/* 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.Text;

namespace OpenSearch.Net
{
	/// <summary>
	/// An <see cref="IConnectionPool"/> implementation that can be seeded with a cloud id
	/// and will signal the right defaults for the client to use for OpenSearch Cloud to <see cref="IConnectionConfigurationValues"/>.
	///
	/// <para>Read more about OpenSearch Cloud Id:</para>
	/// <para></para>
	/// </summary>
	public class CloudConnectionPool : SingleNodeConnectionPool
	{
		/// <summary>
		/// An <see cref="IConnectionPool"/> implementation that can be seeded with a cloud id
		/// and will signal the right defaults for the client to use for OpenSearch Cloud to <see cref="IConnectionConfigurationValues"/>.
		///
		/// <para>Read more about OpenSearch Cloud Id here</para>
		/// <para></para>
		/// </summary>
		/// <param name="cloudId">
		/// The Cloud Id, this is available on your cluster's dashboard and is a string in the form of <c>cluster_name:base_64_encoded_string</c>
		/// <para>Base64 encoded string contains the following tokens in order separated by $:</para>
		/// <para>* Host Name (mandatory)</para>
		/// <para>* OpenSearch UUID (mandatory)</para>
		/// <para>* OpenSearchDashboards UUID</para>
		/// <para>* APM UUID</para>
		/// <para></para>
		/// <para> We then use these tokens to create the URI to your OpenSearch Cloud cluster!</para>
		/// <para></para>
		/// <para> Read more here: </para>
		/// </param>
		public CloudConnectionPool(string cloudId, BasicAuthenticationCredentials credentials, IDateTimeProvider dateTimeProvider = null) : this(ParseCloudId(cloudId), dateTimeProvider) =>
			BasicCredentials = credentials;

		/// <summary>
		/// An <see cref="IConnectionPool"/> implementation that can be seeded with a cloud id
		/// and will signal the right defaults for the client to use for OpenSearch Cloud to <see cref="IConnectionConfigurationValues"/>.
		///
		/// <para>Read more about OpenSearch Cloud Id here</para>
		/// <para></para>
		/// </summary>
		/// <param name="cloudId">
		/// The Cloud Id, this is available on your cluster's dashboard and is a string in the form of <c>cluster_name:base_64_encoded_string</c>
		/// <para>Base64 encoded string contains the following tokens in order separated by $:</para>
		/// <para>* Host Name (mandatory)</para>
		/// <para>* OpenSearch UUID (mandatory)</para>
		/// <para>* OpenSearchDashboards UUID</para>
		/// <para>* APM UUID</para>
		/// <para></para>
		/// <para> We then use these tokens to create the URI to your OpenSearch Cloud cluster!</para>
		/// <para></para>
		/// <para> Read more here: </para>
		/// </param>
		public CloudConnectionPool(string cloudId, ApiKeyAuthenticationCredentials credentials, IDateTimeProvider dateTimeProvider = null) : this(ParseCloudId(cloudId), dateTimeProvider) =>
			ApiKeyCredentials  = credentials;

		private CloudConnectionPool(ParsedCloudId parsedCloudId, IDateTimeProvider dateTimeProvider = null) : base(parsedCloudId.Uri, dateTimeProvider) =>
			ClusterName = parsedCloudId.Name;

		//TODO implement debugger display for IConnectionPool implementations and display it there and its ToString()
		// ReSharper disable once UnusedAutoPropertyAccessor.Local
		private string ClusterName { get; }

		public BasicAuthenticationCredentials BasicCredentials { get; }

		public ApiKeyAuthenticationCredentials ApiKeyCredentials { get; }

		private struct ParsedCloudId
		{
			public ParsedCloudId(string clusterName, Uri uri)
			{
				Name = clusterName;
				Uri = uri;
			}

			public string Name { get; }
			public Uri Uri { get; }
		}

		private static ParsedCloudId ParseCloudId(string cloudId)
		{
			const string exceptionSuffix = "should be a string in the form of cluster_name:base_64_data";
			if (string.IsNullOrWhiteSpace(cloudId))
				throw new ArgumentException($"Parameter {nameof(cloudId)} was null or empty but {exceptionSuffix}", nameof(cloudId));

			var tokens = cloudId.Split(new[] { ':' }, 2);
			if (tokens.Length != 2)
				throw new ArgumentException($"Parameter {nameof(cloudId)} not in expected format, {exceptionSuffix}", nameof(cloudId));

			var clusterName = tokens[0];
			var encoded = tokens[1];
			if (string.IsNullOrWhiteSpace(encoded))
				throw new ArgumentException($"Parameter {nameof(cloudId)} base_64_data is empty, {exceptionSuffix}", nameof(cloudId));

			var decoded = Encoding.UTF8.GetString(Convert.FromBase64String(encoded));
			var parts = decoded.Split(new[] { '$' });
			if (parts.Length < 2)
				throw new ArgumentException($"Parameter {nameof(cloudId)} decoded base_64_data contains less then 2 tokens, {exceptionSuffix}", nameof(cloudId));

			var domainName = parts[0].Trim();
			if (string.IsNullOrWhiteSpace(domainName))
				throw new ArgumentException($"Parameter {nameof(cloudId)} decoded base_64_data contains no domain name, {exceptionSuffix}", nameof(cloudId));

			var opensearchUuid = parts[1].Trim();
			if (string.IsNullOrWhiteSpace(opensearchUuid))
				throw new ArgumentException($"Parameter {nameof(cloudId)} decoded base_64_data contains no opensearch UUID, {exceptionSuffix}", nameof(cloudId));

			return new ParsedCloudId(clusterName, new Uri($"https://{opensearchUuid}.{domainName}"));
		}

		protected override void DisposeManagedResources()
		{
			ApiKeyCredentials?.Dispose();
			BasicCredentials?.Dispose();
		}
	}
}