using System.Net;
using System.Net.Http.Json;
using System.Text.Json.Serialization;
using EventSubscriber.Application;

namespace EventSubscriber.Api;

/// <summary>
/// HTTP client to the ACL service. An Objecten notification carries only the object URL, so the
/// subscriber reads the register record back through the ACL — the only code that may talk to
/// Objecten (§8.1, ADR-0028/ADR-0030) — rather than reading Objecten itself.
/// </summary>
public sealed class AclHttpClient(HttpClient http) : IAclClient
{
    public async Task<RegisterRecord?> GetRegisterRecordAsync(Uri objectUrl, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(objectUrl);

        using var response = await http.PostAsJsonAsync(
            new Uri(http.BaseAddress!, "register-records/read"),
            new ReadRequest(objectUrl.ToString()), ct);

        // The object holds no register record (deleted, or never one) — nothing to project (§8.6).
        if (response.StatusCode == HttpStatusCode.NotFound)
            return null;

        response.EnsureSuccessStatusCode();
        return await response.Content.ReadFromJsonAsync<RegisterRecord>(ct)
            ?? throw new InvalidOperationException("The ACL returned an empty register record response.");
    }

    private sealed record ReadRequest([property: JsonPropertyName("objectUrl")] string ObjectUrl);
}