drinkrate/DrinkRateAPI/Exceptions/ExceptionHandlingMiddleware.cs

using System.Net;
using Microsoft.AspNetCore.Http.HttpResults;

namespace DrinkRateAPI.Exceptions;

public record ExceptionResponse(int StatusCode, string Description);

public class ExceptionHandlingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<ExceptionHandlingMiddleware> _logger;

    public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception ex)
        {
            await HandleExceptionAsync(context, ex);
        }
    }

    private async Task HandleExceptionAsync(HttpContext context, Exception exception)
    {
        _logger.LogError(exception, "An error occurred.");

        var defaultResponse = exception switch
        {
            BadRequestException _ => new ExceptionResponse(StatusCodes.Status400BadRequest, "Application exception occurred."),
            NotFoundException _ => new ExceptionResponse(StatusCodes.Status404NotFound, "The request key not found."),
            UnauthenticatedException _ => new ExceptionResponse(StatusCodes.Status401Unauthorized, "Unauthorized."),
            PaymentRequiredException _ => new ExceptionResponse(StatusCodes.Status402PaymentRequired, "Payment required."),
            ForbiddenException _ => new ExceptionResponse(StatusCodes.Status403Forbidden, "Forbidden."),
            IamATeapotException _ => new ExceptionResponse(StatusCodes.Status418ImATeapot, "I am a teapot."),
            UnavailableForLagalReasonsException _ => new ExceptionResponse(StatusCodes.Status451UnavailableForLegalReasons, "Unavailable for legal reasons."),
            _ => new ExceptionResponse(StatusCodes.Status500InternalServerError, "Internal server error. Please retry later.")
        };
        
        var description = !string.IsNullOrWhiteSpace(exception.Message) 
            ? exception.Message
            : defaultResponse.Description;
        
        var response = defaultResponse with { Description = description };
        
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = response.StatusCode;
        await context.Response.WriteAsJsonAsync(response);
    }
}