using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Kpi;
using ZB.MOM.WW.ScadaBridge.SiteCallAudit.Kpi;

namespace ZB.MOM.WW.ScadaBridge.SiteCallAudit;

/// <summary>
/// Composition root for the Site Call Audit component.
/// </summary>
/// <remarks>
/// <para>
/// Binds <see cref="SiteCallAuditOptions"/> (stuck-call detection + KPI
/// windowing for the read-side query/KPI handlers). The central→site
/// Retry/Discard relay is wired in <see cref="SiteCallAuditActor"/>.
/// </para>
/// <para>
/// The repository (<c>ISiteCallAuditRepository</c>) is registered by
/// <c>ZB.MOM.WW.ScadaBridge.ConfigurationDatabase.ServiceCollectionExtensions.AddConfigurationDatabase</c>,
/// so callers (the Host on the central node) must also call that. The actor's
/// <c>Props</c> are wired up in Host registration.
/// </para>
/// </remarks>
public static class ServiceCollectionExtensions
{
    /// <summary>Configuration section bound to <see cref="SiteCallAuditOptions"/>.</summary>
    public const string OptionsSection = "ScadaBridge:SiteCallAudit";

    /// <summary>
    /// Registers Site Call Audit services: the <see cref="SiteCallAuditOptions"/>
    /// binding consumed by the actor's read-side KPI/query handlers. The actor's
    /// <c>Props</c> are still constructed inline in Host wiring.
    /// </summary>
    /// <param name="services">The service collection to register into.</param>
    /// <returns>The same <paramref name="services"/> collection, for chaining.</returns>
    public static IServiceCollection AddSiteCallAudit(this IServiceCollection services)
    {
        ArgumentNullException.ThrowIfNull(services);

        // Eager startup validation (arch-review 08 §1.5): ValidateOnStart makes a
        // bad ScadaBridge:SiteCallAudit section — a zero/negative cadence that would
        // spin an Akka scheduler, or a non-positive KPI/retention knob — fail fast
        // at boot with a clear, key-naming message.
        services.AddOptions<SiteCallAuditOptions>()
            .BindConfiguration(OptionsSection)
            .ValidateOnStart();
        services.TryAddEnumerable(
            ServiceDescriptor.Singleton<IValidateOptions<SiteCallAuditOptions>, SiteCallAuditOptionsValidator>());

        // KPI History: the central recorder enumerates every registered
        // IKpiSampleSource each sampling pass; this one snapshots the SiteCalls
        // KPIs (global + per-site + per-node) into the KpiSample history store.
        // Scoped so each pass resolves a fresh ISiteCallAuditRepository scope,
        // mirroring the actor's scope-per-message repository access.
        // TryAddEnumerable is idempotent — no double-registration if AddSiteCallAudit
        // is ever called more than once, matching the AuditLog idiom.
        services.TryAddEnumerable(ServiceDescriptor.Scoped<IKpiSampleSource, SiteCallAuditKpiSampleSource>());

        return services;
    }
}
