import type { ILeagueMembershipRepository } from '../../domain/repositories/ILeagueMembershipRepository';
import type { IRaceRepository } from '../../domain/repositories/IRaceRepository';
import type { LeagueStatsOutputPort } from '../ports/output/LeagueStatsOutputPort';
import type { GetDriverRatingInputPort } from '../ports/input/GetDriverRatingInputPort';
import type { GetDriverRatingOutputPort } from '../ports/output/GetDriverRatingOutputPort';
import { Result } from '@core/shared/application/Result';
import type { ApplicationErrorCode } from '@core/shared/errors/ApplicationErrorCode';

export interface GetLeagueStatsUseCaseParams {
  leagueId: string;
}

export class GetLeagueStatsUseCase {
  constructor(
    private readonly leagueMembershipRepository: ILeagueMembershipRepository,
    private readonly raceRepository: IRaceRepository,
    private readonly getDriverRating: (input: GetDriverRatingInputPort) => Promise<GetDriverRatingOutputPort>,
  ) {}

  async execute(params: GetLeagueStatsUseCaseParams): Promise<Result<LeagueStatsOutputPort, ApplicationErrorCode<'REPOSITORY_ERROR'>>> {
    try {
      const memberships = await this.leagueMembershipRepository.getLeagueMembers(params.leagueId);
      const races = await this.raceRepository.findByLeagueId(params.leagueId);
      const driverIds = memberships.map(m => m.driverId);
      
      // Get ratings for all drivers using clean ports
      const ratingPromises = driverIds.map(driverId => 
        this.getDriverRating({ driverId })
      );
      
      const ratingResults = await Promise.all(ratingPromises);
      const validRatings = ratingResults
        .map(result => result.rating)
        .filter((rating): rating is number => rating !== null);
      
      const averageRating = validRatings.length > 0 ? Math.round(validRatings.reduce((sum, r) => sum + r, 0) / validRatings.length) : 0;
      
      const viewModel: LeagueStatsOutputPort = {
        totalMembers: memberships.length,
        totalRaces: races.length,
        averageRating,
      };
      return Result.ok(viewModel);
    } catch {
      return Result.err({ code: 'REPOSITORY_ERROR', message: 'Failed to fetch league stats' });
    }
  }
}