import { useState } from "react";
import { Card, CardContent } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "@/components/ui/dialog";
import { useTeachers, useCreateTeacher } from "@/hooks/queries";
import { api } from "@/lib/api-client";
import { useQueryClient } from "@tanstack/react-query";
import { Search, Plus, Trash2 } from "lucide-react";
import { useToast } from "@/hooks/use-toast";

export default function AdminTeachers() {
  const [search, setSearch] = useState("");
  const [addOpen, setAddOpen] = useState(false);
  const [firstName, setFirstName] = useState("");
  const [lastName, setLastName] = useState("");
  const [email, setEmail] = useState("");
  const [gender, setGender] = useState<"male" | "female">("male");
  const [specialization, setSpecialization] = useState("");
  const { toast } = useToast();
  const qc = useQueryClient();

  const { data: teachersData, isLoading } = useTeachers({ size: 500 });
  const createTeacher = useCreateTeacher();

  const teachers = teachersData?.items ?? [];
  const filtered = teachers.filter(
    (t) =>
      t.name.toLowerCase().includes(search.toLowerCase()) ||
      (t.email || "").toLowerCase().includes(search.toLowerCase()),
  );

  const handleAdd = () => {
    if (!firstName.trim() || !lastName.trim()) {
      toast({ title: "First and last name required", variant: "destructive" });
      return;
    }
    if (!email.trim()) {
      toast({ title: "Email required", variant: "destructive" });
      return;
    }
    createTeacher.mutate(
      {
        first_name: firstName.trim(),
        last_name: lastName.trim(),
        email: email.trim().toLowerCase(),
        gender,
        specialization: specialization.trim() || undefined,
      },
      {
        onSuccess: () => {
          setAddOpen(false);
          setFirstName("");
          setLastName("");
          setEmail("");
          setGender("male");
          setSpecialization("");
          toast({ title: "Teacher created" });
        },
        onError: (e: Error) => {
          toast({ title: "Could not create teacher", description: e.message, variant: "destructive" });
        },
      },
    );
  };

  async function handleDelete(id: number, name: string) {
    if (!window.confirm(`Delete teacher "${name}"?`)) return;
    try {
      await api.delete(`/teachers/${id}`);
      qc.invalidateQueries({ queryKey: ["lms", "teachers"] });
      toast({ title: "Teacher deleted" });
    } catch (e: unknown) {
      const msg = e instanceof Error ? e.message : String(e);
      toast({ title: "Delete failed", description: msg, variant: "destructive" });
    }
  }

  if (isLoading) {
    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 className="flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-bold">Teachers</h1>
          <p className="text-muted-foreground">Manage faculty members.</p>
        </div>
        <Button onClick={() => setAddOpen(true)}>
          <Plus className="mr-2 h-4 w-4" />Add Teacher
        </Button>
      </div>
      <div className="relative max-w-sm">
        <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
        <Input placeholder="Search teachers..." value={search} onChange={(e) => setSearch(e.target.value)} className="pl-9" />
      </div>
      <Card>
        <CardContent className="pt-6">
          <Table>
            <TableHeader>
              <TableRow>
                <TableHead>Teacher</TableHead>
                <TableHead>Specialization</TableHead>
                <TableHead>Subjects</TableHead>
                <TableHead>Department</TableHead>
                <TableHead>Gender</TableHead>
                <TableHead className="w-[60px]" />
              </TableRow>
            </TableHeader>
            <TableBody>
              {filtered.map((t) => {
                const initials = t.name?.split(" ").map((w) => w[0]).join("").slice(0, 2).toUpperCase();
                return (
                  <TableRow key={t.id}>
                    <TableCell>
                      <div className="flex items-center gap-2">
                        <div className="h-7 w-7 rounded-full bg-primary/10 flex items-center justify-center text-xs font-medium text-primary">{initials}</div>
                        <div>
                          <p className="text-sm font-medium">{t.name}</p>
                          <p className="text-xs text-muted-foreground">{t.email || "—"}</p>
                        </div>
                      </div>
                    </TableCell>
                    <TableCell>{t.specialization || "—"}</TableCell>
                    <TableCell>{t.subject_names?.length ? t.subject_names.join(", ") : "—"}</TableCell>
                    <TableCell>{t.department_name || "—"}</TableCell>
                    <TableCell className="capitalize">{t.gender || "—"}</TableCell>
                    <TableCell>
                      <Button variant="ghost" size="icon" onClick={() => handleDelete(t.id, t.name)}><Trash2 className="h-4 w-4 text-destructive" /></Button>
                    </TableCell>
                  </TableRow>
                );
              })}
              {filtered.length === 0 && <TableRow><TableCell colSpan={6} className="text-center text-muted-foreground py-8">No teachers found.</TableCell></TableRow>}
            </TableBody>
          </Table>
        </CardContent>
      </Card>

      <Dialog open={addOpen} onOpenChange={setAddOpen}>
        <DialogContent>
          <DialogHeader><DialogTitle>Add Teacher</DialogTitle></DialogHeader>
          <div className="space-y-4">
            <div className="grid grid-cols-2 gap-4">
              <div className="space-y-2"><Label>First Name *</Label><Input value={firstName} onChange={(e) => setFirstName(e.target.value)} /></div>
              <div className="space-y-2"><Label>Last Name *</Label><Input value={lastName} onChange={(e) => setLastName(e.target.value)} /></div>
            </div>
            <div className="space-y-2"><Label>Email *</Label><Input type="email" value={email} onChange={(e) => setEmail(e.target.value)} /></div>
            <div className="space-y-2">
              <Label>Gender</Label>
              <Select value={gender} onValueChange={(v) => setGender(v as "male" | "female")}>
                <SelectTrigger><SelectValue /></SelectTrigger>
                <SelectContent>
                  <SelectItem value="male">Male</SelectItem>
                  <SelectItem value="female">Female</SelectItem>
                </SelectContent>
              </Select>
            </div>
            <div className="space-y-2"><Label>Specialization</Label><Input value={specialization} onChange={(e) => setSpecialization(e.target.value)} placeholder="e.g. IELTS Writing" /></div>
          </div>
          <DialogFooter>
            <Button variant="outline" onClick={() => setAddOpen(false)}>Cancel</Button>
            <Button onClick={handleAdd} disabled={createTeacher.isPending}>{createTeacher.isPending ? "Saving…" : "Add Teacher"}</Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}
