/**
 * System Date Skill
 * 获取当前日期和农历（使用 lunar-javascript 库）
 */

const { Solar, Lunar } = require('lunar-javascript');

/**
 * 获取北京时间
 */
function getBeijingTime() {
  const now = new Date();
  // UTC + 8 = 北京时间
  return new Date(now.getTime() + (8 * 60 * 60 * 1000));
}

/**
 * 获取农历日期（使用专业库）
 */
function getLunarInfo(beijingDate) {
  // 从公历转换为农历
  const solar = Solar.fromDate(beijingDate);
  const lunar = solar.getLunar();
  
  return {
    lunarDate: lunar.toString(), // 如：二〇二六年正月初八
    lunarDay: lunar.getDayInChinese(), // 如：初八
    lunarMonth: lunar.getMonthInChinese(), // 如：正月
    lunarYear: lunar.getYearInChinese(), // 如：二〇二六
    isLeap: false // lunar-javascript 需要其他方法判断闰月
  };
}

/**
 * 获取当前日期时间（北京时间）
 */
function getCurrentDateTime() {
  const beijingNow = getBeijingTime();
  
  const year = beijingNow.getFullYear();
  const month = beijingNow.getMonth() + 1;
  const day = beijingNow.getDate();
  const weekdays = ['日', '一', '二', '三', '四', '五', '六'];
  const weekday = `星期${weekdays[beijingNow.getDay()]}`;
  
  const lunarInfo = getLunarInfo(beijingNow);
  
  return {
    success: true,
    timezone: 'Asia/Shanghai',
    year: year,
    month: month,
    day: day,
    weekday: weekday,
    fullDate: `${year}年${month}月${day}日`,
    lunarDate: lunarInfo.lunarDate,
    lunarDay: lunarInfo.lunarDay,
    lunarMonth: lunarInfo.lunarMonth,
    lunarYear: lunarInfo.lunarYear,
    isLeap: lunarInfo.isLeap,
    isoString: beijingNow.toISOString()
  };
}

/**
 * 获取相对日期（北京时间）
 */
function getRelativeDate(relative = 'today') {
  const beijingNow = getBeijingTime();
  let targetDate = new Date(beijingNow);
  
  switch (relative.toLowerCase()) {
    case 'today':
    case '今天':
      break;
    case 'tomorrow':
    case '明天':
      targetDate.setDate(targetDate.getDate() + 1);
      break;
    case 'yesterday':
    case '昨天':
      targetDate.setDate(targetDate.getDate() - 1);
      break;
  }
  
  const year = targetDate.getFullYear();
  const month = targetDate.getMonth() + 1;
  const day = targetDate.getDate();
  const weekdays = ['日', '一', '二', '三', '四', '五', '六'];
  const weekday = `星期${weekdays[targetDate.getDay()]}`;
  
  const lunarInfo = getLunarInfo(targetDate);
  
  return {
    success: true,
    relative: relative,
    year: year,
    month: month,
    day: day,
    weekday: weekday,
    fullDate: `${year}年${month}月${day}日`,
    lunarDate: lunarInfo.lunarDate,
    lunarDay: lunarInfo.lunarDay,
    lunarMonth: lunarInfo.lunarMonth,
    lunarYear: lunarInfo.lunarYear,
    isLeap: lunarInfo.isLeap,
    timezone: 'Asia/Shanghai'
  };
}

/**
 * 格式化日期为可读文本
 */
function formatDateInfo(dateInfo, includeLunar = true) {
  const lines = [
    `📅 **${dateInfo.fullDate}**`,
    `**星期:** ${dateInfo.weekday}`,
  ];
  
  if (includeLunar && dateInfo.lunarDate) {
    lines.push(`**农历:** ${dateInfo.lunarDate}`);
    if (dateInfo.isLeap) {
      lines.push(`**闰月:** 是`);
    }
  }
  
  lines.push(`**时区:** ${dateInfo.timezone || 'Asia/Shanghai'}`);
  
  return lines.join('\n');
}

// 命令行测试
if (require.main === module) {
  console.log('=== 农历计算测试（使用 lunar-javascript 库）===\n');
  
  const arg = process.argv[2] || 'today';
  const result = getRelativeDate(arg);
  console.log(formatDateInfo(result));
  console.log('\n详细信息:');
  console.log(`农历年：${result.lunarYear}`);
  console.log(`农历月：${result.lunarMonth}`);
  console.log(`农历日：${result.lunarDay}`);
  console.log(`是否闰月：${result.isLeap ? '是' : '否'}`);
}

module.exports = { getCurrentDateTime, getRelativeDate, formatDateInfo, getLunarInfo, getBeijingTime };