/* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*
*  Licensed to Elasticsearch B.V. under one or more contributor
*  license agreements. See the NOTICE file distributed with
*  this work for additional information regarding copyright
*  ownership. Elasticsearch B.V. licenses this file to you under
*  the Apache License, Version 2.0 (the "License"); you may
*  not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
* 	http://www.apache.org/licenses/LICENSE-2.0
*
*  Unless required by applicable law or agreed to in writing,
*  software distributed under the License is distributed on an
*  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
*  KIND, either express or implied.  See the License for the
*  specific language governing permissions and limitations
*  under the License.
*/

using System;
using System.IO;

namespace OpenSearch.Net
{
	/// <summary>
	/// A factory for creating memory streams using a recyclable pool of <see cref="MemoryStream" /> instances
	/// </summary>
	public class RecyclableMemoryStreamFactory : IMemoryStreamFactory
	{
		private const string TagSource = "OpenSearch.Net";
		private readonly RecyclableMemoryStreamManager _manager;

		public static RecyclableMemoryStreamFactory Default { get; } = new RecyclableMemoryStreamFactory();

		public RecyclableMemoryStreamFactory() => _manager = CreateManager(experimental: false);

		private static RecyclableMemoryStreamManager CreateManager(bool experimental)
		{
			if (!experimental) return new RecyclableMemoryStreamManager() { AggressiveBufferReturn = true };

			const int blockSize = 1024;
			const int largeBufferMultiple = 1024 * 1024;
			const int maxBufferSize = 16 * largeBufferMultiple;
			return new RecyclableMemoryStreamManager(blockSize, largeBufferMultiple, maxBufferSize)
			{
				AggressiveBufferReturn = true, MaximumFreeLargePoolBytes = maxBufferSize * 4, MaximumFreeSmallPoolBytes = 100 * blockSize
			};

		}

		public MemoryStream Create() => _manager.GetStream(Guid.Empty, TagSource);

		public MemoryStream Create(byte[] bytes) => _manager.GetStream(bytes);

		public MemoryStream Create(byte[] bytes, int index, int count) => _manager.GetStream(Guid.Empty, TagSource, bytes, index, count);
	}
}