DeveloperGuide.md

layout	title
page	Developer Guide

• Table of Contents {:toc}

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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

💡 Tip: The .puml files used to create diagrams in this document can be found in the diagrams folder. Refer to the PlantUML Tutorial at se-edu/guides to learn how to create and edit diagrams.

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 has two classes called Main and MainApp. It is responsible for,

• At app launch: Initializes the components in the correct sequence, and connects them up with each other.
• At shut down: Shuts down the components and invokes cleanup methods where necessary.

Commons represents a collection of classes used by multiple other components.

The rest of the App consists of 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.

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:

How the Logic component works:

1. When Logic is called upon to execute a command, it uses the AddressBookParser class to parse the user command.
2. This results in a Command object (more precisely, an object of one of its subclasses e.g., AddCommand) which is executed by the LogicManager.
3. The command can communicate with the Model when it is executed (e.g. to add a person).
4. The result of the command execution is encapsulated as a CommandResult object which is returned back from Logic.

The Sequence Diagram below illustrates the interactions within the Logic component for the execute("delete 1") API call.

ℹ️ **Note:** The lifeline for `DeleteCommandParser` should end at the destroy marker (X) but due to a limitation of PlantUML, the lifeline reaches the end of diagram.

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)

ℹ️ **Note:** An alternative (arguably, a more OOP) model is given below. It has a `Tag` list in the `AddressBook`, which `Person` references. This allows `AddressBook` to only require one `Tag` object per unique tag, instead of each `Person` needing their own `Tag` objects.

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.addressbook.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.

ℹ️ **Note:** If a command fails its execution, it will not call `Model#commitAddressBook()`, so the address book state will not 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.

ℹ️ **Note:** If the `currentStatePointer` is at index 0, pointing to the initial AddressBook state, then there are no previous AddressBook states to restore. The `undo` command uses `Model#canUndoAddressBook()` to check if this is the case. If so, it will return an error to the user rather than attempting to perform the undo.

The following sequence diagram shows how the undo operation works:

ℹ️ **Note:** The lifeline for `UndoCommand` should end at the destroy marker (X) but due to a limitation of PlantUML, the lifeline reaches the end of diagram.

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.

ℹ️ **Note:** If the `currentStatePointer` is at index `addressBookStateList.size() - 1`, pointing to the latest address book state, then there are no undone AddressBook states to restore. The `redo` command uses `Model#canRedoAddressBook()` to check if this is the case. If so, it will return an error to the user rather than attempting to perform the redo.

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:

• administrator of on-campus halls and residences
• has a need to manage a large amount of resident information
• prefer desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps

Value proposition: Manage residents' information faster than a typical mouse/GUI driven app and allow easy enforcement of Covid-19 restrictions

User stories

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

Priority	As a …​	I want to …​	So that I can…​
* * *	admin in a hall/ residence	add a resident’s information into the database	keep track of the residents' data
* * *	admin in a hall/ residence	delete a resident’s information from the database	remove the data of a resident who has moved out
* * *	admin in a hall/ residence	delete many residents in a single command	save a lot of time when deleting multiple residents
* * *	admin in a hall/ residence	edit each resident’s details	update and reflect any changes in the residents’ details
* * *	admin in a hall/ residence	edit the particulars of many residents in a single command	save a lot of time when editing the details of multiple residents
* * *	admin in a hall/ residence	view the residents’ information	see all the information of the current residents
* * *	admin in a hall/ residence	search for the residents by their name, room, email, phone number	find a resident based on the information given
* * *	admin in a hall/ residence	retrieve a list of residents in a certain faculty	easily disseminate faculty-specific information to the residents
* * *	admin in a hall/ residence	filter the residents by their vaccination status	use the information to disseminate information or guidelines that may be different for vaccinated and unvaccinated individuals
* * *	admin in a hall/ residence	retrieve all residents whose FETs that are due within a given date	ensure residents do not miss their FET deadlines by reminding them to do their FETs
* * *	admin in a hall/ residence	retrieve a resident's test kit collection deadlines	ensure residents do not miss their test kit collections by reminding them to collect their kits on time
* * *	admin in a hall/ residence	add a resident's last FET date	track and be aware of the new residents’ FET progress
* * *	admin in a hall/ residence	edit a resident's last FET date	update the current residents’ last FET dates when they take a new FET
* * *	admin in a hall/ residence	add a new event	keep track of current and upcoming events happening in the hall/ residence
* * *	admin in a hall/ residence	add residents to an event	keep track of the residents attending an event and their information
* * *	admin in a hall/ residence	view a list of residents who were present at an event	identify who is at risk if someone in the group catches COVID
* * *	admin in a hall/ residence	check the date of the events	identify who was in contact with the infected person on the day of the event
* * *	admin in a hall/ residence	view the help guide whenever I need to	refresh my memory on how to use the app
* *	admin in a hall/ residence	immediately see residents who have missed their FET deadlines	disseminate a reminder to these residents to take a new FET test
* *	admin in a hall/ residence	retrieve the event venues and its maximum capacity and the number of residents attending an event	ensure that the number of residents attending the event will not exceed the capacity of the event venue
* *	admin in a hall/ residence	retrieve the vaccination statuses of the residents attending an event	ensure that COVID restrictions are adhered to and everyone attending the event is vaccinated
* *	admin in a hall/ residence	delete an event	remove an event that has been cancelled
* *	admin in a hall/ residence	filter the residents by block and level	easily contact a group of students in order to disseminate group-specific information
* *	admin in a hall/ residence	import user data from a CSV file	input multiple residents' information into the system at once without having to add each resident's information line-by-line
*	admin in a hall/ residence	output the emails of the residents whose FET/collection are due soon into a file	disseminate information to the residents more easily
*	admin in a hall/ residence	edit an event	edit an event’s details if there are any changes
*	admin in a hall/ residence	check which CCA booked a certain facility	find out which CCA is responsible in case trouble arises
*	admin in a hall/ residence	check a resident’s prior activities (events/ CCAs)	find out which group has come into contact with the infected person
*	new user of the app	view a detailed guide on how to use basic functions	learn how to navigate within the app and use the commands
*	admin in a hall/ residence	ensure there is no duplication among the residents’ names and rooms	avoid having multiple entries of the same resident
*	admin in a hall/ residence	retrieve a list of residents in a certain CCA	easily disseminate CCA-specific information to the residents
*	admin in a hall/ residence	easily carry out contact tracing	quarantine can be done quickly in the case where one person in the group catches COVID
*	admin in a hall/ residence	see a pop-up of the format of the command once I type it	input the data in the correct format correctly on my first try

{More to be added}

Use cases

(For all use cases below, the System is the SafeFor(H)All app and the Actor is the Hall admin, unless specified otherwise)

Use case: UC01 - Delete a resident

MSS

1. Actor requests to list residents

2. System shows a list of residents

3. Actor requests to delete a specific resident in the list

4. System deletes the resident

   Use case ends.

Extensions

• 2a. The list is empty.

  Use case ends.

• 3a. The given index is invalid.

  • 3a1. System shows an error message.

    Use case resumes at step 2.

Use case: UC02 - Remind residents to take FET

MSS

1. Actor filters residents, specifying desired FET due date.

2. System shows the list of residents filtered.

3. Actor requests for a list of the email addresses of the residents shown.

4. System outputs the list email addresses.

5. Actor sends an email to these residents to remind them to take their FET soon.

   Use case ends.

Extensions

• 2a. The list is empty.

  Use case ends.

Use case: UC03 - View residents involved in an event

MSS

1. Actor navigates to the events tab of the application.

2. Actor requests to view an event.

3. System shows the list of residents involved in the event and their relevant personal information.

   Use case ends.

Extensions

• 3a. The list is empty.

  Use case ends.

Use case: UC04 - View any unvaccinated residents involved in an event

MSS

1. Actor views residents involved in an event (UC03)

2. Actor filters for unvaccinated residents.

3. System shows the list of unvaccinated residents.

   Use case ends.

Extensions

• 3a. The list is empty.

  Use case ends.

{More to be added}

Non-Functional Requirements

1. Should work on any mainstream OS as long as it has Java 11 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. Should be targeted towards a single user and not multi-users.
5. Data stored locally should be in a human editable text file.
6. Do not make use of a DBMS to manage data.
7. Final software should be platform-independent.
8. The software shouldn't depend on our own remote server.
9. Application is to be packaged into a single JAR file.
10. JAR file size to be limited to 100MB and documents to 15MB/file.
11. UG and DG are to be pdf-friendly.

Glossary

• Mainstream OS: Windows, Linux, Unix, OS-X
• 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.

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

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 …​ }