import { useState, useEffect, useMemo } from 'react'
import { Link } from 'react-router-dom'
import api from '../../api'
import toast from 'react-hot-toast'
import { Search, ChevronUp, ChevronDown, Filter, X, Users, Calendar } from 'lucide-react'
import StatusBadge from '../../components/StatusBadge'

export default function AttendanceList() {
  const [records, setRecords] = useState([])
  const [total, setTotal] = useState(0)
  const [loading, setLoading] = useState(true)
  const [search, setSearch] = useState('')
  const [sortBy, setSortBy] = useState('date')
  const [sortOrder, setSortOrder] = useState('desc')
  const [dateFrom, setDateFrom] = useState('')
  const [dateTo, setDateTo] = useState('')
  const [staffFilter, setStaffFilter] = useState('')
  const [statusFilter, setStatusFilter] = useState('')
  const [page, setPage] = useState(1)
  const [statusOptions, setStatusOptions] = useState([])
  const perPage = 50

  const [staffList, setStaffList] = useState([])

  useEffect(() => {
    fetchRecords()
    fetchStatusTexts()
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [page, sortBy, sortOrder, dateFrom, dateTo, staffFilter, statusFilter, search])

  const fetchStatusTexts = async () => {
    try {
      const { data } = await api.get('/api/attendance/status_texts')
      setStatusOptions(data || [])
    } catch (e) { console.error('Failed to fetch status texts', e) }
  }

  const fetchRecords = async () => {
    setLoading(true)
    try {
      const params = new URLSearchParams({
        page,
        per_page: perPage,
        sort_by: sortBy,
        sort_order: sortOrder,
      })
      if (search) params.append('search', search)
      if (dateFrom) params.append('date_from', dateFrom)
      if (dateTo) params.append('date_to', dateTo)
      if (staffFilter) params.append('staff', staffFilter)
      if (statusFilter) params.append('status_text', statusFilter)

      const { data } = await api.get(`/api/attendance/records?${params}`)
      setRecords(data.records || [])
      setTotal(data.total || 0)

      // Extract unique staff names
      const names = [...new Set((data.records || []).map(r => r.employee_name).filter(Boolean))]
      setStaffList(names.sort())
    } catch (err) {
      toast.error('載入失敗')
      console.error(err)
    } finally {
      setLoading(false)
    }
  }

  const handleSearch = (e) => {
    e.preventDefault()
    setPage(1)
    fetchRecords()
  }

  const handleSort = (key) => {
    if (sortBy === key) {
      setSortOrder(sortOrder === 'asc' ? 'desc' : 'asc')
    } else {
      setSortBy(key)
      setSortOrder('asc')
    }
    setPage(1)
  }

  const getSortIcon = (key) => {
    if (sortBy !== key) return null
    return sortOrder === 'asc' ? <ChevronUp size={14} /> : <ChevronDown size={14} />
  }

  const getStatusBadge = (record) => {
    return <StatusBadge code={record.status_code} text={record.status_text} />
  }

  const getRowClass = (code) => {
    if (code === 'abnormal') return 'bg-red-50 hover:bg-red-100'
    if (code === 'missing') return 'bg-gray-100 hover:bg-gray-200'
    if (code === 'late' || code === 'late_early' || code === 'late_ot') return 'bg-orange-50 hover:bg-orange-100'
    if (code === 'early' || code === 'early_ot') return 'bg-blue-50 hover:bg-blue-100'
    if (code === 'ot') return 'bg-purple-50 hover:bg-purple-100'
    return 'hover:bg-slate-50'
  }

  const totalPages = Math.ceil(total / perPage)

  const columns = [
    { key: 'employee_name', label: '員工' },
    { key: 'date', label: '日期' },
    { key: 'weekday', label: '星期' },
    { key: 'shift_code', label: '班次' },
    { key: 'actual_in', label: '上班' },
    { key: 'actual_out', label: '下班' },
    { key: 'expected_in', label: '應上班' },
    { key: 'expected_out', label: '應下班' },
  ]

  return (
    <div className="space-y-4">
      {/* Header */}
      <div className="flex items-center justify-between">
        <h1 className="text-lg sm:text-xl font-bold text-slate-900">出勤記錄 Attendance</h1>
        <div className="flex gap-2">
          <Link to="/" className="flex items-center gap-2 px-4 py-2 bg-slate-100 text-slate-700 text-sm rounded-md hover:bg-slate-200">
            <Calendar size={16} /> Dashboard
          </Link>
          <Link to="/upload" className="flex items-center gap-2 px-4 py-2 bg-blue-600 text-white text-sm rounded-md hover:bg-blue-700">
            上傳 Excel
          </Link>
        </div>
      </div>

      {/* Filters */}
      <div className="card p-4 space-y-3">
        {/* Search row */}
        <form onSubmit={handleSearch} className="flex flex-wrap gap-3 items-end">
          <div className="relative flex-1 min-w-[200px]">
            <Search size={16} className="absolute left-3 top-1/2 -translate-y-1/2 text-slate-400" />
            <input
              type="text"
              value={search}
              onChange={(e) => setSearch(e.target.value)}
              placeholder="搜尋員工姓名..."
              className="w-full pl-9 pr-4 py-2 text-sm border border-slate-300 rounded-md"
            />
          </div>
          <button type="submit" className="px-4 py-2 bg-blue-600 text-white text-sm rounded-md hover:bg-blue-700">
            搜尋
          </button>
        </form>

        {/* Filter row */}
        <div className="flex flex-wrap gap-3 items-end">
          <div className="flex items-center gap-2">
            <span className="text-xs text-slate-500">日期:</span>
            <input
              type="date"
              value={dateFrom}
              onChange={(e) => { setDateFrom(e.target.value); setPage(1) }}
              className="text-sm border border-slate-300 rounded-md px-2 py-1.5"
              placeholder="由"
            />
            <span className="text-slate-400">-</span>
            <input
              type="date"
              value={dateTo}
              onChange={(e) => { setDateTo(e.target.value); setPage(1) }}
              className="text-sm border border-slate-300 rounded-md px-2 py-1.5"
              placeholder="至"
            />
          </div>

          <div className="flex items-center gap-2">
            <span className="text-xs text-slate-500">員工:</span>
            <select
              value={staffFilter}
              onChange={(e) => { setStaffFilter(e.target.value); setPage(1) }}
              className="text-sm border border-slate-300 rounded-md px-2 py-1.5"
            >
              <option value="">全部</option>
              {staffList.map(s => (
                <option key={s} value={s}>{s}</option>
              ))}
            </select>
          </div>

          <div className="flex items-center gap-2">
            <span className="text-xs text-slate-500">狀態:</span>
            <select
              value={statusFilter ? statusFilter : (statusTextFilter || '')}
              onChange={(e) => {
                setStatusFilter(e.target.value)
                setStatusTextFilter('')
                setPage(1)
              }}
              className="text-sm border border-slate-300 rounded-md px-2 py-1.5"
            >
              <option value="">全部</option>
              {statusOptions.map(opt => (
                <option key={opt} value={opt}>{opt}</option>
              ))}
            </select>
          </div>

          <button
            onClick={() => {
              setDateFrom(''); setDateTo(''); setStaffFilter(''); setStatusFilter(''); setSearch(''); setPage(1)
              // Force refetch in case useEffect timing misses the state change.
              setTimeout(() => fetchRecords(), 0)
            }}
            className="flex items-center gap-1 px-3 py-1.5 text-xs text-slate-500 hover:text-slate-700 border border-slate-300 rounded-md"
          >
            <X size={14} /> 清除篩選
          </button>
        </div>

        {/* Stats bar */}
        <div className="flex items-center gap-4 text-xs text-slate-500">
          <span>{total} 筆記錄</span>
          {staffFilter && <span>• 員工: {staffFilter}</span>}
          {statusFilter && <span>• 狀態: {statusFilter}</span>}
          {(dateFrom || dateTo) && <span>• {dateFrom || '...'} 至 {dateTo || '...'}</span>}
        </div>
      </div>

      {/* Table */}
      <div className="card overflow-hidden">
        <div className="overflow-x-auto">
          <table className="w-full text-sm">
            <thead className="bg-slate-100 border-b border-slate-200">
              <tr>
                <th className="px-3 py-2.5 text-left text-xs font-semibold text-slate-600 w-12">#</th>
                {columns.map(col => (
                  <th
                    key={col.key}
                    onClick={() => handleSort(col.key)}
                    className="px-3 py-2.5 text-left text-xs font-semibold text-slate-600 cursor-pointer hover:bg-slate-200"
                  >
                    <div className="flex items-center gap-1">
                      {col.label}
                      {getSortIcon(col.key)}
                    </div>
                  </th>
                ))}
                <th className="px-3 py-2.5 text-center text-xs font-semibold text-slate-600">狀態</th>
                <th className="px-3 py-2.5 text-right text-xs font-semibold text-slate-600 w-16">操作</th>
              </tr>
            </thead>
            <tbody className="divide-y divide-slate-100">
              {loading ? (
                <tr>
                  <td colSpan={10} className="px-3 py-8 text-center text-slate-400">
                    載入中...
                  </td>
                </tr>
              ) : records.length === 0 ? (
                <tr>
                  <td colSpan={10} className="px-3 py-8 text-center text-slate-400">
                    沒有記錄
                  </td>
                </tr>
              ) : (
                records.map((record, idx) => (
                  <tr
                    key={record.id || idx}
                    className={getRowClass(record.status_code)}
                  >
                    <td className="px-3 py-2.5 text-xs text-slate-400">{(page - 1) * perPage + idx + 1}</td>
                    <td className="px-3 py-2.5 text-slate-700 font-medium">{record.employee_name || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-600">{record.date || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-600">{record.weekday || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-600">{record.shift_code || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-600">{record.actual_in || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-600">{record.actual_out || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-400 text-xs">{record.expected_in || '-'}</td>
                    <td className="px-3 py-2.5 text-slate-400 text-xs">{record.expected_out || '-'}</td>
                    <td className="px-3 py-2.5 text-center">
                      {getStatusBadge(record)}
                    </td>
                    <td className="px-3 py-2.5 text-right">
                      <Link
                        to={`/attendance/${record.id}`}
                        className="p-1 text-slate-400 hover:text-blue-600 inline-block"
                      >
                        <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"/><circle cx="12" cy="12" r="3"/></svg>
                      </Link>
                    </td>
                  </tr>
                ))
              )}
            </tbody>
          </table>
        </div>

        {/* Pagination */}
        {totalPages > 1 && (
          <div className="flex items-center justify-between px-4 py-3 border-t border-slate-200 bg-slate-50">
            <span className="text-xs text-slate-500">
              第 {page} / {totalPages} 頁，共 {total} 筆記錄
            </span>
            <div className="flex gap-2">
              <button
                onClick={() => setPage(Math.max(1, page - 1))}
                disabled={page === 1}
                className="px-3 py-1 text-xs border border-slate-300 rounded-md disabled:opacity-50 hover:bg-slate-100"
              >
                上一頁
              </button>
              <button
                onClick={() => setPage(Math.min(totalPages, page + 1))}
                disabled={page === totalPages}
                className="px-3 py-1 text-xs border border-slate-300 rounded-md disabled:opacity-50 hover:bg-slate-100"
              >
                下一頁
              </button>
            </div>
          </div>
        )}
      </div>
    </div>
  )
}