BZNUS Developer Guide

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, OrderListPanel,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, the user input 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. When the command is executed, it can communicate with the Model (e.g., to delete a person and all his/her orders).
   For readability, the diagram omits preliminary interactions with the Model that occur before the delete operations (e.g., retrieving the currently displayed list of persons).
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, EditOrderCommandParser, ...) 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: This includes all Person objects (contained in a UniquePersonList object) and all Order objects (contained in a OrderList object).
• stores the currently 'selected' Person objects and Order objects (e.g., results of a search query) as separate filtered lists which are exposed to outsiders as unmodifiable ObservableList<Person> and ObservableList<Order> 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)

[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}

Product scope

Target user profile:

• is a home-based food and beverage (F&B) business owner
• has a need to manage a significant number of customer contacts from multiple messaging platforms, complex dietary requirements, and food orders with varying deadlines
• prefers desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI (Command Line Interface) apps

Value proposition: Manage customer profiles and track food orders significantly faster than a typical mouse/GUI-driven app.

User stories

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

Use cases

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

Use case: UC01 - Add Customer

MSS:

1. Seller chooses to add a new customer.

2. BZNUS requests for the customer details.

3. Seller enters the requested details.

4. BZNUS saves the contact information.

5. BZNUS shows a success message to show the customer is added.

   Use case ends.

Extensions:

• 3a. BZNUS detects invalid or missing mandatory data (e.g., blank name).

  • 3a1. BZNUS requests for the correct data.

  • 3a2. Seller enters new data.

  • Steps 3a1-3a2 are repeated until the data entered are correct.

    Use case resumes from step 4.

• *a. At any time, Seller chooses to cancel adding a customer.

  • *a1. BZNUS discards the input and returns to the previous view.

    Use case ends.

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Use case: UC02 - Delete Customer
Guarantees:

• If the deletion cannot be completed (e.g. invalid customer index), the system does not remove any customer.
• Only customers that are currently displayed can be deleted.

MSS:

1. User enters the delete customer command along with the specified customer.

2. BZNUS deletes the customer from the system.

3. BZNUS deletes all orders associated with the customer from the system.

4. BZNUS shows a success message to show the customer is deleted.

5. BZNUS updates the displayed list to exclude the deleted customer.

   Use case ends.

Extensions:

• 1a. BZNUS detects invalid or missing fields.

  • 1a1. BZNUS displays an error message.

  • 1a2. User updates the entered details.

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

  Use case resumes from step 2.

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Use case: UC03 - Edit Customer

MSS:

1. User chooses to edit a specific customer profile.

2. BZNUS displays the current contact details and allows editing.

3. User enters the updated details.

4. User saves the changes.

5. BZNUS updates the profile and displays the revised details.

   Use case ends.

Extensions:

• 3a. BZNUS detects invalid data (e.g., letters in a phone number field).

  • 3a1. BZNUS requests for the correct data.

  • 3a2. Seller enters new data.

  • Steps 3a1-3a2 are repeated until the data entered are correct.

  Use case resumes from step 4.

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Use case: UC04 - Add tags to customers

MSS:

1. User chooses to add tags to a specific customer profile.

2. User inputs the desired tags (e.g., "corporate", "vegan", "weekend delivery").

3. User saves the tags.

4. BZNUS updates the customer profile to display the new tags.

   Use case ends.

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Use case: UC05 - Search customer information

MSS:

1. User enters search keywords (e.g., name, phone number, delivery address).

2. BZNUS retrieves and displays a list of customer profiles matching the keywords.

   Use case ends.

Extensions:

• 1a. BZNUS detects no matching customers for the entered keyword.

  • 1a1. BZNUS displays a message indicating no results were found.

    Use case ends.

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Use case: UC06 - Add order
Guarantees:

• The system records the order only if the provided order information is valid.

MSS:

1. User enters the order command along with the order details.

2. BZNUS stores the new order.

3. BZNUS shows a success message to indicate the order is added.

4. BZNUS updates the displayed list to include the order.

   Use case ends.

Extensions:

• 1a. BZNUS detects invalid or missing fields.

  • 1a1. BZNUS displays an error message.

  • 1a2. User updates the entered details.

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

  Use case resumes from step 2.

---

Use case: UC07 - Delete order
Guarantees:

• If the deletion cannot be completed (e.g. invalid order index, order not found), the system does not remove any order.
• Only orders that are currently displayed can be deleted.

MSS:

1. User enters the delete order command along with the order to be deleted.

2. BZNUS removes the specified order from the system.

3. BZNUS shows a success message to indicate the order is deleted.

4. BZNUS updates the displayed list to exclude the deleted order.

   Use case ends.

Extensions:

• 1a. BZNUS detects invalid or missing fields.

  • 1a1. BZNUS displays an error message.

  • 1a2. User updates the entered details.

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

  Use case resumes from step 2.

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 persons and 5000 orders 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. All customer and order data should be stored locally in a human-editable .json or .txt file.
5. The system must be designed as a standalone application and should not depend on a remote server or external database.
6. All valid commands should display results within 2 seconds of the user pressing 'Enter'.
7. The interface should be intuitive enough that a home-based F&B seller with basic computer literacy can navigate the system without needing a comprehensive training manual.
8. The system should handle invalid user inputs gracefully by displaying clear and helpful error messages without crashing.

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 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. Timestamp in the status bar is updated.

   3. Test case: delete 0
      Expected: No person 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 …​ }