using System.Threading.Tasks;

namespace System.Xml {
    internal static partial class BinHexEncoder {

        internal static async Task EncodeAsync( byte[] buffer, int index, int count, XmlWriter writer ) {
            if ( buffer == null ) {
                throw new ArgumentNullException( "buffer" );
            }
            if ( index < 0 ) {
                throw new ArgumentOutOfRangeException( "index" );
            }
            if ( count < 0 ) {
                throw new ArgumentOutOfRangeException( "count" );
            }
            if ( count > buffer.Length - index ) {
                throw new ArgumentOutOfRangeException( "count" );
            }

            char[] chars = new char[ ( count * 2 ) < CharsChunkSize ? ( count * 2 ) : CharsChunkSize ];
            int endIndex = index + count;
            while ( index < endIndex ) {
                int cnt = ( count < CharsChunkSize/2 ) ? count : CharsChunkSize/2;
                int charCount = Encode( buffer, index, cnt, chars );
                await writer.WriteRawAsync( chars, 0, charCount ).ConfigureAwait(false);
                index += cnt;
                count -= cnt;
            }
        }

    } // class
} // namespace