Scheduling algorithm avoided students that have many lectures and leading a bug, its fixed. Also scheduling calendar had scrolling issue that fixed too (Commit error. now i sending the codes)

src/main/java/org/example/se302/controller/ScheduleCalendarController.java

@@ -121,7 +121,7 @@ public class ScheduleCalendarController {
 
     private void initializeSpinners() {
         // Number of days spinner (1-30)
-        SpinnerValueFactory<Integer> daysFactory = new SpinnerValueFactory.IntegerSpinnerValueFactory(1, 30, 5);
+        SpinnerValueFactory<Integer> daysFactory = new SpinnerValueFactory.IntegerSpinnerValueFactory(1, 30, 8);
         numDaysSpinner.setValueFactory(daysFactory);
 
         // Slots per day spinner (1-10)
@@ -362,6 +362,10 @@ public class ScheduleCalendarController {
     }
 
     private void updateStatistics(ScheduleState schedule, long durationMs) {
+        // Update total courses (BUG FIX: this was missing!)
+        totalCoursesLabel.setText(String.valueOf(schedule.getTotalCourses()));
+
+        // Update scheduled courses
         scheduledCoursesLabel.setText(String.valueOf(schedule.getAssignedCourses()));
 
         // Count unique classrooms used
@@ -390,6 +394,12 @@ public class ScheduleCalendarController {
         int numDays = config.getNumDays();
         int slotsPerDay = config.getSlotsPerDay();
 
+        // Dynamically set minimum grid width to fit all columns
+        // Time column (120px) + each day column (200px) + padding
+        double minGridWidth = 120 + (numDays * 200) + 40;
+        scheduleGrid.setMinWidth(minGridWidth);
+        scheduleGrid.setPrefWidth(minGridWidth);
+
         // Column constraints - make columns wider for better visibility
         ColumnConstraints headerCol = new ColumnConstraints();
         headerCol.setMinWidth(100);
@@ -398,9 +408,9 @@ public class ScheduleCalendarController {
 
         for (int day = 0; day < numDays; day++) {
             ColumnConstraints dayCol = new ColumnConstraints();
-            dayCol.setMinWidth(180);
+            dayCol.setMinWidth(135);
-            dayCol.setPrefWidth(220);
+            dayCol.setPrefWidth(150);
-            dayCol.setHgrow(Priority.ALWAYS);
+            dayCol.setHgrow(Priority.NEVER); // Prevent shrinking, allow horizontal scroll
             scheduleGrid.getColumnConstraints().add(dayCol);
         }
 
@@ -531,9 +541,10 @@ public class ScheduleCalendarController {
                 examBox.setOnDragDone(e -> {
                     draggedExam = null;
                     examBox.setOpacity(1.0);
-                    // Refresh grid to reset all cell colors
+                    // Defer grid refresh to after drag event completes to avoid crash
+                    // when modifying scene graph during active event processing
                     if (currentSchedule != null && currentConfig != null) {
-                        displayScheduleGrid(currentSchedule, currentConfig);
+                        Platform.runLater(() -> displayScheduleGrid(currentSchedule, currentConfig));
                     }
                     e.consume();
                 });

src/main/java/org/example/se302/model/ScheduleConfiguration.java

@@ -82,7 +82,7 @@ public class ScheduleConfiguration {
      * Creates a default schedule configuration.
      */
     public ScheduleConfiguration() {
-        this.numDays = 5;
+        this.numDays = 8;
         this.slotsPerDay = 4;
         this.startDate = LocalDate.now().plusDays(7); // Default: start in a week
         this.slotDurationMinutes = 120; // 2 hours

src/main/java/org/example/se302/service/ConstraintValidator.java

@@ -63,28 +63,36 @@ public class ConstraintValidator {
         ValidationResult doubleBookingResult = checkNoDoubleBooking(assignment, scheduleState);
         result.merge(doubleBookingResult);
 
-        // Check student constraints - only check same time slot conflicts (always
+        // Check student constraints
-        // required)
         Course course = dataManager.getCourse(assignment.getCourseCode());
         if (course != null) {
-            // Check if student has another exam at the SAME time slot (hard constraint)
+            // HARD CONSTRAINT: Check if student has another exam at the SAME time slot
+            // This is ALWAYS required
             ValidationResult sameTimeResult = checkNoSameTimeExams(assignment, scheduleState, course);
             result.merge(sameTimeResult);
 
-            // Only check consecutive and max per day if back-to-back is NOT allowed
+            // HARD CONSTRAINT: Max 2 exams per day per student
+            // This is ALWAYS enforced, regardless of allowBackToBack flag
+            for (String studentId : course.getEnrolledStudents()) {
+                ValidationResult maxPerDayResult = checkMaxTwoExamsPerDay(
+                        studentId, assignment, scheduleState);
+                result.merge(maxPerDayResult);
+
+                // If max per day violated, no need to check more students
+                if (!result.isValid()) {
+                    break;
+                }
+            }
+
+            // SOFT CONSTRAINT: No consecutive exams (back-to-back)
+            // Only enforced when allowBackToBack = false
             if (!allowBackToBack) {
                 for (String studentId : course.getEnrolledStudents()) {
-                    // Check no consecutive exams (soft - skip if allowBackToBack)
                     ValidationResult consecutiveResult = checkNoConsecutiveExams(
                             studentId, assignment, scheduleState);
                     result.merge(consecutiveResult);
 
-                    // Check max 2 exams per day
+                    // If consecutive violation, no need to check more students
-                    ValidationResult maxPerDayResult = checkMaxTwoExamsPerDay(
-                            studentId, assignment, scheduleState);
-                    result.merge(maxPerDayResult);
-
-                    // If already invalid, no need to check more students
                     if (!result.isValid()) {
                         break;
                     }

src/main/java/org/example/se302/service/ScheduleGeneratorService.java

@@ -170,10 +170,13 @@ public class ScheduleGeneratorService {
 
             // Try each classroom
             for (Classroom classroom : suitableClassrooms) {
-                // Temporarily assign
+                // Temporarily assign (using updateAssignment to maintain assignedCourses counter)
-                assignment.setDay(timeSlot.day);
+                scheduleState.updateAssignment(
-                assignment.setTimeSlotIndex(timeSlot.slot);
+                        assignment.getCourseCode(),
-                assignment.setClassroomId(classroom.getClassroomId());
+                        timeSlot.day,
+                        timeSlot.slot,
+                        classroom.getClassroomId()
+                );
 
                 // Validate assignment - pass allowBackToBack from config
                 ConstraintValidator.ValidationResult validationResult = validator.validateAssignment(assignment,
@@ -186,10 +189,13 @@ public class ScheduleGeneratorService {
                     }
                 }
 
-                // Backtrack: reset assignment
+                // Backtrack: reset assignment (using updateAssignment to maintain assignedCourses counter)
-                assignment.setDay(-1);
+                scheduleState.updateAssignment(
-                assignment.setTimeSlotIndex(-1);
+                        assignment.getCourseCode(),
-                assignment.setClassroomId(null);
+                        -1,
+                        -1,
+                        null
+                );
             }
         }
 

src/main/resources/org/example/se302/view/import-view.fxml

@@ -101,9 +101,9 @@
         <VBox spacing="12" VBox.vgrow="ALWAYS" styleClass="card">
             <Label text="Import Messages" styleClass="subsection-title"/>
             <TextArea fx:id="messagesArea" editable="false" wrapText="true" VBox.vgrow="ALWAYS"
-                      prefHeight="200"
+                      prefHeight="300" minHeight="250" maxHeight="500"
                       promptText="Validation messages and import results will appear here..."
-                      style="-fx-font-family: 'Consolas', 'Monaco', monospace; -fx-font-size: 12px;"/>
+                      style="-fx-font-family: 'Consolas', 'Monaco', monospace; -fx-font-size: 13px; -fx-padding: 12px;"/>
         </VBox>
 
         <!-- Action Buttons -->

src/main/resources/org/example/se302/view/schedule-calendar-view.fxml

@@ -79,7 +79,7 @@
                     <!-- Summary -->
                     <HBox spacing="12" alignment="CENTER_LEFT" styleClass="summary-row">
                         <Label text="📊 Total Time Slots:" style="-fx-font-weight: 700;"/>
-                        <Label fx:id="summaryLabel" text="5 days × 4 slots = 20 slots" 
+                        <Label fx:id="summaryLabel" text="8 days × 4 slots = 32 slots"
                                styleClass="summary-value"/>
                     </HBox>
                 </VBox>