import {
  CallHandler,
  ExecutionContext,
  Injectable,
  NestInterceptor,
} from "@nestjs/common";
import { Observable } from "rxjs";
import { normalizeUnicodeDigitsDeep } from "src/utils/unicode-digits";

/**
 * Normalizes Unicode decimal digits in JSON request bodies to ASCII before
 * validation and handlers run (Persian/Arabic-Indic → 0-9).
 */
@Injectable()
export class UnicodeDigitsNormalizeInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
    const req = context.switchToHttp().getRequest();
    const contentType = String(req.headers?.["content-type"] ?? "");

    if (
      req.body &&
      typeof req.body === "object" &&
      !Buffer.isBuffer(req.body) &&
      !contentType.includes("multipart/form-data")
    ) {
      req.body = normalizeUnicodeDigitsDeep(req.body);
    }

    return next.handle();
  }
}