import {
  CallHandler,
  ExecutionContext,
  Injectable,
  NestInterceptor,
} from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { Request } from 'express';
import { map, Observable } from 'rxjs';
import { SUCCESS_MESSAGE } from '../constants/response-message.constants';
import {
  API_MESSAGE_METADATA,
} from '../decorators/api-message.decorator';
import { getRequestCost } from '../utils/request-context.util';

@Injectable()
export class ResponseInterceptor implements NestInterceptor {
  constructor(private readonly reflector = new Reflector()) {}

  intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
    const request = context
      .switchToHttp()
      .getRequest<Request & { requestId?: string }>();
    const message =
      this.reflector.get<string>(API_MESSAGE_METADATA, context.getHandler()) ??
      SUCCESS_MESSAGE;

    return next.handle().pipe(
      map((data) => ({
        code: 0,
        data: data ?? {},
        message,
        timestamp: Date.now(),
        requestId: request.requestId,
        cost: `${getRequestCost(request)}ms`,
      })),
    );
  }
}