/**
 * System Date Skill
 * 获取当前日期和时间（支持时区）
 */

/**
 * 获取当前日期时间
 * @param {string} timezone - 时区 (默认 Asia/Shanghai)
 * @returns {Object} 日期时间信息
 */
function getCurrentDateTime(timezone = 'Asia/Shanghai') {
  const now = new Date();
  
  // 转换为指定时区
  const options = {
    timeZone: timezone,
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    weekday: 'long',
    hour: '2-digit',
    minute: '2-digit',
    hour12: false
  };
  
  const formatter = new Intl.DateTimeFormat('zh-CN', options);
  const parts = formatter.formatToParts(now);
  
  const result = {};
  parts.forEach(part => {
    result[part.type] = part.value;
  });
  
  // 计算农历日期（基于 2026 年春节 2 月 17 日）
  const springFestival = new Date('2026-02-17');
  const daysSince = Math.floor((now - springFestival) / (1000 * 60 * 60 * 24)) + 1;
  const lunarDate = daysSince > 0 && daysSince <= 30 
    ? `农历正月初${daysSince}` 
    : '农历日期需查询黄历';
  
  return {
    success: true,
    timezone: timezone,
    year: result.year,
    month: result.month,
    day: result.day,
    weekday: result.weekday,
    hour: result.hour,
    minute: result.minute,
    fullDate: `${result.year}年${parseInt(result.month)}月${parseInt(result.day)}日`,
    lunarDate: lunarDate,
    isoString: now.toISOString()
  };
}

/**
 * 获取相对日期
 * @param {string} relative - 相对日期 (today, tomorrow, yesterday)
 * @param {string} timezone - 时区
 * @returns {Object} 日期信息
 */
function getRelativeDate(relative = 'today', timezone = 'Asia/Shanghai') {
  const now = new Date();
  let targetDate = new Date(now);
  
  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;
  }
  
  // 计算农历日期
  const springFestival = new Date('2026-02-17');
  const daysSince = Math.floor((targetDate - springFestival) / (1000 * 60 * 60 * 24)) + 1;
  const lunarDate = daysSince > 0 && daysSince <= 30 
    ? `农历正月初${daysSince}` 
    : '农历日期需查询黄历';
  
  const options = {
    timeZone: timezone,
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    weekday: 'long'
  };
  
  const formatter = new Intl.DateTimeFormat('zh-CN', options);
  const parts = formatter.formatToParts(targetDate);
  
  const result = {};
  parts.forEach(part => {
    result[part.type] = part.value;
  });
  
  return {
    success: true,
    relative: relative,
    year: result.year,
    month: result.month,
    day: result.day,
    weekday: result.weekday,
    fullDate: `${result.year}年${parseInt(result.month)}月${parseInt(result.day)}日`,
    lunarDate: lunarDate,
    isoString: targetDate.toISOString()
  };
}

/**
 * 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.timezone) {
    lines.push(`**时区:** ${dateInfo.timezone}`);
  }
  
  return lines.join('\n');
}

// 命令行测试
if (require.main === module) {
  const arg = process.argv[2] || 'today';
  const result = getRelativeDate(arg, 'Asia/Shanghai');
  console.log(formatDateInfo(result));
}

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