add: ver()

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

controllers/admin/units.controller.js

@@ -1,17 +1,40 @@
 "use strict";
 
+/***********************************************************************************************************************************************************************
+ * File Name: units.controller.js  (admin)
+ * Type of Program: Controller
+ * Description: Standalone Unit library — Units live independently of Courses.
+ *
+ *   /admin/units                     → library CRUD (list / create / update / archive / restore / permanent delete)
+ *   /admin/units/:unitId/lessons     → attach / detach / reorder standalone Lessons on this Unit
+ *   /admin/units/:unitId/quiz        → the Unit's quiz (travels with the Unit into every course it's attached to)
+ *
+ *   Membership in a course is a course_units row (managed from the course builder);
+ *   archiving here removes the Unit from every course view at once.
+ *
+ * Author: Kenneth Obsequio (@lash0000)
+ * Date Created: Jul. 7, 2026 (junction revamp — Units/Lessons run independently)
+ ***********************************************************************************************************************************************************************/
+
 const { Op } = require("sequelize");
 const sequelize = require("../../config/db.config");
 const R = require("../../utils/response.util");
 const { paginate } = require("../../utils/paginate.util");
 const { archiveOne, archiveMany } = require("../../utils/courses/archive.util");
 const { restoreOne, restoreMany } = require("../../utils/courses/restore.util");
+const { permanentDeleteOne, permanentDeleteMany } = require("../../utils/courses/permanentDelete.util");
+const { getFieldValues } = require("../../utils/fieldValues.util");
+const { flattenLessons, nextOrderIndex, reorderJunction } = require("../../utils/courses/hierarchy.util");
+const { recomputeUnitDuration, recomputeCourseDuration } = require("../../utils/duration.util");
+const logActivity = require("../../utils/logActivity.util");
 
 // ── Models ────────────────────────────────────────────────────────────────────
 
 const {
   Course, Unit, Lesson,
+  CourseUnit, UnitLesson,
   UnitQuiz, QuizQuestion, QuizOption,
+  UnitReadingProgress, LessonReadingProgress,
 } = require("../../models/courses/courses.associations");
 
 const mdl_Users = require("../../models/users/users.mdl");
@@ -19,126 +42,205 @@ const mdl_Users = require("../../models/users/users.mdl");
 const notDeleted  = { deletedAt: null };
 const onlyDeleted = { deletedAt: { [Op.not]: null } };
 
+// Refresh duration of every course this unit is attached to (post-archive/restore).
+async function recomputeParentCourseDurations(unitId) {
+  const links = await CourseUnit.findAll({ where: { unit_id: unitId }, attributes: ["course_id"] });
+  for (const courseId of new Set(links.map((l) => String(l.course_id)))) {
+    await recomputeCourseDuration(courseId);
+  }
+}
+
+const UNIT_LIST_COMPUTED = [
+  {
+    key: "quiz_id",
+    label: "Quiz ID",
+    type: "text",
+    literal: `(SELECT quiz_id FROM unit_quizzes WHERE unit_id = "Unit"."unit_id" AND "deletedAt" IS NULL LIMIT 1)`,
+  },
+  {
+    key: "lesson_count",
+    label: "Lessons",
+    type: "number",
+    literal: `(
+      SELECT CAST(COUNT(*) AS INTEGER)
+      FROM unit_lessons ul
+      JOIN lessons l ON l.lesson_id = ul.lesson_id AND l."deletedAt" IS NULL
+      WHERE ul.unit_id = "Unit"."unit_id"
+    )`,
+  },
+  {
+    key: "course_count",
+    label: "Used in courses",
+    type: "number",
+    literal: `(
+      SELECT CAST(COUNT(*) AS INTEGER)
+      FROM course_units cu
+      JOIN courses c ON c.course_id = cu.course_id AND c."deletedAt" IS NULL
+      WHERE cu.unit_id = "Unit"."unit_id"
+    )`,
+  },
+];
+
 // ══════════════════════════════════════════════════════════════════════════════
-// UNIT
+// UNIT LIBRARY
 // ══════════════════════════════════════════════════════════════════════════════
 
 exports.getUnits = async (req, res) => {
   try {
-    const { courseId } = req.params;
-
-    const course = await Course.findOne({ where: { course_id: courseId, ...notDeleted } });
-    if (!course) return R.error(res, "Course not found.", 404);
-
     const result = await paginate(Unit, req, {
       auditOptions: { mdl_Users, parentAlias: "Unit" },
       context: "list",
+      computedAttributes: UNIT_LIST_COMPUTED,
       findOptions: {
-        where: { course_id: courseId, ...notDeleted },
-        order: [["order_index", "ASC"]],
+        where: { ...notDeleted },
+        order: [["createdAt", "DESC"]],
       },
-      computedAttributes: [
-        {
-          key: "quiz_id",
-          label: "Quiz ID",
-          type: "text",
-          literal: `(SELECT quiz_id FROM unit_quizzes WHERE unit_id = "Unit"."unit_id" AND "deletedAt" IS NULL LIMIT 1)`,
-        },
-      ],
     });
-
     return R.success(res, "Units retrieved.", result);
   } catch (err) {
-    console.error("[UNIT][GET ALL]", err);
+    console.error("[UNIT LIB][GET ALL]", err);
+    return R.error(res, "Could not retrieve units.", 500);
+  }
+};
+
+// Lightweight list for attach pickers: { unit_id, uuid, title, lesson_count, course_count }
+exports.getUnitsFlat = async (req, res) => {
+  try {
+    const rows = await sequelize.query(`
+      SELECT
+        u.unit_id, u.uuid, u.title, u.description, u.duration_seconds,
+        (SELECT CAST(COUNT(*) AS INTEGER) FROM unit_lessons ul
+           JOIN lessons l ON l.lesson_id = ul.lesson_id AND l."deletedAt" IS NULL
+          WHERE ul.unit_id = u.unit_id)                       AS lesson_count,
+        (SELECT CAST(COUNT(*) AS INTEGER) FROM course_units cu
+           JOIN courses c ON c.course_id = cu.course_id AND c."deletedAt" IS NULL
+          WHERE cu.unit_id = u.unit_id)                       AS course_count
+      FROM units u
+      WHERE u."deletedAt" IS NULL
+      ORDER BY u.title ASC
+    `, { type: sequelize.QueryTypes.SELECT });
+    return R.success(res, "Units retrieved.", rows);
+  } catch (err) {
+    console.error("[UNIT LIB][GET FLAT]", err);
     return R.error(res, "Could not retrieve units.", 500);
   }
 };
 
 exports.getUnit = async (req, res) => {
   try {
-    const { courseId, unitId } = req.params;
+    const { unitId } = req.params;
 
     const unit = await Unit.findOne({
-      where: { unit_id: unitId, course_id: courseId, ...notDeleted },
+      where: { unit_id: unitId, ...notDeleted },
       include: [
-        { model: Lesson,   as: "lessons", where: notDeleted, required: false },
+        { model: Lesson,   as: "lessons", where: notDeleted, required: false, through: { attributes: ["order_index"] } },
         { model: UnitQuiz, as: "quiz",    required: false },
+        { model: Course,   as: "courses", where: notDeleted, required: false, attributes: ["course_id", "uuid", "title", "subscription"], through: { attributes: ["order_index"] } },
       ],
-      order: [[{ model: Lesson, as: "lessons" }, "order_index", "ASC"]],
     });
 
     if (!unit) return R.error(res, "Unit not found.", 404);
-    return R.success(res, "Unit retrieved.", { data: unit.toJSON() });
+
+    const plain = unit.toJSON();
+    plain.lessons = flattenLessons(plain.lessons);
+    return R.success(res, "Unit retrieved.", { data: plain });
   } catch (err) {
-    console.error("[UNIT][GET ONE]", err);
+    console.error("[UNIT LIB][GET ONE]", err);
     return R.error(res, "Could not retrieve unit.", 500);
   }
 };
 
 exports.createUnit = async (req, res) => {
+  const t = await sequelize.transaction();
   try {
-    const { courseId } = req.params;
-    const { title, description, order, createdBy } = req.body;
-
+    const { title, description, course_id, order, createdBy } = req.body;
     if (!title) return R.error(res, "Title is required.", 400);
 
-    const course = await Course.findOne({ where: { course_id: courseId, ...notDeleted } });
-    if (!course) return R.error(res, "Course not found.", 404);
-
     const unit = await Unit.create({
-      course_id:        courseId,
       title,
       description:      description ?? null,
-      order_index:      order       ?? 0,
       duration_seconds: 0,
-      createdBy:        createdBy   ?? null,
-    });
+      createdBy:        createdBy ?? req.user?.user_id ?? null,
+    }, { transaction: t });
 
+    // Optional immediate attach — lets the course builder create-and-attach in one call
+    if (course_id) {
+      const course = await Course.findOne({ where: { course_id, ...notDeleted }, transaction: t });
+      if (!course) {
+        await t.rollback();
+        return R.error(res, "Course not found.", 404);
+      }
+      const order_index = order ?? await nextOrderIndex(CourseUnit, { course_id }, t);
+      await CourseUnit.create({
+        course_id,
+        unit_id: unit.unit_id,
+        order_index,
+        createdBy: createdBy ?? req.user?.user_id ?? null,
+      }, { transaction: t });
+    }
+
+    await t.commit();
+    logActivity(req.user?.user_id, "create_unit", { entityType: "unit", entityId: unit.unit_id, details: { title: unit.title, attached_course_id: course_id ?? null } });
     return R.success(res, "Unit created.", { data: unit }, 201);
   } catch (err) {
-    console.error("[UNIT][CREATE]", err);
+    await t.rollback();
+    console.error("[UNIT LIB][CREATE]", err);
     return R.error(res, "Could not create unit.", 500);
   }
 };
 
 exports.updateUnit = async (req, res) => {
   try {
-    const { courseId, unitId } = req.params;
+    const { unitId } = req.params;
 
-    const unit = await Unit.findOne({ where: { unit_id: unitId, course_id: courseId, ...notDeleted } });
+    const unit = await Unit.findOne({ where: { unit_id: unitId, ...notDeleted } });
     if (!unit) return R.error(res, "Unit not found.", 404);
 
-    const { title, description, order, updatedBy } = req.body;
+    const { title, description, updatedBy } = req.body;
 
     if (title       !== undefined) unit.title       = title;
     if (description !== undefined) unit.description = description;
-    if (order       !== undefined) unit.order_index = order;
-    unit.updatedBy = updatedBy ?? null;
+    unit.updatedBy = updatedBy ?? req.user?.user_id ?? null;
 
     await unit.save();
+    logActivity(req.user?.user_id, "update_unit", { entityType: "unit", entityId: Number(unitId) });
     return R.success(res, "Unit updated.", { data: unit });
   } catch (err) {
-    console.error("[UNIT][UPDATE]", err);
+    console.error("[UNIT LIB][UPDATE]", err);
     return R.error(res, "Could not update unit.", 500);
   }
 };
 
-exports.deleteUnit = async (req, res) => {
+exports.getUnitArchiveImpact = async (req, res) => {
+  try {
+    const { unitId } = req.params;
+
+    const [completionCount, progressCount, courseCount] = await Promise.all([
+      UnitReadingProgress.count({ where: { unit_id: unitId, status: "completed" } }),
+      LessonReadingProgress.count({ where: { unit_id: unitId }, distinct: true, col: "user_id" }),
+      CourseUnit.count({ where: { unit_id: unitId } }),
+    ]);
+
+    return R.success(res, "Impact retrieved.", { completionCount, progressCount, courseCount });
+  } catch (err) {
+    console.error("[UNIT LIB][ARCHIVE IMPACT]", err);
+    return R.error(res, "Could not retrieve impact.", 500);
+  }
+};
+
+exports.archiveUnit = async (req, res) => {
   const t = await sequelize.transaction();
   try {
-    const { courseId, unitId } = req.params;
-    const record = await archiveOne(
-      Unit,
-      { unit_id: unitId, course_id: courseId, ...notDeleted },
-      req.body.deletedBy,
-      t
-    );
+    const { unitId } = req.params;
+    const record = await archiveOne(Unit, { unit_id: unitId, ...notDeleted }, req.user.user_id, t);
     if (!record) return R.error(res, "Unit not found.", 404);
     await t.commit();
+    try { await recomputeParentCourseDurations(unitId); } catch (durErr) { console.error("[UNIT LIB][ARCHIVE][DURATION]", durErr); }
+    logActivity(req.user.user_id, "archive_unit", { entityType: "unit", entityId: Number(unitId) });
     return R.success(res, "Unit archived.");
   } catch (err) {
     await t.rollback();
-    console.error("[UNIT][DELETE]", err);
+    console.error("[UNIT LIB][ARCHIVE]", err);
     return R.error(res, "Could not archive unit.", 500);
   }
 };
@@ -146,60 +248,55 @@ exports.deleteUnit = async (req, res) => {
 exports.bulkArchiveUnits = async (req, res) => {
   const t = await sequelize.transaction();
   try {
-    const { courseId } = req.params;
-    const { ids = [], deletedBy } = req.body;
+    const { ids = [] } = req.body;
     if (!ids.length) return R.error(res, "No IDs provided.", 400);
 
-    const units = await Unit.findAll({
-      where: { unit_id: ids, course_id: courseId, ...notDeleted },
-    });
+    const units = await Unit.findAll({ where: { unit_id: ids, ...notDeleted } });
     const validIds = units.map((u) => u.unit_id);
 
-    const count = await archiveMany(Unit, "unit_id", validIds, deletedBy, t);
+    const count = await archiveMany(Unit, "unit_id", validIds, req.user.user_id, t);
     await t.commit();
+    for (const id of validIds) {
+      try { await recomputeParentCourseDurations(id); } catch (durErr) { console.error("[UNIT LIB][BULK ARCHIVE][DURATION]", durErr); }
+    }
+    logActivity(req.user.user_id, "bulk_archive_units", { entityType: "unit", details: { ids: validIds, count } });
     return R.success(res, `${count} unit${count !== 1 ? "s" : ""} archived.`);
   } catch (err) {
     await t.rollback();
-    console.error("[UNIT][BULK ARCHIVE]", err);
+    console.error("[UNIT LIB][BULK ARCHIVE]", err);
     return R.error(res, "Could not archive units.", 500);
   }
 };
 
 exports.getArchivedUnits = async (req, res) => {
   try {
-    const { courseId } = req.params;
-
-    const course = await Course.findOne({ where: { course_id: courseId }, paranoid: false });
-    if (!course) return R.error(res, "Course not found.", 404);
-
     const result = await paginate(Unit, req, {
       auditOptions: { mdl_Users, parentAlias: "Unit" },
-      context: "list",
+      context: "archived",
       findOptions: {
-        where: { course_id: courseId, ...onlyDeleted },
+        where: { ...onlyDeleted },
         paranoid: false,
-        order: [["order_index", "ASC"]],
+        order: [["deletedAt", "DESC"]],
       },
     });
-
     return R.success(res, "Archived units retrieved.", result);
   } catch (err) {
-    console.error("[UNIT][GET ARCHIVES]", err);
+    console.error("[UNIT LIB][GET ARCHIVES]", err);
     return R.error(res, "Could not retrieve archived units.", 500);
   }
 };
 
 exports.getArchivedUnit = async (req, res) => {
   try {
-    const { courseId, unitId } = req.params;
+    const { unitId } = req.params;
     const unit = await Unit.findOne({
-      where: { unit_id: unitId, course_id: courseId, ...onlyDeleted },
+      where: { unit_id: unitId, ...onlyDeleted },
       paranoid: false,
     });
     if (!unit) return R.error(res, "Archived unit not found.", 404);
     return R.success(res, "Archived unit retrieved.", { data: unit.toJSON() });
   } catch (err) {
-    console.error("[UNIT][GET ARCHIVE ONE]", err);
+    console.error("[UNIT LIB][GET ARCHIVE ONE]", err);
     return R.error(res, "Could not retrieve archived unit.", 500);
   }
 };
@@ -207,19 +304,16 @@ exports.getArchivedUnit = async (req, res) => {
 exports.restoreUnit = async (req, res) => {
   const t = await sequelize.transaction();
   try {
-    const { courseId, unitId } = req.params;
-    const record = await restoreOne(
-      Unit,
-      { unit_id: unitId, course_id: courseId, ...onlyDeleted },
-      req.body.restoredBy,
-      t
-    );
+    const { unitId } = req.params;
+    const record = await restoreOne(Unit, { unit_id: unitId, ...onlyDeleted }, req.user.user_id, t);
     if (!record) return R.error(res, "Archived unit not found.", 404);
     await t.commit();
+    try { await recomputeParentCourseDurations(unitId); } catch (durErr) { console.error("[UNIT LIB][RESTORE][DURATION]", durErr); }
+    logActivity(req.user.user_id, "restore_unit", { entityType: "unit", entityId: Number(unitId) });
     return R.success(res, "Unit restored.", { data: record });
   } catch (err) {
     await t.rollback();
-    console.error("[UNIT][RESTORE]", err);
+    console.error("[UNIT LIB][RESTORE]", err);
     return R.error(res, "Could not restore unit.", 500);
   }
 };
@@ -227,35 +321,184 @@ exports.restoreUnit = async (req, res) => {
 exports.bulkRestoreUnits = async (req, res) => {
   const t = await sequelize.transaction();
   try {
-    const { courseId } = req.params;
-    const { ids = [], restoredBy } = req.body;
+    const { ids = [] } = req.body;
     if (!ids.length) return R.error(res, "No IDs provided.", 400);
 
-    const units = await Unit.findAll({
-      where: { unit_id: ids, course_id: courseId, ...onlyDeleted },
-      paranoid: false,
-    });
+    const units = await Unit.findAll({ where: { unit_id: ids, ...onlyDeleted }, paranoid: false });
     const validIds = units.map((u) => u.unit_id);
 
-    const count = await restoreMany(Unit, "unit_id", validIds, restoredBy, t);
+    const count = await restoreMany(Unit, "unit_id", validIds, req.user.user_id, t);
     await t.commit();
+    for (const id of validIds) {
+      try { await recomputeParentCourseDurations(id); } catch (durErr) { console.error("[UNIT LIB][BULK RESTORE][DURATION]", durErr); }
+    }
+    logActivity(req.user.user_id, "bulk_restore_units", { entityType: "unit", details: { ids: validIds, count } });
     return R.success(res, `${count} unit${count !== 1 ? "s" : ""} restored.`);
   } catch (err) {
     await t.rollback();
-    console.error("[UNIT][BULK RESTORE]", err);
+    console.error("[UNIT LIB][BULK RESTORE]", err);
     return R.error(res, "Could not restore units.", 500);
   }
 };
 
+exports.getUnitPermanentDeleteImpact = async (req, res) => {
+  try {
+    const { unitId } = req.params;
+
+    const [lessonCount, courseCount] = await Promise.all([
+      UnitLesson.count({ where: { unit_id: unitId } }),
+      CourseUnit.count({ where: { unit_id: unitId } }),
+    ]);
+
+    return R.success(res, "Impact retrieved.", { lessonCount, courseCount });
+  } catch (err) {
+    console.error("[UNIT LIB][PERMANENT DELETE IMPACT]", err);
+    return R.error(res, "Could not retrieve impact.", 500);
+  }
+};
+
+exports.permanentlyDeleteUnit = async (req, res) => {
+  const t = await sequelize.transaction();
+  try {
+    const { unitId } = req.params;
+    const record = await permanentDeleteOne(Unit, { unit_id: unitId }, t);
+    if (record === null) return R.error(res, "Unit not found.", 404);
+    if (record === false) return R.error(res, "Unit must be archived before it can be permanently deleted.", 400);
+
+    // Junction rows don't cascade from a paranoid destroy — clean them explicitly
+    await CourseUnit.destroy({ where: { unit_id: unitId }, transaction: t });
+    await UnitLesson.destroy({ where: { unit_id: unitId }, transaction: t });
+
+    await t.commit();
+    logActivity(req.user.user_id, "permanently_delete_unit", { entityType: "unit", entityId: Number(unitId) });
+    return R.success(res, "Unit permanently deleted.");
+  } catch (err) {
+    await t.rollback();
+    console.error("[UNIT LIB][PERMANENT DELETE]", err);
+    return R.error(res, "Could not permanently delete unit.", 500);
+  }
+};
+
+exports.bulkPermanentlyDeleteUnits = async (req, res) => {
+  const t = await sequelize.transaction();
+  try {
+    const { ids = [] } = req.body;
+    if (!ids.length) return R.error(res, "No IDs provided.", 400);
+
+    const units = await Unit.findAll({ where: { unit_id: ids }, paranoid: false });
+    const validIds = units.map((u) => u.unit_id);
+
+    const count = await permanentDeleteMany(Unit, "unit_id", validIds, t);
+    await CourseUnit.destroy({ where: { unit_id: validIds }, transaction: t });
+    await UnitLesson.destroy({ where: { unit_id: validIds }, transaction: t });
+
+    await t.commit();
+    logActivity(req.user.user_id, "bulk_permanently_delete_units", { entityType: "unit", details: { ids: validIds, count } });
+    return R.success(res, `${count} unit${count !== 1 ? "s" : ""} permanently deleted.`);
+  } catch (err) {
+    await t.rollback();
+    console.error("[UNIT LIB][BULK PERMANENT DELETE]", err);
+    return R.error(res, "Could not permanently delete units.", 500);
+  }
+};
+
+exports.getUnitFieldValues = getFieldValues(Unit, "UNIT");
+
 // ══════════════════════════════════════════════════════════════════════════════
-// UNIT QUIZ
+// UNIT ⇄ LESSON MEMBERSHIP (attach / detach / reorder)
+// ══════════════════════════════════════════════════════════════════════════════
+
+// POST /admin/units/:unitId/lessons  { lesson_ids: [..] } — append existing lessons
+exports.attachLessons = async (req, res) => {
+  const t = await sequelize.transaction();
+  try {
+    const { unitId } = req.params;
+    const { lesson_ids = [] } = req.body;
+    if (!lesson_ids.length) return R.error(res, "lesson_ids is required.", 400);
+
+    const unit = await Unit.findOne({ where: { unit_id: unitId, ...notDeleted }, transaction: t });
+    if (!unit) return R.error(res, "Unit not found.", 404);
+
+    const lessons = await Lesson.findAll({ where: { lesson_id: lesson_ids, ...notDeleted }, transaction: t });
+    if (lessons.length !== lesson_ids.length) {
+      await t.rollback();
+      return R.error(res, "One or more lessons were not found.", 404);
+    }
+
+    const existing = await UnitLesson.findAll({ where: { unit_id: unitId, lesson_id: lesson_ids }, transaction: t });
+    const existingSet = new Set(existing.map((r) => String(r.lesson_id)));
+    const toAttach = lesson_ids.filter((id) => !existingSet.has(String(id)));
+
+    let order = await nextOrderIndex(UnitLesson, { unit_id: unitId }, t);
+    await UnitLesson.bulkCreate(
+      toAttach.map((lesson_id) => ({
+        unit_id: unitId,
+        lesson_id,
+        order_index: order++,
+        createdBy: req.user?.user_id ?? null,
+      })),
+      { transaction: t }
+    );
+
+    await t.commit();
+    try { await recomputeUnitDuration(unitId); await recomputeParentCourseDurations(unitId); } catch (durErr) { console.error("[UNIT LIB][ATTACH LESSONS][DURATION]", durErr); }
+    logActivity(req.user?.user_id, "attach_lessons", { entityType: "unit", entityId: Number(unitId), details: { lesson_ids: toAttach } });
+    return R.success(res, `${toAttach.length} lesson${toAttach.length !== 1 ? "s" : ""} attached.`, { attached: toAttach, skipped: lesson_ids.filter((id) => existingSet.has(String(id))) });
+  } catch (err) {
+    await t.rollback();
+    console.error("[UNIT LIB][ATTACH LESSONS]", err);
+    return R.error(res, "Could not attach lessons.", 500);
+  }
+};
+
+// DELETE /admin/units/:unitId/lessons/:lessonId — detach (lesson survives in the library)
+exports.detachLesson = async (req, res) => {
+  try {
+    const { unitId, lessonId } = req.params;
+
+    const removed = await UnitLesson.destroy({ where: { unit_id: unitId, lesson_id: lessonId } });
+    if (!removed) return R.error(res, "Lesson is not attached to this unit.", 404);
+
+    try { await recomputeUnitDuration(unitId); await recomputeParentCourseDurations(unitId); } catch (durErr) { console.error("[UNIT LIB][DETACH LESSON][DURATION]", durErr); }
+    logActivity(req.user?.user_id, "detach_lesson", { entityType: "unit", entityId: Number(unitId), details: { lesson_id: Number(lessonId) } });
+    return R.success(res, "Lesson detached.");
+  } catch (err) {
+    console.error("[UNIT LIB][DETACH LESSON]", err);
+    return R.error(res, "Could not detach lesson.", 500);
+  }
+};
+
+// PUT /admin/units/:unitId/lessons/order  { lesson_ids: [orderedIds] }
+exports.reorderLessons = async (req, res) => {
+  const t = await sequelize.transaction();
+  try {
+    const { unitId } = req.params;
+    const { lesson_ids = [] } = req.body;
+    if (!lesson_ids.length) return R.error(res, "lesson_ids is required.", 400);
+
+    const unit = await Unit.findOne({ where: { unit_id: unitId, ...notDeleted }, transaction: t });
+    if (!unit) return R.error(res, "Unit not found.", 404);
+
+    await reorderJunction(UnitLesson, "unit_id", unitId, "lesson_id", lesson_ids, t);
+    await t.commit();
+    logActivity(req.user?.user_id, "reorder_lessons", { entityType: "unit", entityId: Number(unitId), details: { lesson_ids } });
+    return R.success(res, "Lesson order updated.");
+  } catch (err) {
+    await t.rollback();
+    console.error("[UNIT LIB][REORDER LESSONS]", err);
+    return R.error(res, "Could not reorder lessons.", 500);
+  }
+};
+
+// ══════════════════════════════════════════════════════════════════════════════
+// UNIT QUIZ  (1:1 with the Unit — travels with it into every attached course)
 // ══════════════════════════════════════════════════════════════════════════════
 
 exports.getQuiz = async (req, res) => {
   try {
-    const { courseId, unitId } = req.params;
+    const { unitId } = req.params;
 
-    const unit = await Unit.findOne({ where: { unit_id: unitId, course_id: courseId, ...notDeleted } });
+    const unit = await Unit.findOne({ where: { unit_id: unitId, ...notDeleted } });
     if (!unit) return R.error(res, "Unit not found.", 404);
 
     const quiz = await UnitQuiz.findOne({
@@ -270,54 +513,60 @@ exports.getQuiz = async (req, res) => {
     if (!quiz) return R.error(res, "Quiz not found.", 404);
     return R.success(res, "Quiz retrieved.", { data: quiz });
   } catch (err) {
-    console.error("[QUIZ][GET]", err);
+    console.error("[UNIT LIB][QUIZ][GET]", err);
     return R.error(res, "Could not retrieve quiz.", 500);
   }
 };
 
 exports.createQuiz = async (req, res) => {
   try {
-    const { courseId, unitId } = req.params;
-    const { title, is_required, passing_score, createdBy } = req.body;
+    const { unitId } = req.params;
+    const { title, is_required, passing_score, max_questions, shuffle_questions, createdBy } = req.body;
 
-    const unit = await Unit.findOne({ where: { unit_id: unitId, course_id: courseId, ...notDeleted } });
+    const unit = await Unit.findOne({ where: { unit_id: unitId, ...notDeleted } });
     if (!unit) return R.error(res, "Unit not found.", 404);
 
     const existing = await UnitQuiz.findOne({ where: { unit_id: unitId, ...notDeleted } });
     if (existing) return R.error(res, "Quiz already exists for this unit.", 409);
 
     const quiz = await UnitQuiz.create({
-      unit_id:       unitId,
-      title:         title         ?? null,
-      is_required:   is_required   ?? false,
-      passing_score: passing_score ?? 70,
-      createdBy:     createdBy     ?? null,
+      unit_id:           unitId,
+      title:             title ?? null,
+      is_required:       is_required ?? false,
+      passing_score:     passing_score ?? 70,
+      max_questions:     max_questions ?? null,
+      shuffle_questions: shuffle_questions ?? false,
+      createdBy:         createdBy ?? req.user?.user_id ?? null,
     });
 
+    logActivity(req.user?.user_id, "create_quiz", { entityType: "quiz", entityId: quiz.quiz_id });
     return R.success(res, "Quiz created.", { data: quiz }, 201);
   } catch (err) {
-    console.error("[QUIZ][CREATE]", err);
+    console.error("[UNIT LIB][QUIZ][CREATE]", err);
     return R.error(res, "Could not create quiz.", 500);
   }
 };
 
 exports.updateQuiz = async (req, res) => {
   try {
-    const { courseId, unitId, quizId } = req.params;
-    const { title, is_required, passing_score, updatedBy } = req.body;
+    const { unitId, quizId } = req.params;
+    const { title, is_required, passing_score, max_questions, shuffle_questions, updatedBy } = req.body;
 
     const quiz = await UnitQuiz.findOne({ where: { quiz_id: quizId, unit_id: unitId, ...notDeleted } });
     if (!quiz) return R.error(res, "Quiz not found.", 404);
 
-    if (title         !== undefined) quiz.title         = title;
-    if (is_required   !== undefined) quiz.is_required   = is_required;
-    if (passing_score !== undefined) quiz.passing_score = passing_score;
-    quiz.updatedBy = updatedBy ?? null;
+    if (title !== undefined)             quiz.title = title;
+    if (is_required !== undefined)       quiz.is_required = is_required;
+    if (passing_score !== undefined)     quiz.passing_score = passing_score;
+    if (max_questions !== undefined)     quiz.max_questions = max_questions;
+    if (shuffle_questions !== undefined) quiz.shuffle_questions = shuffle_questions;
+    quiz.updatedBy = updatedBy ?? req.user?.user_id ?? null;
 
     await quiz.save();
+    logActivity(req.user?.user_id, "update_quiz", { entityType: "quiz", entityId: Number(quizId) });
     return R.success(res, "Quiz updated.", { data: quiz });
   } catch (err) {
-    console.error("[QUIZ][UPDATE]", err);
+    console.error("[UNIT LIB][QUIZ][UPDATE]", err);
     return R.error(res, "Could not update quiz.", 500);
   }
 };
@@ -326,18 +575,49 @@ exports.deleteQuiz = async (req, res) => {
   const t = await sequelize.transaction();
   try {
     const { unitId, quizId } = req.params;
-    const record = await archiveOne(
-      UnitQuiz,
-      { quiz_id: quizId, unit_id: unitId, ...notDeleted },
-      req.body.deletedBy,
-      t
-    );
+    const record = await archiveOne(UnitQuiz, { quiz_id: quizId, unit_id: unitId, ...notDeleted }, req.user?.user_id, t);
     if (!record) return R.error(res, "Quiz not found.", 404);
     await t.commit();
+    logActivity(req.user?.user_id, "archive_quiz", { entityType: "quiz", entityId: Number(quizId) });
     return R.success(res, "Quiz archived.");
   } catch (err) {
     await t.rollback();
-    console.error("[QUIZ][DELETE]", err);
+    console.error("[UNIT LIB][QUIZ][ARCHIVE]", err);
     return R.error(res, "Could not archive quiz.", 500);
   }
-};
+};
+
+exports.getArchivedQuiz = async (req, res) => {
+  try {
+    const { unitId } = req.params;
+
+    const unit = await Unit.findOne({ where: { unit_id: unitId }, paranoid: false });
+    if (!unit) return R.error(res, "Unit not found.", 404);
+
+    const quiz = await UnitQuiz.findOne({
+      where: { unit_id: unitId, ...onlyDeleted },
+      paranoid: false,
+    });
+    if (!quiz) return R.error(res, "Archived quiz not found.", 404);
+    return R.success(res, "Archived quiz retrieved.", { data: quiz.toJSON() });
+  } catch (err) {
+    console.error("[UNIT LIB][QUIZ][GET ARCHIVE]", err);
+    return R.error(res, "Could not retrieve archived quiz.", 500);
+  }
+};
+
+exports.restoreQuiz = async (req, res) => {
+  const t = await sequelize.transaction();
+  try {
+    const { unitId, quizId } = req.params;
+    const record = await restoreOne(UnitQuiz, { quiz_id: quizId, unit_id: unitId, ...onlyDeleted }, req.user?.user_id, t);
+    if (!record) return R.error(res, "Archived quiz not found.", 404);
+    await t.commit();
+    logActivity(req.user?.user_id, "restore_quiz", { entityType: "quiz", entityId: Number(quizId) });
+    return R.success(res, "Quiz restored.", { data: record });
+  } catch (err) {
+    await t.rollback();
+    console.error("[UNIT LIB][QUIZ][RESTORE]", err);
+    return R.error(res, "Could not restore quiz.", 500);
+  }
+};