ScadaBridge/src/ScadaLink.ExternalSystemGateway/ServiceCollectionExtensions.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using ScadaLink.Commons.Interfaces.Services;

namespace ScadaLink.ExternalSystemGateway;

public static class ServiceCollectionExtensions
{
    public static IServiceCollection AddExternalSystemGateway(this IServiceCollection services)
    {
        services.AddOptions<ExternalSystemGatewayOptions>()
            .BindConfiguration("ScadaLink:ExternalSystemGateway");

        services.AddHttpClient();

        // ExternalSystemGateway-013: wire MaxConcurrentConnectionsPerSystem into the
        // primary handler of every per-system named client ("ExternalSystem_{name}"),
        // so the option an operator configures actually bounds concurrent connections
        // instead of being silently ignored. ConfigureHttpClientDefaults applies to
        // the dynamically-named clients created by ExternalSystemClient.
        services.ConfigureHttpClientDefaults(builder =>
            builder.ConfigurePrimaryHttpMessageHandler(sp =>
            {
                var options = sp.GetRequiredService<IOptions<ExternalSystemGatewayOptions>>().Value;
                return new SocketsHttpHandler
                {
                    MaxConnectionsPerServer = options.MaxConcurrentConnectionsPerSystem,
                };
            }));

        services.AddScoped<ExternalSystemClient>();
        services.AddScoped<IExternalSystemClient>(sp => sp.GetRequiredService<ExternalSystemClient>());
        services.AddScoped<DatabaseGateway>();
        services.AddScoped<IDatabaseGateway>(sp => sp.GetRequiredService<DatabaseGateway>());

        return services;
    }

    public static IServiceCollection AddExternalSystemGatewayActors(this IServiceCollection services)
    {
        // WP-10: Actor registration happens in AkkaHostedService.
        // Script Execution Actors run on dedicated blocking I/O dispatcher.
        return services;
    }
}