/* 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.Collections.Generic;
using OpenSearch.Net.Extensions;
using OpenSearch.Net.Utf8Json;
using OpenSearch.Net.Utf8Json.Internal;


namespace OpenSearch.Client.Specification.IndicesApi
{
	internal class SimilarityFormatter : IJsonFormatter<ISimilarity>
	{
		private static readonly AutomataDictionary Similarities = new AutomataDictionary
		{
			{ "BM25", 0 },
			{ "LMDirichlet", 1 },
			{ "DFR", 2 },
			{ "DFI", 3 },
			{ "IB", 4 },
			{ "LMJelinekMercer", 5 },
			{ "scripted", 6 }
		};

		private static readonly byte[] Type = JsonWriter.GetEncodedPropertyNameWithoutQuotation("type");

		public ISimilarity Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var arraySegment = reader.ReadNextBlockSegment();
			var segmentReader = new JsonReader(arraySegment.Array, arraySegment.Offset);

			var count = 0;
			ArraySegment<byte> type = default;
			while (segmentReader.ReadIsInObject(ref count))
			{
				var propertyName = segmentReader.ReadPropertyNameSegmentRaw();

				if (propertyName.EqualsBytes(Type))
				{
					type = segmentReader.ReadStringSegmentUnsafe();
					break;
				}

				segmentReader.ReadNextBlock();
			}

			segmentReader = new JsonReader(arraySegment.Array, arraySegment.Offset);

			if (Similarities.TryGetValue(type, out var value))
			{
				switch (value)
				{
					case 0:
						return Deserialize<BM25Similarity>(ref segmentReader, formatterResolver);
					case 1:
						return Deserialize<LMDirichletSimilarity>(ref segmentReader, formatterResolver);
					case 2:
						return Deserialize<DFRSimilarity>(ref segmentReader, formatterResolver);
					case 3:
						return Deserialize<DFISimilarity>(ref segmentReader, formatterResolver);
					case 4:
						return Deserialize<IBSimilarity>(ref segmentReader, formatterResolver);
					case 5:
						return Deserialize<LMJelinekMercerSimilarity>(ref segmentReader, formatterResolver);
					case 6:
						return Deserialize<ScriptedSimilarity>(ref segmentReader, formatterResolver);
				}
			}

			var formatter = formatterResolver.GetFormatter<Dictionary<string, object>>();
			var dict = formatter.Deserialize(ref segmentReader, formatterResolver);
			return new CustomSimilarity(dict);
		}

		public void Serialize(ref JsonWriter writer, ISimilarity value, IJsonFormatterResolver formatterResolver)
		{
			if (value == null)
			{
				writer.WriteNull();
				return;
			}

			switch (value.Type)
			{
				case "BM25":
					Serialize<IBM25Similarity>(ref writer, value, formatterResolver);
					break;
				case "LMDirichlet":
					Serialize<ILMDirichletSimilarity>(ref writer, value, formatterResolver);
					break;
				case "DFR":
					Serialize<IDFRSimilarity>(ref writer, value, formatterResolver);
					break;
				case "DFI":
					Serialize<IDFISimilarity>(ref writer, value, formatterResolver);
					break;
				case "IB":
					Serialize<IIBSimilarity>(ref writer, value, formatterResolver);
					break;
				case "LMJelinekMercer":
					Serialize<ILMJelinekMercerSimilarity>(ref writer, value, formatterResolver);
					break;
				case "scripted":
					Serialize<IScriptedSimilarity>(ref writer, value, formatterResolver);
					break;
				default:
					Serialize<ICustomSimilarity>(ref writer, value, formatterResolver);
					break;
			}
		}

		private static void Serialize<TSimilarity>(ref JsonWriter writer, ISimilarity value, IJsonFormatterResolver formatterResolver)
			where TSimilarity : class, ISimilarity
		{
			var formatter = formatterResolver.GetFormatter<TSimilarity>();
			formatter.Serialize(ref writer, value as TSimilarity, formatterResolver);
		}

		private static TSimilarity Deserialize<TSimilarity>(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
			where TSimilarity : ISimilarity
		{
			var formatter = formatterResolver.GetFormatter<TSimilarity>();
			return formatter.Deserialize(ref reader, formatterResolver);
		}
	}
}