Refactor code structure for improved readability and maintainability

server/timetable.js

@@ -3,6 +3,7 @@
 import { semesterView, addDays, weekday, weekIndexOf } from "../shared/weeks.js";
 import { lessonKey, subgroupsOf } from "../shared/lessons.js";
 import { occurrence, peopleAndRooms, roomsOn } from "./directory.js";
+import { apiError } from "./errors.js";
 
 const MAX_DAYS = 62;
 // A whole semester with its session fits easily; the cap only guards against abuse.
@@ -38,22 +39,35 @@ function lessonOut(lesson, group, people, date, status, calendar) {
  */
 export function timetable({ file, schedule, calendar, group, from, days, range, today }) {
   if (!schedule.groups.includes(group)) {
-    const error = new Error(`В документе нет группы ${group}.`);
-    error.status = 404;
-    throw error;
+    throw apiError(404, "group_not_found", `В документе нет группы ${group}.`);
   }
   let count = Math.min(Math.max(Number(days) || 7, 1), MAX_DAYS);
+  const lessons = schedule.lessons.filter((l) => l.groups.includes(group));
+  // A session schedule printed with a date on every day needs no week table: its own dates
+  // say when each lesson takes place, even in a year the table no longer covers.
+  const sessionDates = lessons.every((l) => l.date || l.dates?.length)
+    ? lessons.flatMap((l) => (l.date ? [l.date] : l.dates)).sort()
+    : [];
+  const session = sessionDates.length
+    ? {
+        id: `session-${sessionDates[0]}`,
+        label: schedule.period || "Сессия",
+        start: sessionDates[0],
+        end: sessionDates.at(-1),
+      }
+    : null;
   // range=semester: every day of the semester `today` falls in, so a client can keep
-  // the whole term offline. Without a known semester it keeps the plain from/days window.
+  // the whole term offline; a session schedule keeps its own span. Without either it
+  // keeps the plain from/days window.
   if (range === "semester") {
     const current = semesterView(calendar, schedule, today || from);
-    if (current) {
-      from = current.semester.start;
-      const span = Math.round((Date.parse(current.semester.end) - Date.parse(from)) / DAY_MS) + 1;
-      count = Math.min(Math.max(span, 1), MAX_SEMESTER_DAYS);
+    const span = current?.semester || session;
+    if (span) {
+      from = span.start;
+      const length = Math.round((Date.parse(span.end) - Date.parse(from)) / DAY_MS) + 1;
+      count = Math.min(Math.max(length, 1), MAX_SEMESTER_DAYS);
     }
   }
-  const lessons = schedule.lessons.filter((l) => l.groups.includes(group));
   const entries = lessons.map((lesson) => ({
     doc: { id: file.id, schedule },
     lesson,
@@ -66,7 +80,7 @@ export function timetable({ file, schedule, calendar, group, from, days, range,
     const date = addDays(from, i);
     const week = view ? view.weeks[weekIndexOf(view, date)] || null : null;
     const dayLessons = [];
-    if (view)
+    if (view || session)
       for (const entry of entries) {
         const status = occurrence(entry, date, calendar, views);
         if (status === "yes" || status === "maybe")
@@ -99,8 +113,8 @@ export function timetable({ file, schedule, calendar, group, from, days, range,
       modified: file.modified || schedule.source.modified || null,
     },
     period: schedule.period,
-    semester: view?.semester || null,
-    note: view
+    semester: view?.semester || session,
+    note: view || session
       ? null
       : "Семестр этого расписания не найден в таблице недель: даты не рассчитаны, смотрите строки Word (weekly).",
     subgroups: subgroupsOf(schedule, group),