import { Repository } from 'typeorm';
import { AppDataSource } from '../config/database';
import { WeightRecord } from '../entities/WeightRecord';
import { WeightGoal, GoalStatus } from '../entities/WeightGoal';

export class StatsService {
  private weightRecordRepository: Repository<WeightRecord>;
  private weightGoalRepository: Repository<WeightGoal>;

  constructor() {
    this.weightRecordRepository = AppDataSource.getRepository(WeightRecord);
    this.weightGoalRepository = AppDataSource.getRepository(WeightGoal);
  }

  /**
   * 获取用户统计数据
   */
  async getStats(userId: string, from?: string, to?: string): Promise<any> {
    // 获取记录
    const queryBuilder = this.weightRecordRepository
      .createQueryBuilder('wr')
      .where('wr.userId = :userId', { userId })
      .andWhere('wr.deletedAt IS NULL');

    if (from) {
      queryBuilder.andWhere('wr.recordDate >= :from', { from });
    }
    if (to) {
      queryBuilder.andWhere('wr.recordDate <= :to', { to });
    }

    const records = await queryBuilder
      .orderBy('wr.recordDate', 'ASC')
      .getMany();

    if (records.length === 0) {
      return {
        currentWeight: null,
        weightChange: null,
        daysTracked: 0,
        avgWeeklyChange: null,
        bodyFatChange: null,
        goalProgress: null,
        goalETA: null
      };
    }

    // 基础统计
    const firstRecord = records[0];
    const latestRecord = records[records.length - 1];
    const currentWeight = Number(latestRecord.weight);
    const initialWeight = Number(firstRecord.weight);
    const weightChange = Number((currentWeight - initialWeight).toFixed(2));
    const bodyFatChange = Number((Number(latestRecord.bodyFat) - Number(firstRecord.bodyFat)).toFixed(2));

    // 天数统计
    const firstDate = new Date(firstRecord.recordDate);
    const latestDate = new Date(latestRecord.recordDate);
    const daysTracked = Math.ceil((latestDate.getTime() - firstDate.getTime()) / (1000 * 60 * 60 * 24)) + 1;

    // 平均每周变化
    const weeksTracked = daysTracked / 7;
    const avgWeeklyChange = weeksTracked > 0 ? Number((weightChange / weeksTracked).toFixed(2)) : 0;

    // 获取活跃目标
    const goal = await this.weightGoalRepository.findOne({
      where: { userId, status: GoalStatus.ACTIVE }
    });

    let goalProgress: number | null = null;
    let goalETA: string | null = null;

    if (goal) {
      const totalWeightDiff = Math.abs(Number(goal.targetWeight) - Number(goal.startWeight));
      const currentWeightDiff = Math.abs(Number(goal.targetWeight) - currentWeight);
      goalProgress = totalWeightDiff > 0 
        ? Number((((totalWeightDiff - currentWeightDiff) / totalWeightDiff) * 100).toFixed(1))
        : 100;

      // 计算ETA
      if (avgWeeklyChange !== 0 && currentWeightDiff > 0) {
        const weeksNeeded = currentWeightDiff / Math.abs(avgWeeklyChange);
        const etaDate = new Date();
        etaDate.setDate(etaDate.getDate() + Math.ceil(weeksNeeded * 7));
        goalETA = etaDate.toISOString().split('T')[0];
      }
    }

    return {
      currentWeight,
      weightChange,
      daysTracked,
      avgWeeklyChange,
      bodyFatChange,
      goalProgress,
      goalETA
    };
  }
}