import { Injectable } from '@nestjs/common';
import { EntityManager } from 'typeorm';
import { SolveEntity } from '../../database/entities/solve.entity';

export interface RankInfo {
  rank: number | null;
  points: number;
}

@Injectable()
export class UsersRankService {
  async rankOfUser(manager: EntityManager, userId: string): Promise<RankInfo> {
    const solveRepo = manager.getRepository(SolveEntity);
    const pointsRow = await solveRepo
      .createQueryBuilder('s')
      .select('COALESCE(SUM(s.pointsAwarded), 0)', 'total')
      .where('s.userId = :userId', { userId })
      .getRawOne<{ total: string | number | null }>();
    const points = Number(pointsRow?.total ?? 0);

    if (points <= 0) {
      return { rank: null, points: 0 };
    }

    const ahead = await solveRepo
      .createQueryBuilder('s')
      .select('s.userId', 'userId')
      .addSelect('SUM(s.pointsAwarded)', 'total')
      .groupBy('s.userId')
      .having('SUM(s.pointsAwarded) > :points', { points })
      .getRawMany<{ userId: string }>();
    return { rank: ahead.length + 1, points };
  }
}