using System.Numerics;
using System.Security.Cryptography;

namespace Microsoft.IO.RecyclableMemoryStream.Examples
{
    class Program
    {
        private static readonly RecyclableMemoryStreamManager manager = new();

        static void Main(string[] args)
        {
            var sourceBuffer = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7 };

            using (var stream = manager.GetStream())
            {
                stream.Write(sourceBuffer, 0, sourceBuffer.Length);
            }
        }
    }

    internal class WriteExample
    {
        readonly RecyclableMemoryStreamManager manager = new();
        readonly byte[] sourceBuffer = new byte[100];
        internal void Example()
        {
            // Writing an buffer to a stream
            // START EXAMPLE
            using (var stream = this.manager.GetStream("Program.Main"))
            {
                stream.Write(this.sourceBuffer, 0, this.sourceBuffer.Length);
            }
            // END EXAMPLE

            // Provide buffer in GetStream

            // START EXAMPLE
            using (var stream = this.manager.GetStream("Program.Main", this.sourceBuffer,
                                 0, this.sourceBuffer.Length))
            {

            }
            // END EXAMPLE
        }
    }

    internal class PoolParameters
    {
        internal void Example()
        {
            // START EXAMPLE
            var options = new RecyclableMemoryStreamManager.Options()
            {
                BlockSize = 1024,
                LargeBufferMultiple = 1024 * 1024,
                MaximumBufferSize = 16 * 1024 * 1024,
                GenerateCallStacks = true,
                AggressiveBufferReturn = true,
                MaximumLargePoolFreeBytes = 16 * 1024 * 1024 * 4,
                MaximumSmallPoolFreeBytes = 100 * 1024,
            };

            var manager = new RecyclableMemoryStreamManager(options);
            // END EXAMPLE
        }
    }

    internal class IBufferWriterExample
    {
        readonly RecyclableMemoryStreamManager manager = new();

        internal void Example()
        {
            // START EXAMPLE
            var bigInt = BigInteger.Parse("123456789013374299100987654321");

            using (var stream = this.manager.GetStream())
            {
                Span<byte> buffer = stream.GetSpan(bigInt.GetByteCount());
                bigInt.TryWriteBytes(buffer, out int bytesWritten);
                stream.Advance(bytesWritten);
            }
            //END EXAMPLE
        }
    }

    internal class GetReadOnlySequenceExample
    {
        readonly RecyclableMemoryStreamManager manager = new();

        internal void Example()
        {
            // START EXAMPLE
            using (var stream = this.manager.GetStream())
            using (var sha256Hasher = IncrementalHash.CreateHash(HashAlgorithmName.SHA256))
            {
                foreach (var memory in stream.GetReadOnlySequence())
                {
                    sha256Hasher.AppendData(memory.Span);
                }

                sha256Hasher.GetHashAndReset();
            }
            //END EXAMPLE
        }
    }
}