/// <summary>
/// Initializes a new instance of the <see cref="CorrelationMiddleware"/> class.
/// </summary>
/// <param name="next">The next functionality in the request pipeline to be executed.</param>
/// <param name="service">The service to run the correlation functionality.</param>
/// <param name="logger">The instance to log diagnostic messages during correlation.</param>
/// <exception cref="ArgumentNullException">Thrown when the <paramref name="next"/> or <paramref name="service"/> is <c>null</c>.</exception>
public CorrelationMiddleware(
RequestDelegate next,
HttpCorrelation service,
ILogger <CorrelationMiddleware> logger)
{
Guard.NotNull(next, nameof(next), "Requires a continuation delegate");
Guard.NotNull(service, nameof(service), "Requires the HTTP correlation service");
Guard.NotNull(logger, nameof(logger), "Requires a logger instance");
_next = next;
_service = service;
_logger = logger;
}
/// <summary>
/// Request handling method.
/// </summary>
/// <param name="httpContext">The <see cref="HttpContext" /> for the current request.</param>
/// <param name="service">The service to run the correlation functionality.</param>
/// <returns>
/// A <see cref="Task" /> that represents the execution of this middleware.
/// </returns>
/// <exception cref="ArgumentNullException">Thrown when the <paramref name="httpContext"/> or <paramref name="service"/> is <c>null</c>.</exception>
/// <exception cref="ArgumentException">Thrown when the <paramref name="httpContext"/> response headers are <c>null</c>.</exception>
public async Task Invoke(HttpContext httpContext, HttpCorrelation service)
{
Guard.NotNull(httpContext, nameof(httpContext));
Guard.NotNull(service, nameof(service), "Requires the HTTP correlation service");
Guard.For <ArgumentException>(() => httpContext.Response is null, "Requires a 'Response'");
Guard.For <ArgumentException>(() => httpContext.Response.Headers is null, "Requires a 'Response' object with headers");
if (service.TryHttpCorrelate(out string errorMessage))
{
await _next(httpContext);
}
else
{
_logger.LogError("Unable to correlate the incoming request, returning 400 BadRequest (reason: {ErrorMessage})", errorMessage);
httpContext.Response.StatusCode = StatusCodes.Status400BadRequest;
await httpContext.Response.WriteAsync(errorMessage);
}
}