import { useState, useEffect } from 'react';
import { useParams, useNavigate } from 'react-router-dom';
import { Card } from '../../components/ui/card';
import { Button } from '../../components/ui/button';
import { Badge } from '../../components/ui/badge';
import { Label } from '../../components/ui/label';
import { Input } from '../../components/ui/input';
import { Textarea } from '../../components/ui/textarea';
import { Tabs, TabsList, TabsTrigger, TabsContent } from '../../components/ui/tabs';
import { Separator } from '../../components/ui/separator';
import {
  HiOutlinePlus,
  HiOutlinePencil,
  HiOutlineTrash,
  HiOutlineEye,
  HiOutlineChevronRight,
  HiOutlineBookOpen,
  HiOutlineVideoCamera,
  HiOutlineDocumentText,
  HiOutlineQuestionMarkCircle,
  HiOutlineCodeBracket,
  HiOutlineArrowUpTray,
  HiOutlineFunnel,
} from 'react-icons/hi2';
import courseService from '@/services/courseService';
import lessonService from '@/services/lessonService';
import sectionService from '@/services/sectionService';

const typeConfig = {
  video: { label: 'Video', icon: HiOutlineVideoCamera, color: 'bg-blue-100 text-blue-700' },
  text: { label: 'Text', icon: HiOutlineDocumentText, color: 'bg-purple-100 text-purple-700' },
  quiz: { label: 'Quiz', icon: HiOutlineQuestionMarkCircle, color: 'bg-orange-100 text-orange-700' },
  embed: { label: 'Embed', icon: HiOutlineCodeBracket, color: 'bg-gray-100 text-gray-700' },
};

const statusStyles = {
  Published: 'bg-app-success text-app-success-text',
  Draft: 'bg-app-neutral-badge text-app-neutral-badge-text',
};

function formatDuration(seconds) {
  if (!seconds) return '00:00';
  const m = Math.floor(seconds / 60);
  const s = seconds % 60;
  return `${String(m).padStart(2, '0')}:${String(s).padStart(2, '0')}`;
}

function mapCourse(c) {
  return {
    id: c.id,
    code: c.courseCode,
    title: c.title,
    description: c.description,
    status: c.isPublished ? 'Active' : 'Inactive',
    lastUpdate: c.updatedAt,
    image: c.image,
    isPublished: c.isPublished,
  };
}

function CourseDetail() {
  const { courseId } = useParams();
  const navigate = useNavigate();
  const [course, setCourse] = useState(null);
  const [lessons, setLessons] = useState([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState(null);
  const [activeTab, setActiveTab] = useState('overview');

  const handleTogglePublish = async () => {
    try {
      await courseService.update(courseId, {
        courseCode: course.code,
        title: course.title,
        description: course.description,
        image: course.image,
        isPublished: !course.isPublished,
      });
      setCourse((prev) => ({ ...prev, isPublished: !prev.isPublished, status: prev.isPublished ? 'Inactive' : 'Active' }));
    } catch (err) {
      alert(err.message || 'Failed to update course');
    }
  };

  const handleDeleteLesson = async (lessonId) => {
    if (!window.confirm('Are you sure you want to delete this lesson?')) return;
    try {
      await lessonService.delete(lessonId);
      setLessons((prev) => prev.filter((l) => l.id !== lessonId));
    } catch (err) {
      alert(err.message || 'Failed to delete lesson');
    }
  };

  useEffect(() => {
    const fetchData = async () => {
      try {
        const courseData = await courseService.getById(courseId);
        setCourse(mapCourse(courseData));

        const allLessons = await lessonService.getAll();
        const courseLessons = allLessons.filter((l) => l.courseId === Number(courseId));

        const lessonsWithSections = await Promise.all(
          courseLessons.map(async (lesson) => {
            const sections = await sectionService.getByLessonId(lesson.id);
            const firstSection = sections[0];
            return {
              id: lesson.id,
              title: lesson.title,
              position: lesson.position,
              type: firstSection?.type || 'text',
              duration: firstSection?.type === 'video'
                ? formatDuration(firstSection.durationSeconds)
                : firstSection?.type === 'text'
                  ? `~${Math.max(1, Math.ceil((firstSection.content || '').split(/\s+/).length / 200))} min read`
                  : firstSection?.type === 'quiz'
                    ? `${firstSection.durationSeconds ? Math.floor(firstSection.durationSeconds / 60) : 10}:00`
                    : firstSection?.type === 'embed'
                      ? 'iFrame'
                      : '00:00',
              status: lesson.isPublished ? 'Published' : 'Draft',
              isFreePreview: firstSection?.isFreePreview || false,
              updatedAt: lesson.updatedAt,
            };
          })
        );

        setLessons(lessonsWithSections);
      } catch (err) {
        setError(err.message || 'Failed to load course');
      } finally {
        setLoading(false);
      }
    };
    fetchData();
  }, [courseId]);

  if (loading) {
    return (
      <>
        <div className="flex items-center justify-center py-20 text-app-text-muted">Loading course...</div>
      </>
    );
  }

  if (error || !course) {
    return (
      <>
        <div className="flex flex-col items-center justify-center py-20 text-app-text-muted">
          <HiOutlineBookOpen className="w-16 h-16 mb-4 opacity-30" />
          <p className="text-lg font-medium">{error || 'Course not found'}</p>
          <Button
            variant="link"
            className="mt-2 text-app-primary"
            onClick={() => navigate('/courses')}
          >
            Back to Courses
          </Button>
        </div>
      </>
    );
  }

  const publishedCount = lessons.filter((l) => l.status === 'Published').length;
  const draftCount = lessons.filter((l) => l.status === 'Draft').length;

  return (
    <>

      {/* Breadcrumb */}
      <div className="flex items-center gap-2 text-sm text-app-text-muted mb-4">
        <button
          onClick={() => navigate('/courses')}
          className="hover:text-app-primary transition-colors flex items-center gap-1"
        >
          <HiOutlineBookOpen className="w-4 h-4" />
          Courses
        </button>
        <HiOutlineChevronRight className="w-3.5 h-3.5" />
        <span className="font-medium text-app-text">{course.title}</span>
      </div>

      {/* Header */}
      <div className="flex flex-row items-center justify-between mb-6">
        <div className="flex items-center gap-3">
          <h2 className="text-xl font-bold text-app-text">{course.title}</h2>
          <Badge
            className={`rounded-[6px] text-xs font-medium ${
              course.status === 'Active'
                ? 'bg-app-success text-app-success-text'
                : 'bg-app-neutral-badge text-app-neutral-badge-text'
            }`}
          >
            {course.status}
          </Badge>
        </div>
        <div className="flex flex-row items-center gap-2">
          <Button
            variant="outline"
            className="rounded-xl bg-app-surface-muted text-app-text hover:bg-app-interactive-hover"
            onClick={() => navigate(`/courses/edit/${courseId}`)}
          >
            <HiOutlinePencil className="w-4 h-4 mr-2" />
            Edit
          </Button>
          <Button
            variant="outline"
            className="rounded-xl bg-app-surface-muted text-app-text hover:bg-app-interactive-hover"
            onClick={handleTogglePublish}
          >
            <HiOutlineArrowUpTray className="w-4 h-4 mr-2" />
            {course.isPublished ? 'Inactivate' : 'Activate'}
          </Button>
          <Button
            className="rounded-xl bg-app-primary text-white hover:bg-app-primary-dark"
            onClick={handleTogglePublish}
          >
            {course.isPublished ? 'Unpublish' : 'Publish'}
          </Button>
        </div>
      </div>

      <Separator className="mb-6" />

      {/* Tabs */}
      <Tabs value={activeTab} onValueChange={setActiveTab}>
        <TabsList className="mb-6">
          <TabsTrigger value="overview" className="gap-2">
            <HiOutlineBookOpen className="w-4 h-4" />
            Overview
          </TabsTrigger>
          <TabsTrigger value="lessons" className="gap-2">
            <HiOutlineDocumentText className="w-4 h-4" />
            Lessons
            <Badge className="ml-1 rounded-full bg-app-primary-soft text-app-primary text-[10px] px-1.5 py-0">
              {lessons.length}
            </Badge>
          </TabsTrigger>
        </TabsList>

        {/* Overview Tab */}
        <TabsContent value="overview">
          <Card
            className="w-full max-w-2xl overflow-hidden rounded-xl border border-app-border bg-white"
            style={{ boxShadow: 'rgba(0,0,0,0.03) 0px 4px 24px' }}
          >
            <div className="p-5 border-b border-app-border">
              <h4 className="font-semibold text-app-text">Course Details</h4>
            </div>
            <div className="px-5 pb-5 pt-4">
              <div className="mb-4 w-full max-w-sm">
                <Label className="mb-1.5 block text-app-text text-xs font-semibold uppercase tracking-wider">
                  Course Code
                </Label>
                <Input value={course.code} readOnly className="bg-app-surface-muted" />
              </div>
              <div className="mb-4">
                <Label className="mb-1.5 block text-app-text text-xs font-semibold uppercase tracking-wider">
                  Status
                </Label>
                <Badge
                  className={`rounded-[6px] text-xs font-medium ${
                    course.status === 'Active'
                      ? 'bg-app-success text-app-success-text'
                      : 'bg-app-neutral-badge text-app-neutral-badge-text'
                  }`}
                >
                  {course.status}
                </Badge>
              </div>
              <div className="mb-4 w-full max-w-sm">
                <Label className="mb-1.5 block text-app-text text-xs font-semibold uppercase tracking-wider">
                  Description
                </Label>
                <Textarea
                  className="max-h-40 bg-app-surface-muted"
                  placeholder="Course description..."
                  rows={4}
                  value={course.description}
                  readOnly
                />
              </div>
              <div className="flex items-center gap-6 text-sm text-app-text-muted">
                <span>
                  Last updated:{' '}
                  <span className="font-medium text-app-text">
                    {course.lastUpdate ? new Date(course.lastUpdate).toLocaleDateString('en-GB') : '-'}
                  </span>
                </span>
                <span>
                  Total lessons:{' '}
                  <span className="font-medium text-app-text">{lessons.length}</span>
                </span>
              </div>
            </div>
          </Card>
        </TabsContent>

        {/* Lessons Tab */}
        <TabsContent value="lessons">
          <div className="flex flex-col gap-4">
            {/* Toolbar */}
            <div className="flex flex-wrap items-center justify-between gap-3">
              <div>
                <div className="flex items-center gap-2">
                  <h3 className="text-lg font-semibold text-app-text">Lessons</h3>
                  <Badge className="rounded-full bg-app-surface-muted text-app-text-muted text-xs">
                    {lessons.length} items
                  </Badge>
                </div>
                <p className="text-sm text-app-text-muted mt-0.5">
                  {publishedCount} published, {draftCount} drafts
                </p>
              </div>
              <div className="flex items-center gap-2">
                <Button
                  variant="outline"
                  size="sm"
                  className="rounded-xl bg-app-surface-muted text-app-text hover:bg-app-interactive-hover"
                >
                  <HiOutlineFunnel className="w-4 h-4 mr-1.5" />
                  Filter
                </Button>
                <Button
                  className="rounded-xl bg-app-primary text-white hover:bg-app-primary-dark shadow-sm"
                  onClick={() => navigate(`/courses/${courseId}/lessons/new`)}
                >
                  <HiOutlinePlus className="w-4 h-4 mr-1.5" />
                  Add Lesson
                </Button>
              </div>
            </div>

            {/* Lessons Table */}
            {lessons.length === 0 ? (
              <Card
                className="rounded-xl border border-app-border bg-white p-12 flex flex-col items-center justify-center text-center"
                style={{ boxShadow: 'rgba(0,0,0,0.03) 0px 4px 24px' }}
              >
                <div className="w-16 h-16 rounded-2xl bg-app-surface-muted flex items-center justify-center mb-4">
                  <HiOutlineBookOpen className="w-8 h-8 text-app-text-muted/40" />
                </div>
                <p className="text-lg font-medium text-app-text mb-1">No lessons yet</p>
                <p className="text-sm text-app-text-muted mb-4">
                  Start building your course by adding the first lesson.
                </p>
                <Button
                  className="rounded-xl bg-app-primary text-white hover:bg-app-primary-dark"
                  onClick={() => navigate(`/courses/${courseId}/lessons/new`)}
                >
                  <HiOutlinePlus className="w-4 h-4 mr-2" />
                  Add First Lesson
                </Button>
              </Card>
            ) : (
              <Card
                className="rounded-xl border border-app-border bg-white overflow-hidden"
                style={{ boxShadow: 'rgba(0,0,0,0.03) 0px 4px 24px' }}
              >
                {/* Table Header */}
                <div className="grid grid-cols-12 gap-4 px-5 py-3 bg-app-surface-muted/50 border-b border-app-border text-xs font-semibold text-app-text-muted uppercase tracking-wider">
                  <div className="col-span-1">#</div>
                  <div className="col-span-1">Type</div>
                  <div className="col-span-4">Title</div>
                  <div className="col-span-2">Duration</div>
                  <div className="col-span-2">Status</div>
                  <div className="col-span-1">Preview</div>
                  <div className="col-span-1 text-right">Actions</div>
                </div>

                {/* Table Rows */}
                {lessons.map((lesson) => {
                  const tc = typeConfig[lesson.type] || typeConfig.text;
                  const TypeIcon = tc.icon;
                  return (
                    <div
                      key={lesson.id}
                      className="grid grid-cols-12 gap-4 px-5 py-3.5 border-b border-app-border/50 last:border-b-0 items-center hover:bg-app-surface-muted/30 transition-colors"
                    >
                      <div className="col-span-1 text-sm text-app-text-muted font-mono">
                        {lesson.position}
                      </div>
                      <div className="col-span-1">
                        <span
                          className={`inline-flex items-center gap-1 px-2 py-0.5 rounded-lg text-[11px] font-semibold uppercase ${tc.color}`}
                        >
                          <TypeIcon className="w-3 h-3" />
                          {tc.label}
                        </span>
                      </div>
                      <div className="col-span-4">
                        <span className="text-sm font-medium text-app-text truncate block">
                          {lesson.title}
                        </span>
                      </div>
                      <div className="col-span-2 text-sm text-app-text-muted font-mono">
                        {lesson.duration}
                      </div>
                      <div className="col-span-2">
                        <Badge
                          className={`rounded-[6px] text-[11px] font-medium ${
                            statusStyles[lesson.status]
                          }`}
                        >
                          {lesson.status}
                        </Badge>
                      </div>
                      <div className="col-span-1">
                        {lesson.isFreePreview && (
                          <Badge className="rounded-full bg-blue-50 text-blue-600 text-[10px]">
                            Free
                          </Badge>
                        )}
                      </div>
                      <div className="col-span-1 flex items-center justify-end gap-1">
                        <button
                          onClick={() =>
                            navigate(`/courses/${courseId}/lessons/edit/${lesson.id}`)
                          }
                          className="w-8 h-8 rounded-lg flex items-center justify-center text-app-text-muted hover:text-app-primary hover:bg-app-primary-soft transition-colors"
                          title="Edit"
                        >
                          <HiOutlinePencil className="w-4 h-4" />
                        </button>
                        <button
                          className="w-8 h-8 rounded-lg flex items-center justify-center text-app-text-muted hover:text-app-primary hover:bg-app-primary-soft transition-colors"
                          title="Preview"
                        >
                          <HiOutlineEye className="w-4 h-4" />
                        </button>
                        <button
                          onClick={() => handleDeleteLesson(lesson.id)}
                          className="w-8 h-8 rounded-lg flex items-center justify-center text-app-text-muted hover:text-red-500 hover:bg-red-50 transition-colors"
                          title="Delete"
                        >
                          <HiOutlineTrash className="w-4 h-4" />
                        </button>
                      </div>
                    </div>
                  );
                })}
              </Card>
            )}
          </div>
        </TabsContent>
      </Tabs>
    </>
  );
}

export default CourseDetail;