import { useEffect, useMemo, useState } from 'react';
import { BarChart3, CalendarDays, CarFront, Clock3, RefreshCw, Sun } from 'lucide-react';
import MainCard from '@/components/MainCard';
import LoadingCard from '@/components/LoadingCard';
import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { timeApi } from '@/api/time';
import { planningApi } from '@/api/planning';
import { useAuth } from '@/context/useAuth';
import { dateKey, formatMinutes, personLabel, inputClass } from '@/components/planning/utils';
import StatisticsPeriodSelector from '@/components/statistics/StatisticsPeriodSelector';

const StatCard = ({ icon: Icon, label, value, detail }) => (
  <div className="rounded-xl border bg-card p-4 shadow-sm">
    <div className="flex items-start justify-between gap-3">
      <div className="min-w-0">
        <p className="text-sm text-muted-foreground">{label}</p>
        <p className="mt-1 text-2xl font-semibold tabular-nums">{value}</p>
        {detail && <p className="mt-1 text-xs text-muted-foreground">{detail}</p>}
      </div>
      <span className="flex size-9 shrink-0 items-center justify-center rounded-lg bg-primary/10 text-primary">
        <Icon className="size-4" />
      </span>
    </div>
  </div>
);

const rangeLabel = (stats) => {
  if (!stats) return '';
  const start = new Date(`${stats.start}T12:00:00`);
  const end = new Date(`${stats.end}T12:00:00`);
  if (stats.period === 'day') {
    return start.toLocaleDateString('fr-FR', { weekday: 'long', day: 'numeric', month: 'long', year: 'numeric' });
  }
  if (stats.period === 'week') {
    const startText = start.toLocaleDateString('fr-FR', { day: 'numeric', month: 'short' });
    const endText = end.toLocaleDateString('fr-FR', { day: 'numeric', month: 'long', year: 'numeric' });
    return `Du ${startText} au ${endText}`;
  }
  if (stats.period === 'month') {
    return start.toLocaleDateString('fr-FR', { month: 'long', year: 'numeric' });
  }
  return String(start.getFullYear());
};

export default function UserStatisticsPage() {
  const { user } = useAuth();
  const [people, setPeople] = useState([]);
  const [selectedUserId, setSelectedUserId] = useState('');
  const [period, setPeriod] = useState('month');
  const [anchor, setAnchor] = useState(dateKey());
  const [stats, setStats] = useState(null);
  const [loadingPeople, setLoadingPeople] = useState(true);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState('');
  const [reload, setReload] = useState(0);

  const statsPermission = user?.management_permissions?.view_statistics;
  const allowedIds = useMemo(() => {
    if (user?.is_admin || statsPermission?.all_users) return null;
    return new Set((statsPermission?.user_ids || []).map(String));
  }, [user, statsPermission]);

  useEffect(() => {
    const controller = new AbortController();
    setLoadingPeople(true);
    setError('');
    planningApi.people(controller.signal)
      .then((rows) => {
        const visible = (Array.isArray(rows) ? rows : []).filter((person) => (
          user?.is_admin || allowedIds === null || allowedIds.has(String(person.id))
        ));
        setPeople(visible);
        setSelectedUserId((current) => (
          visible.some((person) => String(person.id) === String(current))
            ? String(current)
            : String(visible[0]?.id || '')
        ));
      })
      .catch((e) => { if (!controller.signal.aborted) setError(e.message); })
      .finally(() => { if (!controller.signal.aborted) setLoadingPeople(false); });
    return () => controller.abort();
  }, [user, allowedIds]);

  useEffect(() => {
    if (!selectedUserId) {
      setStats(null);
      return undefined;
    }
    const controller = new AbortController();
    setLoading(true);
    setError('');
    timeApi.getStats({ user_id: selectedUserId, period, anchor }, controller.signal)
      .then((data) => { if (!controller.signal.aborted) setStats(data); })
      .catch((e) => { if (!controller.signal.aborted) setError(e.message); })
      .finally(() => { if (!controller.signal.aborted) setLoading(false); });
    return () => controller.abort();
  }, [selectedUserId, period, anchor, reload]);

  if (loadingPeople) {
    return <LoadingCard icon={BarChart3} title="Statistiques" message="Chargement des salariés…" />;
  }


  return (
    <MainCard title="Statistiques" icon={BarChart3}>
      <div className="min-h-0 flex-1 overflow-y-auto p-4 sm:p-6">
        <div className="mx-auto max-w-6xl space-y-5">
          <div className="flex flex-col gap-3 rounded-xl border bg-card p-4 lg:flex-row lg:items-end">
            <label className="grid min-w-0 flex-1 gap-1.5 text-sm font-medium">
              Salarié
              <select className={inputClass} value={selectedUserId} onChange={(e) => setSelectedUserId(e.target.value)}>
                {people.length ? people.map((person) => (
                  <option key={person.id} value={person.id}>{personLabel(person)}</option>
                )) : <option value="">Aucun salarié autorisé</option>}
              </select>
            </label>

            <StatisticsPeriodSelector
              period={period}
              anchor={anchor}
              onPeriodChange={setPeriod}
              onAnchorChange={setAnchor}
            />

            <Button type="button" variant="outline" size="icon" disabled={loading} aria-label="Actualiser" onClick={() => setReload((value) => value + 1)}>
              <RefreshCw className={`size-4 ${loading ? 'animate-spin' : ''}`} />
            </Button>
          </div>

          {error && <p role="alert" className="rounded-lg bg-destructive/10 p-3 text-sm text-destructive">{error}</p>}

          {stats && (
            <>
              <div className="flex flex-wrap items-center justify-between gap-2">
                <div>
                  <h2 className="text-lg font-semibold capitalize">{rangeLabel(stats)}</h2>
                  <p className="text-sm text-muted-foreground">{personLabel(stats.user)}</p>
                </div>
                {stats.incomplete_entries > 0 && (
                  <Badge variant="outline">{stats.incomplete_entries} pointage(s) incomplet(s) non compté(s)</Badge>
                )}
              </div>

              <div className="grid gap-3 sm:grid-cols-2 xl:grid-cols-4">
                <StatCard icon={Clock3} label="Travaillées / prévues" value={`${formatMinutes(stats.total_minutes)} / ${formatMinutes(stats.planned_minutes || 0)}`} />
                <StatCard icon={CarFront} label="Aller-retours" value={stats.round_trips} />
                <StatCard icon={Sun} label="Dimanches travaillés" value={stats.sundays_worked} />
                <StatCard icon={CalendarDays} label="Heures le dimanche" value={formatMinutes(stats.sunday_minutes)} />
              </div>

            </>
          )}
        </div>
      </div>
    </MainCard>
  );
}