"Update section and timetable tables when course timings change"

backend/src/controllers/timetable/updateChangedTimetable.ts

@@ -0,0 +1,232 @@
+import type { Request, Response } from "express";
+import { z } from "zod";
+import {
+  courseWithSectionsType,
+  sectionTypeList,
+} from "../../../../lib/src/index.js";
+import { AppDataSource } from "../../db.js";
+import { Course, Section, Timetable } from "../../entity/entities.js";
+import { validate } from "../../middleware/zodValidateRequest.js";
+import { checkForExamTimingsChange } from "../../utils/checkForChange.js";
+import {
+  checkForClassHoursClash,
+  checkForExamHoursClash,
+} from "../../utils/checkForClashes.js";
+import { addExamTimings, removeSection } from "../../utils/updateSection.js";
+import { updateSectionWarnings } from "../../utils/updateWarnings.js";
+
+const dataSchema = z.object({
+  body: z.object({
+    course: courseWithSectionsType,
+  }),
+});
+
+export const updateChangedTimetableValidator = validate(dataSchema);
+
+export const updateChangedTimetable = async (req: Request, res: Response) => {
+  try {
+    // Use a transaction because we will run many dependent mutations
+    const queryRunner = AppDataSource.createQueryRunner();
+    await queryRunner.connect();
+    await queryRunner.startTransaction();
+
+    // Update the course's exam timings, also make sure that the course is not archived
+    const course: Course = req.body.course;
+    try {
+      await queryRunner.manager
+        .createQueryBuilder()
+        .update(Course)
+        .set({
+          midsemStartTime: course?.midsemStartTime,
+          midsemEndTime: course?.midsemEndTime,
+          compreStartTime: course?.compreStartTime,
+          compreEndTime: course?.compreEndTime,
+        })
+        .where("id = :id", { id: course?.id })
+        .andWhere("archived = :archived", { archived: false })
+        .execute();
+    } catch (err: any) {
+      console.log("Error while querying for course: ", err.message);
+      return res.status(500).json({ message: "Internal Server Error" });
+    }
+
+    // Fetch the total types of sections of that course (required later to update warnings)
+    let requiredSectionTypes: sectionTypeList = [];
+    try {
+      const sectionTypeHolders = await queryRunner.manager
+        .createQueryBuilder(Section, "section")
+        .select("section.type")
+        .where("section.courseId = :courseId", { courseId: course.id })
+        .distinctOn(["section.type"])
+        .getMany();
+      requiredSectionTypes = sectionTypeHolders.map((section) => section.type);
+    } catch (err: any) {
+      // will replace the console.log with a logger when we have one
+      console.log(
+        "Error while querying for course's section types: ",
+        err.message,
+      );
+    }
+
+    let timetables: Timetable[] | null = null;
+
+    // Fetch the timetables that are affected, archived timetables cannot be affected
+    try {
+      timetables = await queryRunner.manager
+        .createQueryBuilder(Timetable, "timetable")
+        .leftJoinAndSelect("timetable.sections", "section")
+        .where("section.courseId = :id", { id: course?.id })
+        .andWhere("timetable.archived = :archived", { archived: false })
+        .getMany();
+    } catch (err: any) {
+      console.log("Error while querying for timetable: ", err.message);
+      return res.status(500).json({ message: "Internal Server Error" });
+    }
+
+    for (const timetable of timetables) {
+      // For each timetable, check if the exam times have changed
+      if (checkForExamTimingsChange(timetable, course)) {
+        // If they have, remove the course's exams from the timings
+        timetable.examTimes = timetable.examTimes.filter((examTime) => {
+          return examTime.split("|")[0] !== course?.code;
+        });
+
+        // Convert exam dates to actual dates from strings, since the
+        // checkForExamHoursClash() function compares them with dates
+
+        // This is needed because the course exam dates are not from DB,
+        // but are from the JSON body of the request.
+        // A similar procedure is used during ingestion as well.
+        course.compreStartTime = new Date(course.compreStartTime);
+        course.compreEndTime = new Date(course.compreEndTime);
+        course.midsemStartTime = new Date(course.midsemStartTime);
+        course.midsemEndTime = new Date(course.midsemEndTime);
+
+        // Check if the new timings clash with any other timings of other courses
+        if (checkForExamHoursClash(timetable, course).clash) {
+          // If they do, then remove all sections of the course with updated timings
+          for (const sec of timetable.sections) {
+            await queryRunner.manager
+              .createQueryBuilder()
+              .relation(Timetable, "sections")
+              .of(timetable)
+              .remove(sec);
+            removeSection(timetable, sec);
+          }
+          // Since the timetable has been changed, make it a draft
+          timetable.draft = true;
+          timetable.private = true;
+        } else {
+          // If there is no clash, simply add the new timings to the timetable
+          const newExamTimes = timetable.examTimes;
+          addExamTimings(newExamTimes, course);
+          timetable.examTimes = newExamTimes;
+        }
+      }
+      for (const section of timetable.sections) {
+        // For each section of the course previously in the timetable, find its corresponding replacement
+        const newSection = course.sections.find((el) => el.id === section.id);
+
+        if (newSection !== undefined) {
+          // Start off by removing the existing section, both in DB and the timings column of the timetable
+          removeSection(timetable, section);
+          await queryRunner.manager
+            .createQueryBuilder()
+            .relation(Timetable, "sections")
+            .of(timetable)
+            .remove(section);
+
+          if (checkForClassHoursClash(timetable, newSection).clash) {
+            // If the updated section will cause a clash, then keep the section removed
+            // Also make the timetable a draft, and update its warnings since that
+            // section is now gone
+            timetable.draft = true;
+            timetable.private = true;
+            timetable.warnings = updateSectionWarnings(
+              course.code,
+              section,
+              requiredSectionTypes,
+              false,
+              timetable.warnings,
+            );
+          } else {
+            // If there is no clash, add the new section timings to the timetable
+            const newTimes: string[] = newSection.roomTime.map(
+              (time) =>
+                `${course?.code}:${time.split(":")[2]}${time.split(":")[3]}`,
+            );
+            // Add the section back to the timetable
+            await queryRunner.manager
+              .createQueryBuilder()
+              .relation(Timetable, "sections")
+              .of(timetable)
+              .add(section);
+
+            // Update the timings and the sections in the timetable object
+            timetable.timings = [...timetable.timings, ...newTimes];
+            timetable.sections = [...timetable.sections, newSection];
+          }
+        }
+      }
+
+      // After all that, if the timetable now has 0 sections of that course,
+      // remove its exam timings as well, removing it fully from the timetable
+      const sameCourseSections: Section[] = timetable.sections.filter(
+        (currentSection) => {
+          return currentSection.courseId === course.id;
+        },
+      );
+      if (sameCourseSections.length === 0) {
+        timetable.examTimes = timetable.examTimes.filter((examTime) => {
+          return examTime.split("|")[0] !== course?.code;
+        });
+      }
+    }
+
+    // Remove sections from the timetable before saving in db
+
+    // Since we are fetching only this course's sections in the
+    // timetable query (due to the left join), none of the other sections
+    // end up in timetable.sections. Saving this to db causes all the other
+    // sections of other courses to be wiped. This is why, using some typescript
+    // magic, we redefine the timetable type, and then set sections = undefined.
+    // Since sections = undefined, TypeORM sees that the field isn't present,
+    // and doesn't make any additional changes to timetable sections.
+
+    // If we do want to remove the sections, those db calls have already been
+    // made above. This db call is only here to update timetable timings and examTimes
+    type timetableWithoutSections = Omit<Timetable, "sections"> & {
+      sections: Section[] | undefined;
+    };
+    const timetablesWithoutSections: timetableWithoutSections[] = timetables;
+    await queryRunner.manager.save(
+      timetablesWithoutSections.map((x) => {
+        x.sections = undefined;
+        return x;
+      }),
+    );
+
+    // Regardless of whether or not a section was present in a timetable,
+    // update the section's timings
+    try {
+      for (const section of course.sections) {
+        await queryRunner.manager
+          .createQueryBuilder()
+          .update(Section, { roomTime: section.roomTime })
+          .where("section.id = :id", { id: section?.id })
+          .execute();
+      }
+    } catch (err: any) {
+      console.log("Error while querying for course: ", err.message);
+      return res.status(500).json({ message: "Internal Server Error" });
+    }
+
+    // After everything passes fine, commit the transaction
+    await queryRunner.commitTransaction();
+    queryRunner.release();
+    return res.json({ message: "Timetable successfully updated" });
+  } catch (err: any) {
+    console.log(err);
+    return res.status(500).json({ message: "Internal Server Error" });
+  }
+};

backend/src/routers/courseRouter.ts

@@ -5,10 +5,19 @@ import {
 } from "../controllers/course/getAllCourses.js";
 import { getCourseById } from "../controllers/course/getCourseById.js";
 import { getCourseByIdValidator } from "../controllers/course/getCourseById.js";
+import {
+  updateChangedTimetable,
+  updateChangedTimetableValidator,
+} from "../controllers/timetable/updateChangedTimetable.js";
 
 const courseRouter = express.Router();
 
 courseRouter.get("/", getAllCoursesValidator, getAllCourses);
 courseRouter.get("/:id", getCourseByIdValidator, getCourseById);
+courseRouter.post(
+  "/update",
+  updateChangedTimetableValidator,
+  updateChangedTimetable,
+);
 
 export default courseRouter;

backend/src/utils/checkForChange.ts

@@ -0,0 +1,35 @@
+import { Course, Timetable } from "../entity/entities.js";
+
+export const checkForExamTimingsChange = (
+  timetable: Timetable,
+  course: Course,
+) => {
+  const midsemTimes = timetable.examTimes.filter((examTime) => {
+    return (
+      examTime?.split("|")[0] === course?.code &&
+      examTime?.split("|")[1] === "MIDSEM"
+    );
+  })[0];
+
+  const compreTimes = timetable.examTimes.filter((examTime) => {
+    return (
+      examTime?.split("|")[0] === course?.code &&
+      examTime?.split("|")[1] === "COMPRE"
+    );
+  })[0];
+
+  if (
+    midsemTimes?.split("|")[2] !== `${course.midsemStartTime}` ||
+    midsemTimes?.split("|")[3] !== `${course.midsemEndTime}`
+  ) {
+    return true;
+  }
+  if (
+    compreTimes?.split("|")[2] !== `${course.compreStartTime}` ||
+    compreTimes?.split("|")[3] !== `${course.compreEndTime}`
+  ) {
+    return true;
+  }
+
+  return false;
+};

backend/src/utils/checkForClashes.ts

@@ -63,9 +63,8 @@ export const checkForExamHoursClash = (
   }
 
   if (newCourse.midsemStartTime !== null && newCourse.midsemEndTime !== null) {
-    const newMidsemStartTime = newCourse.midsemStartTime;
-    const newMidsemEndTime = newCourse.midsemEndTime;
-
+    const newMidsemStartTime = new Date(newCourse.midsemStartTime);
+    const newMidsemEndTime = new Date(newCourse.midsemEndTime);
     for (const [key, value] of examTimesMap) {
       const { courseCode, end } = value;
       const start = key;

backend/src/utils/updateSection.ts

@@ -0,0 +1,31 @@
+import { Course, Section, Timetable } from "../entity/entities.js";
+
+export const removeSection = (timetable: Timetable, section: Section) => {
+  const classTimings = section.roomTime.map((time) => {
+    return time.split(":")[2] + time.split(":")[3];
+  });
+
+  timetable.timings = timetable.timings.filter((time) => {
+    return !classTimings.includes(time.split(":")[1]);
+  });
+  timetable.sections = timetable.sections.filter((currentSection) => {
+    return currentSection.id !== section?.id;
+  });
+};
+
+export const addExamTimings = (newExamTimes: Array<string>, course: Course) => {
+  if (course.midsemStartTime !== null && course.midsemEndTime !== null) {
+    newExamTimes.push(
+      `${
+        course.code
+      }|MIDSEM|${course.midsemStartTime.toISOString()}|${course.midsemEndTime.toISOString()}`,
+    );
+  }
+  if (course.compreStartTime !== null && course.compreEndTime !== null) {
+    newExamTimes.push(
+      `${
+        course.code
+      }|COMPRE|${course.compreStartTime.toISOString()}|${course.compreEndTime.toISOString()}`,
+    );
+  }
+};