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

export default defineEventHandler(async () => {
  const allCourses = await db.query.courses.findMany({
    orderBy: (c, { desc }) => desc(c.createdAt),
  });

  if (allCourses.length === 0) return [];

  const courseIds = allCourses.map((c) => c.id);

  const [allTopics, allProgress] = await Promise.all([
    db.query.topics.findMany({ where: inArray(topics.courseId, courseIds) }),
    db.query.userProgress.findMany({ where: inArray(userProgress.courseId, courseIds) }),
  ]);

  // group in memory
  const topicsByCourse = new Map<string, number>();
  for (const t of allTopics) {
    topicsByCourse.set(t.courseId, (topicsByCourse.get(t.courseId) ?? 0) + 1);
  }

  const completedByCourse = new Map<string, number>();
  for (const p of allProgress) {
    if (p.lessonComplete) {
      completedByCourse.set(p.courseId, (completedByCourse.get(p.courseId) ?? 0) + 1);
    }
  }

  return allCourses.map((course) => ({
    ...course,
    topicCount: topicsByCourse.get(course.id) ?? 0,
    completedCount: completedByCourse.get(course.id) ?? 0,
  }));
});