adding skeleton for cache hub proxy

Selector.Web/Pages/Now.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.Extensions.Logging;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.AspNetCore.Identity;
+
+using Selector.Web.Hubs;
+using Selector.Web.Service;
+using Selector.Model;
+
+namespace Selector.Web.Pages
+{
+    public class NowModel : PageModel
+    {
+        private readonly ILogger<NowModel> Logger;
+        private readonly INowPlayingMappingFactory MappingFactory;
+        private readonly CacheHubProxy HubProxy;
+        private readonly UserManager<ApplicationUser> UserManager;
+
+        public NowModel(ILogger<NowModel> logger, 
+            INowPlayingMappingFactory mappingFactory, 
+            CacheHubProxy hubProxy, 
+            UserManager<ApplicationUser> userManager)
+        {
+            Logger = logger;
+            MappingFactory = mappingFactory;
+            HubProxy = hubProxy;
+            UserManager = userManager;
+        }
+
+        public void OnGet()
+        {
+            HubProxy.FormMapping(MappingFactory.Get(UserManager.GetUserId(User)));
+        }
+    }
+}

Selector.Web/Pages/Now.cshtml

@@ -0,0 +1,13 @@
+@page
+@model NowModel
+@{
+    ViewData["Title"] = "Now";
+}
+
+<div class="text-center">
+    <h1 class="display-4">Now</h1>
+</div>
+
+@section Scripts {
+    <script type="module" src="~/js/now.bundle.js"></script>
+}

Selector.Web/Services/CacheHubProxy.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.AspNetCore.SignalR;
+
+using StackExchange.Redis;
+using Selector.Web.Hubs;
+
+namespace Selector.Web.Service
+{
+    public class CacheHubProxy
+    {
+        private readonly ILogger<CacheHubProxy> Logger;
+        private readonly ISubscriber Subscriber;
+        private readonly ServiceProvider Services;
+
+        public CacheHubProxy(ILogger<CacheHubProxy> logger,
+            ISubscriber subscriber,
+            ServiceProvider services
+        )
+        {
+            Logger = logger;
+            Subscriber = subscriber;
+            Services = services;
+        }
+
+        public void FormMapping<THub, T>(ICacheHubMapping<THub, T> mapping) where THub: Hub<T> where T: class
+        {
+            var context = Services.GetService<IHubContext<THub, T>>();
+            mapping.ConstructMapping(Subscriber, context);
+        }
+    }
+
+    // public class CacheHubProxy<THub, T> 
+    //     where THub: Hub<T> 
+    //     where T: class
+    // {
+    //     private readonly ILogger<CacheHubProxy<THub, T>> Logger;
+    //     private readonly ISubscriber Subscriber;
+    //     private readonly IHubContext<THub, T> HubContext;
+    //     private readonly List<ICacheHubMapping<THub, T>> Mappings;
+
+    //     public CacheHubProxy(ILogger<CacheHubProxy<THub, T>> logger,
+    //         ISubscriber subscriber,
+    //         IHubContext<THub, T> hubContext,
+    //         IEnumerable<ICacheHubMapping<THub, T>> mappings 
+    //     )
+    //     {
+    //         Logger = logger;
+    //         Subscriber = subscriber;
+    //         HubContext = hubContext;
+    //         Mappings = mappings.ToList();
+    //     }
+
+    //     public void FormMapping(ICacheHubMapping<THub, T> mapping)
+    //     {
+    //         mapping.ConstructMapping(Subscriber, HubContext);
+    //     }
+
+    //     public void AddMapping(ICacheHubMapping<THub, T> mapping)
+    //     {
+    //         Mappings.Add(mapping);
+    //         FormMapping(mapping);
+    //     }
+    // }
+}

Selector.Web/Services/CacheHubProxyService.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+
+namespace Selector.Web.Service
+{
+    public class CacheHubProxyService: IHostedService
+    {
+        private readonly ILogger<CacheHubProxyService> Logger;
+        private readonly CacheHubProxy Proxy;
+
+        public CacheHubProxyService(
+            ILogger<CacheHubProxyService> logger,
+            CacheHubProxy proxy
+        )
+        {
+            Logger = logger;
+            Proxy = proxy;
+        }
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            Logger.LogInformation("Starting cache hub proxy");
+            return Task.CompletedTask;
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            Logger.LogInformation("Stopping cache hub proxy");
+            return Task.CompletedTask;
+        }
+    }
+}

Selector.Web/Services/Mappings/ICacheHubMapping.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Threading.Tasks;
+
+using Microsoft.AspNetCore.SignalR;
+using StackExchange.Redis;
+
+namespace Selector.Web.Service
+{
+    public interface ICacheHubMapping<THub, T> 
+        where THub : Hub<T>
+        where T : class
+    {
+        public Task ConstructMapping(ISubscriber subscriber, IHubContext<THub, T> hub);
+        // public Task RemoveMapping(ISubscriber subscriber, THub hub);
+    }
+}

Selector.Web/Services/Mappings/MappingFactory.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using SpotifyAPI.Web;
+
+namespace Selector.Web.Service
+{
+    public interface INowPlayingMappingFactory {
+        public NowPlayingMapping Get(string userId);
+    }
+
+    public class NowPlayingMappingFactory : INowPlayingMappingFactory {
+
+        private readonly ILoggerFactory LoggerFactory;
+
+        public NowPlayingMappingFactory(ILoggerFactory loggerFactory)
+        {
+            LoggerFactory = loggerFactory;
+        }
+
+        public NowPlayingMapping Get(string userId)
+        {
+            return new NowPlayingMapping(
+                LoggerFactory?.CreateLogger<NowPlayingMapping>(),
+                userId
+            );
+        }
+    }
+}

Selector.Web/Services/Mappings/NowPlayingMapping.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Text.Json;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging;
+
+using StackExchange.Redis;
+
+using Selector.Web.Hubs;
+using Selector.Cache;
+
+namespace Selector.Web.Service
+{
+    public class NowPlayingMapping : ICacheHubMapping<NowPlayingHub, INowPlayingHubClient>
+    {
+        private readonly string UserId;
+
+        public NowPlayingMapping(ILogger<NowPlayingMapping> logger, string userId)
+        {
+            UserId = userId;
+        }
+
+        public async Task ConstructMapping(ISubscriber subscriber, IHubContext<NowPlayingHub, INowPlayingHubClient> hub)
+        {
+            (await subscriber.SubscribeAsync(Key.CurrentlyPlaying(UserId))).OnMessage(async message => {
+                
+                var deserialised = JsonSerializer.Deserialize<CurrentlyPlayingDTO>(message.ToString());
+                await hub.Clients.User(UserId).OnNewPlaying(deserialised);
+            });
+        }
+    }
+}

Selector.Web/Startup.cs

@@ -15,6 +15,7 @@ using Microsoft.EntityFrameworkCore;
 
 using StackExchange.Redis;
 
+using Selector.Web.Service;
 using Selector.Web.Hubs;
 using Selector.Model;
 using Selector.Model.Authorisation;
@@ -115,6 +116,10 @@ namespace Selector.Web
                 services.AddTransient<IDatabaseAsync>(services => services.GetService<ConnectionMultiplexer>().GetDatabase());
                 services.AddTransient<ISubscriber>(services => services.GetService<ConnectionMultiplexer>().GetSubscriber());
             }
+
+            // HOSTED
+            services.AddSingleton<CacheHubProxy>();
+            services.AddSingleton<INowPlayingMappingFactory, NowPlayingMappingFactory>();
         }
 
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.