The Sharkives Developer Guide

Table of Contents

1. Acknowledgements
2. Setting up, getting started
3. Design
   • Architecture
   • UI component
   • Logic component
   • Model component
   • Storage component
   • Common classes
4. Implementation
   • Add loan feature
   • Payment feature
5. Documentation, logging, testing, configuration, dev-ops
6. Appendix: Requirements
   • Product scope
   • User stories
   • Use cases
   • Non-Functional Requirements
   • Glossary
7. Appendix: Instructions for Manual Testing
8. Appendix: Effort

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Acknowledgements

• SE-Education's AddressBook Level-3, upon which this is built on.

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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 client).
   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.

The following classes were added to support new commands:

• PayCommand and PayCommandParser
• SortCommand and SortCommandParser
• FilterLoanCommand and FilterLoanCommandParser
• DeleteLoanCommand, with DeleteCommandParser updated to return either a DeleteCommand or DeleteLoanCommand

Each new command follows the Command design pattern and extends the abstract Command class.

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.

Add loan feature

Implementation

The loan feature is facilitated by Loanlist, which contains an ArrayList<Loan> that stores the loan list, along with several related methods. Each Person has a LoanList, which contains the loans that have been made to them. Thus, the following classes were created:

• Loan  —  an abstract class that dictates what a Loan class should do and contain.
• SimpleInterestLoan and CompoundInterestLoan, each representing their respective loan type, with different calculations for interest and amount owed.
• LoanCommandParser, which implements Parser. It is passed the arguments from a loan command by the Ui, and in turn generates a LoanCommand object.
• LoanCommand  — , which inherits from Command. When executed, it creates a new loan based on the arguments (if they are all valid), and adds it to the LoanList of a specified Person.

Below is the class diagram showing Loan and its child classes:

Given below is an example usage scenario and how the loan feature behaves at each step.

Step 1. The user adds a Person to Sharkives using an add command.

Step 2. The user uses the loan command to add a loan to that Person (e.g., loan 1 s 1000.00 5.5 2030-12-31).

Step 3. This input is read as a loan command, and the Ui creates a LoanCommandParser object with the args from the command.

Step 4. When parse() is called, it matches the args to a validation regex, which makes sure that the number of arguments and their format is as specified.

Note: Any malformed command causes a ParserException to be thrown, which informs the user that their format is wrong, and the correct usage of the command.

Step 5. Then, these args are split and passed to LoanCommand, which processes and stores these args.

Step 6. execute() in LoanCommand is called, which in turn creates a Loan object based on the provided args and then adds it to the specified person's LoanList.

Design considerations:

• Although the add command uses predicates (e.g. n/, e/), we elected not to use those as having too many predicates would be confusing to the user, and unnecessarily wordy for a relatively shorter command. In addition, none of these arguments are optional.
• As each person has a has-a relationship with loans, we modeled this by making LoanList a new field in each Person, which is initiated empty.

Payment feature

Implementation

The Payment feature is facilitated by LoanList, as described previously. Additionally, it adds the following classes:

• PayCommand  —  a Command class that inherits from Command and implements all of its methods
• PayCommandParser  —  a Parser class that implements Parser and returns a PayCommand

The PayCommand class features an overloaded constructor which supports 3 different ways to pay for a loan - amount, months' worth of instalments, and all at once. A pay command (e.g., pay 1 2 100.00) is parsed by PayCommandParser, which chooses the appropriate constructor and returns a PayCommand object.

The below image illustrates the above relationship:

Given below is an example usage scenario and how the Pay feature behaves at each step.

Step 1. The user creates a loan (e.g., loan 1 s 1000 5.5 2025-12-31) for an existing Person, adding it to their LoanList.

Step 2. The loanee makes a payment, which is recorded by the user using the pay command (e.g., pay 1 1 50.00).

Step 3. The command is read and sent to PayCommandParser, which splits the arguments up. It then looks at the 3rd argument (i.e., 50.00) and sees that it is a float that contains neither M or is all.

Step 4. PayCommandParser chooses the constructor of PayCommand that takes a float as the third argument, and returns the PayCommand.

Step 5. The PayCommand is executed, which looks at the first argument, the index of the loanee who paid, and calls the pay() method in their Person object. This in turn calls the pay() method in their LoanList, which gets the appropriate Loan (from the second argument) and pays the specified amount to it.

Step 6. Assuming no errors occur (such as the amount being more than the remainder owed), the amount is added to amtPaid field in the loan (instead of being deducted directly, which helps with flexible loan repayment calculations) and the remaining owed is updated based on the principal, interest rate, time passed, and amount already paid.

Note: If either index is out-of-bounds, PayCommandParser throws the corresponding ParserException. If the amount exceeds the amount remaining, PayCommand throws the corresponding CommandException.

Note: Other scenarios such as a malformed command or negative values is covered by the validation regex, which ensures that the command follows the specified format.

Design considerations:

• For Compound Interest, a flexible payment schedule (like the one we have implemented) greatly complicates calculations, as early payments can reduce principal earlier and thus overall interest, vice versa. In addition, allowing flexible payments can change the effective interest rate.
• Proposed Extension: allowing the user to choose between a fixed monthly plan and flexible repayment would be a future feature that could alleviate this problem.

[Proposed] Undo/redo feature

Proposed Implementation

The proposed undo/redo mechanism is facilitated by VersionedSharkives. It extends The Sharkives with an undo/redo history, stored internally as an SharkivesStateList and currentStatePointer. Additionally, it implements the following operations:

• VersionedSharkives#commit() — Saves the current address book state in its history.

• VersionedSharkives#undo() — Restores the previous address book state from its history.

• VersionedSharkives#redo() — Restores a previously undone address book state from its history.

These operations are exposed in the Model interface as Model#commitSharkives(), Model#undoSharkives() and Model#redoSharkives() 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 VersionedSharkives 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#commitSharkives(), causing the modified state of the address book after the delete 5 command executes to be saved in the SharkivesStateList, 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#commitSharkives(), causing another modified address book state to be saved into the SharkivesStateList.

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#undoSharkives(), which will shift the currentStatePointer once to the left, pointing it to the previous state, and restores The Sharkives 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#redoSharkives(), 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#commitSharkives(), Model#undoSharkives() or Model#redoSharkives(). Thus, the SharkivesStateList remains unchanged.

Step 6. The user executes clear, which calls Model#commitSharkives(). Since the currentStatePointer is not pointing at the end of the SharkivesStateList, 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}

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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:

• licenced moneylender with a significant number of clients
• needs to keep track of client contacts
• needs to keep track of clients' loans
• prefers desktop apps over other types
• prefers typing input on CLI to mouse interactions

Value proposition: manage client contacts and loans faster than a typical mouse/GUI driven app

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 Sharkives and the Actor is the user, unless specified otherwise)

Use case UC01: Add a client

MSS

1. User requests to add a client and his details to the list
2. The Sharkives adds the person

Use case ends.

Extensions

• 1a. The given input is invalid

  • 1a1. The Sharkives shows an error message.

    Use case resumes at step 1

Use case UC02: Delete a client

MSS

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

2. The Sharkives deletes the client

   Use case ends.

Extensions

• 1a. The given index is invalid.

  • 1a1. The Sharkives shows an error message.

    Use case resumes at step 1.

Use case UC03: Edit a client

MSS

1. User requests an amendment to an existing entry in the list

2. The Sharkives updates the client details

   Use case ends.

Extensions

• 1a. The given index or client details are invalid.

  • 1a1. The Sharkives shows an error message.

    Use case resumes at step 1.

Use case UC04: Add a loan for a client

MSS

1. User requests to add a loan to a specific client in the list

2. The Sharkives adds a loan entry to the client

   Use case ends.

Extensions

• 1a. The given index or loan details are invalid.

  • 1a1. The Sharkives shows an error message.

    Use case resumes at step 1.

Use case UC05: Delete a loan for a client

MSS

1. User requests to delete a loan to a specific client in the list

2. The Sharkives removes the loan entry to the client

   Use case ends.

Extensions

• 1a. The given index of client or loan are invalid.

  • 1a1. The Sharkives shows an error message.

    Use case resumes at step 1.

Use case UC06: Filter loans

MSS

1. User requests to filter loans based on a specified predicate.

2. The Sharkives shows only the loans that fit the specified predicate.

3. User clears filter.

4. The Sharkives shows all the loans again in their default order.

   Use case ends.

Extensions

• 1a. The predicate specified is invalid.

  • 1a1. The Sharkives shows that it did not filter by any predicate, and maintains the default view.

    Use case resumes at step 1.

Use case UC07: Sort loans

MSS

1. User requests to sort by a parameter in a specified order.

2. The Sharkives sorts and orders the clients based on the parameter in the specified order.

   Use case ends.

Extensions

• 1a. The user neglects to specify any arguments.

  • 1a1. The Sharkives defaults to ordering the clients in descending order based on amount.

    Use case ends.

• 1b. The parameter or order is invalid.

  • 1b1. The Sharkives shows an error message.

    Use case resumes at step 1.

{More to be added}

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.

{More to be added}

Glossary

• Mainstream OS: Windows, Linux, Unix, MacOS
• Private contact detail: A contact detail that is not meant to be shared with others
• Simple Interest Loan: A loan that accrues interest based on the principal only
• Compound Interest Loan: A loan that accrues interest based on the principal and any previously accrued interest.
• Args: Short-form for arguments, referring to the components of a command necessary for it to work as specified. These include parameters such as indices, and amount.

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Appendix: Instructions for Manual Testing

Given below are instructions to test the app manually.

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

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Launch and Shutdown

Initial Launch

1. Download the .jar file and place it in an empty folder.
2. Double-click the .jar file. Expected: The app launches with a sample list of persons. The window may not be optimally sized.

Saving Window Preferences

1. Resize and reposition the window to a new location.
2. Close the window and re-launch the .jar file. Expected: The most recent window size and location are retained.

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Deleting a Person

While all persons are shown

1. Prerequisite: Run the list command to display all persons. Ensure there are at least 2 persons in the list.
2. Test case: delete 1 Expected: First person in the list is deleted. Status message displays deleted contact details. Timestamp updates.
3. Test case: delete 0 Expected: No person is deleted. Error message is shown. Status bar remains unchanged.
4. Test case: delete Expected: Error message for missing index.
5. Test case: delete x (where x is larger than the list size) Expected: Error message for invalid index.

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Saving Data

Missing or Corrupted Data File

1. Locate the data/AddressBook.json file and rename/delete it while the app is closed.
2. Re-launch the app. Expected: A new data file is generated with sample data, or an appropriate error message is shown.
3. Alternatively, open AddressBook.json and modify it to an invalid JSON format (e.g., remove a closing brace).
4. Re-launch the app. Expected: App shows error message about corrupted data and starts with an empty dataset.

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Sort Command

1. Test case: sort Expected: List is sorted with overdue loans at the top, followed by others in descending order of loan amount.
2. Test case: sort extraArg Expected: Error message for invalid command format.

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Filter Loan Command

1. Test case: filter pred/ isPaid n in person list page Expected: All persons are still shown, loans under each person will only show unpaid loans
2. Test case: filter 3 pred/ amount > 500 pred/ loanType s in person 3's page Expected: Under person 3, loan list shows only the simple interest loans with amount remaining owed > $500.
3. Test case: filter abc Expected: Input is accepted, however loans are shown as if not filtered.

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Loan Command

1. Test case: loan 1 s 1000.00 5.5 2030-12-31 Expected: First person in list has a simple interest loan with principal 1000.00, interest rate 5.5, and due date 2030-12-31 added to their loan list.
2. Test case: loan 1 c 1000.00 5.5 2030-12-31 Expected: First person in list has a compound interest loan with principal 1000.00, interest rate 5.5, and due date 2030-12-31 added to their loan list.
3. Test case: loan 0 s 1000.00 5.5 2030-12-31 Expected: Error message: Index is not a non-zero unsigned integer.
4. Test case: loan abc Expected: Error message indicating invalid command format with correct usage.

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Pay Command

Prerequisites:

• At least one person in person list
• First person must have at least one loan (add via loan 1 s 1000.00 5.5 2030-12-31 if needed)

1. Test case: pay 1 1 100.00
   Expected:

   • First loan of first person is reduced by $100.00
   • Status message shows payment confirmation
   • Updated loan details visible in person's profile

2. Test case: pay 1 1 2M
   Expected:

   • First loan is reduced by 2 months worth of payments
   • Detailed loan information shows updated installment schedule

3. Test case: pay 1 1 all
   Expected:

   • Loan is fully paid and removed automatically from the person's loan list

4. Test case: pay 0 1 100.00
   Expected:

   • Error: Index is not a non-zero unsigned integer.
   • No changes to any loans

5. Test case: pay 1 1 0.00
   Expected:

   • Error: The amount must be a positive number.
   • No balance changes

6. Test case: pay 1 1 9999.00 (when balance < $9999)
   Expected:

   • Error: Payment exceeds the remaining owed!
   • No balance changes

Appendix: Effort

Our team of 5 spent significant effort extending the base AB3 functionality into a financial loan tracking application.

Challenges:

• Implementing accurate logic for compound vs. simple interest, especially across multiple repayments
• Designing a flexible Loan model to support filtering, sorting, payment tracking
• Maintaining UI consistency while adding new fields (e.g., status, amounts)
• Managing state updates in ModelManager to ensure correct ObservableList behavior
• Designing UI to make sure home screen is not too cluttered while showing necessary information.

Achievements:

• Built fully functional loan, delete loan, pay, filterLoan, and sort commands
• Enhanced UI responsiveness and modularity
• 0 reused code: All logic and data structures were built from scratch
• Edited existing code to fit our requirements
• Completely revamped and customized UI to fit our theme

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