add: ver()

Signed-off-by: Kenneth Obsequio <k80308392@gmail.com>

utils/courses/hierarchy.util.js

@@ -0,0 +1,114 @@
+"use strict";
+
+/***********************************************************************************************************************************************************************
+ * File Name: hierarchy.util.js
+ * Type of Program: Utility
+ * Description: Helpers for the junction-based course hierarchy
+ *              (courses ⇄ course_units ⇄ units ⇄ unit_lessons ⇄ lessons).
+ *
+ *   Sequelize belongsToMany includes surface the junction row under the through-
+ *   model key ("CourseUnit" / "UnitLesson"). These helpers flatten that back to
+ *   the flat `order_index` field the API has always exposed, so response shapes
+ *   stay identical to the pre-junction era.
+ *
+ * Author: Kenneth Obsequio (@lash0000)
+ * Date Created: Jul. 7, 2026
+ ***********************************************************************************************************************************************************************/
+
+const sequelize = require("../../config/db.config");
+
+// ── Response flattening ───────────────────────────────────────────────────────
+
+/** Sort lessons by their unit_lessons.order_index and flatten it onto each row. */
+function flattenLessons(lessons = []) {
+  return [...lessons]
+    .map((l) => {
+      const { UnitLesson: link, ...rest } = l;
+      return { ...rest, order_index: link?.order_index ?? rest.order_index ?? 0 };
+    })
+    .sort((a, b) => (a.order_index ?? 0) - (b.order_index ?? 0));
+}
+
+/** Sort units by their course_units.order_index, flatten it, and recurse into lessons. */
+function flattenUnits(units = []) {
+  return [...units]
+    .map((u) => {
+      const { CourseUnit: link, ...rest } = u;
+      return {
+        ...rest,
+        order_index: link?.order_index ?? rest.order_index ?? 0,
+        ...(rest.lessons ? { lessons: flattenLessons(rest.lessons) } : {}),
+      };
+    })
+    .sort((a, b) => (a.order_index ?? 0) - (b.order_index ?? 0));
+}
+
+// ── Junction row maintenance ──────────────────────────────────────────────────
+
+/** Next order_index for appending to a parent (max + 1, or 0 when empty). */
+async function nextOrderIndex(JunctionModel, where, transaction) {
+  const max = await JunctionModel.max("order_index", { where, transaction });
+  return Number.isFinite(max) ? max + 1 : 0;
+}
+
+/**
+ * Persist a full ordering: ids[i] gets order_index i.
+ * Ignores ids without an existing junction row.
+ */
+async function reorderJunction(JunctionModel, parentField, parentId, childField, orderedIds = [], transaction) {
+  await Promise.all(orderedIds.map((id, i) =>
+    JunctionModel.update(
+      { order_index: i },
+      { where: { [parentField]: parentId, [childField]: id }, transaction }
+    )
+  ));
+}
+
+// ── Structure counts (raw SQL — junction traversals) ──────────────────────────
+
+/** Count non-archived lessons reachable from a course through its attached units. */
+async function countCourseLessons(courseId) {
+  const [row] = await sequelize.query(`
+    SELECT CAST(COUNT(DISTINCT l.lesson_id) AS INTEGER) AS total
+    FROM lessons l
+    JOIN unit_lessons ul ON ul.lesson_id = l.lesson_id
+    JOIN units u         ON u.unit_id = ul.unit_id AND u."deletedAt" IS NULL
+    JOIN course_units cu ON cu.unit_id = u.unit_id AND cu.course_id = :courseId
+    WHERE l."deletedAt" IS NULL
+  `, { replacements: { courseId }, type: sequelize.QueryTypes.SELECT });
+  return Number(row?.total ?? 0);
+}
+
+/** Non-archived unit ids attached to a course, in course order. */
+async function getCourseUnitIds(courseId) {
+  const rows = await sequelize.query(`
+    SELECT u.unit_id
+    FROM units u
+    JOIN course_units cu ON cu.unit_id = u.unit_id AND cu.course_id = :courseId
+    WHERE u."deletedAt" IS NULL
+    ORDER BY cu.order_index ASC
+  `, { replacements: { courseId }, type: sequelize.QueryTypes.SELECT });
+  return rows.map((r) => r.unit_id);
+}
+
+/** Non-archived lesson ids attached to a unit, in unit order. */
+async function getUnitLessonIds(unitId) {
+  const rows = await sequelize.query(`
+    SELECT l.lesson_id
+    FROM lessons l
+    JOIN unit_lessons ul ON ul.lesson_id = l.lesson_id AND ul.unit_id = :unitId
+    WHERE l."deletedAt" IS NULL
+    ORDER BY ul.order_index ASC
+  `, { replacements: { unitId }, type: sequelize.QueryTypes.SELECT });
+  return rows.map((r) => r.lesson_id);
+}
+
+module.exports = {
+  flattenLessons,
+  flattenUnits,
+  nextOrderIndex,
+  reorderJunction,
+  countCourseLessons,
+  getCourseUnitIds,
+  getUnitLessonIds,
+};