using System.IO;
using System.IO.Compression;
using System.Threading.Tasks;

namespace GZipComressionTestApp
{
    class Program
    {
        static void Main(string[] args)
        {
            //var task = Task.Run(() => Compress(File.ReadAllBytes("SkypeSetup.exe"), "SkypeSetup.exe.gz"));
            //task.Wait();
            var task = Task.Run(() => Decompress(DecompressToMemoryStream("SkypeSetup.exe.gz").Result));
            task.Wait();
        }

        public static async Task Compress(byte[] buffer, string outputFile)
        {
            using (var inputStream = new MemoryStream(buffer))
            {
                await Compress(inputStream, outputFile);
            }
        }

        public static async Task Compress(Stream inputStream, string outputFile)
        {
            using (var outputStream = File.Create(outputFile))
            using (var gzipStream = new GZipStream(outputStream, CompressionMode.Compress))
            {
                await inputStream.CopyToAsync(gzipStream);
                gzipStream.Close();
            }
        }

        public static async Task<MemoryStream> DecompressToMemoryStream(string inputFile)
        {
            var outputStream = new MemoryStream();

            using (var inputStream = File.Open(inputFile, FileMode.Open, FileAccess.Read, FileShare.Read))
            using (var gzipStream = new GZipStream(inputStream, CompressionMode.Decompress))
            {
                await gzipStream.CopyToAsync(outputStream);

                gzipStream.Close();
                inputStream.Close();
                outputStream.Position = 0;
                return outputStream;
            }
        }

        public static async Task Decompress(MemoryStream memoryStream)
        {
            using (var fileStream = new FileStream("SkypeSetup.exe", FileMode.Create, FileAccess.Write, FileShare.Write))
            {
                await memoryStream.CopyToAsync(fileStream);
            }
        }
    }
}