import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Badge } from "@/components/ui/badge";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { BookOpen, Users, ClipboardList, TrendingUp, ArrowRight } from "lucide-react";
import { Link } from "react-router-dom";
import { useCourses, useAssignments } from "@/hooks/queries";
import AiInsightsPanel from "@/components/ai/AiInsightsPanel";
import AiTipBanner from "@/components/ai/AiTipBanner";

export default function TeacherDashboard() {
  const { data: coursesData, isLoading: lc } = useCourses();
  const { data: assignmentsData, isLoading: la } = useAssignments();
  const courses = coursesData?.items ?? [];
  const assignments = assignmentsData?.items ?? [];
  const submissions: unknown[] = [];
  const activityFeed: { id: string; action: string; user: string; target: string; time: string }[] = [];
  if (lc || la) 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>;

  const teacherCourses = courses;
  const pendingGrading = (submissions as { id: string; studentName: string; submittedAt: string; status: string }[]).filter(s => s.status === "pending");

  const stats = [
    { label: "Active Courses", value: String(teacherCourses.filter(c => c.status === "active").length), icon: BookOpen, color: "text-primary" },
    { label: "Total Students", value: "55", icon: Users, color: "text-info" },
    { label: "Pending Grading", value: String(pendingGrading.length), icon: ClipboardList, color: "text-warning" },
    { label: "Avg. Pass Rate", value: "82%", icon: TrendingUp, color: "text-success" },
  ];

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-bold">Teacher Dashboard</h1>
        <p className="text-muted-foreground">Overview of your teaching activities.</p>
      </div>

      <AiTipBanner context="teacher-dashboard" variant="recommendation" />

      <AiInsightsPanel />

      <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
        {stats.map(s => (
          <Card key={s.label}>
            <CardContent className="pt-6">
              <div className="flex items-center justify-between">
                <div><p className="text-sm text-muted-foreground">{s.label}</p><p className="text-2xl font-bold">{s.value}</p></div>
                <s.icon className={`h-8 w-8 ${s.color} opacity-80`} />
              </div>
            </CardContent>
          </Card>
        ))}
      </div>

      <div className="grid grid-cols-1 lg:grid-cols-2 gap-6">
        <Card>
          <CardHeader className="flex flex-row items-center justify-between pb-2">
            <CardTitle className="text-lg">My Courses</CardTitle>
            <Button variant="ghost" size="sm" asChild><Link to="/teacher/courses">View All <ArrowRight className="ml-1 h-3 w-3" /></Link></Button>
          </CardHeader>
          <CardContent>
            <Table>
              <TableHeader><TableRow><TableHead>Course</TableHead><TableHead>Students</TableHead><TableHead>Status</TableHead></TableRow></TableHeader>
              <TableBody>
                {teacherCourses.map(c => (
                  <TableRow key={c.id}>
                    <TableCell className="font-medium">{c.title}</TableCell>
                    <TableCell>{c.enrolled}/{c.max_capacity}</TableCell>
                    <TableCell><Badge variant={c.status === "active" ? "default" : "secondary"} className="capitalize">{c.status}</Badge></TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          </CardContent>
        </Card>

        <div className="space-y-6">
          <Card>
            <CardHeader className="flex flex-row items-center justify-between pb-2">
              <CardTitle className="text-lg">Pending Grading</CardTitle>
              <Button variant="ghost" size="sm" asChild><Link to="/teacher/assignments">View All <ArrowRight className="ml-1 h-3 w-3" /></Link></Button>
            </CardHeader>
            <CardContent className="space-y-3">
              {pendingGrading.slice(0, 4).map(s => (
                <div key={s.id} className="flex items-center justify-between p-2 rounded border">
                  <div><p className="text-sm font-medium">{s.studentName}</p><p className="text-xs text-muted-foreground">Submitted {s.submittedAt}</p></div>
                  <Badge variant="secondary">Pending</Badge>
                </div>
              ))}
            </CardContent>
          </Card>

          <Card>
            <CardHeader><CardTitle className="text-lg">Recent Activity</CardTitle></CardHeader>
            <CardContent className="space-y-2">
              {activityFeed.slice(0, 4).map(a => (
                <div key={a.id} className="text-sm">
                  <span className="font-medium">{a.user}</span> <span className="text-muted-foreground">{a.action}</span> <span>{a.target}</span>
                  <span className="text-xs text-muted-foreground ml-2">· {a.time}</span>
                </div>
              ))}
            </CardContent>
          </Card>
        </div>
      </div>
    </div>
  );
}
