Developer Guide

• Table of Contents

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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, 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("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 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)

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.

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Implementation

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

Starred contacts feature

The starred contacts feature adds a starred boolean state to Person, with the following behavior:

1. star INDEX marks the person at the displayed index as starred.
2. unstar INDEX removes the starred state from the person at the displayed index.
3. Repeating star on an already-starred person (or unstar on an already-unstarred person) is handled as an informative no-op.

Model and ordering

• Person stores starred as a data field (default false).
• Person#isSamePerson is unchanged (identity remains name-based).
• Full object equality/hash semantics include starred.
• AddressBook enforces starred-first ordering after person-list mutations.
• Within the starred and unstarred groups, relative order is preserved.

Storage

• JsonAdaptedPerson persists the starred field.
• Backward compatibility is preserved by treating missing starred values in legacy JSON files as false.

UI

• PersonCard renders a subtle star marker for starred contacts.
• The marker is hidden for unstarred contacts to keep the layout compact.

[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 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.

Step 3. The user executes add n/David …​ to add a new person. 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 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.

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

{more aspects and alternatives to be added}

Data archiving

Implementation

The data archiving feature is implemented with an isArchived flag in Person.

• archive INDEX marks a contact as archived.
• unarchive INDEX restores an archived contact to active status.
• list shows only active contacts.
• listarchived shows only archived contacts.

The archive status is persisted in JSON storage through JsonAdaptedPerson using an archived property. To preserve backward compatibility with existing save files, missing archived values are treated as false.

Command flow

1. AddressBookParser routes archive and unarchive to their dedicated parsers.
2. The parsers parse a one-based index using ParserUtil.parseIndex.
3. The command resolves the target Person from Model#getFilteredPersonList.
4. The command creates a new Person copy with the same fields except updated isArchived.
5. Model#setPerson replaces the target person and refreshes the filtered list.

Filtering behavior

The app defaults to showing active contacts only.

• Model.PREDICATE_SHOW_ACTIVE_PERSONS is used by default list views.
• find and filter apply their predicates together with the active predicate.
• listarchived uses Person::isArchived to show archived entries explicitly.

Design considerations

• Alternative considered: physically moving archived contacts into a separate list.
  • Rejected because it would complicate storage and command behavior.
• Current approach: keep a single person list with an archive flag.
  • Simpler migration path and minimal changes to existing command architecture.

Tests

Coverage includes:

• ArchiveCommandTest and UnarchiveCommandTest for command behavior.
• ArchiveCommandParserTest and UnarchiveCommandParserTest for parser validation.
• AddressBookParserTest routing coverage for archive, unarchive, and listarchived.
• JsonAdaptedPersonTest for archive persistence and backward compatibility defaults.
• ModelManagerTest and PersonTest regression checks for archive filtering and object semantics.

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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:

• An NUS CS student (or similar tech-savvy student) involved in multiple project teams, hackathons, and internships simultaneously
• Maintains a large and growing list of contacts such as teammates, tutors, professors, and friends
• Works primarily on a personal laptop
• Prefers CLI-based tools and keyboard-driven workflows
• Values speed, organisation, and minimal distraction
• Often overwhelmed by an unstructured contact list and struggles to retrieve specific contact details quickly

Value proposition: TaskNest helps users who manage many contacts across multiple commitments to store and organise contact information efficiently, search and retrieve contacts quickly via a fast CLI interface, and reduce clutter as their contact list grows — all faster than a typical mouse/GUI-driven app.

User stories

Priorities: High (must have) - * * *, Medium (should have) - * *, Low (nice 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 contact with a name, phone number, and email	store details of people I meet
* * *	user	delete a contact	remove obsolete or incorrectly entered entries
* * *	user	edit a contact’s details	keep information up to date when it changes
* * *	user	list all my contacts	see everyone I have stored at a glance
* * *	user	search for a contact by name	retrieve someone’s details quickly without scrolling through the entire list
* * *	user	receive validation feedback for an invalid email format	ensure my data is accurate and consistent
* * *	user	receive validation feedback for an invalid phone number	ensure my data is accurate and consistent
* * *	user	be asked to confirm before a contact is deleted	avoid accidentally losing important contact information
* *	user with a large contact list	filter contacts by tag	quickly find people associated with a particular group or project
* *	user	have my contacts sorted alphabetically by default	browse the list in a predictable, organised order
* *	user	be warned when I try to add a duplicate contact	avoid cluttering my list with repeated entries
* *	user	search contacts across all fields (name, phone, email, address, tags)	find someone even if I only remember a partial detail
*	user	undo a delete action	recover from accidental deletions
*	user	archive contacts I no longer actively use	keep the main list clean without permanently losing information
*	user	export my contact list	back up my data or share it with others
*	user	store multiple phone numbers or emails for one contact	accommodate contacts who have more than one reachable number or address
*	power user	use keyboard shortcuts for common actions	work even faster without breaking my typing rhythm

Use cases

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

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Use case: UC01 — Add a new contact

MSS

1. User enters the add command with the required fields (name, phone, email) and any optional fields (address, tags).
2. TaskNest validates all provided fields.
3. TaskNest checks that no duplicate contact (same name and phone) exists.

4. TaskNest adds the contact and displays a success message with the new contact’s details.

   Use case ends.

Extensions

• 2a. One or more fields fail validation.

  • 2a1. TaskNest shows the relevant error message for the first invalid field.

    Use case resumes at step 1.

• 3a. A duplicate contact is detected.

  • 3a1. TaskNest shows a duplicate contact error message.

    Use case resumes at step 1.

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Use case: UC02 — Find and edit a contact

MSS

1. User enters the find command with a keyword.
2. TaskNest displays all contacts whose name (or other fields) match the keyword.
3. User identifies the index of the contact to edit from the filtered list.
4. User enters the edit command with the contact’s index and the fields to update.
5. TaskNest validates the new field values.

6. TaskNest updates the contact and displays a success message showing the updated details.

   Use case ends.

Extensions

• 2a. No contacts match the keyword.

  • 2a1. TaskNest shows a message indicating no results were found.

    Use case ends.

• 4a. The provided index is out of range.

  • 4a1. TaskNest shows an invalid index error message.

    Use case resumes at step 3.

• 4b. No fields are provided to the edit command.

  • 4b1. TaskNest shows an error asking the user to specify at least one field.

    Use case resumes at step 4.

• 5a. A field value fails validation.

  • 5a1. TaskNest shows the relevant error message.

    Use case resumes at step 4.

• 5b. The edited contact would duplicate an existing contact.

  • 5b1. TaskNest shows a duplicate contact error and rejects the edit.

    Use case resumes at step 4.

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Use case: UC03 — Find and delete a contact

MSS

1. User enters the find command with a keyword.
2. TaskNest displays all contacts matching the keyword.
3. User identifies the index of the contact to delete from the filtered list.
4. User enters the delete command with the contact’s index.
5. TaskNest prompts the user to confirm the deletion.
6. User confirms.

7. TaskNest removes the contact and displays a success message.

   Use case ends.

Extensions

• 2a. No contacts match the keyword.

  • 2a1. TaskNest shows a message indicating no results were found.

    Use case ends.

• 3a. The provided index is out of range.

  • 3a1. TaskNest shows an invalid index error message.

    Use case resumes at step 3.

• 6a. User cancels the confirmation.

  • 6a1. TaskNest cancels the deletion and shows a cancellation message.

    Use case ends.

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Use case: UC04 — List active contacts

MSS

1. User enters the list command.

2. TaskNest displays only active (non-archived) contacts and a count of the total number shown.

   Use case ends.

Extensions

• 2a. There are no active contacts.

  • 2a1. TaskNest shows an empty list.

    Use case ends.

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Use case: UC05 — Archive and unarchive contacts

MSS

1. User enters the list command.
2. TaskNest displays active contacts.
3. User enters archive INDEX for a contact in the list.
4. TaskNest marks the contact as archived and removes it from active views.
5. User enters the listarchived command.
6. TaskNest displays archived contacts.
7. User enters unarchive INDEX for a contact in the archived list.
8. TaskNest marks the contact as active again.

9. User enters list and sees the contact in active contacts.

   Use case ends.

Extensions

• 3a. INDEX is invalid.

  • 3a1. TaskNest shows an invalid index error.

    Use case resumes at step 2.

• 3b. Contact is already archived.

  • 3b1. TaskNest shows an already archived error.

    Use case resumes at step 2.

• 7a. INDEX is invalid.

  • 7a1. TaskNest shows an invalid index error.

    Use case resumes at step 6.

• 7b. Contact is already active.

  • 7b1. TaskNest shows an already active error.

    Use case ends.

Non-Functional Requirements

1. Portability: Should work on any mainstream OS (Windows, Linux, macOS) with Java 17 or above installed, without requiring any additional installation steps beyond downloading the JAR file.
2. Performance: Should be able to hold up to 1000 contacts without noticeable sluggishness for typical usage. All commands should produce a response within 2 seconds on a modern consumer laptop.
3. Usability: A user with above-average typing speed for regular English text should be able to accomplish most tasks faster using CLI commands than using a mouse-driven GUI.
4. Reliability: Contact data should be persisted to disk automatically after every command so that no data is lost upon a normal application exit.
5. Data integrity: The application should reject all invalid or malformed inputs (e.g., incorrectly formatted phone numbers or emails) and display a clear, specific error message without modifying any stored data.
6. Learnability: A new user who has basic familiarity with CLI tools should be able to complete core tasks (add, find, edit, delete) within 10 minutes of first launch, using only the built-in help command.
7. Scalability: The contact storage format should remain backwards-compatible across minor version updates so that users do not lose data when upgrading the app.
8. Single-user: The product is designed for use by a single user on one machine and does not need to support concurrent access or multi-user synchronisation.

Glossary

• CLI (Command-Line Interface): A text-based interface where the user types commands to interact with the application, as opposed to using a mouse and graphical elements.
• Contact: A person whose details (e.g., name, phone number, email address) are stored in TaskNest.
• Duplicate contact: Two contacts that share the same name (case-insensitive) and phone number, considered to represent the same person.
• Index: The position number displayed next to a contact in the currently visible list. Used to identify which contact a command should act on.
• Mainstream OS: Windows, Linux, Unix, macOS.
• MSS (Main Success Scenario): The sequence of steps in a use case that describes the most straightforward path to a successful outcome.
• MVP (Minimum Viable Product): The smallest set of features required to deliver core value to users. For TaskNest, this includes adding, deleting, editing, listing, and searching contacts with basic validation.
• Tag: A short alphanumeric label that can be attached to a contact to group or categorise them (e.g., friend, work, project-alpha).
• TaskNest: The name of this contact management application, built for tech-savvy students who manage many contacts across multiple commitments.

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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 person

1. Deleting a person while all persons are being shown
   1. Prerequisites: List active persons using the list command. Multiple active persons in the list.

Archiving and unarchiving a person

1. Archiving a person from active contacts
   1. Prerequisites: Use list to show active contacts with at least one person.
   2. Test case: archive 1
      Expected: First listed person is archived. Success message shown. Person no longer appears in list.
   3. Test case: archive 0
      Expected: No person is archived. Error details shown.
2. Viewing archived persons
   1. Prerequisites: At least one archived contact exists.
   2. Test case: listarchived
      Expected: Only archived contacts are shown.
3. Unarchiving a person
   1. Prerequisites: Use listarchived to show archived contacts with at least one person.
   2. Test case: unarchive 1
      Expected: First archived contact is restored to active status. Success message shown.

   3. Test case: unarchive 0
      Expected: No person is unarchived. Error details shown.

   4. 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.

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

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