import { db } from "../../../db/index";
import { courses, topics, lessons } from "../../../db/schema";
import { eq, inArray } from "drizzle-orm";

export default defineEventHandler(async (event) => {
  const id = getRouterParam(event, "id")!;

  const course = await db.query.courses.findFirst({ where: eq(courses.id, id) });
  if (!course) throw createError({ statusCode: 404, message: "Course not found" });

  const topicRows = await db.query.topics.findMany({
    where: eq(topics.courseId, id),
    orderBy: (t, { asc }) => asc(t.order),
  });

  let lessonTopicIds: Set<string> = new Set();

  if (topicRows.length > 0) {
    const topicIds = topicRows.map((t) => t.id);
    const lessonRows = await db.query.lessons.findMany({
      where: inArray(lessons.topicId, topicIds),
    });
    lessonTopicIds = new Set(lessonRows.map((l) => l.topicId));
  }

  return {
    status: course.status,
    stage: course.stage,
    topics: topicRows.map((t) => ({
      id: t.id,
      status: t.status,
      hasLesson: lessonTopicIds.has(t.id),
    })),
  };
});