Inboxintel/src/InboxIntel.Infrastructure/DependencyInjection.cs

using InboxIntel.Application.Abstractions;
using InboxIntel.Domain.Enums;
using InboxIntel.Infrastructure.Ai;
using InboxIntel.Infrastructure.Analytics;
using InboxIntel.Infrastructure.Cleanup;
using InboxIntel.Infrastructure.Configuration;
using InboxIntel.Infrastructure.Export;
using InboxIntel.Infrastructure.Gmail;
using InboxIntel.Infrastructure.Notifications;
using InboxIntel.Infrastructure.Persistence;
using InboxIntel.Infrastructure.Search;
using InboxIntel.Infrastructure.Security;
using InboxIntel.Infrastructure.Sync;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace InboxIntel.Infrastructure;

public static class DependencyInjection
{
    public static IServiceCollection AddInfrastructure(this IServiceCollection services, IConfiguration config)
    {
        // EF Core / PostgreSQL. UseVector() enables pgvector mapping for the semantic-search
        // embedding column (requires the 'vector' extension — added by the AddEmbeddingColumn migration).
        services.AddDbContext<AppDbContext>(opt =>
            opt.UseNpgsql(config.GetConnectionString("Postgres"),
                npg => npg.MigrationsAssembly(typeof(AppDbContext).Assembly.FullName).UseVector()));
        services.AddScoped<IAppDbContext>(sp => sp.GetRequiredService<AppDbContext>());

        // Options
        services.Configure<GoogleOAuthOptions>(config.GetSection(GoogleOAuthOptions.SectionName));
        services.Configure<GmailSyncOptions>(config.GetSection(GmailSyncOptions.SectionName));
        services.Configure<AiOptions>(config.GetSection(AiOptions.SectionName));
        services.Configure<SmtpOptions>(config.GetSection(SmtpOptions.SectionName));
        services.Configure<DigestOptions>(config.GetSection(DigestOptions.SectionName));

        // Security
        services.AddSingleton<ITokenProtector, DataProtectionTokenProtector>();

        // Gmail
        services.AddScoped<GmailClientFactory>();
        services.AddScoped<IGmailService, GmailApiService>();

        // Background sync queue (singleton) + its worker.
        services.AddSingleton<SyncQueue>();
        services.AddSingleton<ISyncQueue>(sp => sp.GetRequiredService<SyncQueue>());
        services.AddHostedService<SyncQueueWorker>();

        // Core services
        services.AddScoped<ISyncService, SyncService>();
        services.AddScoped<IAnalyticsService, AnalyticsService>();
        services.AddScoped<ISearchService, SearchService>();
        services.AddScoped<ICleanupService, CleanupService>();
        services.AddScoped<IUnsubscribeService, UnsubscribeService>();
        services.AddScoped<IExportService, ExportService>();

        // Notifications (digest emails)
        services.AddScoped<IEmailSender, SmtpEmailSender>();
        services.AddScoped<IDigestService, DigestService>();
        services.AddHostedService<DigestWorker>();

        // AUDIT H-3: opt-in local data retention (worker no-ops while disabled).
        services.Configure<DataRetentionOptions>(config.GetSection(DataRetentionOptions.SectionName));
        services.AddScoped<Retention.RetentionService>();
        services.AddHostedService<Retention.RetentionWorker>();

        // HTTP clients
        // V-01: do NOT follow redirects — a validated external URL must not be able to
        // 3xx-redirect into an internal target after SafeHttpGuard has checked it.
        services.AddHttpClient("unsubscribe", c => c.Timeout = TimeSpan.FromSeconds(15))
            .ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler { AllowAutoRedirect = false });
        services.AddHttpClient("ollama");
        services.AddHttpClient("openai");

        // AI provider selected by configured mode. Embeddings come from Ollama when local,
        // otherwise the Null provider (empty vectors) so semantic features degrade to lexical.
        var aiMode = config.GetSection(AiOptions.SectionName).GetValue<AiProviderMode>("Mode");
        switch (aiMode)
        {
            case AiProviderMode.LocalOllama:
                services.AddScoped<IAiProvider, OllamaProvider>();
                services.AddScoped<IEmbeddingProvider, OllamaEmbeddingProvider>();
                break;
            case AiProviderMode.CloudOpenAi:
                services.AddScoped<IAiProvider, OpenAiProvider>();
                services.AddScoped<IEmbeddingProvider, NullEmbeddingProvider>(); // OpenAI embeddings: future
                break;
            default:
                services.AddScoped<IAiProvider, NullAiProvider>();
                services.AddScoped<IEmbeddingProvider, NullEmbeddingProvider>();
                break;
        }
        services.AddScoped<IAiService, AiService>();
        // Feature flags + AI policy gate (docs/discovery/multi-provider/04). Cached 15s,
        // fail-closed. Admin toggle surface arrives with the multi-provider admin phase.
        services.AddMemoryCache();
        services.AddScoped<IFeatureFlags, Features.FeatureFlagService>();
        services.AddScoped<IAiGate, Features.AiGate>();
        // Semantic search: fills Email.Embedding in the background; no-ops when the
        // embedding provider is unavailable (AI disabled), so lexical search is unaffected.
        services.AddHostedService<EmbeddingBackfillWorker>();

        // Background worker (daily incremental sync + aggregate refresh)
        services.AddHostedService<GmailSyncWorker>();

        return services;
    }
}