2;
                _diskCached = _totalSize >= 500_000_000;
            }

            private IPath GetPath()
            {
                return _extractor._indexes[_index].Item1;
            }

            public int Write(byte[] data, uint size, IntPtr processedSize)
            {
                try
                {
                    if (size == _totalSize)
                        WriteSingleCall(data, size);
                    else if (_diskCached)
                        WriteDiskCached(data, size);
                    else
                        WriteMemoryCached(data, size);

                    if (processedSize != IntPtr.Zero)
                    {
                        Marshal.WriteInt32(processedSize, (int)size);
                    }
                    
                    return 0;
                }
                catch (Exception ex)
                {
                    Utils.Log($"Error during extraction {ex}");
                    _extractor.Kill(ex);

                    return 1;
                }
            }

            private void WriteSingleCall(byte[] data, in uint size)
            {
                var result = _extractor._mapFn(_extractor._indexes[_index].Item1, new MemoryBufferFactory(data, (int)size, GetPath())).Result;
                AddResult(result);
                Cleanup();
            }

            private void Cleanup()
            {
                _tmpStream?.Dispose();
                _tmpFile?.DisposeAsync().AsTask().Wait();
            }

            private void AddResult(T result)
            {
                _extractor._results.Add(_extractor._indexes[_index].Item1, result);
            }

            private void WriteMemoryCached(byte[] data, in uint size)
            {
                if (_tmpStream == null)
                    _tmpStream = new MemoryStream();
                _tmpStream.Write(data, 0, (int)size);

                if (_tmpStream.Length != (long)_totalSize) return;

                _tmpStream.Flush();
                _tmpStream.Position = 0;
                var result = _extractor._mapFn(_extractor._indexes[_index].Item1, new MemoryStreamFactory((MemoryStream)_tmpStream, GetPath())).Result;
                AddResult(result);
                Cleanup();
            }

            private void WriteDiskCached(byte[] data, in uint size)
            {
                if (_tmpFile == null)
                {
                    _tmpFile = new TempFile();
                    _tmpStream = _tmpFile.Path.Create().Result;
                }
                
                _tmpStream.Write(data, 0, (int)size);

                if (_tmpStream.Length != (long)_totalSize) return;

                _tmpStream.Flush();
                _tmpStream.Close();
                
                var result = _extractor._mapFn(_extractor._indexes[_index].Item1, new NativeFileStreamFactory(_tmpFile.Path, GetPath())).Result;
                AddResult(result);
                Cleanup();
            }

            public void Seek(long offset, uint seekOrigin, IntPtr newPosition)
            {
                
            }

            public int SetSize(long newSize)
            {
                return 0;
            }
        }

        private void Kill(Exception ex)
        {
            _killException = ex;
        }
    }
}