Refactor getCurrentLessonIndex. (#123)

* Change comments to english. * Make code more readable. * Add a test case. * Rename `AllLessonsOver` to `AllLessonsOverException`.
SharezoneApp · Feb 7, 2022 · 1ce1e50 · 1ce1e50
1 parent 4740e48
commit 1ce1e50
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diff --git a/app/lib/dashboard/bloc/current_lesson_index.dart b/app/lib/dashboard/bloc/current_lesson_index.dart
@@ -8,39 +8,45 @@
 
 part of 'dashboard_bloc.dart';
 
-/// Bestimmt, welcher Index in [views] jetzt oder als nächstes stattfindet.
-/// Hat man jetzt z.B. Deutsch als zweites Fach am Tag, wird der Index 1
-/// zurückgegeben. Es wird also bei 0 angefangen zu zählen.
-int getCurrentLessonIndex(List<LessonView> views) {
-  // Prüfun, ob bisher noch keine Schulstunde stattgefunden hat (also ob die
-  // Schule noch nicht angefangen hat)
-  if (views.where((view) => view.timeStatus == LessonTimeStatus.isYetToCome).length ==
-      views.length)
+/// Return the index of the lesson that is
+/// a. currently taking place [LessonTimeStatus.isNow]
+/// b. the next lesson if there is no lesson taking place right now
+///    (no lesson has [LessonTimeStatus.isNow])
+///
+/// If no lesson has started yet it will return 0 (first lesson).
+/// If every lesson has already passed it will throw [AllLessonsAreOverException].
+///
+/// Example:
+/// We have the lessons [maths, english, german].
+/// If english is currently taking place ([LessonView.timeStatus] ==
+/// [LessonTimeStatus.isNow]) this function will return 1.
+int getCurrentLessonIndex(List<LessonView> lessons) {
+  // School hasn't begun yet.
+  if (lessons
+      .every((lesson) => lesson.timeStatus == LessonTimeStatus.isYetToCome)) {
     return 0;
-  else {
-    // Prüfun, ob alle Schulstunden schon bisher stattgefunden haben (Schulschluss).
-    if (views
-            .where((view) => view.timeStatus == LessonTimeStatus.hasAlreadyTakenPlace)
-            .length ==
-        views.length) throw AllLessonsAreOver();
+  }
 
-    // Jede Stunde prüfen, ob diese gerade stattfindet. Falls ja, wird der
-    // Index der Schulstunde zurückgegeben, die als erstes die Bedingung erfüllt.
-    for (int i = 0; i < views.length; i++) {
-      if (views[i].timeStatus == LessonTimeStatus.isNow) return i;
-    }
+  // School is over.
+  if (lessons.every(
+      (lesson) => lesson.timeStatus == LessonTimeStatus.hasAlreadyTakenPlace))
+    throw AllLessonsAreOverException();
 
-    // Herausfinden, ob der Nutzer gerade in einer Freistunde / Pause ist. Falls ja,
-    // wird die nächste Stunde als aktueller Index zurückgegeben.
-    if (views.length >= 2) {
-      for (int i = 1; i < views.length; i++) {
-        if (views[i - 1].timeStatus == LessonTimeStatus.hasAlreadyTakenPlace &&
-            views[i].timeStatus == LessonTimeStatus.isYetToCome) return i;
-      }
-    }
+  // If a lesson is currently taking place return its index.
+  for (int i = 0; i < lessons.length; i++) {
+    if (lessons[i].timeStatus == LessonTimeStatus.isNow) return i;
+  }
 
-    return 0;
+  // If no lesson is currently taking place (e.g. lunch break) we return the
+  // index of the next lesson to come.
+  if (lessons.length >= 2) {
+    for (int i = 1; i < lessons.length; i++) {
+      if (lessons[i - 1].timeStatus == LessonTimeStatus.hasAlreadyTakenPlace &&
+          lessons[i].timeStatus == LessonTimeStatus.isYetToCome) return i;
+    }
   }
+
+  return 0;
 }
 
-class AllLessonsAreOver implements Exception {}
+class AllLessonsAreOverException implements Exception {}
diff --git a/app/lib/dashboard/timetable/lesson_row.dart b/app/lib/dashboard/timetable/lesson_row.dart
@@ -22,7 +22,7 @@ class _LessonRow extends StatelessWidget {
         int currentIndex;
         try {
           currentIndex = getCurrentLessonIndex(views);
-        } on AllLessonsAreOver {
+        } on AllLessonsAreOverException {
           return _SchoolIsOver();
         }
 

diff --git a/app/test/dashboard/current_lesson_index_test.dart b/app/test/dashboard/current_lesson_index_test.dart
@@ -41,7 +41,7 @@ void main() {
         getLessonViewWithTimeStatus(LessonTimeStatus.hasAlreadyTakenPlace),
       ];
       expect(() => getCurrentLessonIndex(schoolIsOver),
-          throwsA(predicate((e) => e is AllLessonsAreOver)));
+          throwsA(predicate((e) => e is AllLessonsAreOverException)));
     });
 
     test('first lesson is now', () {
@@ -75,5 +75,18 @@ void main() {
       ];
       expect(getCurrentLessonIndex(firstLessonNow), 1);
     });
+
+    test('acceptance test', () {
+      final lessons = [
+        getLessonViewWithTimeStatus(LessonTimeStatus.hasAlreadyTakenPlace),
+        getLessonViewWithTimeStatus(LessonTimeStatus.hasAlreadyTakenPlace),
+        getLessonViewWithTimeStatus(LessonTimeStatus.hasAlreadyTakenPlace),
+        getLessonViewWithTimeStatus(LessonTimeStatus.isNow),
+        getLessonViewWithTimeStatus(LessonTimeStatus.isYetToCome),
+        getLessonViewWithTimeStatus(LessonTimeStatus.isYetToCome),
+        getLessonViewWithTimeStatus(LessonTimeStatus.isYetToCome),
+      ];
+      expect(getCurrentLessonIndex(lessons), 3);
+    });
   });
 }