TheTracker - Developer Guide

By: Team W10-01 Since: Aug2018 Licence: MIT

1. Introduction
2. Setting up
3. Design
4. Implementation
5. Documentation
6. Testing
7. Dev Ops
Appendix A: Suggested Programming Tasks to Get Started
- A.1. Improving each component
- A.2. Creating a new command: remark
Appendix B: Product Scope
Appendix C: User Stories
Appendix D: Use Cases
Appendix E: Non Functional Requirements
Appendix F: Glossary
Appendix G: Instructions for Manual Testing

1. Introduction

TheTracker is a Java application that serves as an organiser for NUS students. It allows them to keep track of their contacts, modules and events in a single app. A basic set of operations is supplied for users to update and modify entries from these three lists. Additionally, users can add contacts to modules and occasions (and vice versa).

TheTracker is optimised for NUS students who are comfortable using a Command Line Interface (CLI). Nevertheless, basic Graphical User Interface (GUI) functionalities are also available.

This Developer Guide contains a broad overview of TheTracker. The implementation key features will be discussed, as well as the general software architecture. By reading through this guide, you should be able to modify the codebase yourself.

2. Setting up

This section explains how to set-up TheTracker’s codebase on your computer.

2.1. Prerequisites

Before proceeding, ensure that the following are correctly installed on your computer: . JDK 9 or later

JDK 10 on Windows will fail to run tests in headless mode due to a JavaFX bug. Windows developers are highly recommended to use JDK 9.

IntelliJ IDE

IntelliJ by default has Gradle and JavaFx plugins installed.
Do not disable them. If you have disabled them, go to File > Settings > Plugins to re-enable them.

2.2. Setting up the project in your computer

To setup and configure TheTracker on your computer, do the following steps in order:

Fork this repo, and clone the fork to your computer
Open IntelliJ (if you are not in the welcome screen, click File > Close Project to close the existing project dialog first)
Set up the correct JDK version for Gradle
1. Click Configure > Project Defaults > Project Structure
2. Click New… and find the directory of the JDK
Click Import Project
Locate the build.gradle file and select it. Click OK
Click Open as Project
Click OK to accept the default settings
Open a console and run the command gradlew processResources (Mac/Linux: ./gradlew processResources). It should finish with the BUILD SUCCESSFUL message.
This will generate all resources required by the application and tests.

2.3. Verifying the setup

To verify that you have TheTracker correctly setup:

Run the seedu.address.MainApp and try a few commands
Run the tests to ensure they all pass.

2.4. Configurations to do before writing code

2.4.1. Configuring the coding style

This project follows oss-generic coding standards. IntelliJ’s default style is mostly compliant with ours but it uses a different import order from ours. To rectify,

Go to File > Settings… (Windows/Linux), or IntelliJ IDEA > Preferences… (macOS)
Select Editor > Code Style > Java
Click on the Imports tab to set the order
- For Class count to use import with '*' and Names count to use static import with '*': Set to 999 to prevent IntelliJ from contracting the import statements
- For Import Layout: The order is import static all other imports, import java.*, import javax.*, import org.*, import com.*, import all other imports. Add a <blank line> between each import

Optionally, you can follow the UsingCheckstyle.adoc document to configure Intellij to check style-compliance as you write code.

2.4.2. Updating documentation to match your fork

After forking the repo, links in the documentation will still refer to the CS2103-AY1819S1-W10-1/main repo.

If you plan to develop this fork as a separate product (i.e. instead of contributing to CS2103-AY1819S1-W10-1/main), you should do the following:

Configure the site-wide documentation settings in build.gradle, such as the site-name, to suit your own project.
Replace the URL in the attribute repoURL in DeveloperGuide.adoc and UserGuide.adoc with the URL of your fork.

2.4.3. Setting up CI

Set up Travis to perform Continuous Integration (CI) for your fork. See UsingTravis.adoc to learn how to set it up.

After setting up Travis, you can optionally set up coverage reporting for your team fork (see UsingCoveralls.adoc).

Coverage reporting could be useful for a team repository that hosts the final version but it is not that useful for your personal fork.

Optionally, you can set up AppVeyor as a second CI (see UsingAppVeyor.adoc).

Having both Travis and AppVeyor ensures your App works on both Unix-based platforms and Windows-based platforms (Travis is Unix-based and AppVeyor is Windows-based)

2.4.4. Getting started with coding

When you are ready to start coding,

Get some sense of the overall design by reading Section 3.1, “Architecture”.
Take a look at Appendix A, Suggested Programming Tasks to Get Started.

3. Design

3.1. Architecture

Figure 1. Architecture Diagram

The Architecture Diagram given above explains the high-level design of the App. Given below is a quick overview of each component.

The .pptx files used to create diagrams in this document can be found in the diagrams folder. To update a diagram, modify the diagram in the pptx file, select the objects of the diagram, and choose Save as picture.

Main has only one class called 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 method where necessary.

Commons represents a collection of classes used by multiple other components. Two of those classes play important roles at the architecture level.

EventsCenter : This class (written using Google’s Event Bus library) is used by components to communicate with other components using events (i.e. a form of Event Driven design)
LogsCenter : Used by many classes to write log messages to the App’s log file.

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.

Each of the four components

Defines its API in an interface with the same name as the Component.
Exposes its functionality using a {Component Name}Manager class.

For example, the Logic component (see the class diagram given below) defines it’s API in the Logic.java interface and exposes its functionality using the LogicManager.java class.

Figure 2. Class Diagram of the Logic Component

Events-Driven nature of the design

The Sequence Diagram below shows how the components interact for the scenario where the user issues the command delete 1.

Figure 3. Component interactions for delete 1 command (part 1)

Note how the Model simply raises a AddressBookChangedEvent when the Address Book data are changed, instead of asking the Storage to save the updates to the hard disk.

The diagram below shows how the EventsCenter reacts to that event, which eventually results in the updates being saved to the hard disk and the status bar of the UI being updated to reflect the 'Last Updated' time.

Figure 4. Component interactions for delete 1 command (part 2)

Note how the event is propagated through the EventsCenter to the Storage and UI without Model having to be coupled to either of them. This is an example of how this Event Driven approach helps us reduce direct coupling between components. The sections below give more details of each component.

3.2. UI component

Figure 5. Structure of the UI Component

API : Ui.java

The MainWindow is made up of parts e.g.CommandBox, ResultDisplay, PersonListPanel, StatusBarFooter, BrowserPanel etc. All these, including the MainWindow, inherit from the abstract UiPart class.

The UI component uses 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.
Binds itself to some data in the Model so that the UI can auto-update when data in the Model change.
Responds to events raised from various parts of the App and updates the UI accordingly.

3.3. Logic component

Figure 6. Structure of the Logic Component

API : Logic.java

Logic uses the AddressBookParser class to parse the user command.
This results in a Command object which is executed by the LogicManager.
The command execution can affect the Model (e.g. adding a person) and/or raise events.
The result of the command execution is encapsulated as a CommandResult object which is passed back to the Ui.

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

Figure 7. Interactions Inside the Logic Component for the delete 1 Command

3.4. Model component

Figure 8. Structure of the Model Component

API : Model.java

The Model,

stores a UserPref object that represents the user’s preferences.
stores TheTracker data.
exposes 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.
does not depend on any of the other three components.

As a more OOP model, we can store a Tag list in Address Book, which Person can reference. This would allow Address Book to only require one Tag object per unique Tag, instead of each Person needing their own Tag object. An example of how such a model may look like is given below.

3.5. Storage component

Figure 9. Structure of the Storage Component

API : Storage.java

The Storage component,

can save UserPref objects in json format and read it back.
can save the Address Book data in xml format and read it back.

3.6. Common classes

Classes used by multiple components are in the seedu.addressbook.commons package.

4. Implementation

This section describes some noteworthy details on how certain features are implemented.

4.1. Dependencies between Persons, Modules and Occasions

TheTracker is an extended address book application. In addition to supporting basic address book features for Person, these features are also made available for Module and Occasion. As a result, TheTracker to be able to track the modules a person takes, as well as the occasions he participates in.

4.1.1. Current Implementation

To facilitate this the underlying structure of Person, Module and Occasion have to be linked in a manner that will facilitate injections of one entity bi-directionally into another. The following class diagram depicts this structure:

Of course, each of the three entities will then have their own independent fields as well.

Below are the class diagrams or Person, Module and Occasion. For simplicity consideration, we divide the class diagrams in three separate ones.

Class Diagram for Person:

Class Diagram for Module:

Class Diagram for Occasion:

4.1.2. Design Considerations

Aspect: Implementation of Dependencies

Alternative 1 (current choice): Have 3 separate classes for Person, Module and Occasion
- Pros: Each class can be designed specifically to accommodate suitable fields
- Cons: Some code duplication in similar methods
Alternative 2: Have a parent Entity class, with all three classes inheriting from it
- Pros: Polymorphism can be implemented for similar methods
- Cons: Difficulty in implementation, (e.g. UniqueEntityList must be implemented in the model and EntityCard, EntityListPanel in the UI).
Decision: Alternative 1 was adopted, as the 3 classes do not have the exact same features. For example, a Person has 2 separate lists of Modules and Occasions respectively, but a Module or Occasion only contains a Person list.

4.2. Duplication of Entities

To facilitate the ease of implementation of the following features, two important methods were conceived off: makeDeepDuplicate and makeShallowDuplicate. These two helper methods allow a Person, Module and Occasion within TheTracker to be copied in a different manner. The following image is a depiction of how makeDeepDuplicate works when it is called on a Person:

As can be seen from the above image makeDeepDuplicate creates a replica of a Person such that the respective Modules within the UniqueModuleList and the Occasions within the UniqueOccasionList are also DeepDuplicated.

The following image depicts how makeShallowDuplicate works when it is called on a Person within TheTracker:

As can be seen from the above image makeShallowDuplicate creates a replica of a Person such that the respective UniqueModuleList and UniqueOccasionList are empty.

4.3. Updating of Lists

When executing commands for a particular type of entry, another type of entry can modified.

Naturally, insertperson and removeperson will affect a person and a module/occasion.
However, both edit and delete also can affect multiple types of entries.

If an entry is edited, all linked entries should reflect the changes accordingly.
If an entry is deleted, all linked entries should remove this entry from their list.

4.3.1. Current Implementation

To facilitate the execution of undo and redo, a new replacement person, module or occasion is created to replace the original entry. By avoiding modification of these entries, previous versions of the ReadOnlyAddressBook will not be incorrectly modified.

Currently, a list only stores a copy of the desired entries, instead of the actual entries.

Suppose that a person needs to be edited/deleted. Then correctly implementing any of these commands requires 3 stages:

Locate all linked modules and occasions
Replace each module and occasion with an updated version
Edit/Delete the person

Methods for the implementation of 1 and 2 are contained in the AttendanceListUtil class.
The code snippets below are extracted with slight modifications, and are used to perform 1 and 2 by updating the person lists in modules after deleting a Person.

while (moduleListIterator.hasNext()) {
    Module module = moduleListIterator.next();
    module.getStudents()
            .asNormalList()
            .stream()
            .filter(person -> person.isSamePerson(personToRemove))
            .findFirst()
            .ifPresent(removePersonFromModule(model, module));
}

The above loop iterates through all modules.
For each module, it filters through its studentList to determine whether it should be edited.
If so, the person is removed from the module.

private static Consumer<Person> removePersonFromModule(Model model, Module module) {
    return person -> {
        List<Person> updatedPersons = module.getStudents().makeShallowDuplicate().asNormalList();
        updatedPersons.remove(person);
        UniquePersonList updatedPersonList = new UniquePersonList(updatedPersons);
        ModuleDescriptor updatedModuleDescriptor = new ModuleDescriptor();
        updatedModuleDescriptor.setStudents(updatedPersonList);
        Module updatedModule = Module.createEditedModule(module, updatedModuleDescriptor);
        model.updateModule(module, updatedModule);
    };
}

In turn, removing a person from a module is done by creating a new list of persons, excluding the one pending deletion.
A new module is then created based on the original module and this new list.
Finally, the new module replaces the original module in the model.

Similar implementations are used for both delete and edit in the various combinations of entries and lists.

4.4. Add Person/Module/Occasion Feature

The add feature is currently implemented the same way to add persons, modules and occasions. There are thus three similar commands which are related to this add command: addperson, addmodule, addoccasion.

The add command adds the entity (person, module, occasion) with the attributes / fields provided by the user.

4.4.1. Current Implementation

As the addperson, addmodule, addoccasion commands' logic are similar to one another, the addperson command will be taken as the sole example in this document.

AddPersonCommand extends the Command class and uses inheritance to facilitate implementation. Its mechanism is facilitated by VersionAddressBook. In addition, it implements the following operations: * VersionedAddressBook#addPerson(Person): Update the targetedPerson with edited fields * VersionedAddressBook#commit(): Saves the current book state in the command history

Provided below is a usage scenario instance. It illustrates how the add mechanism behaves at each step.

Step 1: The user launches TheTracker for the first time. The VersionedAddressBook will be initialised with the initial address book state, which the currentStatePointer is currently pointing to.

Step 2: The user executes addperson n/David… command to add a person named David in his TheTracker. The addperson string input in the command line is passed into the AddressBookParser object, which parses the input and creates an AddPersonCommandParser to help it further parse the argument. This AddPersonCommandParser creates a Person with the Compulsory attribute Name, and optional fields Phone, Email, Address and Tag as provided by the user and passes this person to be added to a new AddPersonCommand. The addPersonCommand calls Model#addPerson(), thus adding the new Person into the versionedAddressBook. The addperson command then calls Model#commitAddressBook(), causing the modified state of TheTracker after the addperson n/ David… command executes to be saved in the addressBookStateList.

The following sequence diagram shows how the addperson operation works: addperson n/David

addmodule and addoccasion works in a similar way as addperson

4.4.2. Design Considerations

Aspect: How addperson/addmodule/addoccasion executes

Alternative 1 (Current Implementation): AddPersonCommand, AddModuleCommand and AddOccasionCommand require users to input only one compulsory attribute, and may also add any number of optional attributes.
- E.g. addperson n/David, addmodule mc/CS2103, addoccasion on/project meeting are the easiest way to add a person, module and occasion
- Pros: This is more user friendly, such that users can add a contact even they only know the name of the contact. And, they can input details of that contact if needed.
- Cons: This may be hard for the storage of TheTracker, and needs to work compatibly with other features.
Alternative 2: AddPersonCommand, AddModuleCommand and AddOccasionCommand require users to input all pre-defined attributes.
- Pros: Easy to implement.
- Cons: Less flexible, such that users cannot add in a contact with some details they do not know.

4.5. Find Person/Module/Occasion Feature

The find feature currently is implemented the same way to find persons, modules, and occasions. There are thus three similar commands which are related to this find command: findperson, findmodule, and findoccasion.

The find command family finds the entity (person, module, occasion), based on their attributes / fields.

The figure below shows how the find command is processed through the logic of TheTracker:

4.5.1. Current Implementation

As the findperson, findmodule, and findoccasion commands' logic are similar to one another, the findperson command will be taken as the sole example in this document. The findperson string input in the command line is passed into the AddressBookParser object, which parses the input and creates a FindPersonCommandParser to help it further parse the argument and create a FindPersonCommand. This FindPersonCommand filters the entire person list based on the keyword in the specific field stipulated and updates the Address Book Model to create an Observable List of persons based on the filter specified.

4.5.2. Design Considerations

Aspect: How find executes

Alternative 1 (current choice): Match full keyword.
- E.g. If there is a person named "Alex", only the command findperson n/alex will find the person. findperson n/ale will not find the person.
- Pros: Very target and precise finding of person.
- Cons: Cannot find parts of the person’s attributes especially if user cannot remember full attribute name, title, etc.
Alternative 2: Match keyword to part of the attribute.
- E.g. If there is a person named "Alex", the commands findperson n/e, findperson n/ex, findperson n/le, findperson n/alex will find the person.
- Pros: Can find multiple entries of persons with keyword in name.
- Cons: May not limit the search of persons, hard to pinpoint exact person.

4.6. Select Person/Module/Occasion Feature

The select feature currently is implemented the same way to select persons, modules, and occasions. Currently, the select feature selects by index in the observed list which has been loaded into the UI.

4.6.1. Current Implementation

The select string command input in the command line is passed into the AddressBookParser object, which parses the input and creates a SelectCommandParser to help it further parse the argument and create a SelectCommand object. This SelectCommand then takes the current list available, takes its size, and tells the EventCenter to post a new event of jumping to the current index of the currently shown list in the UI, by posting a new JumpToListRequestEvent.

4.7. Edit Person/Module/Occasion Feature

edit is a basic feature for TheTracker.
It supports editing of Person, Module and Occasion by command editperson, editmodule and editoccasion respectively.

4.7.1. Current Implementation

The following section will use EditPersonCommand as an example to explain the implementation. EditModuleCommand and EditOccasionCommand use the same mechanism as EditPersonCommand.

EditPersonCommand extends the Command class and uses inheritance to facilitate implementation. It’s mechanism is facilitated by VersionAddressBook. In addition, it implements the following operations:

VersionedAddressBook#commit(): Saves the current book state in the command history
VersionedAddressBook#updatePerson(target, editedPerson): Update the targetedPerson with edited fields
ModelManager#updateFilteredPersonList(Predicate<Person> predicate): Returns an unmodifiable view of the list of Person backed by the internal list of VersionedAddressBook

These operations are exposed in the Model interface as Model#commitAddressBook(), Model#updatePerson(target, editedPerson) and Model#updateFilteredPersonList(Predicate<Person> predicate) respectively.

The following sequence diagram shows how the editperson operation works: editperson 6 p/91234567 e/johndoe@example.com

editmodule and editoccasion works in a similar way as editperson

The mechanism for modifying edit commands to fit insert commands is similiar to and explained in delete command

4.7.2. Design Considerations

Aspect: How editperson/editmodule/editoccasion executes

Alternative 1 (Current Implementation): EditPersonCommand, EditModuleCommand and EditOccasionCommand are three separate classes
- Pros:
  - Implementation is easy to understand
  - Easy to manage the three entity lists
- Cons:
  - Lack of the essence of polymorphism, which is a key feature in OOP
Alternative 2 : Let EditPersonCommand, EditModuleCommand and EditOccasionCommand inherits from EditCommand, then use TypeUtil to detect the kind of entity that is going to be edited
- Pros:
  - A good utilisation of polymorphism
- Cons:
  - Person, Module, Occasion are three relatively independent entities, it could be hard to handle when using polymorphism and put everything together

4.8. InsertPerson feature

The InsertPerson command is an advanced feature for TheTracker. It enables a bi-directional insert of a Person into either one of a module or an occasion.

4.8.1. Current Implementation

For the following example we will use InsertPerson command to insert a person, bi-directionally, into a module. The usage for a bi-directional insert into an occasion is similar.

InsertPerson command extends the Command class and uses inheritance to facilitate implementation. It’s mechanism is facilitated by VersionAddressBook. Below is the associated sequence diagram for the InsertPerson command:

When the user first opens up TheTracker it loads up an instance of a VersionAddressBook and initializes the currentStatePointer to point at this instance of the TheTracker. When the user then executes the InsertPerson command an entirely new copy of the state of TheTracker is created and inserted as a new VersionAddressBook with the currentStatePointer being updated. Below is a diagram that depicts this:

The following steps represent the internal implementation of the InsertPerson command when inserting a Person into a Module:

Create a DeepDuplicate and a ShallowDuplicate of the Both the Person and the Module
Insert the ShallowDuplicate of the module into the DeepDuplicate of the Person’s UniqueModuleList
Insert the ShallowDuplicate of the person into the DeepDuplicate of the Module’s UniquePersonsList

Note: Further elaboration of the above implementation is discussed within the Design Considerations section.

4.8.2. Design Considerations

Why it is non-trivial:

For the feature to work coherently with undo/redo as well as edit an entire new replica of state of TheTracker must be created with the relevant entities bi-directionally inserted after this command has been executed.

We cannot, however, make do with only makeDeepDuplicate in order to implement the InsertPerson feature. The following scenario illustrates why:

Insertion of Person x into Occasion y would cause x’s occasion list to be populated by y and y’s person list to be populated by x
Insertion of Person x into Module z would cause x’s module list to be populated by z and z’s person list to be populated by x. But if we insert a deep copy of x into z this would entail us replicating y, which would entail us replicating the person list of y and, thus, x and so the program will halt in an infinite regress until a StackOverFlow is thrown.

To avoid the above error, upon insertion of a Module into a Person the respective Module’s ShallowDuplicate is inserted.

4.9. RemovePerson Feature

The removeperson command is a complementary feature to the insertperson command. It enables the removal of a Person from either a Module students list or an Occasion attendance list. This thus means that the module or occasion will be removed from the respective list that the Person carries. The activity diagram below illustrates what happens when removeperson is called:

4.9.1. Current Implementation

Currently, removeperson creates a whole new copy of the Person, and a whole new copy of the Module to replace. The difference with the copy and the original is that their internal elements contain one less element, and the new copy is populated with shallow duplicates.

A shallow duplicate is a copy but with an empty internal list. For example, a shallow duplicate of Person contains an empty module list and empty occasion list. A shallow duplicate of Module contains an empty students list.

The reason why this is done will be explained in the design considerations below.

4.9.2. Design Considerations

For this feature to be possible, it has to be possible to somehow remove the link between said Person and Module/Occasion. The link (or pointer) to the objects can be best illustrated in the class diagram below:

As seen, the Person class is associated with the Module class and the Occasion class as Person stores a list of modules and occasions. A person can thus have associations with multiple modules and occasions. This relationship is bidirectional as a Module can have associations with multiple persons. This is the same for occasions with persons. There is no association between Module and occasion. Thus, the relationships between Person and module, & Person and occasion are bidirectional.

Let us take an example of a Person associated with many modules, and vice versa. A possible implementation of the removeperson feature may be to remove the pointers between said Person and the corresponding Module in mind. However, this is not feasible in TheTracker due to our implementation of VersionedAddressBook. TheTracker keeps various states of itself and its components after every command which changes an object. Below is a simple state list diagram of the VersionedAddressBook:

When the user first opens up TheTracker, an instance of the VersionedAddressBook is opened and the currentStatePointer points to instance 1 as shown in the diagram. When the user changes the person object, an entirely new copy of the state of TheTracker is created and inserted as a new VersionedAddressBook with currentStatePointer being updated.

As removing a pointer from an object does not entail changing an attribute inside the object, a brand new object has to be created for every instance when removeperson is called. This would enable the removeperson command to be compatible with undo and redo which use the different VersionedAddressBook to complete the job.

This new object would have to be fundamentally almost an exact replica of the old object, with the only difference being the internal lists of modules Person keeps or internal lists of persons Module keeps. However, let us take an example Person who is linked to several Modules. If this Person severs links with a Module, and a new list is created (only without said Module), this means that the list will try to add the other Modules into itself. These other Modules already contain an old instance of this Person, but their lists will also have to be updated with the new Person, which is adding these Modules in the first place! This creates an infinite recursive loop.

To mitigate this problem, we had to make a shallow duplicate of the Person / Module / Occasion (with an empty list to prevent infinite recursion), and put in a complete duplicate (we named it deep duplicate) when repopulating the internal list of Person / Module / Occasion.

4.10. List feature

The list feature acts as a switching between the lists of Person, Module, Occasion. In essence, it acts as a context switch between the 3.

4.10.1. Current Implementation

Currently, the list command will raise a context switch event, a ShowPersonRequestEvent if the listperson command is called. This then tells the MainWindow to update with the correct list of persons in its list panel, and to change the browser panel to show the lists of Module and Occasion that Person may have.

private void handlePerson() {
    getBrowserPlaceholder().getChildren().clear();
    getEntityListPanelPlaceholder().getChildren().clear();
    personListPanel.clearSelection();

    personListPanel.updatePanel(logic.getFilteredPersonList());
    getBrowserPlaceholder().getChildren().add(personBrowserPanel.getRoot());
    getEntityListPanelPlaceholder().getChildren().add(personListPanel.getRoot());

    logic.setActiveType(PERSON);
    AttendanceListUtil.postClearEvent();
}

The above code shows how the MainWindow deals with the context switch, which includes the setting of the active type (the context of the current window), so that contextual commands such as delete and select are able to function properly with correct indices.

The following sequence diagram shows how the listperson operation works:

4.10.2. Design Considerations

We had to examine whether it was better to: Alternative 1: Be able to make all commands contextual, and commands cannot be used out of context. This means that the list will set the context to limit other commands.

Alternative 2: Leave it possible for other commands to be called even if the context is not correct.

In the end, we chose alternative 1 so that users have the freedom to call specific commands without even looking at the specific list of choice, and to have more freedom to play around in the application.

4.11. Undo/Redo feature

4.11.1. Current Implementation

The undo/redo mechanism is facilitated by VersionAddressBook.It extends AddressBook with an command history, stored internally as an addressBookStateList and currentStatePointer. In addition, it implements the following operations:

VersionedAddressBook#commit(): Saves the current book state in the command history
VersionedAddressBook#undo(): Restores the address book to its previous state.
VersionedAddressBook#redo(): Restores the address book to its previously undone state.

These operations are exposed in the Model interface as Model#commitAddressBook(), Model#undoAddressBook() and Model#redoAddressBook() respectively.

Provided below is a usage scenario instance. It illustrates how the undo/redo mechanism behaves at each step.

Step 1: The user launches TheTracker for the first time. The VersionedAddressBook will be initialised with the initial address book state, which the currentStatePointer is currently pointing to.

Step 2: The user executes add n/David… command to add a person called David in his TheTracker. The add command calls Model#commitAddressBook(), causing the modified state of TheTracker after the add David… 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 delete 7 to delete the 7th person in the address book. The delete command also calls Model#commitAddressBook(), causing another modified address book state to be saved into the addressBookStateList

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: If the user now realizes that deleting the 7th person is 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.

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

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.

The following sequence diagram shows how the undo operation works:

If the currentStatePointer is at index addressBookStateList.size() - 1, pointing to the latest address book state, then there are no undone address book 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 executes the command find. Commands that do not modify the address book, such as find, 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. We designed it this way because it no longer makes sense to redo the delete 7 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:

4.11.2. 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.

Aspect: Data structure to support the undo/redo commands

Alternative 1 (current choice): Use a list to store the history of address book states.
- Pros: Easy for new Computer Science student undergraduates to understand, who are likely to be the new incoming developers of our project.
- Cons: Logic is duplicated twice. For example, when a new command is executed, we must remember to update both HistoryManager and VersionedAddressBook.
Alternative 2: Use HistoryManager for undo/redo
- Pros: We do not need to maintain a separate list, and just reuse what is already in the codebase.
- Cons: Requires dealing with commands that have already been undone: We must remember to skip these commands. Violates Single Responsibility Principle and Separation of Concerns as HistoryManager now needs to do two different things.

4.12. History feature

History feature allows the user to review all the commands he has typed in. The following sequence diagram shows how the history operation works:

4.13. Autocomplete

The autocomplete feature is facilitated by a stored list of commands and its own parser on the user’s command line inputs. The parser will enable the autocomplete to check the user’s input against a list of commands which are final and known by the address book. The autocomplete parser will be checking after every input in the command line, making it a real time feature.

4.13.1. Current Implementation

Currently, the feature calls on ControlsFX API to enable the autocomplete feature. It uses TextFields to have an autocomplete binding on the command box created which takes in the user input for commands. The list is populated by an inbuilt base commands list where all possible known commands are stored.

4.13.2. Proposed Improvements (Coming in v2.0)

While checking, the feature will try to give a regex match of the command and also provide suggestions on correct arguments based on current entities stored in TheTracker’s address book.

4.14. Export

Export is a feature to enhance the functionality of TheTracker. TheTracker (v1.4) supports exporting user data to xml file and txt file.

4.14.1. Current Implementation

ExportXmlCommand and ExportTxtCommand are both inherited from ExportCommand, which inherits from Command class

In order to gain a direct access to the Storage component, the method setStorage(Storage storage) is added to Command
In order to reduce redundant code in commands that are not directly dependent on Storage, setStorage(Storage storage) is designed to be a non-abstract method. Only ExportCommand overrides this method.

For ExportXmlCommand

The following sequence diagram shows how the ExportXmlCommand works.

For ExportTxtCommand

ExportTxtCommand can be regarded as an extension of ExportXmlCommand.

This interaction of ExportTxtCommand and Storage component works in the same way of ExportXmlCommand. The difference is: ExportTxtCommand first stored the exported xml file temp.xml; then, the method XmlToTxtUtil.parse() will parse the xml file to a txt file with defaulted style and layout and stored in the exportedFilePath specified by the user.

4.14.2. Design Considerations

Aspect: The role of exported file type

As a parameter (current implementation):
- Format: export --xml [FILEPATH] and export --txt [FILEPATH]
- Pros:
  - Can utilise polymorphism
  - Can avoid unnecessary repetition of code
- Cons:
  - Not consistent with the format of other commands (command + parameterPrefix + parameter)
As a part of command :
- Format: exportxml fp/[FILEPATH] and exporttxt fp/[FILEPATH]
- Pros:
  - Can keep consistent with the format of other command (command + parameterPrefix + parameter)
- Cons:
  - ExportXmlCommand and ExportTxtCommand have to be two independent commands, which does not utilise polymorphism
  - Have unnecessary repetition of code

Aspect: The Location of valid filepath check

Check in ExportCommand (current implementation) :
- Pros:
  - As only export commands are directly related to external file path that the user types in, which needs to check validation, checking in ExportCommand and its subclasses can avoid unnecessary checking.
  - Easy to implement and clear to understand
- Cons:
  - Can only check the validation of external file path that the user types in
Check in AddressBookStorage :
- Pros:
  - Can check the validation of all the file paths occurred in Storage component of this project
- Cons:
  - Have unnecessary checking of the validation of file paths

4.15. Import (Coming in v 2.0)

4.16. Logging

We are using java.util.logging package for logging. The LogsCenter class is used to manage the logging levels and logging destinations.

The logging level can be controlled using the logLevel setting in the configuration file (See Section 4.17, “Configuration”)
The Logger for a class can be obtained using LogsCenter.getLogger(Class) which will log messages according to the specified logging level
Currently log messages are output through: Console and to a .log file.

Logging Levels

SEVERE : Critical problem detected which may possibly cause the termination of the application
WARNING : Can continue, but with caution
INFO : Information showing the noteworthy actions by the App
FINE : Details that is not usually noteworthy but may be useful in debugging e.g. print the actual list instead of just its size

4.17. Configuration

Certain properties of the application can be controlled (e.g App name, logging level) through the configuration file (default: config.json).

4.18. Delete

4.18.1. Current Implementation

The delete command will delete a Person, Module or Occasion. Similar to other commands, a new ReadOnlyAddressBook is created upon the execution of this command.
It can then be accessed within the VersionedAddressBook when executing undo or redo.

The sequence diagram below (reproduced from Section 3.3, “Logic component”) shows that the high-level implementation is similar to the earlier commands.

However, the current implementation also allows for 2 useful functionalities in this feature:

Inferred Deletion: As we maintain the active type, the deletion will be applied to the currently active list.
Deep Deletion: By updating the associated lists, all references to this entry can be removed (i.e. from other entries' lists).

The following activity diagram gives a broad overview of the deletion process:

In performing deep deletion, almost all "related" objects are copied.

For example, suppose TheTracker is initialised in the following manner:

2 Persons p1, p2 and 2 Modules m1, m2 are created
p1 is inserted into m1, m2
p2 is inserted into m1

The current object diagram can be drawn as follows (unnecessary fields omitted):

After deleting p1, the new object diagram will be:

Notice that:

p1 and its UniqueModuleList is deleted
p2 is not affected
A new version of m1 is created. It has a new UniquePersonList, which contains a new copy of p2 (copied from p2Copy1)
A new version of m2 is created. It has a new UniquePersonList which is empty.

4.18.2. Design Considerations

Aspect: Explicit/Implicit Deletion

Alternative 1 (Current Implementation): Check the active type from the model, and delete from the list.
- Pros:
  - User can use delete instead of typing deleteperson, deletemodule or deleteoccasion in full.
  - User is explicitly prevented from deleting entries from an inactive list
- Cons:
  - Harder to implement.
Alternative 2 : 3 commands deleteperson, deletemodule and deleteoccasion to delete from the respective list.
- Pros:
  - Easier to implement
- Cons:
  - User may delete from the wrong list without realising
  - Inconvenient for user to type out full command

Aspect: Deletion by Index/Fields

Alternative 1 (Current Implementation): Delete entries by index
- Pros:
  - User can easily identify the index from the List Panel
  - User can use the same command for all 3 lists
- Cons:
  - User needs to user a find command first if he cannot find the entry
Alternative 2: Delete entries by field (e.g. delete n/john)
- Pros:
  - User can find an entry and delete them currently
- Cons:
  - Have to decide what to do if multiple entries satisfying the condition are found
  - User has to remember prefixes in order to delete an entry

Aspect: Shallow/Deep Deletion

Alternative 1 (Current Implementation): Deleted entry is removed from all linked entries
- Pros:
  - User can completely remove an entry from all mentions in TheTracker
  - removeperson implementation does not need to check whether an entry still exists in the address book
- Cons:
  - Difficult to implement
Alternative 2: Only allow entries that are not referenced to be deleted
- Pros:
  - User will not accidentally delete an entry that is used
- Cons:
  - User must manually use the removePerson command to eliminate all references
  - Difficult to implement
Alternative 3: Deleted entries can remain in all linked entries
- Pros:
  - Easy to implement
  - User can keep archival information for an entry
- Cons:
  - Very tedious to remove all mentions of an entry after it has been deleted
  - User may be misled that an entry still exists

5. Documentation

We use asciidoc for writing documentation.

We chose asciidoc over Markdown because asciidoc, although a bit more complex than Markdown, provides more flexibility in formatting.

5.1. Editing Documentation

See UsingGradle.adoc to learn how to render .adoc files locally to preview the end result of your edits. Alternatively, you can download the AsciiDoc plugin for IntelliJ, which allows you to preview the changes you have made to your .adoc files in real-time.

5.2. Publishing Documentation

See UsingTravis.adoc to learn how to deploy GitHub Pages using Travis.

5.3. Converting Documentation to PDF format

We use Google Chrome for converting documentation to PDF format, as Chrome’s PDF engine preserves hyperlinks used in webpages.

Here are the steps to convert the project documentation files to PDF format.

Follow the instructions in UsingGradle.adoc to convert the AsciiDoc files in the docs/ directory to HTML format.
Go to your generated HTML files in the build/docs folder, right click on them and select Open with → Google Chrome.
Within Chrome, click on the Print option in Chrome’s menu.
Set the destination to Save as PDF, then click Save to save a copy of the file in PDF format. For best results, use the settings indicated in the screenshot below.

Figure 10. Saving documentation as PDF files in Chrome

5.4. Site-wide Documentation Settings

The build.gradle file specifies some project-specific asciidoc attributes which affects how all documentation files within this project are rendered.

Attributes left unset in the build.gradle file will use their default value, if any.

Table 1. List of site-wide attributes
Attribute name	Description	Default value
`site-name`	The name of the website. If set, the name will be displayed near the top of the page.	not set
`site-githuburl`	URL to the site’s repository on GitHub. Setting this will add a "View on GitHub" link in the navigation bar.	not set
`site-seedu`	Define this attribute if the project is an official SE-EDU project. This will render the SE-EDU navigation bar at the top of the page, and add some SE-EDU-specific navigation items.	not set

5.5. Per-file Documentation Settings

Each .adoc file may also specify some file-specific asciidoc attributes which affects how the file is rendered.

Asciidoctor’s built-in attributes may be specified and used as well.

Attributes left unset in .adoc files will use their default value, if any.

Table 2. List of per-file attributes, excluding Asciidoctor’s built-in attributes
Attribute name	Description	Default value
`site-section`	Site section that the document belongs to. This will cause the associated item in the navigation bar to be highlighted. One of: `UserGuide`, `DeveloperGuide`, `LearningOutcomes`, `AboutUs`, `ContactUs` Official SE-EDU projects only	not set
`no-site-header`	Set this attribute to remove the site navigation bar.	not set

5.6. Site Template

The files in docs/stylesheets are the CSS stylesheets of the site. You can modify them to change some properties of the site’s design.

The files in docs/templates controls the rendering of .adoc files into HTML5. These template files are written in a mixture of Ruby and Slim.

Modifying the template files in docs/templates requires some knowledge and experience with Ruby and Asciidoctor’s API. You should only modify them if you need greater control over the site’s layout than what stylesheets can provide. The SE-EDU team does not provide support for modified template files.

6. Testing

6.1. Running Tests

There are three ways to run tests.

The most reliable way to run tests is the 3rd one. The first two methods might fail some GUI tests due to platform/resolution-specific idiosyncrasies.

Method 1: Using IntelliJ JUnit test runner

To run all tests, right-click on the src/test/java folder and choose Run 'All Tests'
To run a subset of tests, you can right-click on a test package, test class, or a test and choose Run 'ABC'

Method 2: Using Gradle

Open a console and run the command gradlew clean allTests (Mac/Linux: ./gradlew clean allTests)

See UsingGradle.adoc for more info on how to run tests using Gradle.

Method 3: Using Gradle (headless)

Thanks to the TestFX library we use, our GUI tests can be run in the headless mode. In the headless mode, GUI tests do not show up on the screen. That means the developer can do other things on the Computer while the tests are running.

To run tests in headless mode, open a console and run the command gradlew clean headless allTests (Mac/Linux: ./gradlew clean headless allTests)

6.2. Types of tests

We have two types of tests:

GUI Tests - These are tests involving the GUI. They include,
1. System Tests that test the entire App by simulating user actions on the GUI. These are in the systemtests package.
2. Unit tests that test the individual components. These are in seedu.address.ui package.
Non-GUI Tests - These are tests not involving the GUI. They include,
1. Unit tests targeting the lowest level methods/classes.
  e.g. seedu.address.commons.StringUtilTest
2. Integration tests that are checking the integration of multiple code units (those code units are assumed to be working).
  e.g. seedu.address.storage.StorageManagerTest
3. Hybrids of unit and integration tests. These test are checking multiple code units as well as how the are connected together.
  e.g. seedu.address.logic.LogicManagerTest

6.3. Troubleshooting Testing

Problem: HelpWindowTest fails with a NullPointerException.

Reason: One of its dependencies, HelpWindow.html in src/main/resources/docs is missing.
Solution: Execute Gradle task processResources.

7. Dev Ops

7.1. Build Automation

See UsingGradle.adoc to learn how to use Gradle for build automation.

7.2. Continuous Integration

We use Travis CI and AppVeyor to perform Continuous Integration on our projects. See UsingTravis.adoc and UsingAppVeyor.adoc for more details.

7.3. Coverage Reporting

We use Coveralls to track the code coverage of our projects. See UsingCoveralls.adoc for more details.

7.4. Documentation Previews

When a pull request has changes to asciidoc files, you can use Netlify to see a preview of how the HTML version of those asciidoc files will look like when the pull request is merged. See UsingNetlify.adoc for more details.

7.5. Making a Release

Here are the steps to create a new release.

Update the version number in MainApp.java.
Generate a JAR file using Gradle.
Tag the repo with the version number. e.g. v0.1
Create a new release using GitHub and upload the JAR file you created.

7.6. Managing Dependencies

A project often depends on third-party libraries. For example, Address Book depends on the Jackson library for XML parsing. Managing these dependencies can be automated using Gradle. For example, Gradle can download the dependencies automatically, which is better than these alternatives.
a. Include those libraries in the repo (this bloats the repo size)
b. Require developers to download those libraries manually (this creates extra work for developers)

Appendix A: Suggested Programming Tasks to Get Started

Suggested path for new programmers:

First, add small local-impact (i.e. the impact of the change does not go beyond the component) enhancements to one component at a time. Some suggestions are given in Section A.1, “Improving each component”.
Next, add a feature that touches multiple components to learn how to implement an end-to-end feature across all components. Section A.2, “Creating a new command: remark” explains how to go about adding such a feature.

A.1. Improving each component

Each individual exercise in this section is component-based (i.e. you would not need to modify the other components to get it to work).

`Logic` component

Scenario: You are in charge of logic. During dog-fooding, your team realize that it is troublesome for the user to type the whole command in order to execute a command. Your team devise some strategies to help cut down the amount of typing necessary, and one of the suggestions was to implement aliases for the command words. Your job is to implement such aliases.

Do take a look at Section 3.3, “Logic component” before attempting to modify the Logic component.

Add a shorthand equivalent alias for each of the individual commands. For example, besides typing clear, the user can also type c to remove all persons in the list.
- Hints
  
  Just like we store each individual command word constant COMMAND_WORD inside *Command.java (e.g. FindCommand#COMMAND_WORD, DeleteCommand#COMMAND_WORD), you need a new constant for aliases as well (e.g. FindCommand#COMMAND_ALIAS).
  
  AddressBookParser is responsible for analyzing command words.
- Solution
  
  Modify the switch statement in AddressBookParser#parseCommand(String) such that both the proper command word and alias can be used to execute the same intended command.
  
  Add new tests for each of the aliases that you have added.
  
  Update the user guide to document the new aliases.
  
  See this PR for the full solution.

`Model` component

Scenario: You are in charge of model. One day, the logic-in-charge approaches you for help. He wants to implement a command such that the user is able to remove a particular tag from everyone in the address book, but the model API does not support such a functionality at the moment. Your job is to implement an API method, so that your teammate can use your API to implement his command.

Do take a look at Section 3.4, “Model component” before attempting to modify the Model component.

Add a removeTag(Tag) method. The specified tag will be removed from everyone in the address book.
- Hints
  
  The Model and the AddressBook API need to be updated.
  
  Think about how you can use SLAP to design the method. Where should we place the main logic of deleting tags?
  
  Find out which of the existing API methods in AddressBook and Person classes can be used to implement the tag removal logic. AddressBook allows you to update a person, and Person allows you to update the tags.
- Solution
  
  Implement a removeTag(Tag) method in AddressBook. Loop through each person, and remove the tag from each person.
  
  Add a new API method deleteTag(Tag) in ModelManager. Your ModelManager should call AddressBook#removeTag(Tag).
  
  Add new tests for each of the new public methods that you have added.
  
  See this PR for the full solution.

`Ui` component

Scenario: You are in charge of ui. During a beta testing session, your team is observing how the users use your address book application. You realize that one of the users occasionally tries to delete non-existent tags from a contact, because the tags all look the same visually, and the user got confused. Another user made a typing mistake in his command, but did not realize he had done so because the error message wasn’t prominent enough. A third user keeps scrolling down the list, because he keeps forgetting the index of the last person in the list. Your job is to implement improvements to the UI to solve all these problems.

Do take a look at Section 3.2, “UI component” before attempting to modify the UI component.

Use different colors for different tags inside person cards. For example, friends tags can be all in brown, and colleagues tags can be all in yellow.

Before

After
- Hints
  
  The tag labels are created inside the PersonCard constructor (new Label(tag.tagName)). JavaFX’s Label class allows you to modify the style of each Label, such as changing its color.
  
  Use the .css attribute -fx-background-color to add a color.
  
  You may wish to modify DarkTheme.css to include some pre-defined colors using css, especially if you have experience with web-based css.
- Solution
  
  You can modify the existing test methods for PersonCard 's to include testing the tag’s color as well.
  
  See this PR for the full solution.
  
  The PR uses the hash code of the tag names to generate a color. This is deliberately designed to ensure consistent colors each time the application runs. You may wish to expand on this design to include additional features, such as allowing users to set their own tag colors, and directly saving the colors to storage, so that tags retain their colors even if the hash code algorithm changes.
Modify NewResultAvailableEvent such that ResultDisplay can show a different style on error (currently it shows the same regardless of errors).

Before

After
- Hints
  
  NewResultAvailableEvent is raised by CommandBox which also knows whether the result is a success or failure, and is caught by ResultDisplay which is where we want to change the style to.
  
  Refer to CommandBox for an example on how to display an error.
- Solution
  
  Modify NewResultAvailableEvent 's constructor so that users of the event can indicate whether an error has occurred.
  
  Modify ResultDisplay#handleNewResultAvailableEvent(NewResultAvailableEvent) to react to this event appropriately.
  
  You can write two different kinds of tests to ensure that the functionality works:
  
  The unit tests for ResultDisplay can be modified to include verification of the color.
  
  The system tests AddressBookSystemTest#assertCommandBoxShowsDefaultStyle() and AddressBookSystemTest#assertCommandBoxShowsErrorStyle() to include verification for ResultDisplay as well.
  
  See this PR for the full solution.
  
  Do read the commits one at a time if you feel overwhelmed.
Modify the StatusBarFooter to show the total number of people in the address book.

Before

After
- Hints
  
  StatusBarFooter.fxml will need a new StatusBar. Be sure to set the GridPane.columnIndex properly for each StatusBar to avoid misalignment!
  
  StatusBarFooter needs to initialize the status bar on application start, and to update it accordingly whenever the address book is updated.
- Solution
  
  Modify the constructor of StatusBarFooter to take in the number of persons when the application just started.
  
  Use StatusBarFooter#handleAddressBookChangedEvent(AddressBookChangedEvent) to update the number of persons whenever there are new changes to the addressbook.
  
  For tests, modify StatusBarFooterHandle by adding a state-saving functionality for the total number of people status, just like what we did for save location and sync status.
  
  For system tests, modify AddressBookSystemTest to also verify the new total number of persons status bar.
  
  See this PR for the full solution.

`Storage` component

Scenario: You are in charge of storage. For your next project milestone, your team plans to implement a new feature of saving the address book to the cloud. However, the current implementation of the application constantly saves the address book after the execution of each command, which is not ideal if the user is working on limited internet connection. Your team decided that the application should instead save the changes to a temporary local backup file first, and only upload to the cloud after the user closes the application. Your job is to implement a backup API for the address book storage.

Do take a look at Section 3.5, “Storage component” before attempting to modify the Storage component.

Add a new method backupAddressBook(ReadOnlyAddressBook), so that the address book can be saved in a fixed temporary location.
- Hint
  
  Add the API method in AddressBookStorage interface.
  
  Implement the logic in StorageManager and XmlAddressBookStorage class.
- Solution
  
  See this PR for the full solution.

A.2. Creating a new command: `remark`

By creating this command, you will get a chance to learn how to implement a feature end-to-end, touching all major components of the app.

Scenario: You are a software maintainer for addressbook, as the former developer team has moved on to new projects. The current users of your application have a list of new feature requests that they hope the software will eventually have. The most popular request is to allow adding additional comments/notes about a particular contact, by providing a flexible remark field for each contact, rather than relying on tags alone. After designing the specification for the remark command, you are convinced that this feature is worth implementing. Your job is to implement the remark command.

A.2.1. Description

Edits the remark for a person specified in the INDEX.
Format: remark INDEX r/[REMARK]

Examples:

remark 1 r/Likes to drink coffee.
Edits the remark for the first person to Likes to drink coffee.
remark 1 r/
Removes the remark for the first person.

A.2.2. Step-by-step Instructions

[Step 1] Logic: Teach the app to accept 'remark' which does nothing

Let’s start by teaching the application how to parse a remark command. We will add the logic of remark later.

Main:

Add a RemarkCommand that extends Command. Upon execution, it should just throw an Exception.
Modify AddressBookParser to accept a RemarkCommand.

Tests:

Add RemarkCommandTest that tests that execute() throws an Exception.
Add new test method to AddressBookParserTest, which tests that typing "remark" returns an instance of RemarkCommand.

[Step 2] Logic: Teach the app to accept 'remark' arguments

Let’s teach the application to parse arguments that our remark command will accept. E.g. 1 r/Likes to drink coffee.

Main:

Modify RemarkCommand to take in an Index and String and print those two parameters as the error message.
Add RemarkCommandParser that knows how to parse two arguments, one index and one with prefix 'r/'.
Modify AddressBookParser to use the newly implemented RemarkCommandParser.

Tests:

Modify RemarkCommandTest to test the RemarkCommand#equals() method.
Add RemarkCommandParserTest that tests different boundary values for RemarkCommandParser.
Modify AddressBookParserTest to test that the correct command is generated according to the user input.

[Step 3] Ui: Add a placeholder for remark in `PersonCard`

Let’s add a placeholder on all our PersonCard s to display a remark for each person later.

Main:

Add a Label with any random text inside PersonListCard.fxml.
Add FXML annotation in PersonCard to tie the variable to the actual label.

Tests:

Modify PersonCardHandle so that future tests can read the contents of the remark label.

[Step 4] Model: Add `Remark` class

We have to properly encapsulate the remark in our Person class. Instead of just using a String, let’s follow the conventional class structure that the codebase already uses by adding a Remark class.

Main:

Add Remark to model component (you can copy from Address, remove the regex and change the names accordingly).
Modify RemarkCommand to now take in a Remark instead of a String.

Tests:

Add test for Remark, to test the Remark#equals() method.

[Step 5] Model: Modify `Person` to support a `Remark` field

Now we have the Remark class, we need to actually use it inside Person.

Main:

Add getRemark() in Person.
You may assume that the user will not be able to use the add and edit commands to modify the remarks field (i.e. the person will be created without a remark).
Modify SampleDataUtil to add remarks for the sample data (delete your addressBook.xml so that the application will load the sample data when you launch it.)

[Step 6] Storage: Add `Remark` field to `XmlAdaptedPerson` class

We now have Remark s for Person s, but they will be gone when we exit the application. Let’s modify XmlAdaptedPerson to include a Remark field so that it will be saved.

Main:

Add a new Xml field for Remark.

Tests:

Fix invalidAndValidPersonAddressBook.xml, typicalPersonsAddressBook.xml, validAddressBook.xml etc., such that the XML tests will not fail due to a missing <remark> element.

[Step 6b] Test: Add withRemark() for `PersonBuilder`

Since Person can now have a Remark, we should add a helper method to PersonBuilder, so that users are able to create remarks when building a Person.

Tests:

Add a new method withRemark() for PersonBuilder. This method will create a new Remark for the person that it is currently building.
Try and use the method on any sample Person in TypicalPersons.

[Step 7] Ui: Connect `Remark` field to `PersonCard`

Our remark label in PersonCard is still a placeholder. Let’s bring it to life by binding it with the actual remark field.

Main:

Modify PersonCard's constructor to bind the Remark field to the Person 's remark.

Tests:

Modify GuiTestAssert#assertCardDisplaysPerson(…) so that it will compare the now-functioning remark label.

[Step 8] Logic: Implement `RemarkCommand#execute()` logic

We now have everything set up… but we still can’t modify the remarks. Let’s finish it up by adding in actual logic for our remark command.

Main:

Replace the logic in RemarkCommand#execute() (that currently just throws an Exception), with the actual logic to modify the remarks of a person.

Tests:

Update RemarkCommandTest to test that the execute() logic works.

A.2.3. Full Solution

See this PR for the step-by-step solution.

Appendix B: Product Scope

Target user profile:

Sociable and wish to know about his/her NUS peers
Academic and wish to keep track of their grades for certain modules and all the modules can type fast
Wish keep track of schedule of events on a calendar

Value proposition:

Key concepts: Enable NUS students to keep track of their friends, one’s own modules and events, in addition to other personal information.
What users want: A consolidated platform of friends and modules and events so that one’s entire NUS life is conveniently available in one place so as to bolster the organisation of a student’s life.
Limitations of what users can do now: A current undergraduate of NUS' information is spread out over IVLE, MYISIS and NUSMODS without any tracking on the information of close friends within the university.
Benefits users seek to achieve: Integrate existing information on different platforms all into a single platform.
How value proposition is delivered: When we have built a platform that allows the importing of information from multiple pre-existing platforms and consolidates all this information in a neat and presentable manner.

Appendix C: User Stories

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

Priority As a … I want to … So that I can…

Priority	As a …	I want to …	So that I can…
`* * *`	NUS Student	create a profile of myself and be able to edit it to join theTracker	I can share my schedule and profile with other people
`* * *`	NUS Student	find other students in the same faculty/major	I can network with them
`* * *`	people oriented person	see the full list of students in your module / your class	I can see all persons in campus
`* * *`	very selective friend	find specific friends and events in the address book	I can pick and choose certain events from a long list
`* * *`	Active NUS student	find all students who are taking the same modules as me	we can form study/project groups
`* * *`	NUS student	track all the modules I have taken	quickly know about the which modules I have taken
`* *`	NUS student who has joined some CCA	join my CCA group in this App	know who is in the same CCA as me and make friends with them
`* *`	NUS student	track my grades	quickly know about my academic performance for every semester
`* *`	User that may have difficulty spelling names	have similar names suggested when using the find function	ensure I have found the correct person
`* *`	NUS student who is also a Teaching Assistant of other modules	grades for the past modules given permission from the student	understanding of which level this student is in
`* *`	Student reading many modules	add URLs to my saved modules	I can quickly access my modules across NUS platforms
`* *`	Sociable and studious NUS student	see my friends' profiles	I know whether they are taking the same modules as I am and if they are, whether they are in the same tutorial groups as I am
`* *`	careless user	redo/undo instructions I have just done	Correct quickly if I have given an instruction just now that I don’t it anymore
`* *`	NUS Student who stays on campus	know the location of other students	we can arrange meet-ups on campus
`* *`	Current student	set my exam date on the page of addressbook	I can be reminded automatically the date, venue before my exams according to my reminder setting
`* *`	involved student	create new events to place in my schedule in my profile	have many events in schedule with their details recorded

* * *

NUS Student

create a profile of myself and be able to edit it to join theTracker

I can share my schedule and profile with other people

* * *

NUS Student

find other students in the same faculty/major

I can network with them

* * *

people oriented person

see the full list of students in your module / your class

I can see all persons in campus

* * *

very selective friend

find specific friends and events in the address book

I can pick and choose certain events from a long list

* * *

Active NUS student

find all students who are taking the same modules as me

we can form study/project groups

* * *

NUS student

track all the modules I have taken

quickly know about the which modules I have taken

* *

NUS student who has joined some CCA

join my CCA group in this App

know who is in the same CCA as me and make friends with them

* *

NUS student

track my grades

quickly know about my academic performance for every semester

* *

User that may have difficulty spelling names

have similar names suggested when using the find function

ensure I have found the correct person

* *

NUS student who is also a Teaching Assistant of other modules

grades for the past modules given permission from the student

understanding of which level this student is in

* *

Student reading many modules

add URLs to my saved modules

I can quickly access my modules across NUS platforms

* *

Sociable and studious NUS student

see my friends' profiles

I know whether they are taking the same modules as I am and if they are, whether they are in the same tutorial groups as I am

* *

careless user

redo/undo instructions I have just done

Correct quickly if I have given an instruction just now that I don’t it anymore

* *

NUS Student who stays on campus

know the location of other students

we can arrange meet-ups on campus

* *

Current student

set my exam date on the page of addressbook

I can be reminded automatically the date, venue before my exams according to my reminder setting

* *

involved student

create new events to place in my schedule in my profile

have many events in schedule with their details recorded

Appendix D: Use Cases

Use case: Adding an entry

MSS

User asks application to add a new entry.
Application creates a new entry, displays confirmation to user.
User enters additional information for new entry.
Application updates entry, displays info to user.

Use case ends.

Extensions

1a. User creates new entry along with associated information.
- 1a1. Application displays confirmation of entry creation.
- 1a2. Application displays entry along with associated information.
  
  Use case ends.
1b. Entry with same name already exists in AddressBook.
- 1b1. Application informs user, requests for confirmation.
- 1b2. User confirms request.
  
  Use case resumes from step 2.
3a. Wrong keyword or details input by user.
- 3a1. Application prompts user for re-entry.
- 3a2. Application will give example of a proper command.
- 3a3. User gives proper format of input.
  
  Use case resumes from step 4.
3b. Entry with same name already exists in AddressBook.
- 3b1. Application displays numbered list of entries with that same name.
- 3b2. User inputs number associated with correct entry.
  
  Use case resumes from step 4.

Use case: Delete an entry

MSS

User asks application to delete a entry.
Application asks user to confirm deletion.
User confirms deletion.
Application deletes entry, shows confirmation message to user.

Extensions

1a. User’s requested entry does not exist.
- 1a1. Application informs user.
  
  Use case resumes from step 1.
1b. Multiple entries with identical names exist.
- 1b1. Application displays numbered list of entries with that same name.
- 1b2. User inputs number associated with correct entry (or 0 to cancel).
  
  Use case resumes from step 4.
3a. User requests to cancel deletion.
- 3a1. Application displays acknowledgement message.
  
  Use case ends.

Use case: Update an entry

MSS

User searches for an entry name.
Application displays entry and associated information.
User adds info into new fields.
Application displays updated entry.

Extensions

3a. User edits existing field.
- 3a1. Application modifies requested field, displays updated entry.
  
  Use case ends.
3b. User deletes existing field.
- 3b1. Application deletes existing field, displays updated entry.
  
  Use case ends.

Appendix E: Non Functional Requirements

Should work on any mainstream OS as long as it has Java 9 or higher installed.
Should be able to hold up to 1000 persons without a noticeable sluggishness in performance for typical usage.
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.

Appendix F: Glossary

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

Appendix G: Instructions for Manual Testing

Given below are instructions to test the app manually.

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

G.1. Launch and Shutdown

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.
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.

{ more test cases … }

G.2. Deleting a person

Deleting a person while all persons are listed
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) {give more}
  Expected: Similar to previous.

{ more test cases … }

G.3. Saving data

Dealing with missing/corrupted data files
1. {explain how to simulate a missing/corrupted file and the expected behavior}

{ more test cases … }

TheTracker - Developer Guide

Events-Driven nature of the design

Logic component

Model component

Ui component

Storage component

Use case: Adding an entry

Use case: Delete an entry

Use case: Update an entry

`Logic` component

`Model` component

`Ui` component

`Storage` component