Initial commit: teaching institution management API.

Express/MongoDB backend with JWT auth, RBAC, S3 uploads, notifications, and scheduled jobs.

components/courses/courseService.js

@@ -0,0 +1,139 @@
+// /components/courses/courseService.js
+
+const Course = require('./courseModel');
+const Professor = require('../professors/professorModel');
+const AppError = require('../../utils/AppError');
+const eventEmitter = require('../../events/eventEmitter');
+const EVENT_NAMES = require('../../constants/eventNames');
+const { parsePaginationAndSort, buildFilterQuery, calculateMeta } = require('../../utils/pagination');
+
+const normalizeHighlights = (value) => {
+  if (!Array.isArray(value)) return undefined;
+  return value.map((item) => String(item).trim()).filter(Boolean);
+};
+
+const createCourse = async (data, actorId = null) => {
+  if (data.professor) {
+    const professor = await Professor.findById(data.professor);
+    if (!professor) {
+      throw new AppError('PROFESSOR_NOT_FOUND');
+    }
+  }
+
+  const payload = {
+    ...data,
+    highlights: normalizeHighlights(data.highlights) ?? data.highlights
+  };
+
+  const course = await Course.create(payload);
+
+  if (data.professor) {
+    await Professor.findByIdAndUpdate(data.professor, { $addToSet: { courses: course._id } });
+  }
+
+  eventEmitter.emit(EVENT_NAMES.COURSE_CREATED, { courseId: course._id, title: course.title, actorId });
+  return course;
+};
+
+const getCourseById = async (id, { publicOnly = false } = {}) => {
+  const filter = { _id: id };
+  if (publicOnly) filter.showOnFrontend = { $ne: false };
+
+  const course = await Course.findOne(filter).populate('professor', 'name surname title expertise email phoneNumber');
+  if (!course) {
+    throw new AppError('COURSE_NOT_FOUND');
+  }
+  return course;
+};
+
+const getAllCourses = async (queryParams, { publicOnly = false } = {}) => {
+  const { page, limit, skip, sort } = parsePaginationAndSort(queryParams);
+  const filter = buildFilterQuery(queryParams, ['title', 'description'], [
+    'page', 'limit', 'sortBy', 'sortOrder', 'q', 'lang', 'sort'
+  ]);
+
+  if (publicOnly) {
+    // Include legacy docs that predate the field (treat missing as visible)
+    filter.showOnFrontend = { $ne: false };
+  }
+
+  // Support legacy ?sort=-createdAt style from frontend
+  let finalSort = sort;
+  if (queryParams.sort && typeof queryParams.sort === 'string') {
+    const raw = queryParams.sort.trim();
+    if (raw.startsWith('-')) {
+      finalSort = { [raw.slice(1)]: -1 };
+    } else {
+      finalSort = { [raw]: 1 };
+    }
+  }
+
+  const [courses, totalCount] = await Promise.all([
+    Course.find(filter).populate('professor', 'name surname').sort(finalSort).skip(skip).limit(limit),
+    Course.countDocuments(filter)
+  ]);
+
+  const meta = calculateMeta(totalCount, page, limit);
+  return { data: courses, meta };
+};
+
+const updateCourse = async (id, updateData, actorId = null) => {
+  const course = await Course.findById(id);
+  if (!course) {
+    throw new AppError('COURSE_NOT_FOUND');
+  }
+
+  if (updateData.professor && updateData.professor !== String(course.professor)) {
+    const professor = await Professor.findById(updateData.professor);
+    if (!professor) throw new AppError('PROFESSOR_NOT_FOUND');
+
+    if (course.professor) {
+      await Professor.findByIdAndUpdate(course.professor, { $pull: { courses: course._id } });
+    }
+    await Professor.findByIdAndUpdate(updateData.professor, { $addToSet: { courses: course._id } });
+  }
+
+  if (updateData.price !== undefined && updateData.price !== course.price) {
+    eventEmitter.emit(EVENT_NAMES.COURSE_PRICE_CHANGED, {
+      courseId: course._id,
+      oldPrice: course.price,
+      newPrice: updateData.price,
+      actorId
+    });
+  }
+
+  if (updateData.highlights !== undefined) {
+    updateData.highlights = normalizeHighlights(updateData.highlights) || [];
+  }
+
+  Object.assign(course, updateData);
+  await course.save();
+  return course;
+};
+
+const deleteCourse = async (id) => {
+  const course = await Course.findById(id);
+  if (!course) {
+    throw new AppError('COURSE_NOT_FOUND');
+  }
+
+  if (course.professor) {
+    await Professor.findByIdAndUpdate(course.professor, { $pull: { courses: course._id } });
+  }
+
+  await Course.findByIdAndDelete(id);
+  return null;
+};
+
+const searchCourses = async (queryParams) => {
+  return getAllCourses(queryParams);
+};
+
+module.exports = {
+  createCourse,
+  getCourseById,
+  getAllCourses,
+  updateCourse,
+  deleteCourse,
+  searchCourses
+};