Classroom Plus Plus (CPP) Developer Guide

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Acknowledgements

{ list here sources of all reused/adapted ideas, code, documentation, and third-party libraries -- include links to the original source as well }

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Setting up, getting started

Refer to the guide Setting up and getting started.

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Design

Architecture

The Architecture Diagram given above explains the high-level design of the App.

Given below is a quick overview of main components and how they interact with each other.

Main components of the architecture

Main (consisting of classes Main and MainApp) is in charge of the app launch and shut down.

• At app launch, it initializes the other components in the correct sequence, and connects them up with each other.
• At shut down, it shuts down the other components and invokes cleanup methods where necessary.

The bulk of the app's work is done by the following four components:

• UI: The UI of the App.
• Logic: The command executor.
• Model: Holds the data of the App in memory.
• Storage: Reads data from, and writes data to, the hard disk.

Commons represents a collection of classes used by multiple other components.

How the architecture components interact with each other

The Sequence Diagram below shows how the components interact with each other for the scenario where the user issues the command delete 1.

Each of the four main components (also shown in the diagram above),

• defines its API in an interface with the same name as the Component.
• implements its functionality using a concrete {Component Name}Manager class (which follows the corresponding API interface mentioned in the previous point.

For example, the Logic component defines its API in the Logic.java interface and implements its functionality using the LogicManager.java class which follows the Logic interface. Other components interact with a given component through its interface rather than the concrete class (reason: to prevent outside component's being coupled to the implementation of a component), as illustrated in the (partial) class diagram below.

The sections below give more details of each component.

UI component

The API of this component is specified in Ui.java

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, ContactListPanel, StatusBarFooter etc. All these, including the MainWindow, inherit from the abstract UiPart class which captures the commonalities between classes that represent parts of the visible GUI.

The UI component uses the JavaFx UI framework. The layout of these UI parts are defined in matching .fxml files that are in the src/main/resources/view folder. For example, the layout of the MainWindow is specified in MainWindow.fxml

The UI component,

• executes user commands using the Logic component.
• listens for changes to Model data so that the UI can be updated with the modified data.
• keeps a reference to the Logic component, because the UI relies on the Logic to execute commands.
• depends on some classes in the Model component, as it displays Contact object residing in the Model.

Logic component

API : Logic.java

Here's a (partial) class diagram of the Logic component:

The sequence diagram below illustrates the interactions within the Logic component, taking execute("delete 1") API call as an example.

How the Logic component works:

1. When Logic is called upon to execute a command, it is passed to an AddressBookParser object which in turn creates a parser that matches the command (e.g., DeleteCommandParser) and uses it to parse the command.
2. This results in a Command object (more precisely, an object of one of its subclasses e.g., DeleteCommand) which is executed by the LogicManager.
3. The command can communicate with the Model when it is executed (e.g. to delete a contact).
   Note that although this is shown as a single step in the diagram above (for simplicity), in the code it can take several interactions (between the command object and the Model) to achieve.
4. The result of the command execution is encapsulated as a CommandResult object which is returned back from Logic.

Here are the other classes in Logic (omitted from the class diagram above) that are used for parsing a user command:

How the parsing works:

• When called upon to parse a user command, the AddressBookParser class creates an XYZCommandParser (XYZ is a placeholder for the specific command name e.g., AddCommandParser) which uses the other classes shown above to parse the user command and create a XYZCommand object (e.g., AddCommand) which the AddressBookParser returns back as a Command object.
• All XYZCommandParser classes (e.g., AddCommandParser, DeleteCommandParser, ...) inherit from the Parser interface so that they can be treated similarly where possible e.g, during testing.

Model component

API : Model.java

The Model component,

• stores the address book data i.e., all Contact objects (which are contained in a UniqueContactList object).
• stores the currently 'selected' Contact objects (e.g., results of a search query) as a separate filtered list which is exposed to outsiders as an unmodifiable ObservableList<Contact> that can be 'observed' e.g. the UI can be bound to this list so that the UI automatically updates when the data in the list change.
• stores a UserPref object that represents the user’s preferences. This is exposed to the outside as a ReadOnlyUserPref objects.
• does not depend on any of the other three components (as the Model represents data entities of the domain, they should make sense on their own without depending on other components)

Storage component

API : Storage.java

The Storage component,

• can save both address book data and user preference data in JSON format, and read them back into corresponding objects.
• inherits from both AddressBookStorage and UserPrefStorage, which means it can be treated as either one (if only the functionality of only one is needed).
• depends on some classes in the Model component (because the Storage component's job is to save/retrieve objects that belong to the Model)

Common classes

Classes used by multiple components are in the cpp.commons package.

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Implementation

This section describes some noteworthy details on how certain features are implemented.

[Proposed] Undo/redo feature

Proposed Implementation

The proposed undo/redo mechanism is facilitated by VersionedAddressBook. It extends AddressBook with an undo/redo history, stored internally as an addressBookStateList and currentStatePointer. Additionally, it implements the following operations:

• VersionedAddressBook#commit() — Saves the current address book state in its history.
• VersionedAddressBook#undo() — Restores the previous address book state from its history.
• VersionedAddressBook#redo() — Restores a previously undone address book state from its history.

These operations are exposed in the Model interface as Model#commitAddressBook(), Model#undoAddressBook() and Model#redoAddressBook() respectively.

Given below is an example usage scenario and how the undo/redo mechanism behaves at each step.

Step 1. The user launches the application for the first time. The VersionedAddressBook will be initialized with the initial address book state, and the currentStatePointer pointing to that single address book state.

Step 2. The user executes delete 5 command to delete the 5th contact in the address book. The delete command calls Model#commitAddressBook(), causing the modified state of the address book after the delete 5 command executes to be saved in the addressBookStateList, and the currentStatePointer is shifted to the newly inserted address book state.

Step 3. The user executes add n/David …​ to add a new contact. The add command also calls Model#commitAddressBook(), causing another modified address book state to be saved into the addressBookStateList.

Step 4. The user now decides that adding the contact was a mistake, and decides to undo that action by executing the undo command. The undo command will call Model#undoAddressBook(), which will shift the currentStatePointer once to the left, pointing it to the previous address book state, and restores the address book to that state.

The following sequence diagram shows how an undo operation goes through the Logic component:

Similarly, how an undo operation goes through the Model component is shown below:

The redo command does the opposite — it calls Model#redoAddressBook(), which shifts the currentStatePointer once to the right, pointing to the previously undone state, and restores the address book to that state.

Step 5. The user then decides to execute the command list. Commands that do not modify the address book, such as list, will usually not call Model#commitAddressBook(), Model#undoAddressBook() or Model#redoAddressBook(). Thus, the addressBookStateList remains unchanged.

Step 6. The user executes clear, which calls Model#commitAddressBook(). Since the currentStatePointer is not pointing at the end of the addressBookStateList, all address book states after the currentStatePointer will be purged. Reason: It no longer makes sense to redo the add n/David …​ command. This is the behavior that most modern desktop applications follow.

The following activity diagram summarizes what happens when a user executes a new command:

Design considerations

Aspect: How undo & redo executes:

• Alternative 1 (current choice): Saves the entire address book.

  • Pros: Easy to implement.
  • Cons: May have performance issues in terms of memory usage.

• Alternative 2: Individual command knows how to undo/redo by itself.

  • Pros: Will use less memory (e.g. for delete, just save the contact being deleted).
  • Cons: We must ensure that the implementation of each individual command are correct.

{more aspects and alternatives to be added}

[Proposed] Data archiving

{Explain here how the data archiving feature will be implemented}

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Documentation, logging, testing, configuration, dev-ops

• Documentation guide
• Testing guide
• Logging guide
• Configuration guide
• DevOps guide

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Appendix: Requirements

Product scope

Target user profile:

• for educators
• has a need to manage a significant number of student, parent or fellow colleague contacts
• has a need to manage class groups and their associated contacts
• has a need to manage a significant number of tasks and assignments
• prefer desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps

Value proposition:

• manage students, parents, colleagues, supervisors, bosses, etc. faster than a typical mouse/GUI driven app
• provides easy access and management of class groups and assignments in one place

User stories

Priorities: High (must have) - * * *, Medium (nice to have) - * *, Low (unlikely to have) - *

Use cases

(For all use cases below, the System is ClassroomPlusPlus and the Actor is the user (a teacher), unless specified otherwise)

Use Case 1: Add a New Contact

MSS

1. User requests to add a contact with fields (Name, Phone, Email, Address, Class name, Assignment name).
2. System shows updated contact list (Use Case 2).
3. Use case ends.

Extensions

• 1a. User left optional fields blank (e.g. Class name, Assignment name).
  • 1a1. System accepts the input and proceeds.
• 1b. A contact with the same Name and Phone number exists in contact list.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.
• 1c. Invalid or missing fields.
  • 1c1. System shows an error message.
  • 1c2. Use case ends.

Use Case 2: List Contacts

MSS

1. User requests to list contacts.
2. System shows the list of contacts.
3. Use case ends.

Extensions

• 2a. No contacts exist in the list.
  • 2a1. System shows an empty list with a message indicating that no contacts exist.

Use Case 3: Add a New Class

MSS

1. User requests to add a class with fields (Class name).
2. System shows class list (Use Case 4).
3. Use case ends.

Extensions

• 1a. A class with the same name exists in class list.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Invalid or missing fields.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Use Case 4: List Classes

MSS

1. User requests to list classes.
2. System shows the list of classes.
3. Use case ends.

Extensions

• 2a. No classes exist in the list.
  • 2a1. System shows an empty list with a message indicating that no classes exist.
  • 2a2. Use case ends.

Use Case 5: Assign a Contact to a Class

MSS

1. User requests to assign a contact to a class.
2. System assigns the contact to the class.
3. Use case ends.

Extensions

• 1a. Invalid contact or class.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Contact is already assigned to the class.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Use Case 6: Remove a Contact from a Class

MSS

1. User views the list of contacts assigned to a class (Use Case 18).
2. User requests to remove a contact from the class.
3. System removes the contact from the class.
4. Use case ends.

Extensions

• 2a. Invalid contact or class.
  • 2a1. System shows an error message.
  • 2a2. Use case ends.
• 2b. Contact is not assigned to the class.
  • 2b1. System shows an error message.
  • 2b2. Use case ends.

Use Case 7: Add a New Assignment

MSS

1. User requests to add an assignment with fields (Assignment name, Deadline, Class name, Contact indices).
2. System shows updated assignment list (Use Case 8).
3. Use case ends.

Extensions

• 1a. A assignment with the same name exists in assignment list.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Invalid or missing fields.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.
• 1c. User left optional fields blank (e.g. Class name, Contact indices).
  • 1c1. System accepts the input and proceeds.

Use Case 8: List Assignments

MSS

1. User requests to list assignments.
2. System shows the list of assignments.
3. Use case ends.

Extensions

• 2a. No assignments exist in the list.
  • 2a1. System shows an empty list with a message indicating that no assignments exist.
  • 2a2. Use case ends.

Use Case 9: Assign an Assignment

MSS

1. User requests to assign an assignment with fields (Assignment name, Class name, Contact indices).
2. System assigns the assignment to the contacts.
3. Use case ends.

Extensions

• 1a. Invalid assignment or contacts.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Assignment is already assigned to one of the contacts.
  • 1b1. System proceeds with Step 3.
• 1c. User left Class name field blank.
  • 1c1. System proceeds with Step 3, assigning only to contacts specified.
• 1d. User left Contact indices field blank.
  • 1d1. System proceeds with Step 3, assigning to all contacts in the specified class.

Use Case 10: Unassign an Assignment

MSS

1. User views the list of contacts assigned to an assignment (Use Case 19).
2. User requests to unassign an assignment with fields (Assignment name, Class name, Contact indices).
3. System unassigns the assignment from the contacts.
4. Use case ends.

Extensions

• 2a. Invalid assignment, classname, or contacts.
  • 2a1. System shows an error message.
  • 2a2. Use case ends.
• 2b. Assignment is not assigned to one of the contacts.
  • 2b1. System proceeds with Step 3 without the contact.
• 2c. User left Class name field blank.
  • 2c1. System proceeds with Step 3, unassigning only from contacts specified.
• 2d. User left Contact indices field blank.
  • 2d1. System proceeds with Step 3, unassigning from all contacts in the specified class.
• 2e. User left both Class name and Contact indices fields blank.
  • 2e1. System proceeds with Step 3, unassigning from all contacts assigned to the assignment.
• 2f. No contacts are assigned to the assignment.
  • 2f1. System shows an error message.
  • 2f2. Use case ends.

Use Case 11: Delete a Contact

MSS

1. User requests to delete a contact.
2. System removes the contact from the contact list, any classes and assignments it is assigned to.
3. Use case ends.

Extensions

• 1a. Invalid contact.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. User specified multiple contacts to delete.
  • 1b1. System repeats Steps 2 and 3 for all specified contacts.

Use Case 12: Delete a Class

MSS

1. User requests to delete a class.
2. System removes the class from the class list, and from any students belonging to the class.
3. Use case ends.

Extensions

• 1a. Invalid class.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. User specified multiple classes to delete.
  • 1b1. System repeats Steps 2 and 3 for all classes.

Use Case 13: Delete an Assignment

MSS

1. User requests to delete an assignment.
2. System removes the assignment from the assignment list, and from any students who have it assigned.
3. Use case ends.

Extensions

• 1a. Invalid assignment.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. User specified multiple assignments to delete.
  • 1b1. System repeats Steps 2 and 3 for all assignments.

The use cases below are for features that are not part of the MVP, but are proposed to be implemented if time permits.

Use Case 14: Find a Contact

MSS

1. User requests to find contacts by name, phone, class, or email.
2. System displays the matching contacts.
3. Use case ends.

Extensions

• 1a. No contacts match the search query.
  • 1a1. System shows an empty list with a message indicating no matches found.
  • 1a2. Use case ends.
• 1b. Invalid search query (e.g. invalid field, or missing search keyword).
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Use Case 15: Find a Class

MSS

1. User requests to find a class by name.
2. System displays the matching classes.
3. Use case ends.

Extensions

• 1a. No classes match the search query.
  • 1a1. System shows an empty list with a message indicating no matches found.
  • 1a2. Use case ends.

Use Case 16: Find an Assignment

MSS

1. User requests to find an assignment by name or deadline.
2. System displays the matching assignments.
3. Use case ends.

Extensions

• 1a. No assignments match the search query.
  • 1a1. System shows an empty list with a message indicating no matches found.
  • 1a2. Use case ends.
• 1b. Invalid search query (e.g. invalid field, or missing search keyword).
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Use Case 17: View a Contact

MSS

1. User views the list of contacts (Use Case 2).
2. User requests to view a contact.
3. System displays the contact details, including any assignments and their deadlines assigned to the contact.
4. Use case ends.

Extensions

• 2a. Invalid contact.
  • 2a1. System shows an error message.
  • 2a2. Use case ends.

Use Case 18: View a Class

MSS

1. User views the list of classes (Use Case 4).
2. User requests to view a class.
3. System displays the class details and associated contacts.
4. Use case ends.

Extensions

• 2a. Invalid class.
  • 2a1. System shows an error message.
  • 2a2. Use case ends.

Use Case 19: View an Assignment

MSS

1. User views the list of assignments (Use Case 8).
2. User requests to view an assignment.
3. System displays the assignment details and associated contacts.
4. Use case ends.

Extensions

• 2a. Invalid assignment.
  • 2a1. System shows an error message.
  • 2a2. Use case ends.

Use Case 20: Update Submission Status of an Assignment

MSS

1. User requests to update a contact's submission status for an assignment.
2. System updates the assignment's submission status for the contact.
3. Use case ends.

Extensions

• 1a. Invalid contact or assignment.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Contact is not assigned the assignment.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Use Case 21: Mark an Assignment

MSS

1. User requests to mark an assignment for a contact with a score.
2. System marks the assignment as graded for the contact and sets the score.
3. Use case ends.

Extensions

• 1a. Invalid assignment or contact.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Assignment is already graded for the contact.
  • 1b1. System continues with Step 3, overwriting the previous score.
• 1c. Invalid score.
  • 1c1. System shows an error message.
  • 1c2. Use case ends.

Use Case 22: Unmark an Assignment

MSS

1. User requests to unmark an assignment for a contact.
2. System ungrades the assignment for the contact and removes the score.
3. Use case ends.

Extensions

• 1a. Invalid assignment or contact.
  • 1a1. System shows an error message.
  • 1a2. Use case ends.
• 1b. Assignment is not marked for the contact.
  • 1b1. System shows an error message.
  • 1b2. Use case ends.

Non-Functional Requirements

1. Should work on any mainstream OS as long as it has Java 17 or above installed.
2. Should be able to hold up to 1000 contacts without a noticeable sluggishness in performance for typical usage.
3. A user with above average typing speed for regular English text (i.e. not code, not system admin commands) should be able to accomplish most of the tasks faster using commands than using the mouse.
4. Should respond to user commands within 2 seconds to ensure a smooth user experience.
5. Should be capable of handling up to 50 classes and 500 assignments without noticeable reduction in performance for typical usage.
6. Should launch and load existing data within 5 seconds.
7. Should gracefully handle invalid inputs by providing clear, red-colored error messages instructing the user on the correct format.
8. Should work well for standard screen resolutions of 1920x1080 and higher (at 100% and 125% screen scales), and must remain fully usable for resolutions of 1280x720 and higher (at 150% screen scale).
9. Data should be stored locally in a human-editable text file (JSON) without the use of any Database Management System.
10. Should automatically save data to the hard disk after any command that modifies the state to prevent data loss.

Glossary

• Assignment: A task created by the user containing minimally a deadline, and may include submission status and grading. Can be assigned to Classes and Contacts.
• Class: A user-defined group of contacts.
• CLI (Command Line Interface): The text-based interface through which users interact with the system by typing command.
• Command: A text-based instruction entered into the CLI that triggers a system action.
• Contact: An individual entry of a student or teacher, containing minimally a name, phone number, email address, and may include Classes and Assignments.
• Deadline: Time and date specifying the due date of an Assignment.
• Filtered List: A dynamically updated subset of Contacts currently displayed in the GUI.
• GUI (Graphical User Interface): The visual interface of the application that displays tabs, lists, and feedback messages.
• Index: The number shown beside an item in the currently displayed list.
• Invalid: Violates one or more specified formats or constraints defined by the system.
• JSON (JavaScript Object Notation): The human-readable file format used to automatically save and load application data locally.
• Mainstream OS: Windows, Linux, Unix, MacOS
• Private contact detail: A contact detail that is not meant to be shared with others
• Submission status: The state of an Assignment for a specified Contact (e.g. not submitted, submitted).
• Tags: A user-defined, optional label attached to a Contact for categorization and filtering (e.g. "Prefect").
• Valid: Satisfies all specified format and constraints defined by the system.

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Appendix: Instructions for manual testing

Given below are instructions to test the app manually.

Launch and shutdown

1. Initial launch

   1. Download the jar file and copy into an empty folder

   2. Double-click the jar file Expected: Shows the GUI with a set of sample contacts. The window size may not be optimum.

2. Saving window preferences

   1. Resize the window to an optimum size. Move the window to a different location. Close the window.

   2. Re-launch the app by double-clicking the jar file.
      Expected: The most recent window size and location is retained.

3. { more test cases …​ }

Deleting a contact

1. Deleting a contact while all contacts are being shown

   1. Prerequisites: List all contacts using the list command. Multiple contacts in the list.

   2. Test case: delete 1
      Expected: First contact is deleted from the list. Details of the deleted contact shown in the status message. Timestamp in the status bar is updated.

   3. Test case: delete 0
      Expected: No contact is deleted. Error details shown in the status message. Status bar remains the same.

   4. Other incorrect delete commands to try: delete, delete x, ... (where x is larger than the list size)
      Expected: Similar to previous.

2. { more test cases …​ }

Saving data

1. Dealing with missing/corrupted data files

   1. {explain how to simulate a missing/corrupted file, and the expected behavior}

2. { more test cases …​ }