"use client";

import React, { useEffect, useMemo, useRef, useState } from "react";
import { useAuth } from "@/hooks/useAuth";
import { useRouter } from "next/navigation";
import { apiFetch } from "@/lib/api";
import { useStableState } from "@/hooks/useStableState";
import { useVisiblePolling } from "@/hooks/useVisiblePolling";
import { QrCode, Ticket, Activity, UserCheck, Clock } from "lucide-react";
import { StatCard, StatCardRow } from "@/components/shared/StatCard";
import { QuickActionTile, QuickActionGrid } from "@/components/shared/QuickActionTile";

const QUICK_ACTIONS = [
  { href: "/dashboard/staff/ticket-scanning", label: "Scan tickets", description: "Use your device camera to validate tickets", icon: QrCode },
  { href: "/dashboard/staff/event-tickets", label: "Event tickets & printing", description: "Browse event tickets and print lists", icon: Ticket },
] as const;

export default function StaffDashboardPage() {
  const { user, loading, token } = useAuth();
  const router = useRouter();

  // Access control (staff/supervisor/admin)
  const canView = useMemo(() => {
    const role = user?.role;
    return role === "admin" || role === "supervisor" || role === "staff";
  }, [user]);

  useEffect(() => {
    if (loading) return;
    if (!user) router.replace("/login");
  }, [user, loading, router]);

  // Stats and recent scans for quick overview — both come from one endpoint
  // (/api/stats/staff) instead of two separate calls. useStableState skips re-renders when
  // a poll returns identical data, and hasLoadedOnce below means "Refreshing…" only shows
  // on the very first load — together these stop the stats panel from flickering.
  const [stats, setStats] = useStableState<any | null>(null);
  const [recentScans, setRecentScans] = useStableState<any[]>([]);
  const [loadingStats, setLoadingStats] = useState(false);
  const hasLoadedOnce = useRef(false);

  const loadStats = async () => {
    if (!token) return;
    const isFirstLoad = !hasLoadedOnce.current;
    try {
      if (isFirstLoad) setLoadingStats(true);
      const data = await apiFetch<any>("/api/stats/staff", { authToken: token });
      setStats(data.scanStats);
      setRecentScans(Array.isArray(data.recentScans) ? data.recentScans : []);
    } catch (e) {
      // ignore
    } finally {
      hasLoadedOnce.current = true;
      if (isFirstLoad) setLoadingStats(false);
    }
  };

  useEffect(() => {
    if (!token) return;
    loadStats();
  }, [token]);

  // Poll every 10s while the tab is visible; pause in the background and refetch
  // immediately on return instead of leaving stale numbers up.
  useVisiblePolling(() => {
    if (!token) return;
    loadStats();
  }, 10000, !!token);

  return (
    <div className="max-w-6xl mx-auto w-full">
      <div className="mb-6">
        <h1 className="text-2xl font-semibold text-gray-900">Welcome back{user ? `, ${user.name}` : ""} 👋</h1>
        <p className="text-sm text-gray-500 mt-1">Here&apos;s today&apos;s scanning activity.</p>
      </div>

      {!canView && (
        <div className="p-3 border rounded bg-yellow-50 text-yellow-800 text-sm mb-4">
          You need staff, supervisor, or admin access to use staff tools.
        </div>
      )}

      <StatCardRow>
        <StatCard icon={Activity} label="Scans today" value={stats ? stats.totalToday : "—"} tone="brand" />
        <StatCard icon={UserCheck} label="My scans today" value={stats ? stats.myToday : "—"} tone="blue" />
        <StatCard icon={Clock} label="Last hour" value={stats ? stats.lastHour : "—"} tone="amber" />
      </StatCardRow>

      <div className="border rounded-xl p-4 bg-white shadow-sm my-6">
        <div className="text-lg font-semibold mb-3">Quick actions</div>
        <QuickActionGrid>
          {QUICK_ACTIONS.map(a => (
            <QuickActionTile key={a.href} icon={a.icon} title={a.label} description={a.description} href={a.href} />
          ))}
        </QuickActionGrid>
      </div>

      <div className="grid lg:grid-cols-3 gap-6">
        <div className="lg:col-span-2">
          <div className="border rounded-xl p-4 bg-white shadow-sm">
            <div className="flex items-center justify-between mb-3">
              <h2 className="text-lg font-semibold">Recent scans</h2>
              {loadingStats && <span className="text-xs text-gray-500">Refreshing…</span>}
            </div>
            <ul className="text-sm space-y-2 max-h-96 overflow-auto pr-2">
              {recentScans.map((u: any) => (
                <li key={u.id} className="border rounded p-2">
                  <div className="flex justify-between">
                    <div className="font-medium">{u.ticket?.event?.title || u.ticket?.eventId || 'Event'}</div>
                    <div className="text-xs text-gray-500">{new Date(u.scannedAt).toLocaleString()}</div>
                  </div>
                  <div className="text-xs text-gray-600">{u.ticket?.registrationOption?.eventOption?.name || 'Ticket'} — #{String(u.ticket?.id || '').slice(0, 8)}</div>
                  <div className="text-xs text-gray-500">Scanned by: {u.scannedBy?.name || u.scannedById}</div>
                </li>
              ))}
              {recentScans.length === 0 && <li className="text-gray-500">No scans yet.</li>}
            </ul>
          </div>
        </div>

        <div>
          <div className="border rounded-xl p-4 bg-white shadow-sm">
            <h2 className="text-lg font-semibold mb-3">Today by staff</h2>
            {stats?.byStaff?.length > 0 ? (
              <ul className="text-sm text-gray-700 space-y-1">
                {stats.byStaff.map((s: any) => (
                  <li key={s.scannedById} className="flex justify-between">
                    <span>{s.name || 'Staff'}</span>
                    <span className="font-medium">{s.count}</span>
                  </li>
                ))}
              </ul>
            ) : (
              <div className="text-sm text-gray-500">No scans recorded yet today.</div>
            )}
          </div>
        </div>
      </div>
    </div>
  );
}