import { createFileRoute, Link } from "@tanstack/react-router";
import { useAuth, highestRole } from "@/hooks/use-auth";
import { useQuery } from "@tanstack/react-query";
import { supabase } from "@/integrations/supabase/client";
import { Users, ClipboardCheck, Receipt, CalendarDays, ClipboardList, AlertTriangle } from "lucide-react";
import { COMPLIANCE_CLASS, complianceState, formatDate } from "@/lib/plans";

export const Route = createFileRoute("/_authenticated/dashboard")({
  head: () => ({ meta: [{ title: "Dashboard — School Portal" }] }),
  component: Dashboard,
});

function Dashboard() {
  const { user, roles } = useAuth();
  const role = highestRole(roles);

  const { data: studentCount } = useQuery({
    queryKey: ["students-count"],
    queryFn: async () => {
      const { count } = await supabase.from("students").select("*", { count: "exact", head: true });
      return count ?? 0;
    },
  });

  const { data: todayAttendance } = useQuery({
    queryKey: ["attendance-today"],
    queryFn: async () => {
      const today = new Date().toISOString().slice(0, 10);
      const { count } = await supabase.from("attendance").select("*", { count: "exact", head: true }).eq("date", today);
      return count ?? 0;
    },
  });

  const { data: upcoming } = useQuery({
    queryKey: ["upcoming-events"],
    queryFn: async () => {
      const today = new Date().toISOString().slice(0, 10);
      const { data } = await supabase.from("calendar_events").select("*").gte("date", today).order("date").limit(5);
      return data ?? [];
    },
  });

  // RLS scopes this to plans the viewer may see, so it is empty for most users.
  const { data: planAlerts } = useQuery({
    queryKey: ["plan-alerts"],
    queryFn: async () => {
      const { data } = await supabase
        .from("student_plans")
        .select("id, student_id, next_annual_review_date, next_reevaluation_date, students(first_name, last_name)")
        .neq("status", "archived");
      return (data ?? []).flatMap((p) => {
        const rows: { key: string; student_id: string; name: string; kind: string; date: string }[] = [];
        const name = `${p.students?.first_name ?? ""} ${p.students?.last_name ?? ""}`.trim();
        if (p.next_annual_review_date) rows.push({ key: `${p.id}-ar`, student_id: p.student_id, name, kind: "Annual review", date: p.next_annual_review_date });
        if (p.next_reevaluation_date) rows.push({ key: `${p.id}-re`, student_id: p.student_id, name, kind: "Re-evaluation", date: p.next_reevaluation_date });
        return rows;
      })
        .filter((r) => complianceState(r.date) === "overdue" || complianceState(r.date) === "due_soon")
        .sort((a, b) => (a.date < b.date ? -1 : 1));
    },
  });

  return (
    <div className="p-8 max-w-6xl">
      <h1 className="text-2xl font-semibold">Welcome back</h1>
      <p className="text-muted-foreground">Signed in as <span className="capitalize">{role}</span></p>

      <div className="grid grid-cols-1 md:grid-cols-3 gap-4 mt-6">
        <Stat icon={Users} label="Students" value={studentCount ?? "—"} />
        <Stat icon={ClipboardCheck} label="Attendance recorded today" value={todayAttendance ?? "—"} />
        <Stat icon={CalendarDays} label="Upcoming events" value={upcoming?.length ?? "—"} />
      </div>

      {planAlerts && planAlerts.length > 0 && (
        <div className="mt-8 bg-card border rounded-lg p-6">
          <h2 className="font-semibold mb-3 flex items-center gap-2">
            <ClipboardList className="h-4 w-4" /> 504 / IEP compliance needing attention
          </h2>
          <ul className="space-y-2 text-sm">
            {planAlerts.slice(0, 8).map((a) => (
              <li key={a.key} className="flex justify-between gap-3 border-b last:border-0 py-2">
                <span className="flex items-center gap-2">
                  {complianceState(a.date) === "overdue" && <AlertTriangle className="h-3.5 w-3.5 text-destructive shrink-0" />}
                  <Link to="/students/$id" params={{ id: a.student_id }} className="text-primary hover:underline">{a.name}</Link>
                  <span className="text-muted-foreground">· {a.kind}</span>
                </span>
                <span className={COMPLIANCE_CLASS[complianceState(a.date)]}>{formatDate(a.date)}</span>
              </li>
            ))}
          </ul>
          {planAlerts.length > 8 && (
            <Link to="/plans" className="text-xs text-primary hover:underline mt-3 inline-block">
              View all {planAlerts.length} alerts
            </Link>
          )}
        </div>
      )}

      <div className="mt-8 bg-card border rounded-lg p-6">
        <h2 className="font-semibold mb-3 flex items-center gap-2"><CalendarDays className="h-4 w-4" /> Upcoming on the calendar</h2>
        {upcoming && upcoming.length > 0 ? (
          <ul className="space-y-2 text-sm">
            {upcoming.map((e) => (
              <li key={e.id} className="flex justify-between border-b last:border-0 py-2">
                <span>{e.title}</span>
                <span className="text-muted-foreground">{new Date(e.date).toLocaleDateString()}</span>
              </li>
            ))}
          </ul>
        ) : (
          <p className="text-sm text-muted-foreground">No upcoming events.</p>
        )}
      </div>
    </div>
  );
}

function Stat({ icon: Icon, label, value }: { icon: typeof Users; label: string; value: number | string }) {
  return (
    <div className="bg-card border rounded-lg p-6">
      <Icon className="h-5 w-5 text-primary mb-2" />
      <div className="text-3xl font-semibold">{value}</div>
      <div className="text-sm text-muted-foreground">{label}</div>
    </div>
  );
}