/* 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;
using System.Threading;
using System.Threading.Tasks;

namespace OpenSearch.Net
{
	/// <summary>
	/// Represents an instance of <see cref="PostData"/> that can handle <see cref="PostType.StreamHandler"/>.
	/// Allows users full control over how they want to write data to the stream to OpenSearch
	/// </summary>
	/// <typeparam name="T">The data or a state object used during writing, passed to the handlers to avoid boxing</typeparam>
	public class StreamableData<T> : PostData, IPostData<T>
	{
		private readonly T _state;
		private readonly Action<T, Stream> _syncWriter;
		private readonly Func<T, Stream, CancellationToken, Task> _asyncWriter;

		public StreamableData(T state, Action<T, Stream> syncWriter, Func<T, Stream, CancellationToken, Task> asyncWriter)
		{
			_state = state;
			const string message = "PostData.StreamHandler needs to handle both synchronous and async paths";
			_syncWriter = syncWriter ?? throw new ArgumentNullException(nameof(syncWriter), message);
			_asyncWriter = asyncWriter ?? throw new ArgumentNullException(nameof(asyncWriter), message);
			if (_syncWriter == null || _asyncWriter == null)
				throw new ArgumentNullException();
			Type = PostType.StreamHandler;
		}

		public override void Write(Stream writableStream, IConnectionConfigurationValues settings)
		{
			MemoryStream buffer = null;
			var stream = writableStream;
			BufferIfNeeded(settings, ref buffer, ref stream);
			_syncWriter(_state, stream);
			FinishStream(writableStream, buffer, settings);
		}

		public override async Task WriteAsync(Stream writableStream, IConnectionConfigurationValues settings, CancellationToken cancellationToken)
		{
			MemoryStream buffer = null;
			var stream = writableStream;
			BufferIfNeeded(settings, ref buffer, ref stream);
			await _asyncWriter(_state, stream, cancellationToken).ConfigureAwait(false);
			await FinishStreamAsync(writableStream, buffer, settings, cancellationToken).ConfigureAwait(false);
		}
	}
}