Developer Guide

• Acknowledgements
• Setting up, getting started
• Design
  • Architecture
  • UI component
  • Logic component
  • Model component
  • Storage component
  • Common classes
• Implementation
  • [Proposed] Undo/redo feature
    • Proposed Implementation
    • Design considerations:
  • [Proposed] Data archiving
• Documentation, logging, testing, configuration, dev-ops
• Appendix: Requirements
  • Product scope
  • User stories
  • Use cases
  • Non-Functional Requirements
  • Glossary
• Appendix: Instructions for manual testing
  • Launch and shutdown
  • Deleting a person
  • Saving data

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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.

[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}

[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:

• has a need to manage a significant number of contacts
• prefer desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps
• is a student with a need track the transactions made on a daily basis due to frequent splitting of bills with saved contacts

Value proposition: Simplifies expense tracking for students, making it easy to split and manage shared costs with clarity and peace of mind.

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	delete a person	remove entries that I no longer need
* * *	user	find a person by name	locate details of persons without having to go through the entire list
* *	user	hide private contact details	minimize chance of someone else seeing them by accident
*	user with many persons in the address book	sort persons by name	locate a person easily
* * *	user	mark and unmark expenses that are paid off/not paid	track which expenses have been settled
* * *	user	see how much a specific contact owes	pay them back easily
*	user living abroad	handle currency conversion	track expenses accurately when paying in different currencies
*	user who frequently travels	tag expenses by event	manage and track costs associated with specific activities or trips
* * *	user	view a summary of all expenses and balances	quickly see who owes what and who has overpaid
* *	student tight on budget	set limits on certain categories	better manage my spendings
* *	user	access frequently contacted people quickly	record a transaction in a short amount of time
* *	user	create templates	add transactions quicker
* * *	user	set up recurring transactions	automate my transactions
* * *	student	generate a summary report of all expenses	share it with the group and settle payments
* *	user	detect duplicate expenses	avoid accidentally double-tracking a payment
* *	student managing multiple categories	tag expenses by category	organize and search for them easily later

Use cases

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

UC01 - View Usage Instructions

Actor: New User

MSS

1. The new user clicks on “Help” at top bar of the application.
2. The system displays usage instructions in a browser.
3. The user reviews the instructions.

Extensions

• 2a. The user can switch between different sections of the instructions (e.g., FAQs, How-to sections, etc.).

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UC02 - Add a New Person

MSS

1. A user request to add a new person with required details (e.g., name, email, phone number, address).
2. The system validates the input (e.g., checks for valid email format, non-empty fields).
3. The system saves the new person to the address book and displays a success message.
4. The new person is added to the list.

Extensions

• 4a. The system detects an invalid email format or phone number.
  • 4a1. The system shows an error message.
  • 4a2. The user have to restart from step 1.

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UC03 - Delete a person

MSS

1. A user requests to list persons
2. The system shows a list of persons
3. The user requests to delete a specific person in the list
4. The system deletes the person

Extensions

• 2a. The list is empty.
  • 2a1. Use case ends.
• 3a. The given index is invalid.
  • 3a1. AddressBook shows an error message.
  • 3a2. Use case resumes at step 2.

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UC04 - Find a Person by Name

MSS

1. A user requests to search for a person by first or last name.
2. The system performs a search and displays matched person’s details.

Extensions

• 2a. The system finds no match.
  • 2a1. The system displays a message indicating no results.
  • 2a2. Use case ends.
• 2b. The system finds multiple people with identical first or last names.
  • 2b1. The system displays the lists of found person along with a message for the user to specify which person.
  • 2b2. The user specify which exact person within the list using index.
  • 2b3. The system displays the specified person’s details.
  • 2b4. Use case ends.

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UC05 - Mark and Unmark Expenses

MSS

1. A user requests to list expenses
2. The system shows a list of expenses
3. The user requests to mark or unmark the selected expense.
4. The system updates the status of the expense.
5. The system displays a success message indicating the change.

Extensions

• 3a. The expense is a recurring expense.
  • 3a1. The system asks whether to apply the change to all future occurrences or just the current one.
  • 3a2. The user confirms.
  • 3a3. Use case resumes from step 4.

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UC06 - View Person’s Owed Amount

MSS

1. A user requests to list all person.
2. The user selects a person to view.
3. The system displays how much the user own to the selected person.

Extensions

• 3a. The system includes currency conversion.
  • 3a1. The system converts the owed amount to a default currency.
  • 3a2. Use case resumes from step 3.

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UC07 - View Summary of Expenses and Balances

MSS

1. A user chooses to view a summary of all expenses and balances.
2. The system calculates the total expenses, balances, and individual amounts owed.
3. The system displays the summary to the user in a tabular format.

Extensions

• 3a. The user wants to see the summary in a graphical format.
  • 3a1. The system provides a graphical representation (e.g., pie charts, bar graphs).
  • 3a2. Use case resumes from step 3.
• 3b. The user requests a filtered summary (e.g., by date or category).
  • 3b1. The system filters the summary based on the user’s input.
  • 3b2. Use case resumes from step 3.

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UC08 - Set Up Recurring Transactions

MSS

1. A user requests to add an expense as a recurring transaction with required details (e.g., frequency, start date, end date).
2. The system sets up the recurring transaction and displays a confirmation message.

Extensions

• 2a. The user requests a custom interval (e.g., bi-weekly).
  • 2a1. The system allows the user to specify a custom interval.
  • 2a2. Use case resumes from step 3.
• 2b. The user requests reminders before the transaction is processed.
  • 2b1. The system sends reminders before the recurring transaction is processed.
  • 2b2. 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 persons 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. There should be only one type of currency used in all transactions for MVP, defaulted to SGD.
5. The parameters that related to amount of currency should be dominated in dollars with at most 2 decimal places for cents, delimited by a decimal point (.).
6. The current format of the JSON format should be compatible with previous version of the software.
7. The product is used only for expense tracking and consolidation, no real world exchange of money will be carried out.
8. The user should be able to restore and use a backup save file as part of disaster recovery.
9. The user should be able to save the save file on a portable device and continue to work on the save file on another computer.

Glossary

• Mainstream OS: Windows, Linux, Unix, macOS
• Private contact detail: A contact detail that is not meant to be shared with others
• Transactions: A Transaction represents a record of a financial interaction between the user and another party (another contact). It can either be an income (positive value) or an expense (negative value).
• Balance: Refers to the net difference between the user’s total income and total expenses over a period. It can be positive, indicating a surplus, or negative, indicating a deficit.

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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 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 …​ }