AmiClient.Observable.cs

/* Copyright © Alex Forster. All rights reserved.
 * https://github.com/alexforster/AmiClient/
 *
 * Licensed 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.
 */

namespace Ami
{
    using System;
    using System.IO;
    using System.Text;
    using System.Collections.Generic;
    using System.Collections.Concurrent;
    using System.Net.Sockets;
    using System.Threading;
    using System.Threading.Tasks;
    using System.Linq;
    using System.Reactive.Linq;
    using System.Security.Cryptography;

    using ByteArrayExtensions;

    public sealed partial class AmiClient : IObservable<AmiMessage>
    {
        private void Dispatch(AmiMessage message)
        {
            foreach(var observer in this.observers.Keys)
            {
                observer.OnNext(message);
            }
        }

        public IDisposable Subscribe(IObserver<AmiMessage> observer)
        {
            if(observer == null)
            {
                throw new ArgumentNullException(nameof(observer));
            }

            return this.observers.GetOrAdd(observer, _ => new Subscription(this, observer));
        }

        public void Unsubscribe(IObserver<AmiMessage> observer)
        {
            if(observer == null)
            {
                throw new ArgumentNullException(nameof(observer));
            }

            this.observers.TryRemove(observer, out _);
        }

        private sealed class Subscription : IDisposable
        {
            private readonly AmiClient client;

            private readonly IObserver<AmiMessage> observer;

            internal Subscription(AmiClient client, IObserver<AmiMessage> observer)
            {
                this.client = client;
                this.observer = observer;
            }

            public void Dispose()
            {
                this.client.Unsubscribe(this.observer);
            }
        }
    }
}