Developer Guide

Table of Contents

Acknowledgements

  • It is based on the AddressBook-Level3 (AB3) project created by the SE-EDU initiative. In addition to the functionalities provided in AB3, we introduce features that can help NUS students better manage their contacts’ information.
  • GitHub Copilot Inline Editor was used as an autocomplete to complete repititive and tedious code.
  • GitHub Copilot Inline Editor was used to generate some testcases.
  • GitHub Copilot was used to generate some commit messages.
  • ChatGPT was used to format and correct the wordings and format of User Guide and Developer Guide, including the glossary.

Setting up, getting started

Refer to the guide Setting up and getting started.

Design

The .puml files used to create diagrams in this document docs/diagrams folder. Refer to the PlantUML Tutorial at se-edu/guides to learn how to create and edit diagrams.

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

Structure of the UI Component

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, PersonListPanel, 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 Person 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("edit 2 y/2") API call as an example.

Interactions Inside the Logic Component for the `edit 2 y/2` Command

The lifeline for EditCommandParser should end at the destroy marker (X) but due to a limitation of PlantUML, the lifeline continues till the end of diagram.

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., EditCommandParser) 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., EditCommand) which is executed by the LogicManager.
  3. The command can communicate with the Model when it is executed (e.g. to edit a person).
    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 Person objects (which are contained in a UniquePersonList object).
  • stores the currently ‘selected’ Person objects (e.g., results of a search query) as a separate filtered list which is exposed to outsiders as an unmodifiable ObservableList<Person> 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)

An alternative (arguably, a more OOP) model is given below. It has a Tag list in the AddressBook, which Person references. This allows AddressBook to only require one Tag object per unique tag, instead of each Person needing their own Tag objects.

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 seedu.address.commons package.

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.

UndoRedoState0

Step 2. The user executes delete 5 command to delete the 5th person 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.

UndoRedoState1

Step 3. The user executes add n/David …​ to add a new person. This activity diagram summarizes the process of adding a new person.

AddPersonActivityDiagram

The add command also calls Model#commitAddressBook(), causing another modified address book state to be saved into the addressBookStateList.

UndoRedoState2

If a command fails its execution, it will not call Model#commitAddressBook(), so the address book state will not be saved into the addressBookStateList.

Step 4. The user now decides that adding the person 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.

UndoRedoState3

If the currentStatePointer is at index 0, pointing to the initial AddressBook state, then there are no previous AddressBook states to restore. The undo command uses Model#canUndoAddressBook() to check if this is the case. If so, it will return an error to the user rather than attempting to perform the undo.

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

UndoSequenceDiagram

The lifeline for UndoCommand should end at the destroy marker (X) but due to a limitation of PlantUML, the lifeline reaches the end of diagram.

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

UndoSequenceDiagram

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.

If the currentStatePointer is at index addressBookStateList.size() - 1, pointing to the latest address book state, then there are no undone AddressBook states to restore. The redo command uses Model#canRedoAddressBook() to check if this is the case. If so, it will return an error to the user rather than attempting to perform the redo.

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.

UndoRedoState4

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.

UndoRedoState5

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 person being deleted).
    • Cons: We must ensure that the implementation of each individual command are correct.

Documentation, logging, testing, configuration, dev-ops

Appendix: Requirements

Product scope

Target user profile:

NUS undergraduate students who

  • frequently use NUSMods to plan, record, and share their course schedules
  • are socially active in NUS with a need to manage the contacts of their fellow NUS undergraduate students
  • are tech-savvy and familiar with installing jar files
  • can type fast and prefer using CLI apps over mouse interactions

Value proposition:

NUSMates allows NUS undergraduate students to record the contact details of their fellow NUS undergraduate students with NUS-specific contact information such as year, major, housing, and modules. Tailored towards frequent NUSMods users, the app makes it seamless to record module information using NUSMods links, helping users easily find friends who are taking the same modules - so they can form project groups, share notes or know who to reach out to for help.

User stories

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

Priority As a … I want to … So that I can…
* * * new user see usage instructions refer to instructions when I forget how to use the App
* * * user add a new person  
* * * user record a person’s year of study  
* * * user record a person’s NUS major  
* * * user record a person’s housing  
* * * user record a person’s Singaporean phone number  
* * * user record a person’s email  
* * * user record the link of a person’s NUSMods schedule record the modules and timetables of contacts
* * * user view a person’s modules  
* * * user delete a person remove contacts that I no longer need
* * * user edit a contact’s details update outdated or incorrect information
* * * user find contacts by name locate details of contacts without having to go through the entire list
* * * user find contacts by module find friends to take modules with
* * * user view a list of all my contacts quickly find and access their details
* * * user copy the link to my contact’s NUSMods schedule easily paste it into my browser to open their schedule on the NUSMods website
* * * user clear all contacts at once reset my address book when needed
* * * user exit the application using a command close it quickly when I am done using it
* * user have my contacts saved automatically make sure my data is not lost when I close the application
* * user interact with a graphical interface while using command-line inputs visually confirm my actions and navigate the application more easily
* * user back up my data make sure my data won’t get lost
* * user import contacts from a backup file  
* advanced user edit the data file directly modify my contact list without using the application interface

Use cases

For all use cases below, the System is the AddressBook and the Actor is the user, unless specified otherwise. All use cases also require the precondition that the app already be open, along with any additional use cases specified.

Use Case: UC01 – Add Contacts

MSS

  1. User provides contact details to add.
  2. System adds new contact.

  3. System shows new contact.

    Use Case Ends.

Extensions:

  • 1a. System detects an error in the entered data.

    • 1a1. System requests for correct data.

    • 1a2. User provides new data.

      Steps 1a1-1a2 are repeated until the data entered are correct.

      Use case resumes from step 2.

Use case: UC02 – Delete a Contact

Preconditions:

  • A non-empty list of persons is currently displayed to the user

MSS

  1. User requests to delete a specific contact in the list.

  2. AddressBook deletes the person.

    Use case ends.

Extensions

  • 1a. The given index is invalid.

    • 1a1. System shows an error message and requests for a correct index.
    • 1a2. User provides a new index.

    Steps 1a1-1a2 are repeated until the index entered is correct.

    Use case resumes at step 2.

Use Case: UC03 – Link a contact to NUSMods schedule

Preconditions

  • The contact to be linked exists, or the user is in the process of creating a new valid contact.

MSS

  1. User provides a contact and a NUSMods timetable link during creation or editing of the contact.
  2. System links the provided timetable to the contact, replacing any previously linked timetable if present.

  3. System displays the updated contact with the updated modules from the timetable.

    Use Case Ends.

Extensions

  • 2a. Provided timetable link is invalid.
    • 2a1. System informs the user that the link is invalid and requests a new link.

    • 2a2. User provides a new link.

      Steps 2a1-2a2 are repeated until the link entered is correct.

      Use case resumes from step 2.

Use Case: UC04 – Find Contacts Taking a Specific Module

Actor: NUS Undergraduate Student

MSS

  1. User enters the findMod command along with a module code.
  2. The system searches for contacts who are taking the specified module.

  3. The system lists matching contacts.

    Use Case Ends.

Extensions

  • 1a. User provides an invalid module code.

    • 1a1. System requests for correct data.

    • 1a2. User provides new data.

      Steps 1a1-1a2 are repeated until the data entered are valid.

      Use case resumes from step 2.

Use Case: UC05 – Find Contacts By Name

Actor: NUS Undergraduate Student

MSS

  1. User enters the find command along with keywords.
  2. The system searches for contacts whose names contain at least one of the given keywords.

  3. The system lists matching contacts.

    Use Case Ends.

Extensions

  • 1a. No matching contacts.

    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 users 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. Searches should return results within 1 second for a dataset of 1000 contacts.

Glossary

  • Mainstream OS: Windows, Linux, Unix, MacOS
  • NUSMods: A website used by NUS students to view and plan their module timetables
  • Contact: A person’s details that are stored in the address book
  • Private contact detail: A contact detail that is not meant to be shared with others
  • CLI (Command Line Interface): A means of interacting with a computer program by inputting lines of text called command lines
  • GUI (Graphical User Interface): A means of interacting with a computer program using a graphical interface, such as windows, icons, and buttons
  • Tag: A keyword or label associated with a contact
  • Module: A subject or course that NUS students take as part of their degree programme. Each module has a unique code (e.g., CS2103T) and typically includes lectures, tutorials, and/or labs.

Appendix: Instructions for manual testing

Given below are instructions to test the app manually.

These instructions only provide a starting point for testers to work on; testers are expected to do more exploratory testing.

Launch and shutdown

  1. Initial launch

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

    2. Open a terminal and cd into the folder you put the jar file.
    3. Use the command java -jar "nusmates.jar" to run the application.
      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.

Deleting a person

  1. Deleting a person while all persons are being shown

    1. Prerequisites: List all persons using the list command. Multiple persons 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.

    3. Test case: delete 0
      Expected: No person is deleted. Error details shown in the status message.

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

Editing a Person

  1. Editing a person while all persons are being shown

    1. Prerequisites: List all persons using the list command. Multiple persons listed. No one is named “John Doe”.

    2. Test case: edit 1 n/John Doe
      Expected: First contact is updated with the new name. Name of the updated contact shown in the status message.

    3. Test case: edit 1
      Expected: No person is edited. Error details shown in the status message.

    4. Other incorrect delete commands to try: edit 0, edit 0 n/Joe edit x, ... (where x is larger than the list size)
      Expected: Similar to previous.

  2. Editing the link of a person while all persons are being shown

    1. Prerequisites: List all persons using the list command. Multiple persons listed.

    2. Test case: edit 1 l/https://nusmods.com/timetable/sem-2/share?CS1010S=LEC:1,TUT:1&CS2030=LEC:1,LAB:1
      Expected: First contact is updated with the new link. Updated details of the contact shown in the status message. Clicking on NUSMods Schedule of the first person will result in copying the link which can be pasted in the browser.

    3. Test case: edit 1 l/google.com
      Expected: No person is edited. Error details shown in the status message.

Saving data

  1. Dealing with missing/corrupted data files

    1. Test case: Editing the JSON file so that it is still valid (e.g. changing "year" : "2", to "year" : "3",) Expected: The app should not crash. It should load the address book with the new data.

    2. Test case: Editing the JSON file to make it invalid (e.g. removing a comma) Expected: The app should not crash. It should create a new empty address book and delete the corrupted file. It should show an error message in the console.

    3. Test case: Deleting the JSON file Expected: The app should not crash. It should create a new address book with sample data. It should create the JSON file again upon any valid command.

Appendix: Planned Enhancements

Team size: 4

  1. Optional fields should be able to be cleared: Currently optional fields cannot be cleared once set. Optional fields should be able to be cleared using the edit command, just like tags. For example: Phone should be able to be cleared by doing edit 1 p/ (with nothing after the space).
  2. Fix issue of tags overflowing out of the UI: Currently, extremely long tags which overflow out of the UI get abruptly cut off, such as in the screenshot below. This off-screen overflow should be handles more elegantly, such as truncating the tag with a ... before cutting it within the UI boundary. TagUiOverflow.png
  3. Allow names with /: Currently, names cannot include the / character, even though there are valid names which include this character. In the future, this should be allowed to make NUSMates more inclusive.
  4. Long error messages: Currently, the error messages returned when entering an invlaid command are quite long and hard to read. In the future, this should be fixed by having line breaks or making the messages shorter to improve readbility.
  5. More Robust Link Validation: Currently, our link validation for the NUSMods timetable works in the following manner: verify that the link is indeed from nusmods.com, then parse the module codes from it ensuring that they satisfy some basic constraints (2-4 alphabet prefix, then 4 digits, and finally 0-5 alphanumeric characters). In the future, we plan to make this validation even more robust by verifying that the parsed codes are actually modules that exist (for example) by maintaining an offline list of valid codes.