Remove person on display after deletion

src/main/java/tuteez/logic/commands/DeleteCommand.java

@@ -61,6 +61,15 @@ public CommandResult execute(Model model) throws CommandException {
             personToDelete = getPersonToDeleteByName(model, targetName);
         }
 
+        if (model.getLastViewedPerson().get().isPresent()) {
+            if (personToDelete.equals(model.getLastViewedPerson().get().get())) {
+                model.removeLastViewedPerson();
+                String logMessageForPerson =
+                        String.format("Student on display is deleted, Student: %s", personToDelete);
+                logger.info(logMessageForPerson);
+            }
+        }
+
         logger.info("Student deleted - " + personToDelete);
         model.deletePerson(personToDelete);
         return new CommandResult(String.format(MESSAGE_DELETE_PERSON_SUCCESS, Messages.format(personToDelete)));

src/main/java/tuteez/model/Model.java

@@ -101,10 +101,15 @@ public interface Model {
     ObjectProperty<Optional<Person>> getLastViewedPerson();
 
     /**
-     * Updates the lastViewedPerson after a DisplayCommand is called.
+     * Updates the lastViewedPerson.
      */
     void updateLastViewedPerson(Person personOnDisplay);
 
+    /**
+     * Deletes the lastViewedPerson.
+     */
+    void removeLastViewedPerson();
+
     /**
      * Returns the {@code person} in the address book with the given name.
      */

src/main/java/tuteez/model/ModelManager.java

@@ -166,6 +166,12 @@ public void updateLastViewedPerson(Person personOnDisplay) {
         logger.info("Last viewed person updated: " + personOnDisplay.getName().fullName);
     }
 
+    @Override
+    public void removeLastViewedPerson() {
+        lastViewedPerson.set(Optional.empty());
+        logger.info("Last viewed person removed");
+    }
+
     @Override
     public boolean equals(Object other) {
         if (other == this) {