// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.IO;
using SevenZip.Compression.LZMA;
 
namespace Microsoft.SignCheck.Verification
{
    public class LZMAUtils
    {
        /// <summary>
        /// Decompresses an LZMA stream.
        /// </summary>
        /// <param name="sourceFile">The file containing the LZMA compressed stream.</param>
        /// <param name="destinationFile">The output file containing the decompressed LZMA stream.</param>
        public static void Decompress(string sourceFile, string destinationFile)
        {
            string destinationDir = Path.GetDirectoryName(destinationFile);
 
            if (!Directory.Exists(destinationDir))
            {
                Directory.CreateDirectory(destinationDir);
            }
 
            using (FileStream inFile = new FileStream(sourceFile, FileMode.Open))
            using (FileStream outFile = new FileStream(destinationFile, FileMode.Create))
            {
                Decoder decoder = new Decoder();
                byte[] properties = new byte[5];
                byte[] fileLengthBytes = new byte[8];
 
                ReadExactly(inFile, properties, 0, 5);
                ReadExactly(inFile, fileLengthBytes, 0, 8);
 
                long fileLength = BitConverter.ToInt64(fileLengthBytes, 0);
                decoder.SetDecoderProperties(properties);
 
                decoder.Code(inFile, outFile, inFile.Length, fileLength, progress: null);
            }
        }
 
#if NET
        private static void ReadExactly(FileStream stream, byte[] buffer, int offset, int count)
        {
            stream.ReadExactly(buffer, offset, count);
        }
#else
        private static void ReadExactly(FileStream stream, byte[] buffer, int offset, int count)
        {
            while (count > 0)
            {
                int read = stream.Read(buffer, offset, count);
                if (read <= 0)
                {
                    throw new EndOfStreamException();
                }
                offset += read;
                count -= read;
            }
        }
#endif
    }
}