using System;
using System.Collections.Generic;
using System.IO;

namespace fis.Vid
{
    public enum OperationMode
    {
        Open,
        Create
    }

    public enum VidImageFormat
    {
        Jpeg = 0,
        Png = 1,
        H264 = 2,
        Zip = 3,
        Diff = 4,
    }

    public class VinnoImageData : IDisposable
    {
        private OperationMode _operationMode;
        private readonly Stream _stream;
        private readonly VinnoStreamReader _reader;
        private readonly VinnoStreamWriter _writer;

        private readonly string _filePath;

        private readonly List<long> _imagePositionList;

        private bool _disposed;
        private bool _closed;

        private readonly object _addGetLocker = new object();

        private const string Header = "VINNO IMAGE DATA";

        private const string CacheHeader = "VINNOIMGCACHE";

        /// <summary>
        /// Gets the version of this image data.
        /// </summary>
        public int Version { get; }

        /// <summary>
        /// Gets the image count of this image data.
        /// </summary>
        public int ImageCount { get; private set; }

        /// <summary>
        /// Gets the probe information.
        /// </summary>
        public VinnoProbe Probe { get; private set; }

        /// <summary>
        /// Gets the image format of this image data.
        /// </summary>
        public VidImageFormat ImageFormat { get; }

        /// <summary>
        /// Gets or sets the extended data.
        /// </summary>
        public byte[] ExtendedData { get; set; }

        /// <summary>
        /// Create a VINNO Image Data.
        /// </summary>
        /// <param name="filePath">The file path to read or create.</param>
        /// <param name="mode">The operation mode, create to create a vid file, open to open a vid file.</param>
        public VinnoImageData(string filePath, OperationMode mode)
        {
            try
            {
                ImageFormat = VidImageFormat.Jpeg;
                _filePath = filePath;
                _operationMode = mode;
                ExtendedData = new byte[0];
                if (mode == OperationMode.Create)
                {
                    //Create temp file.
                    var tempFile = _filePath + ".tmp";
                    _stream = new FileStream(tempFile, FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite);
                    _writer = new VinnoStreamWriter(_stream);
                    Version = 3;
                    Probe = null;
                    _imagePositionList = new List<long>();
                    ImageCount = 0;
                }
                else
                {
                    if (!File.Exists(_filePath) && File.Exists(_filePath + ".tmp"))
                    {
                        _filePath = _filePath + ".tmp";
                    }
                    _stream = new FileStream(_filePath, FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite);
                    _reader = new VinnoStreamReader(_stream);
                    var header = _reader.ReadString();
                    if (header != Header && header != CacheHeader)
                    {
                        _stream.Dispose();
                        throw new InvalidDataException("File is not a VID file.");
                    }
                    Version = _reader.ReadInt();
                    //Get probe info
                    var probeData = _reader.ReadBytes();
                    Probe = VinnoProbe.FromBytes(probeData);
                    ImageFormat = (VidImageFormat)_reader.ReadInt();
                    ExtendedData = _reader.ReadBytes();
                    //Get the index list.
                    _imagePositionList = new List<long>(_reader.ReadLongs());
                    ImageCount = _imagePositionList.Count;
                }
            }
            catch (Exception ex)
            {
                _stream?.Dispose();
            }
        }

        /// <summary>
        /// Create a VINNO Image Data.
        /// </summary>
        /// <param name="stream"></param>
        public VinnoImageData(Stream stream)
        {
            try
            {
                ImageFormat = VidImageFormat.Jpeg;
                ExtendedData = new byte[0];
                _stream = stream;
                _reader = new VinnoStreamReader(_stream);
                var header = _reader.ReadString();
                if (header != Header)
                {
                    _stream.Dispose();
                    throw new InvalidDataException("File is not a VID file.");
                }
                Version = _reader.ReadInt();
                //Get probe info
                var probeData = _reader.ReadBytes();
                Probe = VinnoProbe.FromBytes(probeData);
                ImageFormat = (VidImageFormat)_reader.ReadInt();
                ExtendedData = _reader.ReadBytes();
                //Get the index list.
                _imagePositionList = new List<long>(_reader.ReadLongs());
                ImageCount = _imagePositionList.Count;
            }
            catch (Exception ex)
            {
                _stream?.Dispose();
            }
        }

        /// <summary>
        /// Add probe info into vid.
        /// </summary>
        /// <param name="probe"></param>
        public void AddProbe(VinnoProbe probe)
        {
            Probe = probe;
        }

        /// <summary>
        /// Add dicom info into vid
        /// </summary>
        /// <param name="extendedData"></param>
        public void AddExtendedData(byte[] extendedData)
        {
            ExtendedData = extendedData;
        }

        /// <summary>
        /// Add one image into vid.
        /// </summary>
        /// <param name="image"></param>
        public void AddImage(VinnoImage image)
        {
            if (_closed)
            {
                throw new InvalidOperationException("ImageData closed.");
            }
            if (_operationMode != OperationMode.Create)
            {
                throw new InvalidOperationException("Can not add image under open mode.");
            }
            lock (_addGetLocker)
            {
                var postion = _stream.Position;
                _writer.WriteBytes(image.ToBytes());
                _imagePositionList.Add(postion);
                ImageCount++;
            }
        }

        /// <summary>
        /// Gets one image from the vid.
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public VinnoImage GetImage(int index)
        {
            if (_closed)
            {
                throw new InvalidOperationException("ImageData closed.");
            }
            if (_operationMode != OperationMode.Open)
            {
                throw new InvalidOperationException("Can not open image under create mode.");
            }
            if (index >= ImageCount || index < 0)
            {
                throw new IndexOutOfRangeException("Can not find image Data");
            }
            lock (_addGetLocker)
            {
                //Jump to image.
                _stream.Position = _imagePositionList[index];
                var imageData = _reader.ReadBytes();
                return VinnoImage.FromBytes(imageData);
            }
        }

        public void Close()
        {
            if (!_closed)
            {
                lock (_addGetLocker)
                {
                    if (_operationMode == OperationMode.Create && !string.IsNullOrWhiteSpace(_filePath) && ImageCount > 0)
                    {
                        using (var stream = File.Create(_filePath))
                        {
                            var writer = new VinnoStreamWriter(stream);
                            writer.WriteString(Header);
                            writer.WriteInt(Version);
                            writer.WriteBytes(Probe.ToBytes());
                            writer.WriteInt((int)ImageFormat);
                            writer.WriteBytes(ExtendedData);
                            //Position data length = imagecount(int 4bytes) + imagecount * positionSize(long 8bytes)
                            var positionsDataLength = _imagePositionList.Count * sizeof(long) + 4;
                            var offset = stream.Length + positionsDataLength;
                            for (var i = 0; i < _imagePositionList.Count; i++)
                            {
                                _imagePositionList[i] = _imagePositionList[i] + offset;
                            }
                            writer.WriteLongs(_imagePositionList.ToArray());
                            _stream.Position = 0;
                            _stream.CopyTo(stream);
                        }
                    }
                    _stream?.Dispose();
                    if (_operationMode == OperationMode.Create && !string.IsNullOrWhiteSpace(_filePath))
                    {
                        var tempFile = _filePath + ".tmp";
                        File.Delete(tempFile);
                    }
                }
                _closed = true;
            }
        }

        protected void Dispose(bool disposing)
        {
            if (!_disposed)
            {
                Close();
            }
            _disposed = true;
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
    }
}