using System.Collections.Generic;
using System.Linq;
using NCC.Extend.Entitys.lq_attendance_record;

namespace NCC.Extend
{
    /// <summary>
    /// 按自然月从打卡记录中的考勤组名称快照生成展示文案（多月多组按首次出现日期用 → 连接）。
    /// </summary>
    public static class AttendanceMonthGroupDisplayHelper
    {
        /// <summary>
        /// 根据当月有效打卡记录中的 <c>F_AttendanceGroupName</c> 聚合展示；无任何快照时使用主档分组名称；仍无则「无」。
        /// </summary>
        /// <param name="monthRecords">该员工该自然月内的打卡记录（通常已为有效记录）</param>
        /// <param name="profileAttendanceGroupName">员工主档当前绑定的考勤组名称（兜底）</param>
        public static string BuildDisplay(
            IEnumerable<LqAttendanceRecordEntity> monthRecords,
            string profileAttendanceGroupName)
        {
            var list = monthRecords == null
                ? new List<LqAttendanceRecordEntity>()
                : monthRecords.Where(r => r != null).ToList();

            var orderedNames = list
                .Where(r => !string.IsNullOrWhiteSpace(r.AttendanceGroupName))
                .Select(r => new { Name = r.AttendanceGroupName.Trim(), Date = r.AttendanceDate.Date })
                .GroupBy(x => x.Name)
                .Select(g => new { Name = g.Key, FirstDate = g.Min(x => x.Date) })
                .OrderBy(x => x.FirstDate)
                .Select(x => x.Name)
                .ToList();

            if (orderedNames.Count == 0)
            {
                return string.IsNullOrWhiteSpace(profileAttendanceGroupName)
                    ? "无"
                    : profileAttendanceGroupName.Trim();
            }

            return orderedNames.Count == 1
                ? orderedNames[0]
                : string.Join("→", orderedNames);
        }
    }
}