/* 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 OpenSearch.Net.Utf8Json;

namespace OpenSearch.Client.Specification.IndicesApi
{
	[JsonFormatter(typeof(AutoExpandReplicasFormatter))]
	public class AutoExpandReplicas
	{
		private const string AllMaxReplicas = "all";
		private Union<int?, string> _maxReplicas;
		private int? _minReplicas;

		public static AutoExpandReplicas Disabled { get; } = new AutoExpandReplicas();

		/// <summary>
		/// Whether auto expand replicas is enabled
		/// </summary>
		public bool Enabled { get; private set; }

		/// <summary>
		/// The upper bound of replicas. Can be an integer value or a string value of "all"
		/// </summary>
		public Union<int?, string> MaxReplicas
		{
			get => _maxReplicas;
			private set
			{
				if (value == null && _minReplicas == null) Enabled = false;
				else Enabled = true;
				_maxReplicas = value;
			}
		}

		/// <summary>
		/// The lower bound of replicas
		/// </summary>
		public int? MinReplicas
		{
			get => _minReplicas;
			private set
			{
				if (value == null && _maxReplicas == null) Enabled = false;
				else Enabled = true;
				_minReplicas = value;
			}
		}

		/// <summary>
		/// Creates an <see cref="AutoExpandReplicas" /> with the specified lower and upper bounds of replicas
		/// </summary>
		public static AutoExpandReplicas Create(int minReplicas, int maxReplicas)
		{
			if (minReplicas < 0)
				throw new ArgumentException("minReplicas must be greater than or equal to 0", nameof(minReplicas));

			if (maxReplicas < 0)
				throw new ArgumentException("maxReplicas must be greater than or equal to 0", nameof(minReplicas));

			if (minReplicas > maxReplicas)
				throw new ArgumentException("minReplicas must be less than or equal to maxReplicas", nameof(minReplicas));

			return new AutoExpandReplicas
			{
				Enabled = true,
				MinReplicas = minReplicas,
				MaxReplicas = maxReplicas
			};
		}

		/// <summary>
		/// Creates an <see cref="AutoExpandReplicas" /> with the specified lower bound of replicas and an
		/// "all" upper bound of replicas
		/// </summary>
		public static AutoExpandReplicas Create(int minReplicas)
		{
			if (minReplicas < 0)
				throw new ArgumentException("minReplicas must be greater than or equal to 0", nameof(minReplicas));

			return new AutoExpandReplicas
			{
				Enabled = true,
				MinReplicas = minReplicas,
				MaxReplicas = AllMaxReplicas
			};
		}

		/// <summary>
		/// Creates an <see cref="AutoExpandReplicas" /> with the specified lower and upper bounds of replicas.
		/// </summary>
		/// <example>0-5</example>
		/// <example>0-all</example>
		public static AutoExpandReplicas Create(string value)
		{
			if (value.IsNullOrEmpty())
				throw new ArgumentException("cannot be null or empty", nameof(value));

			if (value.Equals("false", StringComparison.OrdinalIgnoreCase))
				return Disabled;

			var expandReplicaParts = value.Split('-');
			if (expandReplicaParts.Length != 2)
				throw new ArgumentException("must contain a 'from' and 'to' value", nameof(value));

			if (!int.TryParse(expandReplicaParts[0], out var minReplicas))
				throw new FormatException("minReplicas must be an integer");

			var maxReplicas = 0;
			var parsedMaxReplicas = false;
			var allMaxReplicas = expandReplicaParts[1] == AllMaxReplicas;

			if (!allMaxReplicas)
				parsedMaxReplicas = int.TryParse(expandReplicaParts[1], out maxReplicas);

			if (!parsedMaxReplicas && !allMaxReplicas)
				throw new FormatException("minReplicas must be an integer or 'all'");

			return parsedMaxReplicas
				? Create(minReplicas, maxReplicas)
				: Create(minReplicas);
		}

		public static implicit operator AutoExpandReplicas(string value) =>
			value.IsNullOrEmpty() ? null : Create(value);

		public override string ToString()
		{
			if (!Enabled) return "false";

			var maxReplicas = MaxReplicas.Match(i => i.ToString(), s => s);
			return string.Join("-", MinReplicas, maxReplicas);
		}
	}

	internal class AutoExpandReplicasFormatter : IJsonFormatter<AutoExpandReplicas>
	{
		public AutoExpandReplicas Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var token = reader.GetCurrentJsonToken();

			if (token == JsonToken.False)
				return AutoExpandReplicas.Disabled;
			if (token == JsonToken.String)
				return AutoExpandReplicas.Create(reader.ReadString());

			throw new Exception($"Cannot deserialize {typeof(AutoExpandReplicas)} from {token}");
		}

		public void Serialize(ref JsonWriter writer, AutoExpandReplicas value, IJsonFormatterResolver formatterResolver)
		{
			if (value == null || !value.Enabled)
			{
				writer.WriteBoolean(false);
				return;
			}

			writer.WriteString(value.ToString());
		}
	}
}