/* 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;

namespace OpenSearch.Net.Diagnostics
{
	public abstract class TypedDiagnosticObserverBase<TOnNext> : IObserver<KeyValuePair<string, object>>
	{
		private readonly Action<KeyValuePair<string, TOnNext>> _onNext;
		private readonly Action<Exception> _onError;
		private readonly Action _onCompleted;

		protected TypedDiagnosticObserverBase(
			Action<KeyValuePair<string, TOnNext>> onNext,
			Action<Exception> onError = null,
			Action onCompleted = null
		)
		{
			_onNext= onNext;
			_onError = onError;
			_onCompleted = onCompleted;
		}

		void IObserver<KeyValuePair<string, object>>.OnCompleted() => _onCompleted?.Invoke();

		void IObserver<KeyValuePair<string, object>>.OnError(Exception error) => _onError?.Invoke(error);

		void IObserver<KeyValuePair<string, object>>.OnNext(KeyValuePair<string, object> value)
		{
			if (value.Value is TOnNext next) _onNext?.Invoke(new KeyValuePair<string, TOnNext>(value.Key, next));
			else if (value.Value == null) _onNext?.Invoke(new KeyValuePair<string, TOnNext>(value.Key, default));

			else throw new Exception($"{value.Key} received unexpected type {value.Value.GetType()}");

		}
	}
	public abstract class TypedDiagnosticObserverBase<TOnNextStart, TOnNextEnd> : IObserver<KeyValuePair<string, object>>
	{
		private readonly Action<KeyValuePair<string, TOnNextStart>> _onNextStart;
		private readonly Action<KeyValuePair<string, TOnNextEnd>> _onNextEnd;
		private readonly Action<Exception> _onError;
		private readonly Action _onCompleted;

		protected TypedDiagnosticObserverBase(
			Action<KeyValuePair<string, TOnNextStart>> onNextStart,
			Action<KeyValuePair<string, TOnNextEnd>> onNextEnd,
			Action<Exception> onError = null,
			Action onCompleted = null
		)
		{
			_onNextStart = onNextStart;
			_onNextEnd = onNextEnd;
			_onError = onError;
			_onCompleted = onCompleted;
		}

		void IObserver<KeyValuePair<string, object>>.OnCompleted() => _onCompleted?.Invoke();

		void IObserver<KeyValuePair<string, object>>.OnError(Exception error) => _onError?.Invoke(error);

		void IObserver<KeyValuePair<string, object>>.OnNext(KeyValuePair<string, object> value)
		{
			if (value.Value is TOnNextStart nextStart) _onNextStart?.Invoke(new KeyValuePair<string, TOnNextStart>(value.Key, nextStart));
			else if (value.Key.EndsWith(".Start") && value.Value is null) _onNextStart?.Invoke(new KeyValuePair<string, TOnNextStart>(value.Key, default));

			else if (value.Value is TOnNextEnd nextEnd) _onNextEnd?.Invoke(new KeyValuePair<string, TOnNextEnd>(value.Key, nextEnd));
			else if (value.Key.EndsWith(".Stop") && value.Value is null) _onNextEnd?.Invoke(new KeyValuePair<string, TOnNextEnd>(value.Key, default));

			else throw new Exception($"{value.Key} received unexpected type {value.Value.GetType()}");

		}
	}
}