encoach_frontend_v4/src/pages/admin/AdminBatchDetail.tsx

import { useParams, Link } from "react-router-dom";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { useBatches, useStudents, useTimetable } from "@/hooks/queries";
import { ArrowLeft, Users, Calendar, BookOpen } from "lucide-react";

export default function AdminBatchDetail() {
  const { id } = useParams();
  const batchId = id ? Number(id) : NaN;
  const { data: batchesData, isLoading: lb } = useBatches();
  const { data: studentsData, isLoading: ls } = useStudents(
    Number.isFinite(batchId) ? { batch_id: batchId, size: 500 } : { size: 500 },
  );
  const { data: timetableData, isLoading: ltt } = useTimetable();
  const batches = batchesData?.items ?? [];
  const students = studentsData?.items ?? [];
  const timetableSessions = Array.isArray(timetableData) ? timetableData : [];
  if (lb || ls || ltt) 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 batch = batches.find(b => String(b.id) === id);

  if (!batch) return <div className="p-8 text-center text-muted-foreground">Batch not found.</div>;

  const studentIds = Array.isArray(batch.student_ids) ? batch.student_ids : [];
  const batchStudents = Number.isFinite(batchId)
    ? students.filter((s) => s.batch_id === batchId)
    : students.filter((s) => studentIds.includes(s.id));
  const coursePrefix = (batch.course_name || "").split(" ")[0];
  const batchSessions = timetableSessions.filter(s =>
    s.batch_name === batch.name || (coursePrefix && (s.course_name || "").includes(coursePrefix)),
  );

  return (
    <div className="space-y-6">
      <div className="flex items-center gap-3">
        <Button variant="ghost" size="icon" asChild><Link to="/admin/batches"><ArrowLeft className="h-4 w-4" /></Link></Button>
        <div>
          <h1 className="text-2xl font-bold">{batch.name}</h1>
          <p className="text-muted-foreground">{batch.course_name} · {batch.teacher_name}</p>
        </div>
      </div>

      <div className="grid grid-cols-1 sm:grid-cols-4 gap-4">
        <Card><CardContent className="pt-4"><Users className="h-4 w-4 text-primary mb-1" /><p className="text-lg font-bold">{batch.student_count}/{batch.capacity}</p><p className="text-xs text-muted-foreground">Students</p></CardContent></Card>
        <Card><CardContent className="pt-4"><Calendar className="h-4 w-4 text-info mb-1" /><p className="text-sm font-bold">{batch.schedule}</p><p className="text-xs text-muted-foreground">Schedule</p></CardContent></Card>
        <Card><CardContent className="pt-4"><BookOpen className="h-4 w-4 text-success mb-1" /><p className="text-sm font-bold">{batch.start_date} — {batch.end_date}</p><p className="text-xs text-muted-foreground">Duration</p></CardContent></Card>
        <Card><CardContent className="pt-4"><Badge variant={batch.status === "active" ? "default" : "secondary"} className="capitalize">{batch.status}</Badge><p className="text-xs text-muted-foreground mt-1">Status</p></CardContent></Card>
      </div>

      <Card>
        <CardHeader><CardTitle className="text-lg">Enrolled Students</CardTitle></CardHeader>
        <CardContent>
          <Table>
            <TableHeader><TableRow><TableHead>Student</TableHead><TableHead>Attendance</TableHead><TableHead>Avg Grade</TableHead><TableHead>Risk</TableHead></TableRow></TableHeader>
            <TableBody>
              {batchStudents.map(s => (
                <TableRow key={s.id}>
                  <TableCell className="font-medium">{s.name}</TableCell>
                  <TableCell>—</TableCell>
                  <TableCell>—</TableCell>
                  <TableCell><Badge variant="secondary" className="capitalize">—</Badge></TableCell>
                </TableRow>
              ))}
            </TableBody>
          </Table>
        </CardContent>
      </Card>

      <Card>
        <CardHeader><CardTitle className="text-lg">Timetable</CardTitle></CardHeader>
        <CardContent className="space-y-2">
          {batchSessions.length === 0 ? (
            <p className="text-muted-foreground text-sm">No sessions scheduled.</p>
          ) : batchSessions.map(s => (
            <div key={s.id} className="flex items-center justify-between p-3 rounded border">
              <div>
                <p className="text-sm font-medium">{s.day} {s.start_time}–{s.end_time}</p>
                <p className="text-xs text-muted-foreground">{s.room}</p>
              </div>
              <span className="text-xs px-2 py-1 rounded text-white bg-primary">{s.course_name}</span>
            </div>
          ))}
        </CardContent>
      </Card>
    </div>
  );
}