backend/src/middleware/errors.ts

import type { NextFunction, Request, Response } from "express";
import { ZodError } from "zod";
import { isProduction } from "../config/env";
import { HttpError, getErrorMessage } from "../utils/httpError";

export function notFoundHandler(req: Request, _res: Response, next: NextFunction): void {
  next(new HttpError(404, "not_found", `Route not found: ${req.method} ${req.path}`));
}

export function errorHandler(error: unknown, _req: Request, res: Response, _next: NextFunction): void {
  if (error instanceof ZodError) {
    res.status(400).json({
      error: {
        code: "validation_error",
        message: "Request validation failed",
        issues: error.issues
      }
    });
    return;
  }

  if (error instanceof HttpError) {
    res.status(error.status).json({
      error: {
        code: error.code,
        message: error.message
      }
    });
    return;
  }

  res.status(500).json({
    error: {
      code: "internal_error",
      message: isProduction ? "Internal server error" : getErrorMessage(error)
    }
  });
}