using System.Net.Http.Headers;

namespace ZymonicServices;

// HACK: request/response logger - remove after diagnosis
static class RequestLogger
{
  private static readonly string _dir = Path.Combine(AppContext.BaseDirectory, "requests");
  private static int _seq = 0;

  public static async Task Log(HttpRequestMessage request, HttpResponseMessage? response, Exception? ex)
  {
    Directory.CreateDirectory(_dir);
    var n = System.Threading.Interlocked.Increment(ref _seq);
    var file = Path.Combine(_dir, $"{n:D4}_{DateTime.Now:HHmmss_fff}.txt");
    var sb = new System.Text.StringBuilder();
    sb.AppendLine($"=== REQUEST {n} {DateTime.Now:O} ===");
    sb.AppendLine($"{request.Method} {request.RequestUri}");
    foreach (var h in request.Headers) sb.AppendLine($"  {h.Key}: {string.Join(", ", h.Value)}");
    if (request.Content != null)
    {
      foreach (var h in request.Content.Headers) sb.AppendLine($"  {h.Key}: {string.Join(", ", h.Value)}");
      sb.AppendLine(await request.Content.ReadAsStringAsync());
    }
    sb.AppendLine();
    if (response != null)
    {
      sb.AppendLine($"=== RESPONSE {(int)response.StatusCode} {response.StatusCode} ===");
      foreach (var h in response.Headers) sb.AppendLine($"  {h.Key}: {string.Join(", ", h.Value)}");
      sb.AppendLine(await response.Content.ReadAsStringAsync());
    }
    if (ex != null) sb.AppendLine($"=== EXCEPTION ===\n{ex}");
    await File.WriteAllTextAsync(file, sb.ToString());
  }
}

// https://github.com/reactiveui/refit?tab=readme-ov-file#reducing-header-boilerplate-with-delegatinghandlers-authorization-headers-worked-example


class ZymonicAPIHandler : DelegatingHandler
{
  private readonly IZymonicAA authTokenStore;
  private readonly IZymonicLogger _logger;
  public ZymonicAPIHandler(IZymonicLogger logger, IZymonicAA authTokenStore, HttpMessageHandler? innerHandler = null) : base(innerHandler ?? new HttpClientHandler() { UseCookies = false })
  {

    this.authTokenStore = authTokenStore ?? throw new ArgumentNullException(nameof(authTokenStore));
    _logger = logger;
  }

  protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
  {

    var token = await authTokenStore.GetToken();

    request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);

    try
    {

      var result = await base.SendAsync(request, cancellationToken).ConfigureAwait(true);

      // Buffer content so the logger can read it without consuming the stream
      // UNCOMMENT THE TWO LINES BELOW TO GET INDIVIDUAL API requests logged to disk.
      // await result.Content.LoadIntoBufferAsync();
      // await RequestLogger.Log(request, result, null);

      result.EnsureSuccessStatusCode();

      return result;
    }
    catch (Exception e)
    {
      await RequestLogger.Log(request, null, e);
      debugInnerException(e);

      throw;
    }

  }

  private void debugInnerException(Exception exception)
  {
    _logger.LogError(exception.ToString());
    if (exception.InnerException != null)
    {
      debugInnerException(exception.InnerException);
    }
  }
}