import {
  BadRequestException,
  Injectable,
  PipeTransform,
} from '@nestjs/common';
import { Pipes } from '../../index';

/**
 * OrderByPipe is a PipeTransform implementation used to validate and parse
 * the orderBy query parameter.
 */
@Injectable()
export default class OrderByPipe implements PipeTransform {
  /**
   * Validates and parses the orderBy query parameter.
   * @param value The orderBy query parameter.
   * @returns The parsed orderBy query parameter.
   * @throws BadRequestException if the orderBy query parameter is invalid.
   */
  transform(value: string): Pipes.Order | undefined {
    if (value == null) return undefined;

    try {
      const rules = value.split(',').map((val) => val.trim());
      const orderBy: Pipes.Order = {};

      rules.forEach((rule) => {
        const [key, order] = rule.split(':') as [string, 'asc' | 'desc'];
        const orderLowerCase = order.trim().toLocaleLowerCase();

        if (!['asc', 'desc'].includes(orderLowerCase)) {
          throw new BadRequestException(`Invalid order: ${orderLowerCase}`);
        }
        orderBy[key] = orderLowerCase as 'asc' | 'desc';
      });

      return orderBy;
    } catch (error) {
      console.error(error);
      throw new BadRequestException('Invalid orderBy query parameter');
    }
  }
}