ScadaBridge/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/ServiceCollectionExtensions.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.ScadaBridge.Communication.Grpc;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Deployment;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Persistence;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Repositories;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;
using ZB.MOM.WW.ScadaBridge.SiteRuntime.Streaming;

namespace ZB.MOM.WW.ScadaBridge.SiteRuntime;

public static class ServiceCollectionExtensions
{
    /// <summary>
    /// Registers Site Runtime services including SiteStorageService for SQLite persistence.
    /// The caller must register an <see cref="ISiteStorageConnectionProvider"/> or call the
    /// overload with an explicit connection string.
    /// </summary>
    /// <param name="services">The DI service collection to register services into.</param>
    /// <returns>The same <see cref="IServiceCollection"/> to allow chaining.</returns>
    public static IServiceCollection AddSiteRuntime(this IServiceCollection services)
    {
        // SiteStorageService is registered by the Host using AddSiteRuntime(connectionString)
        // This overload is for backward compatibility / skeleton placeholder
        return services;
    }

    /// <summary>
    /// Registers Site Runtime services with an explicit SQLite connection string.
    /// </summary>
    /// <param name="services">The DI service collection to register services into.</param>
    /// <param name="siteDbConnectionString">The SQLite connection string for the site local storage database.</param>
    /// <returns>The same <see cref="IServiceCollection"/> to allow chaining.</returns>
    public static IServiceCollection AddSiteRuntime(this IServiceCollection services, string siteDbConnectionString)
    {
        services.AddSingleton(sp =>
        {
            var logger = sp.GetRequiredService<ILogger<SiteStorageService>>();
            return new SiteStorageService(siteDbConnectionString, logger);
        });

        services.AddHostedService<SiteStorageInitializer>();

        // Script compilation service
        services.AddSingleton<ScriptCompilationService>();

        // Shared script library
        services.AddSingleton<SharedScriptLibrary>();

        // Site stream manager — registered as singleton and exposed as ISiteStreamSubscriber
        // so the gRPC server can subscribe relay actors to instance events.
        // ActorSystem is injected later via Initialize() after AkkaHostedService starts.
        services.AddSingleton(sp =>
        {
            var options = sp.GetRequiredService<IOptions<SiteRuntimeOptions>>().Value;
            var logger = sp.GetRequiredService<ILogger<SiteStreamManager>>();
            return new SiteStreamManager(options, logger);
        });
        services.AddSingleton<ISiteStreamSubscriber>(sp => sp.GetRequiredService<SiteStreamManager>());

        // Site-local repository implementations backed by SQLite
        services.AddScoped<IExternalSystemRepository, SiteExternalSystemRepository>();

        // Notify-and-fetch: typed HttpClient for fetching deployment configs from central.
        services.AddHttpClient<IDeploymentConfigFetcher, HttpDeploymentConfigFetcher>()
            .ConfigureHttpClient((sp, c) =>
                c.Timeout = TimeSpan.FromSeconds(
                    sp.GetRequiredService<IOptions<SiteRuntimeOptions>>().Value.ConfigFetchTimeoutSeconds));

        // S2/UA5: periodically lift the shared script-execution scheduler gauges
        // (queue depth, busy threads, oldest-busy age) onto the site health report.
        // Registered via factory-lambda so ISiteHealthCollector (registered by the
        // Host's AddSiteHealthMonitoring) is resolved lazily at host start.
        services.AddHostedService(sp => new ScriptSchedulerStatsReporter(
            sp.GetRequiredService<HealthMonitoring.ISiteHealthCollector>(),
            sp.GetRequiredService<IOptions<SiteRuntimeOptions>>().Value,
            sp.GetRequiredService<ILogger<ScriptSchedulerStatsReporter>>()));

        return services;
    }

    /// <summary>Registers any additional DI services needed by the Site Runtime Akka actors.</summary>
    /// <param name="services">The DI service collection to register services into.</param>
    /// <returns>The same <see cref="IServiceCollection"/> to allow chaining.</returns>
    public static IServiceCollection AddSiteRuntimeActors(this IServiceCollection services)
    {
        // Actor registration is handled by AkkaHostedService.RegisterSiteActors()
        // which creates the DeploymentManager singleton and proxy
        return services;
    }
}