/* 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.
*/

namespace OpenSearch.Net
{
	/// <summary>
	/// Produces the meta header when this functionality is enabled in the <see cref="ConnectionConfiguration"/>.
	/// </summary>
	public class MetaHeaderProvider
	{
		private const string MetaHeaderName = "opensearch-client-meta";
		
		private readonly MetaDataHeader _asyncMetaDataHeader;
		private readonly MetaDataHeader _syncMetaDataHeader;

		public MetaHeaderProvider()
		{
			var clientVersionInfo = ClientVersionInfo.Create<IOpenSearchLowLevelClient>();
			_asyncMetaDataHeader = new MetaDataHeader(clientVersionInfo, "opensearch", true);
			_syncMetaDataHeader = new MetaDataHeader(clientVersionInfo, "opensearch", false);
		}
		
		public string HeaderName => MetaHeaderName;

		public string ProduceHeaderValue(RequestData requestData)
		{
			try
			{
				if (requestData.ConnectionSettings.DisableMetaHeader)
					return null;

				var headerValue = requestData.IsAsync
					? _asyncMetaDataHeader.ToString()
					: _syncMetaDataHeader.ToString();

				if (requestData.RequestMetaData.TryGetValue(RequestMetaData.HelperKey, out var helperSuffix))
					headerValue = $"{headerValue},h={helperSuffix}";

				return headerValue;
			}
			catch
			{
				// don't fail the application just because we cannot create this optional header
			}

			return string.Empty;
		}
	}
}