'use client';

import { useEffect, useState } from 'react';
import { ARBEITSZEIT_KUNDE_FIX, type ArbeitszeitEintrag } from '@/types/arbeitszeit';
import { toDecimalHours, mehrarbeit, weekdayName, formatHours, hatZeiten } from '@/lib/calc';

interface Props {
  pause: number;
  refreshKey: number;
  onEdit: (entry: ArbeitszeitEintrag) => void;
  limit?: number;
  compact?: boolean;
}

const pad = (n: number) => String(n).padStart(2, '0');
const MONATE = ['Januar','Februar','März','April','Mai','Juni','Juli','August','September','Oktober','November','Dezember'];

function currentMonth() {
  const d = new Date();
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}`;
}
function monthLabel(ym: string) {
  const [y, m] = ym.split('-').map(Number);
  return `${MONATE[m - 1]} ${y}`;
}
function prevMonth(ym: string) {
  const [y, m] = ym.split('-').map(Number);
  return m === 1 ? `${y - 1}-12` : `${y}-${pad(m - 1)}`;
}
function nextMonth(ym: string) {
  const [y, m] = ym.split('-').map(Number);
  return m === 12 ? `${y + 1}-01` : `${y}-${pad(m + 1)}`;
}
function formatDate(d: string) {
  const m = /^(\d{4})-(\d{2})-(\d{2})$/.exec(d);
  return m ? `${m[3]}.${m[2]}.${m[1]}` : d;
}

export default function ArbeitszeitList({ pause, refreshKey, onEdit, limit = 15, compact = false }: Props) {
  const [entries, setEntries] = useState<ArbeitszeitEintrag[]>([]);
  const [month, setMonth] = useState(compact ? '' : currentMonth());
  const [deleteId, setDeleteId] = useState<number | null>(null);
  const [deleteErr, setDeleteErr] = useState('');

  // Lade-/Fehlerzustand wird aus dem Ergebnis abgeleitet, nicht synchron im Effekt gesetzt.
  const paramsKey = `${refreshKey}|${limit}|${month}`;
  const [fetchResult, setFetchResult] = useState<{ ok: boolean; forKey: string } | null>(null);
  const loading = fetchResult?.forKey !== paramsKey;
  const fetchError = fetchResult?.forKey === paramsKey && !fetchResult.ok ? 'Fehler beim Laden.' : '';
  const error = fetchError || deleteErr;

  useEffect(() => {
    let cancelled = false;
    const url =
      `/api/arbeitszeit?limit=${limit}&offset=0` + (month ? `&month=${encodeURIComponent(month)}` : '');
    fetch(url)
      .then((r) => { if (!r.ok) throw new Error(); return r.json(); })
      .then((data) => {
        if (!cancelled) {
          setEntries(data.entries);
          setDeleteErr('');
          setFetchResult({ ok: true, forKey: paramsKey });
        }
      })
      .catch(() => { if (!cancelled) setFetchResult({ ok: false, forKey: paramsKey }); });
    return () => { cancelled = true; };
  }, [refreshKey, limit, month, paramsKey]);

  async function confirmDelete(id: number) {
    try {
      const res = await fetch(`/api/arbeitszeit/${id}`, { method: 'DELETE' });
      if (!res.ok) throw new Error();
      setEntries((prev) => prev.filter((e) => e.id !== id));
    } catch {
      setDeleteErr('Fehler beim Löschen.');
    } finally {
      setDeleteId(null);
    }
  }

  const cell = compact
    ? 'px-1.5 py-1 border border-gray-200 text-xs text-gray-900'
    : 'px-3 py-2 border border-gray-200 text-gray-900';
  const head = compact
    ? 'px-1.5 py-1 border border-gray-300 text-xs font-semibold text-gray-900'
    : 'px-3 py-2 border border-gray-300 text-gray-900';

  return (
    <div>
      {!compact && (
        <div className="flex items-center gap-1 mb-3 print:hidden">
          <button onClick={() => setMonth((m) => prevMonth(m))} className="px-2 py-1 text-sm rounded-lg bg-[#86C28B] hover:bg-[#6FB075]">←</button>
          <input
            type="month"
            value={month}
            max={currentMonth()}
            onChange={(e) => setMonth(e.target.value > currentMonth() ? currentMonth() : e.target.value)}
            className="border border-green-600 rounded-lg px-2 py-1 text-sm text-gray-900 focus:outline-none focus:ring-2 focus:ring-inset focus:ring-green-700"
          />
          <button onClick={() => setMonth((m) => nextMonth(m))} disabled={month >= currentMonth()} className="px-2 py-1 text-sm rounded-lg bg-[#86C28B] hover:bg-[#6FB075] disabled:opacity-40 disabled:cursor-not-allowed">→</button>
          {month !== currentMonth() && (
            <button onClick={() => setMonth(currentMonth())} className="text-sm text-green-700 hover:underline ml-1">Aktueller Monat</button>
          )}
        </div>
      )}

      {loading && <div className="text-gray-500 text-sm py-4">Lade Einträge...</div>}
      {error && <div className="text-red-600 text-sm py-4">{error}</div>}

      {!loading && !error && (
        <div className="overflow-x-auto">
          <table className="w-full border-collapse" style={{ fontSize: compact ? '0.75rem' : '0.875rem' }}>
            <thead>
              <tr className="bg-gray-100 text-left">
                <th className={`${head} whitespace-nowrap`}>Datum</th>
                <th className={head}>Wochentag</th>
                <th className={head}>Ort</th>
                <th className={`${head} text-right whitespace-nowrap`}>Arbeitszeit Kunde</th>
                <th className={`${head} text-right`}>Mehrarbeit</th>
                <th className={`${head} text-right`}>Reisezeit</th>
                <th className={`${head} text-right whitespace-nowrap`}>Vertriebsunt.</th>
                <th className={head}>Kommentar</th>
                <th className={`${head} text-center print:hidden`}>Aktionen</th>
              </tr>
            </thead>
            <tbody>
              {entries.length === 0 ? (
                <tr>
                  <td colSpan={9} className="px-3 py-4 text-gray-500 text-sm text-center">
                    {month ? `Keine Einträge für ${monthLabel(month)}.` : 'Keine Einträge vorhanden.'}
                  </td>
                </tr>
              ) : entries.map((e) => {
                const zeiten = hatZeiten(e.beginn, e.ende);
                const mehr = mehrarbeit(toDecimalHours(e.beginn, e.ende), pause);
                return (
                  <tr key={e.id} className="hover:bg-gray-50">
                    <td className={`${cell} whitespace-nowrap`}>{formatDate(e.datum)}</td>
                    <td className={cell}>{weekdayName(e.datum)}</td>
                    <td className={cell}>{e.ort}</td>
                    <td className={`${cell} text-right`}>{zeiten ? formatHours(ARBEITSZEIT_KUNDE_FIX) : '—'}</td>
                    <td className={`${cell} text-right ${zeiten && mehr < 0 ? 'text-red-600' : ''}`}>{zeiten ? formatHours(mehr) : '—'}</td>
                    <td className={`${cell} text-right`}>{e.reisezeit ? formatHours(e.reisezeit) : '—'}</td>
                    <td className={`${cell} text-right`}>{e.vertriebsunterstuetzung ? formatHours(e.vertriebsunterstuetzung) : '—'}</td>
                    <td className={cell}>{e.kommentar}</td>
                    <td className={`${cell} text-center whitespace-nowrap print:hidden`}>
                      <button onClick={() => onEdit(e)} className="text-green-700 hover:text-green-900 mr-2 font-medium">✎</button>
                      <button onClick={() => setDeleteId(e.id)} className="text-red-600 hover:text-red-800 font-medium">✕</button>
                    </td>
                  </tr>
                );
              })}
            </tbody>
          </table>
        </div>
      )}

      {deleteId !== null && (
        <div className="fixed inset-0 bg-black/40 flex items-center justify-center z-50">
          <div className="bg-white rounded-xl shadow-xl p-6 max-w-sm w-full mx-4">
            <h3 className="text-lg font-semibold mb-3">Eintrag löschen?</h3>
            <p className="text-sm text-gray-600 mb-5">Dieser Eintrag wird unwiderruflich gelöscht.</p>
            <div className="flex gap-3 justify-end">
              <button onClick={() => setDeleteId(null)} className="px-4 py-2 bg-gray-200 hover:bg-gray-300 text-gray-700 rounded-lg text-sm">Abbrechen</button>
              <button onClick={() => confirmDelete(deleteId)} className="px-4 py-2 bg-red-600 hover:bg-red-700 text-white rounded-lg text-sm">Löschen</button>
            </div>
          </div>
        </div>
      )}
    </div>
  );
}