// src/views/AgentChat/utils/sessionUtils.js
// 会话管理工具函数

/**
 * 格式化日期为显示标签
 * @param {Date} date - 日期对象
 * @param {Date} today - 今天的日期
 * @returns {string} 格式化后的日期标签
 */
const formatDateLabel = (date, today) => {
  const daysDiff = Math.floor((today - date) / (1000 * 60 * 60 * 24));

  if (daysDiff === 0) {
    return '今天';
  } else if (daysDiff === 1) {
    return '昨天';
  } else if (daysDiff < 7) {
    const weekDays = ['周日', '周一', '周二', '周三', '周四', '周五', '周六'];
    return weekDays[date.getDay()];
  } else {
    // 超过一周，显示具体日期
    return `${date.getMonth() + 1}月${date.getDate()}日`;
  }
};

/**
 * 获取日期的纯日期字符串（用于分组 key）
 * @param {Date} date - 日期对象
 * @returns {string} YYYY-MM-DD 格式的日期字符串
 */
const getDateKey = (date) => {
  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')}`;
};

/**
 * 按日期分组会话列表（新版本 - 按具体日期分组）
 *
 * @param {Array} sessions - 会话列表
 * @returns {Array} 分组后的会话数组 [{ dateKey, label, sessions, date }]
 *
 * @example
 * const groups = groupSessionsByDate(sessions);
 * // 返回: [
 * //   { dateKey: '2025-11-30', label: '今天', sessions: [...], date: Date },
 * //   { dateKey: '2025-11-29', label: '昨天', sessions: [...], date: Date },
 * //   ...
 * // ]
 */
export const groupSessionsByDate = (sessions) => {
  if (!sessions || sessions.length === 0) {
    return [];
  }

  const today = new Date();
  today.setHours(0, 0, 0, 0);

  // 按日期分组到 Map
  const groupMap = new Map();

  sessions.forEach((session) => {
    const sessionDate = new Date(session.created_at || session.timestamp);
    if (isNaN(sessionDate.getTime())) {
      // 无效日期，归到今天
      const todayKey = getDateKey(today);
      if (!groupMap.has(todayKey)) {
        groupMap.set(todayKey, {
          dateKey: todayKey,
          label: '今天',
          sessions: [],
          date: today,
        });
      }
      groupMap.get(todayKey).sessions.push(session);
      return;
    }

    const dateOnly = new Date(sessionDate);
    dateOnly.setHours(0, 0, 0, 0);
    const dateKey = getDateKey(dateOnly);

    if (!groupMap.has(dateKey)) {
      groupMap.set(dateKey, {
        dateKey,
        label: formatDateLabel(dateOnly, today),
        sessions: [],
        date: dateOnly,
      });
    }
    groupMap.get(dateKey).sessions.push(session);
  });

  // 转换为数组并按日期降序排序
  const groups = Array.from(groupMap.values()).sort((a, b) => b.date - a.date);

  // 每个分组内部按时间降序排序
  groups.forEach((group) => {
    group.sessions.sort((a, b) => {
      const dateA = new Date(a.created_at || a.timestamp);
      const dateB = new Date(b.created_at || b.timestamp);
      return dateB - dateA;
    });
  });

  return groups;
};

/**
 * 旧版分组函数（保留兼容性）
 * @deprecated 请使用 groupSessionsByDate 替代
 */
export const groupSessionsByDateLegacy = (sessions) => {
  const today = new Date();
  const yesterday = new Date(today);
  yesterday.setDate(yesterday.getDate() - 1);
  const weekAgo = new Date(today);
  weekAgo.setDate(weekAgo.getDate() - 7);

  const groups = {
    today: [],
    yesterday: [],
    thisWeek: [],
    older: [],
  };

  sessions.forEach((session) => {
    const sessionDate = new Date(session.created_at || session.timestamp);
    const daysDiff = Math.floor((today - sessionDate) / (1000 * 60 * 60 * 24));

    if (daysDiff === 0) {
      groups.today.push(session);
    } else if (daysDiff === 1) {
      groups.yesterday.push(session);
    } else if (daysDiff <= 7) {
      groups.thisWeek.push(session);
    } else {
      groups.older.push(session);
    }
  });

  return groups;
};