Working implementation

RAIC.Extensions.Configuration.EntityFrameworkCore.SqlServer/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,76 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+using Options = RAIC.Extensions.Configuration.EntityFrameworkCore.SqlServer.SqlServerNotificationConfigurationReloaderOptions;
+
+namespace RAIC.Extensions.Configuration.EntityFrameworkCore.SqlServer.Extensions;
+
+public static class ServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds <see cref="SqlServerNotificationConfigurationReloader{,}"/> (a <see cref="Microsoft.Extensions.Hosting.IHostedService"/> implementation)
+    /// and supporting services to the <see cref="IServiceCollection"/>, obtaining its connection string from a <typeparamref name="TDbContext"/> instance.
+    /// </summary>
+    /// <typeparam name="TDbContext">Type of the <see cref="DbContext"/> which implements <see cref="ISettingsDbContext{TSettingDbSet, TSetting}"/></typeparam>
+    /// <typeparam name="TSetting">Concrete type which implements <see cref="ISetting"/></typeparam>
+    /// <param name="services">The service collection to add the services too</param>
+    /// <returns>The service collection it was called on now with added services</returns>
+    /// <remarks>If your connection string contains a password then this method may not work, please use another overload</remarks>
+    /// <exception cref="NullReferenceException">If your <typeparamref name="TDbContext"/> does not have a connection string</exception>
+    public static IServiceCollection AddSqlServerNotificationConfigurationReloadService<TDbContext, TSetting>(this IServiceCollection services)
+        where TDbContext : DbContext, ISettingsDbContext<DbSet<TSetting>, TSetting>
+        where TSetting : class, ISetting
+    {
+        var optionsBuilder = services.AddCoreServices<TDbContext, TSetting>();
+
+        optionsBuilder.Configure<TDbContext>((options, dependency) =>
+        {
+            options.ConnectionString = dependency.Database.GetConnectionString() ?? throw new NullReferenceException($"{typeof(TDbContext).Name} ConnectionString is null");
+        });
+
+        return services;
+    }
+
+    /// <summary>
+    /// Adds <see cref="SqlServerNotificationConfigurationReloader{,}"/> (a <see cref="Microsoft.Extensions.Hosting.IHostedService"/> implementation)
+    /// and supporting services to the <see cref="IServiceCollection"/>.
+    /// </summary>
+    /// <typeparam name="TDbContext">Type of the <see cref="DbContext"/> which implements <see cref="ISettingsDbContext{,}"/></typeparam>
+    /// <typeparam name="TSetting">Concrete type which implements <see cref="ISetting"/></typeparam>
+    /// <param name="services">The service collection to add the services too</param>
+    /// <param name="configure">
+    /// Action to manually configure the <see cref="Options"/> instance consumed by <see cref="SqlServerNotificationConfigurationReloader{,}"/> eg.
+    /// <code>
+    /// options => {
+    ///     options.ConnectionString = context.Configuration.GetConnectionString("Default");
+    /// }
+    /// </code>
+    /// </param>
+    /// <returns>The service collection it was called on now with added services</returns>
+    public static IServiceCollection AddSqlServerNotificationConfigurationReloadService<TDbContext, TSetting>(this IServiceCollection services, Action<Options> configure)
+        where TDbContext : DbContext, ISettingsDbContext<DbSet<TSetting>, TSetting>
+        where TSetting : class, ISetting
+    {
+        var optionsBuilder = services.AddCoreServices<TDbContext, TSetting>();
+
+        optionsBuilder.Configure(configure);
+
+        return services;
+    }
+
+
+    private static OptionsBuilder<Options> AddCoreServices<TDbContext, TSetting>(this IServiceCollection services)
+        where TDbContext : DbContext, ISettingsDbContext<DbSet<TSetting>, TSetting>
+        where TSetting : class, ISetting
+    {
+        services.AddSingleton(static provider =>
+        {
+            var configRoot = (IConfigurationRoot)provider.GetRequiredService<IConfiguration>(); // DEBT: Is this cast always safe?
+            return configRoot.Providers.OfType<IEntityFrameworkCoreDbSetConfigurationProvider>().Single();
+        });
+
+        return services.AddHostedService<SqlServerNotificationConfigurationReloader<TDbContext, TSetting>>()
+                       .AddOptions<Options>().ValidateDataAnnotations().ValidateOnStart();
+    }
+}