import type { FastifyInstance, FastifyRequest } from "fastify";
import { randomUUID } from "node:crypto";

declare module "fastify" {
  interface FastifyRequest {
    requestId: string;
  }
}

const firstHeaderValue = (
  value: string | string[] | undefined,
): string | undefined => (Array.isArray(value) ? value[0] : value);

export const createRequestId = (
  incomingRequestId: string | string[] | undefined,
): string => {
  const requestId = firstHeaderValue(incomingRequestId);

  return requestId && /^[A-Za-z0-9_-]{1,128}$/.test(requestId)
    ? requestId
    : `req-${randomUUID()}`;
};

export const requestIdPlugin = async (app: FastifyInstance) => {
  app.addHook("onRequest", async (request, reply) => {
    request.requestId = request.id;
    reply.header("x-request-id", request.requestId);
  });
};

export const getRequestId = (request: FastifyRequest): string =>
  request.requestId ?? request.id ?? `req-${randomUUID()}`;