import { randomUUID } from "node:crypto";
import { type Request, type Response, Router } from "express";

const problemDetails = (req: Request, status: number, body: unknown) => {
  const record =
    typeof body === "object" && body !== null
      ? (body as Record<string, unknown>)
      : {};
  const detail =
    typeof record.detail === "string"
      ? record.detail
      : typeof record.message === "string"
        ? record.message
        : `Request failed with status ${status}`;
  const codeByStatus: Record<number, string> = {
    400: "invalid_request",
    401: "unauthenticated",
    403: "forbidden",
    404: "not_found",
    409: "conflict",
    422: "validation_error",
    503: "dependency_unavailable",
  };
  const code = codeByStatus[status] ?? "request_error";
  return {
    type: `https://tjwater.example/problems/${code.replaceAll("_", "-")}`,
    title: code.replaceAll("_", " "),
    status,
    detail,
    instance: req.originalUrl.split("?")[0],
    code,
    trace_id: req.header("x-request-id") ?? randomUUID(),
    errors: record.detail && typeof record.detail === "object" ? [record.detail] : [],
  };
};

export const buildAgentPublicRouter = (chatRouter: Router) => {
  const router = Router();

  router.use((req, res, next) => {
    const json = res.json.bind(res);
    res.json = ((body: unknown) => {
      if (res.statusCode >= 400) {
        res.type("application/problem+json");
        return json(problemDetails(req, res.statusCode, body));
      }
      return json(body);
    }) as Response["json"];
    next();
  });

  router.use(chatRouter);

  return router;
};