import { Injectable, NestMiddleware } from '@nestjs/common';
import { randomUUID } from 'crypto';
import type { Request, Response, NextFunction } from 'express';

export const REQUEST_ID_HEADER = 'x-request-id';

export type RequestWithId = Request & { requestId?: string };

@Injectable()
export class RequestIdMiddleware implements NestMiddleware {
  use(req: RequestWithId, res: Response, next: NextFunction) {
    const incoming = req.headers[REQUEST_ID_HEADER];
    const requestId =
      typeof incoming === 'string' && incoming.trim()
        ? incoming.trim().slice(0, 64)
        : randomUUID();
    req.requestId = requestId;
    res.setHeader('X-Request-Id', requestId);
    next();
  }
}