backend/src/middleware/errorHandler.js

import { ZodError } from "zod";
import { AppError } from "../shared/errors/index.js";

export function errorHandler(err, _req, res, _next) {
  if (err instanceof ZodError) {
    return res.status(400).json({ error: "validation_error", details: err.errors });
  }

  if (err instanceof AppError) {
    return res.status(err.statusCode).json({ error: err.message, ...(err.details ?? {}) });
  }

  if (err?.code === "ER_DUP_ENTRY" || err?.nativeError?.code === "ER_DUP_ENTRY") {
    return res.status(409).json({ error: "Registro duplicado (login ou email já cadastrado)." });
  }

  const status = Number(err?.statusCode ?? err?.status ?? 500);
  const message = typeof err?.message === "string" ? err.message : "internal_error";

  if (status >= 500) {
    console.error("[error]", err);
  }

  res.status(status).json({ error: message });
}