import type { KR, ProjectStatus, Checkin } from '@/types/database';

export function getTodayInTokyo(): string {
  const now = new Date();
  const tokyoTime = new Date(now.toLocaleString('en-US', { timeZone: 'Asia/Tokyo' }));
  return tokyoTime.toISOString().split('T')[0];
}

export function calculateProgress(kr: KR): number {
  if (kr.direction === 'increase') {
    return kr.target_value > 0 ? kr.current_value / kr.target_value : 0;
  } else {
    return kr.current_value > 0 ? kr.target_value / kr.current_value : 0;
  }
}

export function calculateExpectedProgress(kr: KR): number {
  const today = getTodayInTokyo();
  const start = new Date(kr.period_start);
  const end = new Date(kr.period_end);
  const current = new Date(today);

  const totalDays = Math.ceil((end.getTime() - start.getTime()) / (1000 * 60 * 60 * 24)) + 1;
  const elapsedDays = Math.max(0, Math.ceil((current.getTime() - start.getTime()) / (1000 * 60 * 60 * 24)) + 1);

  return Math.min(1, elapsedDays / totalDays);
}

export function determineKRStatus(
  kr: KR,
  recentCheckins: Checkin[] = []
): ProjectStatus {
  const progress = calculateProgress(kr);
  const expectedProgress = calculateExpectedProgress(kr);
  const progressGap = expectedProgress - progress;

  const consecutiveYellows = recentCheckins
    .slice(0, 2)
    .filter(c => c.status_snapshot === 'yellow').length >= 2;

  if (consecutiveYellows) {
    return 'red';
  }

  if (kr.confidence < 50 || progressGap > 0.15) {
    return 'red';
  }

  if ((kr.confidence >= 50 && kr.confidence < 80) || (progressGap > 0.05 && progressGap <= 0.15)) {
    return 'yellow';
  }

  if (kr.confidence >= 80 && progressGap <= 0.05) {
    return 'green';
  }

  return 'yellow';
}

export function determineProjectStatus(krs: KR[]): ProjectStatus {
  if (krs.length === 0) return 'green';

  const redCount = krs.filter(kr => kr.status === 'red').length;
  const yellowCount = krs.filter(kr => kr.status === 'yellow').length;

  if (redCount > 0) return 'red';

  const yellowRatio = yellowCount / krs.length;
  if (yellowRatio > 0.3) return 'red';

  if (yellowCount > 0) return 'yellow';

  return 'green';
}

export function formatDateRange(start: string, end: string): string {
  const startDate = new Date(start);
  const endDate = new Date(end);

  const formatOptions: Intl.DateTimeFormatOptions = { month: 'short', day: 'numeric' };

  return `${startDate.toLocaleDateString('zh-CN', formatOptions)} - ${endDate.toLocaleDateString('zh-CN', formatOptions)}`;
}

export function getDaysRemaining(endDate: string): number {
  const today = new Date(getTodayInTokyo());
  const end = new Date(endDate);
  return Math.ceil((end.getTime() - today.getTime()) / (1000 * 60 * 60 * 24));
}

export function isKRActive(kr: KR): boolean {
  const today = getTodayInTokyo();
  return kr.period_start <= today && kr.period_end >= today;
}