import { Link } from "react-router-dom";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Users, GraduationCap, Building2, UserCog, BarChart3, School, Building, Ticket, BookOpen, DollarSign } from "lucide-react";
import { useQuery } from "@tanstack/react-query";
import { api } from "@/lib/api-client";
import { useStudents, useTeachers } from "@/hooks/queries";
import { useEntities } from "@/hooks/queries/useEntities";
import AiInsightsPanel from "@/components/ai/AiInsightsPanel";

interface PlatformStats {
  total_students?: number;
  total_teachers?: number;
  total_entities?: number;
  total_courses?: number;
  active_courses?: number;
  total_batches?: number;
  active_batches?: number;
  total_classrooms?: number;
  total_tickets?: number;
  open_tickets?: number;
  total_exams?: number;
  total_assignments?: number;
  total_revenue?: number;
  total_payments?: number;
  total_subjects?: number;
  total_resources?: number;
  total_exam_sessions?: number;
}

export default function AdminDashboard() {
  const { data: stats } = useQuery<PlatformStats>({
    queryKey: ["platform", "stats"],
    queryFn: async () => {
      const res = await api.get<{ data: PlatformStats }>("/stats");
      return (res as { data: PlatformStats }).data ?? res;
    },
    staleTime: 30_000,
  });

  const { data: studentsData, isLoading: ls } = useStudents({ size: 5 });
  const { data: teachersData, isLoading: lt } = useTeachers({ size: 5 });
  const { data: entitiesData, isLoading: le } = useEntities({ size: 50 });

  const students = studentsData?.items ?? [];
  const teachers = teachersData?.items ?? [];
  const entities = entitiesData?.items ?? [];

  const loading = ls || lt || le;

  const statCards = [
    { label: "Students", count: stats?.total_students ?? 0, icon: GraduationCap, color: "bg-primary/10 text-primary" },
    { label: "Teachers", count: stats?.total_teachers ?? 0, icon: UserCog, color: "bg-info/10 text-info" },
    { label: "Entities", count: stats?.total_entities ?? 0, icon: Building2, color: "bg-warning/10 text-warning" },
    { label: "Active Courses", count: stats?.active_courses ?? 0, icon: BookOpen, color: "bg-success/10 text-success" },
  ];

  const shortcuts = [
    { label: "Exams", count: stats?.total_exams ?? 0, url: "/admin/exams", icon: BarChart3 },
    { label: "Classrooms", count: stats?.total_classrooms ?? 0, url: "/admin/classrooms", icon: School },
    { label: "Entities", count: stats?.total_entities ?? 0, url: "/admin/entities", icon: Building2 },
    { label: "Tickets", count: `${stats?.open_tickets ?? 0} open`, url: "/admin/tickets", icon: Ticket },
  ];

  if (loading) {
    return (
      <div className="flex items-center justify-center min-h-[400px]">
        <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-primary" />
      </div>
    );
  }

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-bold tracking-tight">Platform Dashboard</h1>
        <p className="text-muted-foreground">Overview of platform activity and user statistics.</p>
      </div>

      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
        {statCards.map((s) => (
          <Card key={s.label} className="border-0 shadow-sm">
            <CardContent className="p-5 flex items-center gap-4">
              <div className={`h-12 w-12 rounded-xl flex items-center justify-center ${s.color}`}>
                <s.icon className="h-6 w-6" />
              </div>
              <div>
                <p className="text-2xl font-bold">{s.count.toLocaleString()}</p>
                <p className="text-sm text-muted-foreground">{s.label}</p>
              </div>
            </CardContent>
          </Card>
        ))}
      </div>

      <AiInsightsPanel />

      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
        {shortcuts.map((s) => (
          <Link key={s.label} to={s.url}>
            <Card className="border-0 shadow-sm hover:shadow-md transition-shadow cursor-pointer">
              <CardContent className="p-5 flex items-center justify-between">
                <div className="flex items-center gap-3">
                  <s.icon className="h-5 w-5 text-muted-foreground" />
                  <span className="text-sm font-medium">{s.label}</span>
                </div>
                <Badge variant="secondary">{s.count}</Badge>
              </CardContent>
            </Card>
          </Link>
        ))}
      </div>

      <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
        {[
          { label: "Batches", value: `${stats?.active_batches ?? 0} / ${stats?.total_batches ?? 0}` },
          { label: "Subjects", value: stats?.total_subjects ?? 0 },
          { label: "Resources", value: stats?.total_resources ?? 0 },
          { label: "Revenue", value: `$${(stats?.total_revenue ?? 0).toLocaleString()}` },
        ].map(s => (
          <Card key={s.label} className="border-0 shadow-sm">
            <CardContent className="p-4">
              <p className="text-lg font-bold">{s.value}</p>
              <p className="text-xs text-muted-foreground">{s.label}</p>
            </CardContent>
          </Card>
        ))}
      </div>

      <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
        <Card className="border-0 shadow-sm">
          <CardHeader className="pb-3">
            <CardTitle className="text-base font-semibold">Recent Students</CardTitle>
          </CardHeader>
          <CardContent className="space-y-3">
            {students.length === 0 && <p className="text-sm text-muted-foreground">No students found.</p>}
            {students.map((s) => (
              <div key={s.id} className="flex items-center justify-between">
                <div className="flex items-center gap-3">
                  <div className="h-8 w-8 rounded-full bg-primary/10 flex items-center justify-center text-xs font-semibold text-primary">
                    {(s.name || "?").split(" ").map(n => n[0]).join("").slice(0, 2).toUpperCase()}
                  </div>
                  <div>
                    <p className="text-sm font-medium">{s.name}</p>
                    <p className="text-xs text-muted-foreground">{s.email || "—"}</p>
                  </div>
                </div>
                <Badge variant="outline">{s.status || "active"}</Badge>
              </div>
            ))}
          </CardContent>
        </Card>

        <Card className="border-0 shadow-sm">
          <CardHeader className="pb-3">
            <CardTitle className="text-base font-semibold">Recent Teachers</CardTitle>
          </CardHeader>
          <CardContent className="space-y-3">
            {teachers.length === 0 && <p className="text-sm text-muted-foreground">No teachers found.</p>}
            {teachers.map((t) => (
              <div key={t.id} className="flex items-center justify-between">
                <div className="flex items-center gap-3">
                  <div className="h-8 w-8 rounded-full bg-info/10 flex items-center justify-center text-xs font-semibold text-info">
                    {(t.name || "?").split(" ").map(n => n[0]).join("").slice(0, 2).toUpperCase()}
                  </div>
                  <div>
                    <p className="text-sm font-medium">{t.name}</p>
                    <p className="text-xs text-muted-foreground">{t.email || "—"}</p>
                  </div>
                </div>
                <Badge variant="outline">{t.department_name || "—"}</Badge>
              </div>
            ))}
          </CardContent>
        </Card>

        <Card className="border-0 shadow-sm">
          <CardHeader className="pb-3">
            <CardTitle className="text-base font-semibold">Entities</CardTitle>
          </CardHeader>
          <CardContent className="space-y-3">
            {entities.length === 0 && <p className="text-sm text-muted-foreground">No entities found.</p>}
            {entities.map((e) => (
              <div key={e.id} className="flex items-center justify-between">
                <div className="flex items-center gap-3">
                  <Building className="h-4 w-4 text-muted-foreground" />
                  <p className="text-sm font-medium">{e.name}</p>
                </div>
                <Badge variant="outline">{e.entity_type || e.type || "—"}</Badge>
              </div>
            ))}
          </CardContent>
        </Card>

        <Card className="border-0 shadow-sm">
          <CardHeader className="pb-3">
            <CardTitle className="text-base font-semibold">Platform Summary</CardTitle>
          </CardHeader>
          <CardContent className="space-y-3">
            {[
              { label: "Exam Sessions", value: stats?.total_exam_sessions ?? 0 },
              { label: "Assignments", value: stats?.total_assignments ?? 0 },
              { label: "Total Tickets", value: stats?.total_tickets ?? 0 },
              { label: "Completed Payments", value: stats?.total_payments ?? 0 },
            ].map(item => (
              <div key={item.label} className="flex items-center justify-between">
                <p className="text-sm text-muted-foreground">{item.label}</p>
                <p className="text-sm font-semibold">{item.value}</p>
              </div>
            ))}
          </CardContent>
        </Card>
      </div>
    </div>
  );
}
