import pool from '../config/database';
import { PerformanceLevel } from '../dao/PerformanceDAO';

export interface AttendanceInput {
  leaveDays: number;
  lateTimes: number;
  lackCardTimes: number;
}

export interface LevelAndReward {
  level: PerformanceLevel;
  rewardPunish: string;
}

export interface ConsecutiveLowScoreResult {
  consecutiveMonths: number;
  warning: 'none' | 'written_warning' | 'dismissal';
}

/**
 * Calculate attendance score.
 * Base: 10 points. Deduct 5 per leave day, 2 per late/lack-card occurrence. Minimum 0.
 * Requirements: 11.1, 11.2, 11.3, 11.5
 */
export function calculateAttendanceScore(input: AttendanceInput): number {
  const { leaveDays, lateTimes, lackCardTimes } = input;
  const deduction = leaveDays * 5 + lateTimes * 2 + lackCardTimes * 2;
  return Math.max(0, 10 - deduction);
}

/**
 * Calculate performance level and reward/punishment description based on total score.
 * Requirements: 5.1, 5.2, 5.3, 5.4, 5.5
 */
export function calculateLevelAndReward(totalScore: number): LevelAndReward {
  if (totalScore >= 90) {
    return { level: 'excellent', rewardPunish: '优秀，按公司规定给予奖励' };
  } else if (totalScore >= 80) {
    return { level: 'qualified', rewardPunish: '合格，扣除当月绩效工资100元' };
  } else if (totalScore >= 70) {
    return { level: 'qualified', rewardPunish: '合格，扣除当月绩效工资200元' };
  } else if (totalScore >= 60) {
    return { level: 'need_motivation', rewardPunish: '需激励，扣除当月绩效工资300元' };
  } else {
    return { level: 'unqualified', rewardPunish: '不合格，扣除当月绩效工资600元' };
  }
}

/**
 * Check consecutive low score warning for an employee.
 * Queries the most recent completed performance records and counts consecutive months below 60.
 * Requirements: 5.6, 5.7
 */
export async function checkConsecutiveLowScore(
  userId: number,
  lookbackMonths: number = 3
): Promise<ConsecutiveLowScoreResult> {
  const [rows] = await pool.query<any[]>(
    `SELECT total_score FROM performance_month
     WHERE user_id = ? AND status = 'completed' AND total_score IS NOT NULL
     ORDER BY month DESC
     LIMIT ?`,
    [userId, lookbackMonths]
  );

  let consecutiveMonths = 0;
  for (const row of rows) {
    if (row.total_score < 60) {
      consecutiveMonths++;
    } else {
      break;
    }
  }

  let warning: ConsecutiveLowScoreResult['warning'] = 'none';
  if (consecutiveMonths >= 3) {
    warning = 'dismissal';
  } else if (consecutiveMonths >= 2) {
    warning = 'written_warning';
  }

  return { consecutiveMonths, warning };
}