/* 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 System.Linq.Expressions;
using System.Runtime.Serialization;

namespace OpenSearch.Client
{
	/// <summary>
	/// An aggregation that computes metrics based on values extracted in
	/// one way or another from the documents that are being aggregated.
	/// </summary>
	public interface IMetricAggregation : IAggregation
	{
		/// <summary>
		/// The field on which to aggregate
		/// </summary>
		[DataMember(Name ="field")]
		Field Field { get; set; }

		/// <summary>
		/// The value to use when the aggregation finds a missing value in a document
		/// </summary>
		[DataMember(Name ="missing")]
		double? Missing { get; set; }

		/// <summary>
		/// The script to use for the aggregation
		/// </summary>
		[DataMember(Name ="script")]
		IScript Script { get; set; }
	}

	/// <summary>
	/// A metric aggregation that can accept a format to use for the output of the aggregation
	/// </summary>
	public interface IFormattableMetricAggregation : IMetricAggregation
	{
		/// <summary>
		/// The format to use for the output of the aggregation
		/// </summary>
		[DataMember(Name = "format")]
		string Format { get; set; }
	}

	public abstract class MetricAggregationBase : AggregationBase, IMetricAggregation
	{
		internal MetricAggregationBase() { }

		protected MetricAggregationBase(string name, Field field) : base(name) => Field = field;

		public Field Field { get; set; }
		public double? Missing { get; set; }
		public virtual IScript Script { get; set; }
	}

	public abstract class FormattableMetricAggregationBase : MetricAggregationBase, IFormattableMetricAggregation
	{
		internal FormattableMetricAggregationBase() { }

		protected FormattableMetricAggregationBase(string name, Field field) : base(name, field) { }

		/// <inheritdoc />
		public string Format { get; set; }
	}

	public abstract class MetricAggregationDescriptorBase<TMetricAggregation, TMetricAggregationInterface, T>
		: DescriptorBase<TMetricAggregation, TMetricAggregationInterface>, IMetricAggregation
		where TMetricAggregation : MetricAggregationDescriptorBase<TMetricAggregation, TMetricAggregationInterface, T>
		, TMetricAggregationInterface, IMetricAggregation
		where T : class
		where TMetricAggregationInterface : class, IMetricAggregation
	{
		Field IMetricAggregation.Field { get; set; }

		IDictionary<string, object> IAggregation.Meta { get; set; }

		double? IMetricAggregation.Missing { get; set; }

		string IAggregation.Name { get; set; }

		IScript IMetricAggregation.Script { get; set; }

		/// <inheritdoc cref="IMetricAggregation.Field"/>
		public TMetricAggregation Field(Field field) => Assign(field, (a, v) => a.Field = v);

		/// <inheritdoc cref="IMetricAggregation.Field"/>
		public TMetricAggregation Field<TValue>(Expression<Func<T, TValue>> field) => Assign(field, (a, v) => a.Field = v);

		/// <inheritdoc cref="IMetricAggregation.Script"/>
		public virtual TMetricAggregation Script(string script) => Assign((InlineScript)script, (a, v) => a.Script = v);

		/// <inheritdoc cref="IMetricAggregation.Script"/>
		public virtual TMetricAggregation Script(Func<ScriptDescriptor, IScript> scriptSelector) =>
			Assign(scriptSelector, (a, v) => a.Script = v?.Invoke(new ScriptDescriptor()));

		/// <inheritdoc cref="IMetricAggregation.Missing"/>
		public TMetricAggregation Missing(double? missing) => Assign(missing, (a, v) => a.Missing = v);

		/// <inheritdoc cref="IAggregation.Meta"/>
		public TMetricAggregation Meta(Func<FluentDictionary<string, object>, FluentDictionary<string, object>> selector) =>
			Assign(selector, (a, v) => a.Meta = v?.Invoke(new FluentDictionary<string, object>()));
	}

	public abstract class FormattableMetricAggregationDescriptorBase<TFormattableMetricAggregation, TFormattableMetricAggregationInterface, T>
		: MetricAggregationDescriptorBase<TFormattableMetricAggregation, TFormattableMetricAggregationInterface, T>, IFormattableMetricAggregation
		where TFormattableMetricAggregation :
		FormattableMetricAggregationDescriptorBase<TFormattableMetricAggregation, TFormattableMetricAggregationInterface, T>
		, TFormattableMetricAggregationInterface, IFormattableMetricAggregation
		where T : class
		where TFormattableMetricAggregationInterface : class, IFormattableMetricAggregation
	{
		string IFormattableMetricAggregation.Format { get; set; }

		/// <inheritdoc cref="IFormattableMetricAggregation.Format"/>
		public TFormattableMetricAggregation Format(string format) =>
			Assign(format, (a, v) => a.Format = v);
	}
}