MeetingBook - Developer Guide

By: Team CS2103T-AY1819S1-W17-3 Since: Aug 2018 Licence: MIT

1. Setting up
2. Design
3. Implementation
4. Documentation
5. Testing
6. 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: Product Survey
Appendix H: Instructions for Manual Testing

1. Setting up

1.1. Prerequisites

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.

1.2. Setting up the project in your computer

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.

1.3. Verifying the setup

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

1.4. Configurations to do before writing code

1.4.1. 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.

1.4.2. Updating documentation to match your fork

After forking the repo, the documentation will still have the SE-EDU branding and refer to the se-edu/addressbook-level4 repo.

If you plan to develop this fork as a separate product (i.e. instead of contributing to se-edu/addressbook-level4), 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.

1.4.3. 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)

1.4.4. Getting started with coding

When you are ready to start coding,

Get some sense of the overall design by reading Section 2.1, “Architecture”.
Take a look at Appendix A, Suggested Programming Tasks to Get Started.

2. Design

2.1. 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

x 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 MeetingBookChangedEvent when MeetingBook 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.

2.2. UI component

Figure 5. Structure of the UI Component

API : Ui.java

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, PersonListPanel, StatusBarFooter, GroupListPanel 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.

2.3. Logic component

Figure 6. Structure of the Logic Component

API : Logic.java

Logic uses the MeetingBookParser 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

2.4. 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 the MeetingBook data.
exposes an unmodifiable ObservableList<Person> and an unmodifiable ObservableList<Group> 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 and a Group list in MeetingBook, which Person can reference. This would allow MeetingBook to only require one Tag object per unique Tag, and one Group object per unique Group, instead of each Person needing their own Tag and Group object.

2.5. 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 MeetingBook data in xml format and read it back.

2.6. Common classes

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

3. Implementation

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

3.1. Person feature

3.1.1. Current Implementation

Figure 10. The enhanced Person class

API : Person.java

Person now supports group identification. Every person will keep a list of groups that he/she has enrolled in.
Every Person in MeetingBook can be added or removed from an existing group. Use the methods addGroup() and removeGroup.
Person can check whether he/she is in a particular group by hasGroup(Group group) method.

3.2. Group feature

3.2.1. Current Implementation

Figure 11. The new Group class

API : Group.java

The Group,

is identified by Title and Description.
contains the Meeting details for this particular group. This is an optional field.
keeps track of its members in a UniquePersonList. The method hasMember(Person person) can check the enrollment of a particular Person.
supports add and remove member using methods addMember(Person toAdd) and removeMember(Person toRemove).
exposes an unmodifiable List<Person> for observation of member enrollment status by getMembersView().
supports set and cancel of Meeting of this group by methods setMeeting(Meeting meeting) and cancelMeeting().

3.2.2. Usage of Group class

A Group can be added and removed from MeetingBook using addGroup and deleteGroup command respectively.

Once the Group exists in the MeetingBook, the existing Person can be assigned to that group using join command. The person can also be removed from the group by leave command.

Each Group can keep track of a list of its members. This is supported by UniquePersonList class.

Each Person can also keep a list of groups he/she enrols in. An UniqueGroupList is added to support this functionality.

3.2.3. Design Consideration

Aspect: Management of group relationship

Alternative 1 (current choice): The add and remove operations support bidirectional update of relationships.
- Pros: Less complexity in current project structure.
- Cons: The future optimisation of these operations is less flexible.
Alternative 2: Use a central groupManager to manage the group-person relationships on the MeetingBook level.
- Pros: Greater room for possible future improvement, and ability to contain more complex relationships required by potential users.
- Cons: The idea is less compatible with the current project structure. Extensive change in structure and logic must be performed, and is error-prone.

3.3. UniqueGroupList feature

Figure 12. The UniqueGroupList class

API : UniqueGroupList.java

The UniqueGroupList,

ensures a list of Group objects without duplicates.
supports add, remove and replace operations on groups in the list.
exposes an unmodifiable ObservableList<Group> for observation of the list.

Both UniqueGroupList, UniquePersonList and UniqueMeetingList implements Iterable interface.

3.4. AddGroup and DeleteGroup feature

The AddGroup and DeleteGroup commands modify the UniqueGroupList in the versionedMeetingBook. This section shows how the addGroup and deleteGroup commands are implemented.

3.4.1. `addGroup` command usage

The addGroup command allows user to add a new group with user input title to the MeetingBook. This command is executed with the following syntax:

Syntax: addGroup n/[Name]

Example: addGroup n/CS2103T: adds a new group with title 'CS2103T' into the MeetingBook.

The follow sequence diagram shows how addGroup command functions.

Figure 13. Sequence diagram for addGroup command

3.4.2. `deleteGroup` command usage

The deleteGroup command allows user to remove an existing group from the MeetingBook. This command is executed with the following syntax:

Syntax: deleteGroup n/[Name]

Example: deleteGroup n/CS2101: removes the existing group with title 'CS2101' from the MeetingBook.

The follow sequence diagram shows how deleteGroup command functions.

Figure 14. Sequence diagram for deleteGroup command

3.4.3. Implementation of `addGroup` and `deleteGroup` commands

The versionedMeetingBook maintains a UniqueGroupList to keep track of all groups that exist in this MeetingBook. The commands thus modify and update this list of groups through ModelManager.

3.5. Join and Leave feature

The Join and Leave commands modify the relationship between groups existed in the UniqueGroupList and people in the UniquePersonList maintained by versionedMeetingBook. This section provides description of the usage and implementation of these commands.

3.5.1. `join` command usage

The join command updates relationship between a person and a group existed in the MeetingBook. The person specified by name now becomes a member of the group specified by title. This command is executed with the following syntax:

Syntax: join n/[Name] g/[Group]

Example: join n/Derek g/CS2101: makes the person 'Derek' become a member of group 'CS2101'

The follow sequence diagram shows how join command functions.

Figure 15. Sequence diagram for join command

3.5.2. `leave` command usage

The leave command updates relationship between person and group in the same way as the join command. The person specified by name now stops to be a member of the group specified by title. And the person is removed from this group. This command is executed with the following syntax:

Syntax: leave n/[Name] g/[Group]

Example: leave n/Ben g/CS2103T: removes the person Ben from the group CS2103T.

The follow sequence diagram shows how leave command functions.

Figure 16. Sequence diagram for leave command

3.5.3. Implementation of `join` and `leave` commands

The versionedMeetingBook maintains a UniqueGroupList to keep track of all groups that exist in this MeetingBook. It also maintains a UniquePersonList to keep track of all people that exist in this MeetingBook. The commands thus modify and update a pair of person and group, as specified by user input, in their respective list through ModelManager.

3.6. Meeting feature

Meeting is one of the central feature of this application. It allows the user to create a reminder of an upcoming event associated with a Group.

3.6.1. Current Implementation

Meetings are encapsulated using the Meeting class.

Figure 17. Diagram of the meeting class

API : Meeting.java

Meeting have the following properties:

It contains the title, time, location and description of the meeting it describes.
Each Group object can have a maximum of one meeting.
Two Meetings are considered similar if they share the same title, time, and location.

3.6.2. Using the Meeting class

In the current implementation, Meeting is related to Group by composition. To facilitate the meeting feature, Group implements the following operations:

Group#hasMeeting() — This returns true if there is a meeting associated with the group
Group#getMeeting() — This group’s meeting or null if the group has no meeting.
Group#setMeeting(Meeting meeting) — This assigns meeting to the group.
Group#cancelMeeting() — This removes the meeting associated witht the group.

These operations can be accessed through the model using the following operations:

Model#setMeeting(Group group, Meeting meeting) — This assigns the meeting meeting to the group group.
Model#cancelMeeting(Group group) — This cancels the meeting associated with the group group

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

Step 1. The application is launched.

We assumes that the groups Project2103, Presentation and FrisbeeTeam are present in the MeetingBook, and that none of the groups mentioned has a meeting scheduled.

Figure 18. The UniqueGroupList after Step 1.

Meeting field in a group without a meeting is an empty Optional

Step 2. The command meet FrisbeeTeam n/Sunday Practice t/28-10-2018@10:00 l/UTown Green d/Practice for Inter-College Games is executed. This schedules a meeting named Sunday Practice with the group FrisbeeTeam.

Figure 19. The UniqueGroupList after Step 2.

Step 3. The command meet Project2103 n/Weekly Meeting… is executed. This schedules a meeting named Weekly Meeting with the group Project2103.

… represents any valid arguments that legally completes the command.

Figure 20. The UniqueGroupList after Step 3.

Step 4. The command cancel FrisbeeTeam is executed. This removes the meeting Sunday Practice from the group FrisbeeTeam.

Figure 21. The UniqueGroupList after Step 4.

Calling cancel on a group without meeting returns an error

calling meet GROUP_NAME without argument is equivalent to calling cancel GROUP_NAME.

Step 5. The command meet Project2103 n/Demo Preparation… is executed. This overwrites the meeting Weekly Meeting associated with the group Project2103 with the new meeting named Demo Preparation.

Figure 22. The UniqueGroupList after Step 5.

This operation creates a new Meeting object which replaces the old one.

The following sequence diagrams show how the meet and cancel command function.

Figure 23. Sequence diagram for meet command

Figure 24. Sequence diagram for cancel command

3.6.3. Design Considerations

Aspect: Storage of meetings

Alternative 1 (current choice): Storing meetings inside groups
- Pros: This design simplifies the source code by not requiring a separate class to store meetings.
- Cons: This design requires iterating through all groups to retreive the list of meetings
Alternative 2: Storing meetings in a separate uniqueMeetingList class
- Pros: This design simplifies retreival of the list of meetings.
- Cons: This design causes the code becomes more complicated and more difficult to test.

Aspect: Specification of target group for meet and cancel commands

Alternative 1 (current choice): Specifying the group using its name.
- Pros: This design makes the command syntax natural and intuitive.
- Cons: This design forces the user have to manually type in the group name.
Alternative 2: Specifying the group using its index.
- Pros: This design is easier to use when the number of groups is high.
- Cons: This design causes the command syntax to become unnatural, and makes the program more suspectible to errors.

3.7. Sort and Find feature

The Sort and Find commands modifies the ObservableList<Person> in Model that the UI is bound to. This section will detail how the sort and find commands are implemented.

3.7.1. `sort` command usage

3.8. Sorting the list of displayed persons: `sort`

The sort command sorts the list in the display of persons. The user can specify whether to sort by name, phone number, email address, or home address, in lexicographical order or numerical order.

Format:
sort <name|phone|email|address>

<name|phone|email|address>: this parameter specifies whether to sort by name, phone, email address, or home address in lexicographical order or numerical order.

Examples:

sort name: Sorts the list of persons by name in lexicographical order.
sort phone: Sorts the list of persons by phone number in numerical order.
sort email: Sorts the list of persons by email address in lexicographical order.
sort address: Sorts the list of persons by home address in lexicographical order.

3.8.1. `find` command usage

3.9. Finding a group / person / meeting: `find`

The find command searches the MeetingBook for specified person, group, or meeting, and displays the results on the panel.

Format:
Longhand: find <person|group|meeting> [a/KEYWORDS] [s/KEYWORDS] [n/KEYWORDS]
Shorthand: find <p|g|m> [KEYWORDS]

<person|group|meeting>, <p|g|m>: this parameter specifies whether to search for persons, groups, or meetings. This parameter is required to execute this command.
- person, p: specifies to search for persons.
- group, g: specifies to search for groups.
- meeting, m: specifies to search for meetings.
KEYWORDS: this tag contains any number of keywords separated by a space.
[all], [a]: this parameter specifies that the results must contain every keyword specified in <keywords>. This parameter may be omitted.
[some], [s]: this parameter specifies that the results must contain at least one keyword specified in <keywords>. This parameter may be omitted.
[none], [n]: this parameter specifies that the results must not contain any keyword specified in <keywords>. This parameter may be omitted.

When the shorthand format is used, the keywords will be placed in the a/ parameter.

Examples:

find p Alex: finds all persons whose name contains Alex. (Refer to diagram above)

find p s/yu li: finds all persons whose name contains one of yu or li. (Refer to diagram above)

find p n/Alex Bernice: finds all persons whose name does not contain Alex or Bernice (Refer to diagram above)
find p Betty Charles: finds all persons whose name contains Betty and Charles.
find p s/David Eric n/James: finds all persons whose name contains one of David or Eric, and whose name does not contain James.
find group project: finds all groups whose title contains project.
find g a/team n/school: finds all groups whose title contains team and whose title does not contain school.
find meeting s/official important: finds all meetings whose title contains one of official or important.
find m a/urgent n/basketball: finds all meetings whose titles contains urgent and whose title does not contain basketball.

3.9.1. Implementation of `find` command

Structure of `find` command

When the user executes a find command, the FindCommandParser returns either a FindPersonCommand, a FindMeetingCommand, or a FindGroupCommand, depending on the user’s input. FindPersonCommand, FindMeetingCommand, and FindGroupCommand extends the FindCommand<Person>, FindCommand<Meeting>, and FindCommand<Group> abstract classes respectively. The FindCommand<E> abstract class extends the Command abstract class.

public abstract class FindCommand<E> extends Command {

    public static final String COMMAND_WORD = "find";

    public static final String MESSAGE_USAGE = ...

    protected final Predicate<E> predicate;

    FindCommand(Predicate<E> predicate) {...}

    @Override
    public boolean equals(Object other) {...}
}

ModelManager maintains 3 lists of type FilteredList. The lists are filteredPersons, filteredMeetings, and filteredGroups. When the find command is executed, a predicate is passed into the respective FilteredList. The elements in the list that passes the predicate test will be displayed in the UI.

Referring to the code snippet above, FindCommand<E> implements the equals() method and contains a predicate of type Predicate<E>. This predicate will be applied to the filteredPersons list if FindPersonCommand is executed, filteredGroups list if FindGroupCommand is executed, and filteredMeetings list if FindMeetingCommand is executed. Each of FindPersonCommand, FindGroupCommand, and FindMeetingCommand implements the execute() method required by the Command abstract class.

Structure of Predicates

The predicates are created using the abstract class EntityContainsKeywordsPredicate<E>. PersonNameContainsKeywordsPredicate extends EntityContainsKeywordsPredicate<Person>, GroupTitleContainsKeywordsPredicate extends EntityContainsKeywordsPredicate<Group>, and MeetingTitleContainsKeywordsPredicate extends EntityContainsKeywordsPredicate<Meeting>.

public abstract class EntityContainsKeywordsPredicate<E> implements Predicate<E> {
    private final List<String> allKeywords;
    private final List<String> someKeywords;
    private final List<String> noneKeywords;

    private final Function<E, Predicate<String>> testKeywordPredicateGetter;

    public EntityContainsKeywordsPredicate(List<String> allKeywords, List<String> someKeywords, List<String> noneKeywords, Function<E, String> entityKeywordGetter) {...}

    @Override
    public boolean test(E element) {...}

    @Override
    public boolean equals(Object other) {...}
}

As seen in the code snippet above, EntityContainsKeywordsPredicate maintains 3 lists of String, the allKeywords list, the someKeywords list, and the noneKeywords list. The lists of strings are generated by the FindCommandParser that parses the find command entered. testKeywordPredicateGetter is used to generate the predicate that will be used to test whether each keyword matches the element being tested.

Each of PersonNameContainsKeywordsPredicate, GroupTitleContainsKeywordsPredicate, and MeetingTitleContainsKeywordsPredicate contains a predefined function used to retrieve the Person name, Group title, or Meeting title. This predefined function will be used passed into the constructor of EntityContainsKeywordsPredicate to generate testKeywordPredicateGetter.

When the predicate is passed into the FilteredList in ModelManager, the test() method in this predicate will be used to test the elements in the list.

3.9.2. How the `sort` command works with the `find` command

In the current implementation, the sort command only applies on the list of persons.

ModelManager maintains a sortedPersons list of type SortedList<Person> and a filteredPersons list of type FilteredList<Person>.

Illustrated in the figure above, sortedPersons list wraps the filteredPersons list and filteredPersons list wraps the persons list of type ObservableList<Person> maintained by versionedMeetingBook. persons list in versionedMeetingBook contains all the persons stored in the MeetingBook.

The list displayed in the UI is bound to the sortedPersons list. Hence, the persons list has two layers of modification before being displayed in the GUI as sortedPersons.

Before the user executes any find or sort commands, no Comparator<Person> and no Predicate<Person> is applied to the persons list. The UI will display the all the persons in the MeetingBook as expected.

When the user executes a find command, an appropriate Predicate<Person> will be created based on the user’s input, and the Predicate<Person> will be applied to the persons list. This modification will be reflected in the sortedPersons list and in the displayed list in the GUI.

Similarly, when a user executes a sort command, an appropriate Comparator<Person> will be applied to the filteredPersons list. This modification will be reflected in the displayed list in the UI.

3.9.3. Design considerations

Due to this two-layered structure. The user can chain find and sort commands back-to-back to display the desired list.

An example can be seen in the diagram above by executing the command find p s/yu li followed by sort name. After applying the sort command, the find filter remains applied. The next example will demonstrate a different order.

The diagram above shows another example of back-to-back execution. The diagram shows the execution of sort name followed by find p s/yeoh li. As can be seen in the diagram, the sorting order remains even after executing the find command.

3.10. Undo/Redo feature

3.10.1. Current Implementation

The undo/redo mechanism is facilitated by VersionedMeetingBook. It extends MeetingBook with an undo/redo history, stored internally as an meetingBookStateList and currentStatePointer. Additionally, it implements the following operations:

VersionedMeetingBook#commit() — Saves the current MeetingBook state in its history.
VersionedMeetingBook#undo() — Restores the previous MeetingBook state from its history.
VersionedMeetingBook#redo() — Restores a previously undone MeetingBook state from its history.

These operations are exposed in the Model interface as Model#commitMeetingBook(), Model#undoMeetingBook() and Model#redoMeetingBook() 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 VersionedMeetingBook will be initialized with the initial MeetingBook state, and the currentStatePointer pointing to that single MeetingBook state.

Step 2. The user executes delete 5 command to delete the 5th person in the MeetingBook. The delete command calls Model#commitMeetingBook(), causing the modified state of the MeetingBook after the delete 5 command executes to be saved in the meetingBookStateList, and the currentStatePointer is shifted to the newly inserted MeetingBook state.

Step 3. The user executes add n/David … to add a new person. The add command also calls Model#commitMeetingBook(), causing another modified MeetingBook state to be saved into the meetingBookStateList.

If a command fails its execution, it will not call Model#commitMeetingBook(), so the MeetingBook state will not be saved into the meetingBookStateList.

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#undoMeetingBook(), which will shift the currentStatePointer once to the left, pointing it to the previous MeetingBook state, and restores the MeetingBook to that state.

If the currentStatePointer is at index 0, pointing to the initial MeetingBook state, then there are no previous MeetingBook states to restore. The undo command uses Model#canUndoMeetingBook() 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:

The redo command does the opposite — it calls Model#redoMeetingBook(), which shifts the currentStatePointer once to the right, pointing to the previously undone state, and restores the MeetingBook to that state.

If the currentStatePointer is at index meetingBookStateList.size() - 1, pointing to the latest MeetingBook state, then there are no undone MeetingBook states to restore. The redo command uses Model#canRedoMeetingBook() 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 MeetingBook, such as list, will usually not call Model#commitMeetingBook(), Model#undoMeetingBook() or Model#redoMeetingBook(). Thus, the meetingBookStateList remains unchanged.

Step 6. The user executes clear, which calls Model#commitMeetingBook(). Since the currentStatePointer is not pointing at the end of the meetingBookStateList, all MeetingBook states after the currentStatePointer will be purged. We designed it this way because 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:

3.10.2. Design Considerations

Aspect: How undo & redo executes

Alternative 1 (current choice): Saves the entire MeetingBook.
- 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 MeetingBook 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 VersionedMeetingBook.
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.

3.11. Select feature

The select command selects the GroupCard, MeetingCard or PersonCard in the ObservableList<Group>, ObservableList<Meeting>, or ObservableList<Person> respectively in Model that is bounded to the UI. This section will explain current implementation of select command, execution sequence, and design considerations of multiple implementations.

3.11.1. Current Implementation

The select mechanism is facilitated by ModelManager. It extends Model with three lists, UniquePersonList, UniqueMeetingList and UniqueGroupList and implements the following operations:

Model#updateFilteredPersonList — Updates person list with a specific Predicate.
Model#updateFilteredGroupList — Updates group list with specific Predicate.
Model#updateFilteredMeetingList — Updates meeting list with specific Predicate.

Given below is an example usage scenario and how the select mechanism behaves at each step.

Step 1. The user launches the application for the first time. The ModelManager will be initialized with the initial MeetingBook state, and UniquePersonList, UniqueMeetingList and UniqueGroupList contains all person, meetings and groups respectively without filter.

Step 2. The user executes select command to select the item type with the specified index in the MeetingBook. The SelectCommandParser parses the command to determine the select type, and the command executes the following steps:

Step 2.1. If the prefix is g/, a JumpToGroupListRequestEvent is sent to update the UI to select the group card, Model#updateFilteredPersonList is called to filter UniquePersonList to contain only person that are associated with the group, and Model#updateFilteredMeetingList is called to filter UniqueMeetingList to show only meeting that is associated with the group.
Step 2.2. If the prefix is m/, a JumpToMeetingListRequestEvent is sent to the UI to select the meeting card.
Step 2.3. If the prefix is p/, a JumpToListRequestEvent is sent to the UI to select the person card.

If a group is selected, subsequent select calls to person and meeting list will only select the person or meeting in the filtered UniquePersonList or UniqueMeetingList respectively.

Figure 25. Select group sequence diagram when user executes select group 1

Figure 26. Select command activity diagram

3.11.2. Design Considerations

Aspect: Data structure to support the select command

Alternative 1 (current choice): Use a single select class to perform all select operations.
- Pros: Easy to implement as there are fewer lines of code required.
- Cons: Harder to extend if need to implement select command for other items, select class will become bloated if too many items require select command.
Alternative 2: Abstract select class containing required variables and methods without implementation, and select commands inherit from the abstract class and implement the execution functionality.
- Pros: Good data structure, easy to extend functionality to select other items.
- Cons: Requires more code to implement.

3.12. List feature

The list command removes any filters applied to UniqueGroupList, UniquePersonList and UniqueMeetingList by other commands. This section will explain current implementation of list command and design considerations during development phase.

3.12.1. Current implementation

The list mechanism is facilitated by ModelManager. It uses the same operations as mentioned in select feature, namely Model#updateFilteredPersonList, Model#updateFilteredGroupList and Model#updateFilteredMeetingList.

Given below is an example usage scenario and operations executed by list mechanism at each step.

Step 1. The user launches the application. ModelManager will be initialized with initial MeetingBook state, and UniquePersonList, UniqueMeetingList and UniqueGroupList contains all person, meetings and groups respectively without filter.

Step 2. The user executes list command with additional parameter to specify the list to show all items. Available parameters are person, meeting, group and all, or their shorthand equivalent p, m, g and a. ListCommandParser parses the command to determine the list type, and the command executes the following steps:

Step 2.1. If the parameter is group / g, Model#updateFilteredGroupList is called with PREDICATE_SHOW_ALL_GROUPS to remove any filters applied to UniqueGroupList.
Step 2.2. If the parameter is meeting / m, Model#updateFilteredMeetingList is called with PREDICATE_SHOW_ALL_MEETINGS to remove any filters applied to UniqueMeetingList.
Step 2.3. If the parameter is person / p, Model#updateFilteredPersonList is called with PREDICATE_SHOW_ALL_PERSONS to remove any filters applied to UniquePersonList.
Step 2.4. If the parameter is all / a / empty, steps 2.1., 2.2. and 2.3. will be executed.

List will remain unchanged if it does not have any filters applied before executing list command.

Figure 27. List group sequence diagram

Below is the pseudo code of list command execution.

public CommandResult execute(Model model, CommandHistory history) {
    requireNonNull(model);
    switch (listCommandType) {
        case PERSON:
            // Show all persons, return success
        case GROUP:
            // Show all groups, return success
        case MEETING:
            // Show all meetings, return success
        default:
            // Show all persons, groups and meetings, return success
    }
}

3.12.2. Design considerations

Aspect: Data structure to support the list command

Alternative 1 (current choice) : Use a single list class to perform all list operations.
- Pros: Easy to implement as fewer lines of code are required.
- Cons: Harder to extend list functionality if need to implement list command for other items, list class will become bloated if too many items require list command.
Alternative 2 : Abstract list class containing required variables and methods without implementation, and specific list commands inherit from the abstract class and implement the execution functionality.
- Pros: Good data structure, easy to extend functionality to other items that require list command.
- Cons: Requires more lines of code to implement.

3.13. Export feature

3.13.1. Current Implementation

Overview

The export mechanism is facilitated by ExportCommand. ExportCommandParser is responsible for parsing the input arguments. The end result of this command is a Xtensible Markup Language (XML) file containing data of MeetingBook when is executed successfully.

If there is no filepath provided, export command will return an invalid message, which the usage information to the user.

The following sequence diagram shows how export operation works:

Figure 28. Sequence diagram of ExportCommand

The program will raise a MeetingBookExportEvent to EventCenter. StorageManager which subscribed to the EventCenter will trigger StorageManager#handleMeetingBookExportEvent when received MeetingBookExportEvent. This method will then attempt to export the data as a XML file using Model#exportMeetingBook.

Export to a XML file

The translation from MeetingBook to XML formatted file is handled by XmlFileStorage#saveDataToFile. As MeetingBook stores Person, Group, Meeting as Objects, these information have to be properly formatted into Java Architecture for XML Binding (JAXB)-friendly version before it can be successfully saved. Objects are modelled using their respective XMLAdapted classes which contain directions for it to parse into JAXB-friendly version. Marshal Object will then marshal all the JAXB-friendly version of Person, Meeting, Group and assemble it into a XML file.

Figure 29. Class diagram of XmlAdapted classes and their associations

3.13.2. Design Consideration

Aspect: Make export undoable

Alternative 1 (current choice): Does not allow it to be undo.
- Pros: Easy to implement and verify if the command is executed successfully.
- Cons: Hard for the user as the user have to manually navigate through the directory to delete the XML file to achieve the same result as undoing the command.
Alternative 2: Allow it to be undoable.
- Pros: Allow user to undo the command.
- Cons: Make it difficult to implement as there is a need to consider on how to resolve the following scenarios:
  - After user export data, user may directly make changes to the XML file exported. Does undoing the operation deletes the file or not since it have been modified after the export command?
  - After user export data, user rename the XML file or move the XML file. This causes the original file referenced by the export command to be lost and unable to continue the undo operation.
These scenarios create unnecessary complications when we want to attempt undoing the operation. Therefore, we choose to not allow the command to be undoable.

3.14. Import feature

3.14.1. Current implementation

Overview

The import command allow the user to import a XML file containing of MeetingBook data into his MeetingBook. This is facilitated by is facilitated by ImportCommand. ImportCommandParser is responsible for parsing the input arguments. The end result of this command is entries of Person, Group, Meeting added into the current MeetingBook.

Import from XML file

The translation from XML formatted file to MeetingBook is handled by XmlFileStorage#loadDataToFile. As MeetingBook consists Person, Group, Meeting as Objects, these information have to be properly formatted back into Java Architecture for XML Binding (JAXB)-friendly version before it can then modelled into its respective classes (i.e. xmlAdaptedPerson modelled back into Person object). Each Objects has their respective XMLAdapted class which contain directions to model back from JAXB-friendly version . Unmarshal Object is solely responsible for disassemble the XML file into JAXB-friendly versions of Person, Meeting, Group, which will then be feed as parameters to create another instance of MeetingBook. The imported MeetingBook will then merge with the current MeetingBook using MeetingBook#merge.

Figure 30. Class diagram of XmlAdapted classes and their associations

3.14.2. Handling of conflicting entries

The default behavior of handling conflicting entries is to ignore any conflicting entries. However, user can choose to change this behavior to overwrite any conflicting entries using --force option when entering the command. An example of the command set to the overwriting behaviour is import --force f/backup.xml.

The code snippet below showcase how MeetingBook toggle between the behaviours.

public void merge(ReadOnlyMeetingBook imported, boolean overwrite) {
        // If Both book contains same entries
        if (equals(imported)) {
            return;
        }

        if (!(imported instanceof MeetingBook)) {
            return;
        }
        MeetingBook importedBook = (MeetingBook) imported;
        importedBook.persons.iterator()
                .forEachRemaining((person) -> mergePerson(person, overwrite));

        importedBook.groups.iterator()
                .forEachRemaining((group) -> mergeGroup(group, overwrite));
    }

3.14.3. Handling of irrelevant imported data

The default conflicting resolving behavior (ignoring any conflict files) may cause Person to lose their association with Group.

Take this case for example. Current MeetingBook and the imported MeetingBook both have a Person named "Alex Lim" with the following attributes.

Figure 31. Object Diagram of "Alex Lim" Person Object in current MeetingBook and imported MeetingBook

When the default conflicting resolving behaviour is used, "Alex Lim" of the imported MeetingBook will not be imported into current MeetingBook.

However, "Alex Lim" of the imported MeetingBook belongs to a Group.

Figure 32. Object Diagram of "Alex Lim" Person of imported MeetingBook belonging to a Group before merging to current MeetingBook

Therefore, when importing the Group that "Alex Lim" of the imported MeetingBook is in, the Group will be imported without "Alex Lim" of the imported MeetingBook. The Group will not contains "Alex Lim" of the current MeetingBook as these two "Alex Lim" are not of the same Person. If "Alex Lim" of the imported MeetingBook is the sole member of the Group, the Group will still be created but with no members instead.

Figure 33. Object Diagram of "Alex Lim" Person of imported MeetingBook belonging to a Group after merging to current MeetingBook

3.14.4. Design Consideration

Aspect: Handling of conflict entries

Alternative 1 (current choice): Either ignore or overwrite conflicting entries.
- Pros: Easy to handle conflicting cases.
- Cons: Loss of data as information is destroyed or lost when importing. When we choose to ignore, we lose data from the XML file as they are not imported in. If we were to overwrite conflicting entries, we lose information in our current MeetingBook as they are overwritten by the imported data.
Alternative 2: Append an arbitrary number to the name of Person/Group.
- Pros: No loss of data when importing.
- Cons: End up with lots of data with arbitrary number appended to it. This may cause confusion to the user as there is many similar entries of the Person/Group object only to be differ by an arbitrary number. This will also cause find command to not work as expected. find command currently matches exact search term and the arbitrary number appended cause it to no longer match the name of the Object.

3.15. [Proposed] Data Encryption

{Explain here how the data encryption feature will be implemented}

3.16. 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 3.17, “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

3.17. Configuration

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

4. 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.

4.1. 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.

4.2. Publishing Documentation

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

4.3. 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 34. Saving documentation as PDF files in Chrome

4.4. 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

4.5. 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

4.6. 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.

5. Testing

5.1. 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)

5.2. 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.meeting.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.meeting.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.meeting.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.meeting.logic.LogicManagerTest

5.3. 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.

6. Dev Ops

6.1. Build Automation

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

6.2. Continuous Integration

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

6.3. Coverage Reporting

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

6.4. 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.

6.5. 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.

6.6. Managing Dependencies

A project often depends on third-party libraries. For example, MeetingBook 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 2.3, “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).
  
  MeetingBookParser is responsible for analyzing command words.
- Solution
  
  Modify the switch statement in MeetingBookParser#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 MeetingBook, 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 2.4, “Model component” before attempting to modify the Model component.

Add a removeTag(Tag) method. The specified tag will be removed from everyone in the MeetingBook.
- Hints
  
  The Model and the MeetingBook 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 MeetingBook and Person classes can be used to implement the tag removal logic. MeetingBook allows you to update a person, and Person allows you to update the tags.
- Solution
  
  Implement a removeTag(Tag) method in MeetingBook. Loop through each person, and remove the tag from each person.
  
  Add a new API method deleteTag(Tag) in ModelManager. Your ModelManager should call MeetingBook#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 MeetingBook 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 2.2, “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 MeetingBookSystemTest#assertCommandBoxShowsDefaultStyle() and MeetingBookSystemTest#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 MeetingBook.

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 MeetingBook is updated.
- Solution
  
  Modify the constructor of StatusBarFooter to take in the number of persons when the application just started.
  
  Use StatusBarFooter#handleMeetingBookChangedEvent(MeetingBookChangedEvent) to update the number of persons whenever there are new changes to the MeetingBook.
  
  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 MeetingBookSystemTest 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 MeetingBook to the cloud. However, the current implementation of the application constantly saves the MeetingBook 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 MeetingBook storage.

Do take a look at Section 2.5, “Storage component” before attempting to modify the Storage component.

Add a new method backupMeetingBook(ReadOnlyMeetingBook), so that the MeetingBook can be saved in a fixed temporary location.
- Hint
  
  Add the API method in MeetingBookStorage interface.
  
  Implement the logic in StorageManager and XmlMeetingBookStorage 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 MeetingBook, 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 MeetingBookParser to accept a RemarkCommand.

Tests:

Add RemarkCommandTest that tests that execute() throws an Exception.
Add new test method to MeetingBookParserTest, 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 MeetingBookParser 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 MeetingBookParserTest 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 meetingBook.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 invalidAndValidPersonMeetingBook.xml, typicalPersonsMeetingBook.xml, validMeetingBook.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:

is a student taking modules in NUS
has a need to manage a significant number of meetings
prefer desktop apps over other types
can type fast
prefers typing over mouse input
is reasonably comfortable using CLI apps

Value proposition: manage meetings faster than a typical mouse/GUI driven app

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…
`* * *`	user	undo my commands	revert unwanted changes
`* * *`	user	add a new person
`* * *`	user	edit group	make changes to existing group
`* * *`	user with many groups	find group	retrieve relevant groups
`* * *`	user	schedule meeting
`* * *`	organized user	categorize persons by group	navigate person list more easily
`* * *`	new user	have commands that can be easily understood	learn how to use the software without steep learning curve
`* * *`	organized user	assign meeting to group	know that I am scheduled to meet the group
`* *`	impatient user	have autocomplete when typing my commands	execute my commands faster
`* *`	user	edit meeting	reschedule the meeting
`* *`	user	import and export data	transfer data between machines
`* *`	new user	has a quick rundown of functionalities	fully understand the software features
`* *`	user	see an overview of meeting list for the day	plan schedule for the day
`* *`	user	pin some meeting on top	be reminded of meeting of highest importance
`* *`	confused user	check usage of particular functionality before using it	understand the function to use it
`* *`	user	highlight meeting as urgent	prioritize schedule
`* *`	user	see meeting	prioritize schedule
`*`	user	see usage statistics	understand working habits / productivity
`*`	artist	change application themes	personalize the app
`*`	international user	have multilingual typefaces	use the app in native language
`*`	multi-device user	have access from smartphone	check meeting list on the go without computer
`*`	user	security features	prevent information leakage

* * *

user

undo my commands

revert unwanted changes

* * *

user

add a new person

* * *

user

edit group

make changes to existing group

* * *

user with many groups

find group

retrieve relevant groups

* * *

user

schedule meeting

* * *

organized user

categorize persons by group

navigate person list more easily

* * *

new user

have commands that can be easily understood

learn how to use the software without steep learning curve

* * *

organized user

assign meeting to group

know that I am scheduled to meet the group

* *

impatient user

have autocomplete when typing my commands

execute my commands faster

* *

user

edit meeting

reschedule the meeting

* *

user

import and export data

transfer data between machines

* *

new user

has a quick rundown of functionalities

fully understand the software features

* *

user

see an overview of meeting list for the day

plan schedule for the day

* *

user

pin some meeting on top

be reminded of meeting of highest importance

* *

confused user

check usage of particular functionality before using it

understand the function to use it

* *

user

highlight meeting as urgent

prioritize schedule

* *

user

see meeting

prioritize schedule

*

user

see usage statistics

understand working habits / productivity

*

artist

change application themes

personalize the app

*

international user

have multilingual typefaces

use the app in native language

*

multi-device user

have access from smartphone

check meeting list on the go without computer

*

user

security features

prevent information leakage

{More to be added}

Appendix D: Use Cases

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

Use case: Add person

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student enters add command with relevant parameters such as name, number, address of the person.
MeetingBook updates the person list.
MeetingBook informs the student that the person has been successfully added, and refreshes the main page to reflect the newly updated person list.

Use case ends.

Extensions

5a. Student enters invalid parameter.
- 5a1. MeetingBook informs the student that he/she has entered invalid parameters.
  
  Use case ends.

Use case: Add group

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student enters command to create a new group.
MeetingBook creates the group.
MeetingBook feedbacks that the group had been successfully created.

Use case ends.

Extensions

1a. Student enters group that already exists.
- 1a1. MeetingBook informs the student that the group already exists.
  
  Use case ends.

Use case: Find group

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student enters command and keyword of group on command field.
MeetingBook returns the list of group that matches the keyword.

Use case ends.

Extensions

4a. Student enters keyword that does not exist in the database.
- 4a1. MeetingBook informs the student that there are no group that match the keyword entered.
  
  Use case ends.

Use case: Cancel meeting

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student enters command to cancel meeting from a group.
MeetingBook remove meeting from the group.

Use case ends.

Use case: Edit group

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student enters command and the group with relevant fields that he/she wishes to edit.
MeetingBook returns a feedback to inform user that the group has been successfully edited.
MeetingBook updates the group list with updated information.

Use case ends.

Extensions

4a. Student enters invalid field.

Use case ends.
4b. Student enters group that does not exist in the database.

Use case ends.

Use case: Import data

MSS

Student copies out the storage file from the exporting machine.
Student pastes the storage file on the importing machine.
Student starts the MeetingBook.
MeetingBook starts up.
Student type command to import.
MeetingBook scans and imports the data.

Use case ends.

Extensions

6. The storage file is invalid / corrupted.
- 6a1. MeetingBook will show an error telling the student that the file is corrupted.
  
  Use case ends.

Use case: Export data

MSS

Student start uo MeetingBook.
MeetingBook starts up.
Student type command to export.
MeetingBook copies out the storage file from the machine.

Use case ends.

Extensions

4. MeetingBook unable to write to file.
- 4a1. MeetingBook will show an error telling the student that the operation failed.
  
  Use case ends.

Use case: Toggle autocomplete

MSS

Student start up MeetingBook.
MeetingBook starts up.
Student types part of the command on command field.
Student uses tab to scroll through available commands.
MeetingBook updates the command field with the highlighted command from the suggestion list.

Use case ends.

Extensions

5a. No command autocomplete is available.

Use case ends.

{More to be added}

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 100 groups and 1000 person 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
NUS module: Modules offered by NUS in a semester
CLI: Command line interface
GUI: Graphical user interface

Appendix G: Product Survey

Product Name

Author: …

Pros:

Cons:

Appendix H: 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.

H.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 … }

H.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 … }

H.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 … }

MeetingBook - Developer Guide

Events-Driven nature of the design

Logic component

Model component

Ui component

Storage component

Use case: Add person

Use case: Add group

Use case: Find group

Use case: Cancel meeting

Use case: Edit group

Use case: Import data

Use case: Export data

Use case: Toggle autocomplete

`Logic` component

`Model` component

`Ui` component

`Storage` component