'use client';

import React, { useEffect, useState } from 'react';
import { SidebarProvider, SidebarInset } from '@/components/ui/sidebar';
import { AppSidebar } from '@/components/app-sidebar';
import { SiteHeader } from '@/components/site-header';
import { useRouter } from 'next/navigation';
import { toast } from 'sonner';
import {
  Card,
  CardContent,
  CardHeader,
  CardTitle,
} from '@/components/ui/card';
import {
  Field,
  FieldGroup,
  FieldLabel,
} from '@/components/ui/field';
import { Input } from '@/components/ui/input';
import { Button } from '@/components/ui/button';
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from '@/components/ui/table';
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogHeader,
  AlertDialogTitle,
  AlertDialogTrigger,
} from '@/components/ui/alert-dialog';
import { Trash2Icon } from 'lucide-react';

type Course = { id: string; title: string; code?: string };

function CoursesUI() {
  const router = useRouter();
  const [courses, setCourses] = useState<Course[]>([]);
  const [loading, setLoading] = useState(false);
  const [courseTitle, setCourseTitle] = useState('');
  const [courseCode, setCourseCode] = useState('');
  const [deletingId, setDeletingId] = useState<string | null>(null);

  useEffect(() => {
    fetchCourses();
  }, []);

  async function fetchCourses() {
    try {
      const res = await fetch('/api/admin/meta');
      if (res.ok) {
        const json = await res.json();
        setCourses(json.courses || []);
      }
    } catch (err) {
      console.error('Failed to fetch courses', err);
      toast.error('Failed to fetch courses');
    }
  }

  async function createCourse(e: React.FormEvent) {
    e.preventDefault();
    setLoading(true);
    try {
      const res = await fetch('/api/admin/create-course', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ title: courseTitle, code: courseCode }),
      });
      if (res.ok) {
        toast.success('Course created');
        setCourseTitle('');
        setCourseCode('');
        await fetchCourses();
        router.refresh();
      } else {
        const txt = await res.text();
        toast.error('Failed to create course: ' + txt);
      }
    } catch (err: any) {
      toast.error('Error: ' + String(err.message ?? err));
    } finally {
      setLoading(false);
    }
  }

  async function deleteCourse(courseId: string) {
    setDeletingId(courseId);
    try {
      const res = await fetch(`/api/admin/delete-course`, {
        method: 'DELETE',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ courseId }),
      });
      if (res.ok) {
        toast.success('Course deleted');
        await fetchCourses();
        router.refresh();
      } else {
        const txt = await res.text();
        toast.error('Failed to delete course: ' + txt);
      }
    } catch (err: any) {
      toast.error('Error: ' + String(err.message ?? err));
    } finally {
      setDeletingId(null);
    }
  }

  return (
    <div className="flex flex-col gap-6 py-4 md:gap-6 md:py-6 px-4 lg:px-16">
      <Card>
        <CardHeader>
          <CardTitle>Create Course</CardTitle>
        </CardHeader>
        <CardContent>
          <form onSubmit={createCourse}>
            <FieldGroup>
              <Field>
                <FieldLabel htmlFor="courseTitle">Course title</FieldLabel>
                <Input
                  id="courseTitle"
                  required
                  value={courseTitle}
                  onChange={(e) => setCourseTitle(e.target.value)}
                  placeholder="3D ANIMATION 300"
                />
              </Field>

              <Field>
                <FieldLabel htmlFor="courseCode">Course code</FieldLabel>
                <Input
                  id="courseCode"
                  value={courseCode}
                  onChange={(e) => setCourseCode(e.target.value)}
                  placeholder="3D100"
                />
              </Field>

              <Field>
                <Button type="submit" disabled={loading}>
                  Create course
                </Button>
              </Field>
            </FieldGroup>
          </form>
        </CardContent>
      </Card>

      <Card>
        <CardHeader>
          <CardTitle>Courses</CardTitle>
        </CardHeader>
        <CardContent>
          {courses.length === 0 ? (
            <div className="text-center py-8 text-muted-foreground">
              No courses yet
            </div>
          ) : (
            <div className="overflow-x-auto">
              <Table>
                <TableHeader>
                  <TableRow>
                    <TableHead>Title</TableHead>
                    <TableHead>Code</TableHead>
                    <TableHead className="text-right">Actions</TableHead>
                  </TableRow>
                </TableHeader>
                <TableBody>
                  {courses.map((course) => (
                    <TableRow key={course.id}>
                      <TableCell className="font-medium">
                        {course.title}
                      </TableCell>
                      <TableCell>{course.code || '—'}</TableCell>
                      <TableCell className="text-right">
                        <AlertDialog>
                          <AlertDialogTrigger asChild>
                            <Button
                              variant="ghost"
                              size="sm"
                              disabled={deletingId === course.id}
                            >
                              <Trash2Icon className="w-4 h-4" />
                            </Button>
                          </AlertDialogTrigger>
                          <AlertDialogContent>
                            <AlertDialogHeader>
                              <AlertDialogTitle>Delete Course</AlertDialogTitle>
                              <AlertDialogDescription>
                                Are you sure? This will delete the course and all
                                associated playlists and videos.
                              </AlertDialogDescription>
                            </AlertDialogHeader>
                            <div className="flex gap-2 justify-end">
                              <AlertDialogCancel>Cancel</AlertDialogCancel>
                              <AlertDialogAction
                                onClick={() => deleteCourse(course.id)}
                              >
                                Delete
                              </AlertDialogAction>
                            </div>
                          </AlertDialogContent>
                        </AlertDialog>
                      </TableCell>
                    </TableRow>
                  ))}
                </TableBody>
              </Table>
            </div>
          )}
        </CardContent>
      </Card>
    </div>
  );
}

export default function CoursesAdminClient() {
  return (
    <SidebarProvider
      style={
        {
          '--sidebar-width': 'calc(var(--spacing) * 72)',
          '--header-height': 'calc(var(--spacing) * 12)',
        } as React.CSSProperties
      }
    >
      <AppSidebar variant="inset" />
      <SidebarInset>
        <SiteHeader />
        <div className="flex flex-1 flex-col">
          <div className="@container/main flex flex-1 flex-col gap-2">
            <CoursesUI />
          </div>
        </div>
      </SidebarInset>
    </SidebarProvider>
  );
}