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

namespace CompatApiClient.Compression
{
    public abstract class Compressor : ICompressor
    {
        public abstract string EncodingType { get; }
        public abstract Stream CreateCompressionStream(Stream output);
        public abstract Stream CreateDecompressionStream(Stream input);

        public virtual async Task<long> CompressAsync(Stream source, Stream destination)
        {
            using (var memStream = new MemoryStream())
            {
                using (var compressed = CreateCompressionStream(memStream))
                    await source.CopyToAsync(compressed).ConfigureAwait(false);
                memStream.Seek(0, SeekOrigin.Begin);
                await memStream.CopyToAsync(destination).ConfigureAwait(false);
                return memStream.Length;
            }
        }

        public virtual async Task<long> DecompressAsync(Stream source, Stream destination)
        {
            using (var memStream = new MemoryStream())
            {
                using (var decompressed = CreateDecompressionStream(source))
                    await decompressed.CopyToAsync(memStream).ConfigureAwait(false);
                memStream.Seek(0, SeekOrigin.Begin);
                await memStream.CopyToAsync(destination).ConfigureAwait(false);
                return memStream.Length;
            }
        }
    }
}