DocumentOrganizer/Diligent.WebAPI.Host/Middlewares/ExceptionMiddleware.cs

using Diligent.WebAPI.Contracts.Exceptions;
using Diligent.WebAPI.Contracts.Models;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System.Diagnostics;
using System.Net;
using System.Runtime.Serialization;

namespace Diligent.WebAPI.Host.Middlewares
{
    [ExcludeFromCodeCoverage]
    public class DiligBadRequestException : Exception
    {
        public const string ExceptionMessage = "Bad request from custom middleware";
        public const string ExceptionCode = "DiligBadRequestException";
        public const HttpStatusCode HttpResponseCode = HttpStatusCode.BadRequest;

        public DiligBadRequestException() : base(ExceptionMessage) { }
        public DiligBadRequestException(string message) : base(message) { }
        public DiligBadRequestException(string message, Exception innerException) : base(message, innerException) { }
        public DiligBadRequestException(SerializationInfo info, StreamingContext context) : base(info, context) { }
    }
    [ExcludeFromCodeCoverage]
    public class DiligExceptionMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger<DiligExceptionMiddleware> _logger;
        private readonly IWebHostEnvironment _env;
        private readonly ApiBehaviorOptions _options;

        public DiligExceptionMiddleware(RequestDelegate next, ILogger<DiligExceptionMiddleware> logger, IWebHostEnvironment env, IOptions<ApiBehaviorOptions> options)
            => (_next, _logger, _env, _options) = (next, logger, env, options.Value);

        public async Task InvokeAsync(HttpContext httpContext)
        {
            try
            {
                await _next(httpContext);
            }
            // Some custom Exceptions
            catch (EntityNotFoundException ex)
            {
                _logger.LogError(ex, DiligBadRequestException.ExceptionMessage);
                await HandleExceptionAsync(httpContext, ex, DiligBadRequestException.ExceptionMessage, HttpStatusCode.NotFound);
            }
            catch (Exception ex)
            {
                // Better solution is to use switch statement
                if(HasInternalExceptionOfType<DiligBadRequestException>(ex))
                {
                    _logger.LogError(ex, DiligBadRequestException.ExceptionMessage);
                    await HandleExceptionAsync(httpContext, ex, DiligBadRequestException.ExceptionMessage, DiligBadRequestException.HttpResponseCode);
                }
                else
                {
                    await HandleSomethingWentWrongAsync(httpContext, ex);
                }
            }
        }

        private async Task HandleSomethingWentWrongAsync(HttpContext httpContext, Exception ex)
        {
            _logger.LogError(ex, "Something went wrong");
            await HandleExceptionAsync(httpContext, ex);
        }

        private bool HasInternalExceptionOfType<T>(Exception e)
        {
            if(e.InnerException != null)
            {
                return e is T || HasInternalExceptionOfType<T>(e.InnerException);
            }
            return e is T;
        }

        private Task HandleExceptionAsync(HttpContext context, Exception exception, string? message = null, HttpStatusCode? responseCode = null)
        {
            context.Response.ContentType = "application/json";
            context.Response.StatusCode = (int)(responseCode ?? HttpStatusCode.InternalServerError);
            string type = null;

            if (_options.ClientErrorMapping.TryGetValue(context.Response.StatusCode, out var clientErrorData))
            {
                type = clientErrorData.Link;
            }

            var errorTitle = message ?? (_env.IsDevelopment() ? exception.Message : "Internal server error");
            var errorMessage = _env.IsDevelopment() ? exception.StackTrace : "Something went wrong" ;

            var serializerSettings = new JsonSerializerSettings
            {
                ContractResolver = new CamelCasePropertyNamesContractResolver()
        };
            var resultError = new ResultError(errorTitle);
            var httpResultError = new HttpResultError()
            {
                ErrorMessage = errorMessage,
                ErrorCode = responseCode ?? HttpStatusCode.InternalServerError
            };
            resultError.AddCustomError(httpResultError);
            var responseString = JsonConvert.SerializeObject(
                new BaseResult<Exception>
                {
                    // Type = type,
                    // TraceId = Activity.Current?.Id ?? context?.TraceIdentifier,
                    IsSuccess = false,
                    Errors = { resultError }
                }, serializerSettings);

            return context.Response.WriteAsync(responseString);
        }
    }
    [ExcludeFromCodeCoverage]
    public static class DiligExceptionMiddlewareExtensions
    {
        public static IApplicationBuilder UseDiligExceptionHandler(this IApplicationBuilder app)
        {
            return app.UseMiddleware<DiligExceptionMiddleware>();
        }
    }
}