register-referentie/services/bff/Bff.Api/DownstreamClients.cs

using System.Net.Http.Json;

namespace Bff.Api;

/// <summary>What the self-service submit returns to the portal (the domain's registration id + status).</summary>
public sealed record SubmitAccepted(string RegistrationId, string Status);

/// <summary>The caller's current open registration, for resuming the self-service portal after a
/// refresh (S-26): the reference (registration id) + its status.</summary>
public sealed record CurrentRegistration(string RegistrationId, string Status);

/// <summary>A projection row as the projection-api serves it. <c>Bsn</c>/<c>NaamPlaceholder</c> are
/// read but never surfaced by the openbaar endpoint (public-safe filtering, ADR-0010/S-09).
/// <c>Reference</c> is the public-safe citizen reference (the zaak identificatie, #78).</summary>
public sealed record ProjectionEntry(string Id, string Status, string? Reference, string? Bsn, string? NaamPlaceholder);

/// <summary>A public-safe openbaar register row — only non-sensitive fields leave the BFF.</summary>
public sealed record OpenbaarEntry(string Id, string Status, string? Reference);

/// <summary>A behandelaar's werkbak row: a registration awaiting beoordeling, with the bsn + status a
/// behandelaar sees (staff view — reached only behind medewerker/behandelaar authorization, S-12c).</summary>
public sealed record WerkbakItem(string RegistrationId, string Bsn, string Status);

/// <summary>Port to the Domain Service (§8.3: the BFF is the portals' only backend; it fans out).</summary>
public interface IDomainClient
{
    Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default);

    /// <summary>The caller's current open registration (resume after refresh, S-26), or <c>null</c>
    /// when they have none in flight. Owner-scoped by <paramref name="bsn"/>.</summary>
    Task<CurrentRegistration?> GetCurrentRegistrationAsync(string bsn, CancellationToken ct = default);

    /// <summary>Withdraw the caller's own registration ("trek aanvraag in"). Owner-scoped by
    /// <paramref name="bsn"/>. Returns <c>false</c> when the domain reports the registration is
    /// unknown or not the caller's (404), so the BFF can relay a 404 rather than a 500.</summary>
    Task<bool> WithdrawRegistrationAsync(string registrationId, string bsn, CancellationToken ct = default);

    /// <summary>Provide (upload) the diploma the caller's own registration is waiting for ("documenten
    /// aanleveren"). The file is carried base64-encoded. Owner-scoped by <paramref name="bsn"/>. Returns
    /// <c>false</c> when the domain reports the registration is unknown or not the caller's (404).</summary>
    Task<bool> ProvideDocumentsAsync(
        string registrationId, string bsn, string contentBase64, string? fileName, string? contentType, CancellationToken ct = default);

    /// <summary>The behandelaar's werkbak — registrations awaiting beoordeling.</summary>
    Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default);

    /// <summary>Apply a behandelaar's decision (<c>goedkeuren</c>/<c>afwijzen</c>) to a registration.</summary>
    Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default);
}

/// <summary>Port to the read projection.</summary>
public interface IProjectionClient
{
    Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default);
}

/// <summary>Calls the Domain Service's <c>POST /registrations</c>.</summary>
public sealed class DomainClient(HttpClient http) : IDomainClient
{
    public async Task<SubmitAccepted> SubmitRegistrationAsync(string bsn, CancellationToken ct = default)
    {
        using var response = await http.PostAsJsonAsync("registrations", new { bsn }, ct);
        response.EnsureSuccessStatusCode();
        var dto = await response.Content.ReadFromJsonAsync<DomainResponse>(ct)
            ?? throw new InvalidOperationException("The Domain Service returned an empty registration response.");
        return new SubmitAccepted(dto.RegistrationId, dto.Status);
    }

    public async Task<CurrentRegistration?> GetCurrentRegistrationAsync(string bsn, CancellationToken ct = default)
    {
        using var response = await http.GetAsync($"registrations/current?bsn={Uri.EscapeDataString(bsn)}", ct);
        // The domain 404s when the citizen has no open registration — that's "none", not an error.
        if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
            return null;
        response.EnsureSuccessStatusCode();
        var dto = await response.Content.ReadFromJsonAsync<DomainResponse>(ct)
            ?? throw new InvalidOperationException("The Domain Service returned an empty registration response.");
        return new CurrentRegistration(dto.RegistrationId, dto.Status);
    }

    public async Task<bool> WithdrawRegistrationAsync(string registrationId, string bsn, CancellationToken ct = default)
    {
        using var response = await http.PostAsJsonAsync(
            $"registrations/{registrationId}/withdraw", new { bsn }, ct);
        // The domain 404s an unknown or not-owned registration; relay that rather than fail hard.
        if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
            return false;
        response.EnsureSuccessStatusCode();
        return true;
    }

    public async Task<bool> ProvideDocumentsAsync(
        string registrationId, string bsn, string contentBase64, string? fileName, string? contentType, CancellationToken ct = default)
    {
        using var response = await http.PostAsJsonAsync(
            $"registrations/{registrationId}/documents",
            new { bsn, contentBase64, fileName, contentType }, ct);
        // The domain 404s an unknown or not-owned registration; relay that rather than fail hard.
        if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
            return false;
        response.EnsureSuccessStatusCode();
        return true;
    }

    public async Task<IReadOnlyList<WerkbakItem>> GetWerkbakAsync(CancellationToken ct = default)
        => await http.GetFromJsonAsync<List<WerkbakItem>>("behandel/werkbak", ct) ?? [];

    public async Task DecideAsync(string registrationId, string besluit, CancellationToken ct = default)
    {
        using var response = await http.PostAsJsonAsync(
            $"registrations/{registrationId}/decide", new { besluit }, ct);
        response.EnsureSuccessStatusCode();
    }

    private sealed record DomainResponse(string RegistrationId, string Status, string? ZaakUrl);
}

/// <summary>Calls the projection-api's <c>GET /register</c>.</summary>
public sealed class ProjectionClient(HttpClient http) : IProjectionClient
{
    public async Task<IReadOnlyList<ProjectionEntry>> GetRegisterAsync(CancellationToken ct = default)
        => await http.GetFromJsonAsync<List<ProjectionEntry>>("register", ct) ?? [];
}