import { notFound, redirect } from "next/navigation";
import { db } from "@/lib/prisma";
import { requireUser } from "@/lib/auth/requireUser";
import StudentClassroomClient from "@/components/courses/StudentClassroomClient";
import { parseLessonDescriptionMeta } from "@/lib/courses/lessonContent";

type LessonSelect = {
  id: string;
  title: unknown;
  description: unknown;
  videoUrl: string | null;
  youtubeUrl: string | null;
  estimatedDuration: number;
  isFreePreview: boolean;
};
type ModuleSelect = { id: string; title: unknown; lessons: LessonSelect[] };
type CourseWithModules = { id: string; slug: string; title: unknown; price: unknown; modules: ModuleSelect[] };

function getText(value: unknown): string {
  if (!value) return "";
  if (typeof value === "string") return value;
  if (typeof value === "object") {
    const record = value as Record<string, unknown>;
    if (typeof record.es === "string") return record.es;
    if (typeof record.en === "string") return record.en;
  }
  return "";
}

type PageProps = {
  params: Promise<{ slug: string }>;
  searchParams: Promise<{ lesson?: string }>;
};

export default async function CourseLearnPage({ params, searchParams }: PageProps) {
  const { slug } = await params;
  const { lesson: requestedLessonId } = await searchParams;

  const user = await requireUser();

  const courseSelect = {
    id: true,
    slug: true,
    title: true,
    price: true,
    modules: {
      orderBy: { orderIndex: "asc" as const },
      select: {
        id: true,
        title: true,
        lessons: {
          orderBy: { orderIndex: "asc" as const },
            select: {
              id: true,
              title: true,
              description: true,
              videoUrl: true,
              youtubeUrl: true,
              estimatedDuration: true,
              isFreePreview: true,
            },
        },
      },
    },
  };
  const course = (await db.course.findUnique({
    where: { slug },
    select: courseSelect,
  })) as CourseWithModules | null;

  if (!course) {
    notFound();
  }

  let enrollment: { id: string } | null = null;
  let isEnrolled: boolean;

  if (!user?.id) {
    // Anonymous: no enrollment, preview-only access
    const allLessons = course.modules.flatMap((m) =>
      m.lessons.map((l) => ({ id: l.id, isFreePreview: l.isFreePreview }))
    );
    const firstPreviewLesson = allLessons.find((l) => l.isFreePreview);
    if (!firstPreviewLesson) {
      redirect(`/courses/${slug}`);
    }
    isEnrolled = false;
  } else {
    enrollment = await db.enrollment.findUnique({
      where: {
        userId_courseId: {
          userId: user.id,
          courseId: course.id,
        },
      },
      select: { id: true },
    });

    const isFree = Number(course.price) === 0;

    if (!enrollment) {
      if (isFree) {
        enrollment = await db.enrollment.create({
          data: {
            userId: user.id,
            courseId: course.id,
            amountPaid: 0,
          },
          select: { id: true },
        });
        isEnrolled = true;
      } else {
        // Paid course, no enrollment: allow only if there are preview lessons
        const allLessons = course.modules.flatMap((m) =>
          m.lessons.map((l) => ({ id: l.id, isFreePreview: l.isFreePreview }))
        );
        const firstPreviewLesson = allLessons.find((l) => l.isFreePreview);
        if (!firstPreviewLesson) {
          redirect(`/courses/${slug}`);
        }
        isEnrolled = false;
      }
    } else {
      isEnrolled = true;
    }
  }

  const completedProgress =
    isEnrolled && user
      ? await db.userProgress.findMany({
          where: {
            userId: user.id,
            isCompleted: true,
            lesson: {
              module: { courseId: course.id },
            },
          },
          select: { lessonId: true },
        })
      : [];

  const modules = course.modules.map((module) => ({
    id: module.id,
    title: getText(module.title) || "Untitled module",
    lessons: module.lessons.map((lesson) => {
      const lessonMeta = parseLessonDescriptionMeta(lesson.description);
      return {
        id: lesson.id,
        title: getText(lesson.title) || "Untitled lesson",
        description: lessonMeta.text,
        contentType: lessonMeta.contentType,
        materialUrl: lessonMeta.materialUrl,
        videoUrl: lesson.videoUrl,
        youtubeUrl: lesson.youtubeUrl,
        estimatedDuration: lesson.estimatedDuration,
        isFreePreview: lesson.isFreePreview,
      };
    }),
  }));

  const flattenedLessons = modules.flatMap((module) => module.lessons);
  const flattenedLessonIds = flattenedLessons.map((l) => l.id);

  let initialSelectedLessonId: string;
  if (isEnrolled) {
    initialSelectedLessonId =
      requestedLessonId && flattenedLessonIds.includes(requestedLessonId)
        ? requestedLessonId
        : flattenedLessonIds[0] ?? "";
  } else {
    const firstPreview = flattenedLessons.find((l) => l.isFreePreview);
    const requestedLesson = requestedLessonId
      ? flattenedLessons.find((l) => l.id === requestedLessonId)
      : null;
    if (requestedLesson?.isFreePreview) {
      initialSelectedLessonId = requestedLessonId!;
    } else {
      initialSelectedLessonId = firstPreview?.id ?? "";
    }
  }

  return (
    <StudentClassroomClient
      courseSlug={course.slug}
      courseTitle={getText(course.title) || "Untitled course"}
      modules={modules}
      initialSelectedLessonId={initialSelectedLessonId}
      initialCompletedLessonIds={completedProgress.map((p) => p.lessonId)}
      isEnrolled={isEnrolled}
    />
  );
}