using Fitness_core_BE.Exceptions;
using Fitness_core_BE.Models.IOs;

namespace Fitness_core_BE.Helpers
{
    // The app has no central exception->HTTP mapping today -- an unhandled NotFoundException/
    // BadRequestException/etc. (or the equivalent BCL KeyNotFoundException/ArgumentException
    // many services throw) 500s with a raw stack trace instead of the ApiResponse shape every
    // other error path returns. AgentController.cs already hand-rolls this exact mapping
    // per-action (see its catch blocks); this middleware applies the same mapping once, for
    // every controller, without having to add a try/catch to each action.
    public class GlobalExceptionMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger<GlobalExceptionMiddleware> _logger;

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

        public async Task InvokeAsync(HttpContext context)
        {
            try
            {
                await _next(context);
            }
            catch (Exception ex)
            {
                var (statusCode, message) = ex switch
                {
                    NotFoundException or KeyNotFoundException => (404, ex.Message),
                    BadRequestException or ArgumentException => (400, ex.Message),
                    UnauthorizedException => (401, ex.Message),
                    ForbiddenException => (403, ex.Message),
                    ServiceUnavailableException => (503, ex.Message),
                    _ => (500, "An unexpected error occurred."),
                };

                if (statusCode == 500)
                    _logger.LogError(ex, "Unhandled exception for {Method} {Path}", context.Request.Method, context.Request.Path);

                if (context.Response.HasStarted)
                    throw;

                context.Response.Clear();
                context.Response.StatusCode = statusCode;
                context.Response.ContentType = "application/json";
                await context.Response.WriteAsJsonAsync(new ApiResponse<object>
                {
                    StatusCode = statusCode,
                    Message = message,
                    Data = null!
                });
            }
        }
    }
}