AB-3 Developer Guide

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Acknowledgements

• {List the sources of reused or adapted ideas, code, documentation, and third-party libraries here, with links to the originals.}

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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.

The following provides a quick overview of the main components and their interactions.

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.
• provides its functionality through a concrete {Component Name}Manager class that implements the corresponding API interface.

For example, the Logic component defines its API in Logic.java and implements it in LogicManager.java. Other components interact with a component through its interface rather than its concrete class, preventing them from coupling to that component's implementation, as illustrated in the following partial class diagram.

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 and its parts, such as CommandBox, ResultDisplay, PersonListPanel, and StatusBarFooter. All of these, including MainWindow, inherit from the abstract UiPart class, which captures common behavior among classes that represent visible GUI parts.

The UI component uses the JavaFX UI framework. The layouts of these UI parts are defined in matching .fxml files in src/main/resources/view. For example, MainWindow.fxml specifies the layout of MainWindow.

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 because it displays Person objects from 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, the command 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, the code can require several interactions between the command object and the Model to complete the operation.
4. The result of the command execution is encapsulated as a CommandResult object which is returned 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). The parser uses the other classes shown above to parse the user command and create an XYZCommand object (e.g., AddCommand). The AddressBookParser returns that object as a Command object.
• All XYZCommandParser classes, such as AddCommandParser and DeleteCommandParser, implement the Parser interface so they can be treated similarly where appropriate, for example 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 Person objects selected by the current filter, such as search results, in a separate filtered list. It exposes this list as an unmodifiable ObservableList<Person> that the UI can observe and bind to, so the UI updates when the list changes.
• stores a UserPrefs object that represents the user’s preferences (currently, just the GUI settings). This is exposed to the outside as a ReadOnlyUserPrefs object.
• 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.
• is implemented by StorageManager, which delegates the actual JSON file access to JsonAddressBookStorage and JsonUserPrefsStorage (one class per data file).
• 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.

[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 execute:

• 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 is 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, dev-ops

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

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Appendix: Requirements

Product scope

Target user profile:

• has a need to manage a significant number of contacts
• prefers desktop apps over other types of applications
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps

Value proposition: Manage contacts faster than with a typical mouse-driven GUI application.

User stories

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

{More to be added}

Use cases

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

Use case: Delete a person

MSS

1. User requests to list persons

2. AddressBook shows a list of persons

3. User requests to delete a specific person in the list

4. AddressBook deletes the person

   Use case ends.

Extensions

• 2a. The list is empty.

  Use case ends.

• 3a. The given index is invalid.

  • 3a1. AddressBook shows an error message.

    Use case resumes at step 2.

{More to be added}

Non-Functional Requirements

1. Should work on any mainstream OS as long as it has Java 25 or above installed.
2. Should be able to hold up to 1000 persons without 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.

{More to be added}

Glossary

• Mainstream OS: Windows, Linux, Unix, or macOS
• Private contact detail: A contact detail that is not meant to be shared with others

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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 it into an empty folder.

   2. Double-click the JAR file.
      Expected: The GUI opens with a set of sample contacts. The window size may not be optimal.

2. Saving window preferences

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

   2. Relaunch the app by double-clicking the JAR file.
      Expected: The most recent window size and location are retained.

3. { more test cases … }

Deleting a person

1. Deleting a person while all persons are being shown

   1. Prerequisites: List all persons using the list command, with multiple persons in the list.

   2. Test case: delete 1
      Expected: The first contact is deleted from the list. The status message shows the deleted contact's details.

   3. Test case: delete 0
      Expected: No person is deleted. The status message shows error details.

   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 missing or corrupted data files and state the expected behavior.}

2. { more test cases … }