export type ChinaWorkdayType = 'workday' | 'weekend' | 'holiday' | 'makeup_workday';

export interface ChinaWorkdayInfo {
  date: string;
  type: ChinaWorkdayType;
  label: string;
  isWorkday: boolean;
  source: 'official_2026' | 'weekend_fallback';
}

type OverrideInfo = {
  type: Extract<ChinaWorkdayType, 'holiday' | 'makeup_workday'>;
  label: string;
};

export const CHINA_HOLIDAY_SOURCE_2026 = {
  name: '国务院办公厅关于2026年部分节假日安排的通知',
  url: 'https://www.gov.cn/zhengce/zhengceku/202511/content_7047091.htm',
} as const;

const OFFICIAL_2026_OVERRIDES: Record<string, OverrideInfo> = {
  '2026-01-01': { type: 'holiday', label: '元旦' },
  '2026-01-02': { type: 'holiday', label: '元旦' },
  '2026-01-03': { type: 'holiday', label: '元旦' },
  '2026-01-04': { type: 'makeup_workday', label: '元旦调休上班' },

  '2026-02-14': { type: 'makeup_workday', label: '春节调休上班' },
  '2026-02-15': { type: 'holiday', label: '春节' },
  '2026-02-16': { type: 'holiday', label: '春节' },
  '2026-02-17': { type: 'holiday', label: '春节' },
  '2026-02-18': { type: 'holiday', label: '春节' },
  '2026-02-19': { type: 'holiday', label: '春节' },
  '2026-02-20': { type: 'holiday', label: '春节' },
  '2026-02-21': { type: 'holiday', label: '春节' },
  '2026-02-22': { type: 'holiday', label: '春节' },
  '2026-02-23': { type: 'holiday', label: '春节' },
  '2026-02-28': { type: 'makeup_workday', label: '春节调休上班' },

  '2026-04-04': { type: 'holiday', label: '清明节' },
  '2026-04-05': { type: 'holiday', label: '清明节' },
  '2026-04-06': { type: 'holiday', label: '清明节' },

  '2026-05-01': { type: 'holiday', label: '劳动节' },
  '2026-05-02': { type: 'holiday', label: '劳动节' },
  '2026-05-03': { type: 'holiday', label: '劳动节' },
  '2026-05-04': { type: 'holiday', label: '劳动节' },
  '2026-05-05': { type: 'holiday', label: '劳动节' },
  '2026-05-09': { type: 'makeup_workday', label: '劳动节调休上班' },

  '2026-06-19': { type: 'holiday', label: '端午节' },
  '2026-06-20': { type: 'holiday', label: '端午节' },
  '2026-06-21': { type: 'holiday', label: '端午节' },

  '2026-09-20': { type: 'makeup_workday', label: '国庆节调休上班' },
  '2026-09-25': { type: 'holiday', label: '中秋节' },
  '2026-09-26': { type: 'holiday', label: '中秋节' },
  '2026-09-27': { type: 'holiday', label: '中秋节' },

  '2026-10-01': { type: 'holiday', label: '国庆节' },
  '2026-10-02': { type: 'holiday', label: '国庆节' },
  '2026-10-03': { type: 'holiday', label: '国庆节' },
  '2026-10-04': { type: 'holiday', label: '国庆节' },
  '2026-10-05': { type: 'holiday', label: '国庆节' },
  '2026-10-06': { type: 'holiday', label: '国庆节' },
  '2026-10-07': { type: 'holiday', label: '国庆节' },
  '2026-10-10': { type: 'makeup_workday', label: '国庆节调休上班' },
};

const DATE_KEY_PATTERN = /^(\d{4})-(\d{2})-(\d{2})/;

export function getDateKey(value: string | Date): string {
  if (value instanceof Date) {
    return formatDateKey(value);
  }
  const matched = value.match(DATE_KEY_PATTERN);
  if (matched) return `${matched[1]}-${matched[2]}-${matched[3]}`;
  const parsed = new Date(value);
  return Number.isNaN(parsed.getTime()) ? '' : formatDateKey(parsed);
}

export function getChinaWorkdayInfo(value: string | Date): ChinaWorkdayInfo {
  const date = getDateKey(value);
  const override = OFFICIAL_2026_OVERRIDES[date];
  if (override) {
    return {
      date,
      type: override.type,
      label: override.label,
      isWorkday: override.type === 'makeup_workday',
      source: 'official_2026',
    };
  }

  const parsed = parseDateKey(date);
  const weekend = parsed ? isWeekend(parsed) : false;
  return {
    date,
    type: weekend ? 'weekend' : 'workday',
    label: weekend ? '周末' : '工作日',
    isWorkday: !weekend,
    source: 'weekend_fallback',
  };
}

export function isChinaWorkday(value: string | Date): boolean {
  return getChinaWorkdayInfo(value).isWorkday;
}

function formatDateKey(date: Date): string {
  const yyyy = date.getFullYear();
  const mm = String(date.getMonth() + 1).padStart(2, '0');
  const dd = String(date.getDate()).padStart(2, '0');
  return `${yyyy}-${mm}-${dd}`;
}

function parseDateKey(dateKey: string): Date | null {
  const matched = dateKey.match(DATE_KEY_PATTERN);
  if (!matched) return null;
  const year = Number(matched[1]);
  const month = Number(matched[2]);
  const day = Number(matched[3]);
  if (!year || !month || !day) return null;
  return new Date(year, month - 1, day);
}

function isWeekend(date: Date): boolean {
  const day = date.getDay();
  return day === 0 || day === 6;
}
