/* 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.Threading;

namespace OpenSearch.Client
{
	public partial interface IOpenSearchClient
	{
		/// <summary>
		/// Helper method that allows you to reindex from one index into another using ScrollAll and BulkAll.
		/// </summary>
		/// <returns>An IObservable&lt;ReindexResponse&lt;T&gt;$gt; you can subscribe to to listen to the progress of the reindex process</returns>
		IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			Func<TSource, TTarget> mapper,
			Func<ReindexDescriptor<TSource, TTarget>, IReindexRequest<TSource, TTarget>> selector,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class
			where TTarget : class;

		/// <summary>
		/// Helper method that allows you to reindex from one index into another using ScrollAll and BulkAll.
		/// </summary>
		/// <returns>An IObservable&lt;ReindexResponse&lt;T&gt;$gt; you can subscribe to to listen to the progress of the reindex process</returns>
		IObservable<BulkAllResponse> Reindex<TSource>(
			Func<ReindexDescriptor<TSource, TSource>, IReindexRequest<TSource, TSource>> selector,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class;

		/// <summary>
		/// Helper method that allows you to reindex from one index into another using ScrollAll and BulkAll.
		/// </summary>
		/// <param name="request">a request object to describe the reindex operation</param>
		/// <returns>An IObservable&lt;ReindexResponse&lt;T&gt;$gt; you can subscribe to to listen to the progress of the reindex process</returns>
		IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			IReindexRequest<TSource, TTarget> request,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class
			where TTarget : class;

		/// <summary>
		/// Helper method that allows you to reindex from one index into another using ScrollAll and BulkAll.
		/// </summary>
		/// <param name="request">a request object to describe the reindex operation</param>
		/// <returns>An IObservable&lt;ReindexResponse&lt;T&gt;$gt; you can subscribe to to listen to the progress of the reindex process</returns>
		IObservable<BulkAllResponse> Reindex<TSource>(
			IReindexRequest<TSource> request,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class;

		/// <summary>
		/// Simplified form for reindex which will cover 80% of its usecases. Allows you to index all documents of type T from
		/// <paramref name="fromIndex" /> to <paramref name="toIndex" />
		/// optionally limiting the documents found in <paramref name="fromIndex" /> by using <paramref name="selector" />.
		/// </summary>
		/// <param name="fromIndex">The source index, from which all types will be returned</param>
		/// <param name="toIndex">
		/// The target index, if it does not exist already will be created using the same settings of
		/// <paramref name="fromIndex" />
		/// </param>
		/// <param name="selector">an optional query limiting the documents found in <paramref name="fromIndex" /></param>
		IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			IndexName fromIndex,
			IndexName toIndex,
			Func<TSource, TTarget> mapper,
			Func<QueryContainerDescriptor<TSource>, QueryContainer> selector = null,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class
			where TTarget : class;

		/// <summary>
		/// Simplified form for reindex which will cover 80% of its use cases. Allows you to index all documents of type T from
		/// <paramref name="fromIndex" /> to <paramref name="toIndex" />
		/// optionally limiting the documents found in <paramref name="fromIndex" /> by using <paramref name="selector" />.
		/// </summary>
		/// <param name="fromIndex">The source index, from which all types will be returned</param>
		/// <param name="toIndex">
		/// The target index, if it does not exist already will be created using the same settings of
		/// <paramref name="fromIndex" />
		/// </param>
		/// <param name="selector">an optional query limiting the documents found in <paramref name="fromIndex" /></param>
		IObservable<BulkAllResponse> Reindex<TSource>(
			IndexName fromIndex,
			IndexName toIndex,
			Func<QueryContainerDescriptor<TSource>, QueryContainer> selector = null,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class;
	}

	public partial class OpenSearchClient
	{
		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource>(
			Func<ReindexDescriptor<TSource, TSource>, IReindexRequest<TSource, TSource>> selector,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class =>
			Reindex(selector.InvokeOrDefault(new ReindexDescriptor<TSource, TSource>(s => s)));

		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			Func<TSource, TTarget> mapper,
			Func<ReindexDescriptor<TSource, TTarget>, IReindexRequest<TSource, TTarget>> selector,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TTarget : class
			where TSource : class =>
			Reindex(selector.InvokeOrDefault(new ReindexDescriptor<TSource, TTarget>(mapper)));

		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource>(
			IReindexRequest<TSource> request,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class =>
			Reindex<TSource, TSource>(request, cancellationToken);


		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			IReindexRequest<TSource, TTarget> request,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TTarget : class
			where TSource : class
		{
			if (request.ScrollAll == null)
				throw new ArgumentException(
					"ScrollAll property must be set in order to get the source of a Reindex operation");
			if (request.BulkAll == null)
				throw new ArgumentException(
					"BulkAll property must set in order to get the target of a Reindex operation");

			return new ReindexObservable<TSource, TTarget>(this, ConnectionSettings, request, cancellationToken);
		}

		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource, TTarget>(
			IndexName fromIndex,
			IndexName toIndex,
			Func<TSource, TTarget> mapper,
			Func<QueryContainerDescriptor<TSource>, QueryContainer> selector = null,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TTarget : class
			where TSource : class =>
			Reindex(
				mapper,
				SimplifiedReindexer<TSource, TTarget>(fromIndex, toIndex, selector)
				, cancellationToken);

		/// <inheritdoc />
		public IObservable<BulkAllResponse> Reindex<TSource>(
			IndexName fromIndex,
			IndexName toIndex,
			Func<QueryContainerDescriptor<TSource>, QueryContainer> selector = null,
			CancellationToken cancellationToken = default(CancellationToken)
		)
			where TSource : class =>
			Reindex(
				s => s,
				SimplifiedReindexer<TSource, TSource>(fromIndex, toIndex, selector)
				, cancellationToken);

		private static Func<ReindexDescriptor<TSource, TTarget>, IReindexRequest<TSource, TTarget>> SimplifiedReindexer<TSource, TTarget>(
			IndexName fromIndex,
			IndexName toIndex,
			Func<QueryContainerDescriptor<TSource>, QueryContainer> selector
		)
			where TTarget : class
			where TSource : class => r => r
			.ScrollAll("1m", -1, search => search
				.Search(ss => ss
					.Size(CoordinatedRequestDefaults.ReindexScrollSize)
					.Index(fromIndex)
					.Query(selector)
				)
			)
			.BulkAll(b => b.Index(toIndex));
	}
}