using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;
using SabreTools.Hashing;
using SabreTools.IO.Extensions;
#if NET462_OR_GREATER || NETCOREAPP
using SharpCompress.Compressors.Xz;
#endif

namespace SabreTools.FileTypes.Archives
{
    /// <summary>
    /// Represents a TorrentXZ archive for reading and writing
    /// </summary>
    public class XZArchive : BaseArchive
    {
        /* (Torrent)XZ Header Format
            https://tukaani.org/xz/xz-file-format.txt

            00-05		Identification (0xFD, '7', 'z', 'X', 'Z', 0x00) XzSignature
            06			Flags (0x01 - CRC32, 0x04 - CRC64, 0x0A - SHA-256)
            07-0A		Flags CRC32 (uint, little-endian)
        */

        #region Fields

        /// <summary>
        /// Positive value for depth of the output depot, defaults to 4
        /// </summary>
        public int Depth { get; set; } = 4;

        #endregion

        #region Constructors

        /// <summary>
        /// Create a new TorrentGZipArchive with no base file
        /// </summary>
        public XZArchive()
            : base()
        {
        }

        /// <summary>
        /// Create a new TorrentGZipArchive from the given file
        /// </summary>
        /// <param name="filename">Name of the file to use as an archive</param>
        /// <param name="read">True for opening file as read, false for opening file as write</param>
        /// <param name="getHashes">True if hashes for this file should be calculated, false otherwise (default)</param>
        public XZArchive(string filename, bool getHashes = false)
            : base(filename, getHashes)
        {
        }

        #endregion

        #region Extraction

        /// <inheritdoc/>
        public override bool CopyAll(string outDir)
        {
#if NET462_OR_GREATER || NETCOREAPP
            bool encounteredErrors = true;

            try
            {
                // Create the temp directory
                Directory.CreateDirectory(outDir);

                // Decompress the _filename stream
                FileStream outstream = File.Create(Path.Combine(outDir, Path.GetFileNameWithoutExtension(this.Filename)!));
                var xz = new XZStream(File.OpenRead(this.Filename!));
                xz.CopyTo(outstream);

                // Dispose of the streams
                outstream.Dispose();
                xz.Dispose();

                encounteredErrors = false;
            }
            catch (EndOfStreamException ex)
            {
                // Catch this but don't count it as an error because SharpCompress is unsafe
                logger.Verbose(ex);
            }
            catch (InvalidOperationException ex)
            {
                logger.Warning(ex);
                encounteredErrors = true;
            }
            catch (Exception ex)
            {
                logger.Error(ex);
                encounteredErrors = true;
            }

            return encounteredErrors;
#else
            // TODO: Support XZ archives in old .NET
            return true;
#endif
        }

        /// <inheritdoc/>
        public override string? CopyToFile(string entryName, string outDir)
        {
            // Try to extract a stream using the given information
            (Stream? stream, string? realEntry) = GetEntryStream(entryName);
            if (stream == null || realEntry == null)
                return null;

            // If the stream and the entry name are both non-null, we write to file
            realEntry = Path.Combine(outDir, realEntry);

            // Create the output subfolder now
            Directory.CreateDirectory(Path.GetDirectoryName(realEntry)!);

            // Now open and write the file if possible
            FileStream fs = File.Create(realEntry);
            if (fs != null)
            {
                if (stream.CanSeek)
                    stream.Seek(0, SeekOrigin.Begin);

                byte[] zbuffer = new byte[_bufferSize];
                int zlen;
                while ((zlen = stream.Read(zbuffer, 0, _bufferSize)) > 0)
                {
                    fs.Write(zbuffer, 0, zlen);
                    fs.Flush();
                }

                stream?.Dispose();
                fs?.Dispose();
            }
            else
            {
                stream?.Dispose();
                fs?.Dispose();
                realEntry = null;
            }

            return realEntry;
        }

        /// <inheritdoc/>
        public override (Stream?, string?) GetEntryStream(string entryName)
        {
#if NET462_OR_GREATER || NETCOREAPP
            // If we have an invalid file
            if (this.Filename == null)
                return (null, null);

            try
            {
                // Open the entry stream
                string realEntry = Path.GetFileNameWithoutExtension(this.Filename);
                var stream = new XZStream(File.OpenRead(this.Filename));

                // Return the stream
                return (stream, realEntry);
            }
            catch (Exception ex)
            {
                logger.Error(ex);
                return (null, null);
            }
#else
            // TODO: Support XZ archives in old .NET
            return (null, null);
#endif
        }

        #endregion

        #region Information

        /// <inheritdoc/>
        public override List<BaseFile>? GetChildren()
        {
            // If we have children cached already
            if (_children != null && _children.Count > 0)
                return _children;

#if NET462_OR_GREATER || NETCOREAPP
            _children = [];

            string? gamename = Path.GetFileNameWithoutExtension(this.Filename);
            BaseFile? possibleTxz = GetTorrentXZFileInfo();

            // If it was, then add it to the outputs and continue
            if (possibleTxz != null && possibleTxz.Filename != null)
            {
                _children.Add(possibleTxz);
                return _children;
            }

            try
            {
                // Create a blank item for the entry
                BaseFile xzEntryRom = new();

                // Perform a quickscan, if flagged to
                if (this.AvailableHashTypes.Length == 1 && this.AvailableHashTypes[0] == HashType.CRC32)
                {
                    xzEntryRom.Filename = gamename;

                    using BinaryReader br = new(File.OpenRead(this.Filename!));
                    br.BaseStream.Seek(-8, SeekOrigin.End);
                    xzEntryRom.CRC = br.ReadBytesBigEndian(4);
                    xzEntryRom.Size = br.ReadInt32BigEndian();
                }
                // Otherwise, use the stream directly
                else
                {
                    var xzStream = new XZStream(File.OpenRead(this.Filename!));
                    xzEntryRom = GetInfo(xzStream, hashes: this.AvailableHashTypes);
                    xzEntryRom.Filename = gamename;
                    xzStream.Dispose();
                }

                // Fill in common details and add to the list
                xzEntryRom.Parent = gamename;
                _children.Add(xzEntryRom);
            }
            catch (Exception ex)
            {
                logger.Error(ex);
                return null;
            }

            return _children;
#else
            // TODO: Support XZ archives in old .NET
            return [];
#endif
        }

        /// <inheritdoc/>
        public override List<string> GetEmptyFolders()
        {
            // XZ files don't contain directories
            return [];
        }

        /// <inheritdoc/>
        public override bool IsTorrent()
        {
            // Check for the file existing first
            if (this.Filename == null || !File.Exists(this.Filename))
                return false;

            string datum = Path.GetFileName(this.Filename).ToLowerInvariant();

            // Check if the name is the right length
            if (!Regex.IsMatch(datum, @"^[0-9a-f]{" + Constants.SHA1Length + @"}\.xz"))
            {
                logger.Warning($"Non SHA-1 filename found, skipping: '{Path.GetFullPath(this.Filename)}'");
                return false;
            }

            return true;
        }

        /// <summary>
        /// Retrieve file information for a single torrent XZ file
        /// </summary>
        /// <returns>Populated DatItem object if success, empty one on error</returns>
        public BaseFile? GetTorrentXZFileInfo()
        {
            // Check for the file existing first
            if (this.Filename == null || !File.Exists(this.Filename))
                return null;

            string datum = Path.GetFileName(this.Filename).ToLowerInvariant();

            // Check if the name is the right length
            if (!Regex.IsMatch(datum, @"^[0-9a-f]{" + Constants.SHA1Length + @"}\.xz"))
            {
                logger.Warning($"Non SHA-1 filename found, skipping: '{Path.GetFullPath(this.Filename)}'");
                return null;
            }

            BaseFile baseFile = new()
            {
                Filename = Path.GetFileNameWithoutExtension(this.Filename).ToLowerInvariant(),
                SHA1 = Path.GetFileNameWithoutExtension(this.Filename).FromHexString(),

                Parent = Path.GetFileNameWithoutExtension(this.Filename).ToLowerInvariant(),
            };

            return baseFile;
        }

        #endregion

        #region Writing

        /// <inheritdoc/>
        public override bool Write(string inputFile, string outDir, BaseFile? baseFile)
        {
            // Check that the input file exists
            if (!File.Exists(inputFile))
            {
                logger.Warning($"File '{inputFile}' does not exist!");
                return false;
            }

            inputFile = Path.GetFullPath(inputFile);

            // Get the file stream for the file and write out
            return Write(File.OpenRead(inputFile), outDir, baseFile);
        }

        /// <inheritdoc/>
        public override bool Write(Stream? inputStream, string outDir, BaseFile? baseFile)
        {
#if NET462_OR_GREATER || NETCOREAPP
            bool success = false;

            // If the stream is not readable, return
            if (inputStream == null || !inputStream.CanRead)
                return success;

            // Make sure the output directory exists
            if (!Directory.Exists(outDir))
                Directory.CreateDirectory(outDir);

            outDir = Path.GetFullPath(outDir);

            // Now get the Rom info for the file so we have hashes and size
            baseFile = GetInfo(inputStream, keepReadOpen: true);

            // Get the output file name
            string outfile = Path.Combine(outDir, Core.Tools.Utilities.GetDepotPath(baseFile.SHA1, Depth)!);
            outfile = outfile.Replace(".gz", ".xz");

            // Check to see if the folder needs to be created
            if (!Directory.Exists(Path.GetDirectoryName(outfile)))
                Directory.CreateDirectory(Path.GetDirectoryName(outfile)!);

            // If the output file exists, don't try to write again
            if (!File.Exists(outfile))
            {
                // Compress the input stream
                XZStream outputStream = new(File.Create(outfile));
                inputStream.CopyTo(outputStream);

                // Dispose of everything
                outputStream.Dispose();
            }

            return true;
#else
            // TODO: Support XZ archives in old .NET
            return false;
#endif
        }

        /// <inheritdoc/>
        public override bool Write(List<string> inputFiles, string outDir, List<BaseFile>? baseFiles)
        {
            throw new NotImplementedException();
        }

        #endregion
    }
}