PDF++ - Developer Guide

By: Team T12-4 Since: Feb 2019 Licence: MIT

1. Introduction

1.1. Software Overview

PDF++ is an all-in-one document management tool that allows users to easily manage and manipulate their files.
The current version of this application only deals with PDF files.
There are many unique features to the application such as the ability to search within the content of files, merging several files together, setting of deadlines and many more. These features can be referred to within the Implementation Section of this document.

1.2. Developer Guide Usage

This document is for developers who aim to further improve upon the application or change it to suit the needs of your target audience.
Each feature and design component has its own sub-heading and can be referred through the links in the table-of-contents.
They contain sufficient diagrams and detailed explanations that will be extremely useful to you.

2. Setting up

This section will assist you in setting up the project for the first time in your computer. This will allow you to work on the application without any issue in the future.

2.1. 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 have 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

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 dialogue 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.
Open MainWindow.java and check for any code errors
1. Due to an ongoing issue with some of the newer versions of IntelliJ, code errors may be detected even if the project can be built and run successfully
2. To resolve this, place your cursor over any of the code section highlighted in red. Press ALT+ENTER, and select Add '--add-modules=…' to module compiler options for each error
Repeat this for the test folder as well (e.g. check HelpWindowTest.java for code errors, and if so, resolve it the same way)

2.3. Verifying the setup

Run the seedu.pdf.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. 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)

2.4.3. 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

This section allows you to visualise the application in a top-down view, where you are able to see the general structure of the different components within PDF++.

3.1. Architecture

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

Figure 1. Architecture Diagram

The .pptx or .xml 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 or xml 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. The following class plays an important role at the architecture level:

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 PDF++ App.
Logic: The command executor.
Model: Stores 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

How the architecture components interact with each other

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

Figure 3. Delete Image

The sections below give more details of each component.

3.2. UI component

Figure 4. Structure of the UI Component

API : Ui.java

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, PdfListPanel, 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.
Listens for changes to Model data so that the UI can be updated with the modified data.

3.3. Logic component

Figure 5. Structure of the Logic Component

API : Logic.java

Logic uses the PdfBookParser 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 pdf).
The result of the command execution is encapsulated as a CommandResult object which is passed back to the Ui.
In addition, the CommandResult object can also instruct the Ui to perform certain actions, such as displaying help to the user.

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

Figure 6. Interactions Inside the Logic Component for the delete 1 Command

3.4. Model component

Figure 7. Structure of the Model Component

API : Model.java

The Model,

stores a UserPref object that represents the user’s preferences.
stores the Pdf Book data.
exposes an unmodifiable ObservableList<Pdf> 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 Pdf Book, which Pdf can reference. This would allow Pdf Book to only require one Tag object per unique Tag, instead of each Pdf needing their own Tag object. An example of how such a model may look like is given below.

Figure 8. OOP Diagram

The Pdf Class Diagram below shows the structure of the Pdf class, which is the most used class throughout the application.

Figure 9. Pdf Class Diagram

3.5. Storage component

Figure 10. 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 Pdf Book data in json format and read it back.

3.6. Common classes

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

4. Implementation

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

Items with … after them can be used multiple times including zero times e.g. TAG… can be used as (i.e. 0 times), MyTag, TagA TagB TagC etc.

4.1. Add Feature

4.1.1. Current Implementation

This feature is facilitated by both the AddCommandParser and AddCommand. This feature adds the PDF file to the app using the path specified by your users. Other features such as the Section 4.3, “Rename Feature” and Section 4.2, “Open feature” can only be performed on files that are added to the application.

The AddCommandParser uses the prefixes defined in CliSyntax to identify the different types of arguments that are entered along with the add command. These arguments will then be used to construct a new Pdf which will represent the Pdf to be added.

The implementation of the AddCommand execution can be summarised in the following activity diagram:

Figure 11. Add Command Activity Diagram

The current PdfBook Model is checked to determine if identical Pdf has already been added.
1. If such a Pdf already exists, a CommandException will be thrown and the execution will be ended.
The Pdf to be added is loaded into a third-party API to verify for any errors.
1. Pdf will be loaded as PDDocument, which verifies the file that the user wishes to add to the program.
2. Created PDDocument will be closed after loading as it is unused.
3. Errors in adding the Pdf would throw IOException. Errors would most likely be due to:
  1. File not found at location
  2. Lack of user permissions to open file
  3. File has encryption
  4. File corruption
4. Thrown IOException is intercepted, a CommandException will be thrown and the execution will be ended.
The Pdf is recorded in the Model and the changes are committed.
CommandResult is returned upon successful execution.

4.1.2. Considerations

The implementation design of this feature was built upon the original implementation used by the addressbook. As the application is primarily meant to be operated through the CLI, it was decided to continue using the same prefix for the command input to keep its consistency.

Due to the handling of files, additional checks have to be added such as the use of PDDocument to ascertain that it is a .pdf file and that it can be used with Apache PDFBox® library API.

4.1.3. Future Implementation

Currently, PDF++ only supports PDF files, any other types of files will not be accepted. As the goal of the application is to be the sole manager of files, the application will be upgraded to work with all files in v2.0.

4.2. Open feature

4.2.1. Current Implementation

The open feature is facilitated by both the OpenCommandParser and OpenCommand. Essentially upon opening a Pdf that is tracked by the application, the user will be able to execute the PDF with the operating system’s default PDF reader application.

The Open feature has the following syntax:

open <INDEX>

<INDEX> refers to the index of the Pdf that you wish to edit.

The index value can be referenced from the list in the main application, or from the result of the Filter, Find or List feature.

4.2.2. Feature Breakdown

Illustrated below is a sample usage scenario that provides a clear view of the inner workings of the Open feature.

Step 1: The user launches an application with either an existing set of Pdf or a new sample set of Pdf stored within as shown below.

Step 2: The user chooses a Pdf that they wish to open, in this case,a.pdf, and enters the open command into the CLI Interface, following the outlined Syntax as illustrated below.

Step 3: Upon hitting enter to execute the command, the OpenCommandParser parses the input in the following method:

Extract the INDEX that is input that was entered by the user.
Verify that it contains a valid integer.
- This is done by initialising the Index objects that verify the above properties on instantiation.
- If the supplied parameter is invalid a ParseException is thrown and the open command is terminated.
Upon successfully parsing the input Index, a OpenCommand object is created with the relevant index and returned to the LogicManager for execution.

Step 4: The LogicManager attempts to execute the OpenCommand by supplying it the model and commandHistory.

Step 5: The OpenCommand checks that the supplied Index matches a Pdf in the model and sources for the default application within the Operating System to open the file.

Step 6: Finally, the OpenCommand supplies the default application with the file-path of the Pdf to open and returns a successful CommandResult to the LogicManager.

Should there be an issue with the parsing of the Pdf due to invalid directories or a corrupted Pdf file, the CommandException will be thrown and the OpenCommand will be terminated. A "Fail Message" will then be displayed to the user.

The implementation of the OpenCommand execution can be summarised in the following activity diagram:

Figure 12. Open Command Activity Diagram

For more information about the behaviour of sourcing for the default application to open the Pdf, please refer to Java SE 9 class Desktop.

4.3. Rename Feature

4.3.1. Current Implementation

The rename feature is facilitated by both the RenameCommandParser and RenameCommand. Essentially upon adding a Pdf to be tracked by the application, the user will be able to change certain attributes tied to the PDF such as the Name and tied to a particular Pdf.

Figure 13. Rename Command Activity Diagram

4.4. Move feature

4.4.1. Current Implementation

The move feature is facilitated by both MoveCommand and MoveCommandParser. This feature functions as a simplified version of Section 4.3, “Rename Feature”, as in nature it is making an edit to the directory of the file. However, in addition to making changes to the directory in the application storage, it also ensures that the directory changes are reflected in the local filesystem.

The design consideration into separating move as a new command from edit factored in the purpose of the application; as a document manager, the term "edit" is synonymous with making content or characteristic changes when it is applied in the context of documents.

The Move feature has the following syntax:

move

move <INDEX> <NEWDIRECTORY>

<INDEX> refers to the index of the file that you wish to move.
<NEWDIRECTORY> refers to the address of the new location the file is to be moved.
Entering move without <INDEX> or <NEWDIRECTORY> will open the default file selection GUI for the user to select the file directly.

The index value can be referenced from the list in the main application, or from the result of the Filter, Find or List feature.

4.4.2. Feature breakdown

Illustrated below is a sample usage scenario that provides a clear view of the inner workings of the move feature.

Step 1: From the main interface of the application, the user chooses a Pdf that they wish to move, and enters the move command into the CLI Interface, following the outlined Syntax as illustrated below.

Figure 14. Step 1

In this scenario, there is a file document.pdf in the windows Desktop directory, and the move command entered is intended for the file to be moved to the windows Documents directory.

Step 2: After executing the command, the MoveCommandParser parses the input into relevant objects that are required to be executed by the MoveCommand object. In particular, it ensures that there are correctly two arguments passed as described in the above Syntax. Upon parsing, the parser then creates a new MoveCommand that will execute the user’s input.

Step 3: The MoveCommand is then executed. Successful execution of the command would return a CommandResult object, while unsuccessful execution due to validation failure will throw a CommandException.

4.5. Merge feature

4.5.1. Current Implementation

The merge feature is facilitated by both MergeCommand and MergeCommandParser. This feature utilise the Apache PDFBox® library, specifically the PDFMergerUtility API to append two or more PDFs and create a new file with the merged content. As there will be one additional file added to the application, this feature also implicitly performs Section 4.1, “Add Feature” to add the new PDF to the application.

The implementation of the MergeCommand execution can be summarised in the following activity diagram:

Figure 15. Merge Command Activity Diagram

The provided indices are checked to be valid i.e. referring to a specific Pdf in the PdfBook.
1. If there is at least one invalid index, a CommandException will be thrown and the execution will be ended.
The required Pdfs are retrieved from the PdfBook based on indices.
A File object is created for each Pdf which allows file operations to be performed on the Pdf.
PDFMergerUtility is created. The directory must be set for the merged file prior to merging, which also includes the name of the file. By default, the directory of the Pdf based on the first index is used.
A unique name is created for the merged file and combined with the aforementioned directory to create the full directory for the merged file.
1. To avoid issues with duplicate names at the directory, the name is created based on hash code. The created name will also be verified unique at the directory - and changed if necessary.
The Files will be loaded as PDDocument, which is an indicator if the application can perform other operations on the Pdf that need it to be handled as a .pdf file.
1. Errors in accessing Pdf would throw IOException. Errors would most likely be due to:
  1. File not found at location
  2. Lack of user permissions to open file
  3. File has encryption
  4. File corruption
2. Thrown IOException is intercepted, a CommandException will be thrown and the execution will be ended.
The Files are added to the PDFMergerUtility.
1. Errors in adding to PDFMergerUtility would throw IOException. The cause for error would be similar to above.
2. Thrown IOException is intercepted, a CommandException will be thrown and the execution will be ended.
All loaded PDDocument are closed.
A new Pdf is created to represent the merged file created.
The Pdf is recorded in the Model and the changes are committed.
CommandResult is returned upon successful execution.

This sequence diagram demonstrates the interactions involved from start of MergeCommandParser to end of MergeCommand execution:

Figure 16. Merge Command Sequence Diagram

4.5.2. Considerations

The default directory of the merged file is currently set to the directory of the first index of the files to be merged. There were considerations to make flexibility in the merge command input to allow for the user to specify the desired directory of the merged file. As the current version of PDF++ is focused on a working product, it was decided to simplify the command to focus on the merge operation. Users can also make use of Section 4.4, “Move feature” to move the file; such implementation is more intuitive if the user is going to be using the application for everyday needs.

For the merging of files, the current implementation involves adding all files to a single PDFMergerUtility to merge together. One alternative to merging multiple files would be to create a separate PDFMergerUtility for every pair of files and merge the content recursively into a final merged file. The advantage of this would be better stability in performance when merging multiple large files as there will be lesser workload on each PDFMergerUtility. However, this would undoubtedly cause the performance to be slower as more merge operations are done overall. As the case of instability occurs only in very large files, it was decided to go with a focus on performance.

4.5.3. Future Implementation

There are performance issues encountered when performing the merge operations with many files of large size. In future versions, the merge operation has to not only ensure performance but stability as well. By v2.0, the merging will be able to support larger files without any concern for the application to freeze or crash while merging. Currently, there are no means to make the merging operation perform faster due to the merging operation being performed through the PDFMergerUtility API.

4.6. Delete feature

4.6.1. Current Implementation

The delete feature is facilitated by both DeleteCommand and DeleteCommandParser. This feature performs either a soft or hard remove operation on a file in the application based on the index provided.

The implementation of the DeleteCommand execution can be summarised in the following activity diagram:

Figure 17. Delete Command Activity Diagram

Soft delete is defined as removing a file from the application but not from the local filesystem; the physical file is left intact within the user’s operating system, but the user will not be able to access or use the features of the application on said file - unless it is added back to the application.
Hard delete is defined as removing a file both from the application and the local filesystem; the physical file will be deleted and the user will not be able to access or perform any operations on the file, either through the application or through the user’s operating system.

As of v1.4, there is no way to completely undo the hard delete operation. When the file is deleted from the filesystem, it is permanently erased.

The delete feature has the following syntax:

delete <INDEX>

delete <INDEX> hard

<INDEX> refers to the index of the file in the list that you wish to perform the action on.
If the keyword hard is not specified, the soft delete operation will be performed. Otherwise, the hard delete operation will be performed.

The index value can be referenced from the list in the main application, or from the result of the Filter, Find or List feature.

4.6.2. Feature breakdown

Illustrated below is a sample usage scenario that provides a clear view of the inner workings of the delete feature.

Step 1: From the main interface, the user chooses a file that they wish to delete, and enters the delete command into the CLI Interface, following the outlined Syntax mentioned.

Step 2: Upon hitting enter to execute the command, the DeleteCommandParser parses the input into relevant objects that are required to be executed by the DeleteCommand object. Upon parsing, the parser then creates a new DeleteCommand that will execute the user’s input.

Step 3: The DeleteCommand is then executed. Successful execution will return a CommandResult indicating that the changes have been made.

Figure 18. Delete Command Activity Diagram

Figure 19. Delete Command Sequence Diagram

4.7. Clear feature

4.7.1. Current Implementation

The clear feature is facilitated by both ClearCommand and ClearCommandParser. This feature removes all the PDF files that were previously stored in PDF++. It is similar to the Section 4.6, “Delete feature” in that it removes files from the application, with multiple files instead of one at a time. However, it differs that it does not have the option to delete the file from the local filesystem.

The Clear feature has the following syntax:

clear

The clear command will be executed regardless if there is any invalid text that comes after the command
All files will be removed from the application, but not from the local filesystem.

Since the clear feature is very easily executed, if you have accidentally entered the clear command and wish to revert the action, please refer to [Undo/Redo feature] for more information.

Figure 20. Clear Command Activity Diagram.

4.8. Deadline feature

4.8.1. Current Implementation

The deadline feature is facilitated by both Deadline, DeadlineCommand and DeadlineCommandParser This feature allows you to set or remove deadlines of the file specified by you from PDF++. The deadlines will be recorded and displayed both in the list of files as well as in the information panel for each individual file.

The implementation of the Deadline model can be represented in the following class diagram:

Figure 21. Deadline Class Diagram

A Deadline model has a Java.time.LocalDate date attribute and a boolean isDone. The date is the date for the deadline assigned to the file, the isDone attribute evaluates to true if the deadline is set to be done, false if it is not done.

The implementation of the DeadlineCommand execution can be summarised in the following activity diagram:

Figure 22. Deadline Command Activity Diagram

The provided index is checked to be valid i.e. referring to a specific Pdf in the PdfBook.
1. If the index is invalid, a CommandException will be thrown and the execution will be ended.
The required Pdf is retrieved from the PdfBook based on the index.
A duplicate Pdf of the required Pdf is created.
For cases of assigning a new deadline,
1. The duplicate Pdf is assigned with new deadline attributes.
For cases of setting an existing deadline as done or removed,
1. The existing deadline from the retrieved Pdf is tested to be a valid deadline.
  1. If the existing deadline is a valid deadline, the duplicate Pdf is assigned with new deadline attributes.
  2. If the existing deadline is not a valid deadline, a CommandException will be thrown and the execution will be ended.
The duplicate Pdf with new deadline attributes is recorded in the Model and the changes are committed.
CommandResult is returned upon successful execution.

This sequence diagram demonstrates the interactions involved from start of DeadlineCommandParser to end of DeadlineCommand execution:

Figure 23. Interactions Inside the Logic Component for the deadline 1 done Command

After a deadline has been added to the PDF file specified, the date will be color-coded according to days remaining from the current day until the deadline date.

4.8.2. Considerations

There are some discrepancy for the representation of a file without a deadline in the Jackson adapted storage and the Pdf book model. In the Pdf book model, files without a deadline will be assigned with the default deadline whereas the date is set to LocalDate.MIN. In the Jackson adapted storage, we simply set the deadline attribute of a file without a deadline as empty. In our previous implementation, we used to assign the default date LocalDate.MIN to the deadline attribute in the Jackson adapted Storage as well, however, this might confuse the users if they read the pdfplusplus.json and find out the non-existence deadline. Besides, this implementation also makes the displaying process of deadlines through the UI tedious.

In order to comply with the two distinct representation of deadline model, we implemented a default deadline toString method that prints the Pdf book model version, and a modified toJsonString that prints the Jackson adapted storage version of the deadline.

4.8.3. Future Implementation

Our current color-coded deadlines are predefined based on the due date from the current date. Suggested improvement for this area would be providing user-defined color codes for a better user experience of our application.

4.9. Help feature

4.9.1. Current Implementation

The help feature brings up the UserGuide in a browser window as a html file. Following other features, the command is parsed and a HelpCommand object is created to be executed.

The help feature has the following syntax:

help

After execution, the user will be directed to the start of the UserGuide.adoc as shown. Users can reference from the UserGuide directly on how to navigate the guide.

Figure 24. User Guide

4.10. Exit feature

4.10.1. Current Implementation

The exit feature is facilitated by ExitCommand. This feature allows you to exit from PDF++.

The exit feature has the following syntax:

exit…

The exit command will be executed regardless if there is any invalid text that comes after the command

Your files and commands are immediately stored after execution and can be retrieved on reopening the application.

4.11. List feature

4.11.1. Current Implementation

The list feature is facilitated by ListCommand. This feature will display all of the files currently stored within the application at the main interface. By default, all of the files will be displayed when the application is started. However, the display of the interface can be changed to reflect the results of Find feature or Filter feature.

Certain features such as Merge Feature rely on the index of the file(s) displayed on the main interface. Since the find or filter feature would list a sample of all the files at the main interface, no commands can be executed on the files not included in the results. Hence, the list feature is added to allow for a "reset" of the view of the files.

The List feature has the following syntax:

list

4.12. Find feature

4.12.1. Current Implementation

The find feature is facilitated by FindCommand and FindCommandParser. This feature lists a subset of all the files in the application based on the keyword(s) provided. Using the keyword(s), the application will check the names of all files, as well as the content of the text within the files prior to revealing the results.

The find feature has the following syntax:

Format: find <KEYWORD> …

<KEYWORD> refers to the word that the application will use as a reference to find files. There must be at least one provided.

Example: * find Resume * find Introduction

4.12.2. Feature Breakdown

Figure 25. Find Command Activity Diagram

The following image briefly summarises the interactions of the find command with some of its immediate components.

Figure 26. General Internal Illustration of Find Command.

When the user enters the CLI Input for the find command, the command is first passed from the LogicManager to the PdfBookParser will carry out the following steps.

The user inputs a request to find a keyword within the files of the application. e.g. find keyword.
The PdfBookParser creates a new FindCommandParser upon recognising that the user wishes to use the find feature.
Parse method within the FindCommandParser would create a NameContainsKeywordPredicate which will allow the Model to filter its list of files to show the user the requested files.
Finally, the FindCommand object is returned to the LogicManager.

Upon receiving the FindCommand from the PdfBookParser the following steps are carried out.

The execute method is invoked from the LogicManager with the parameters of model and history.
The model then uses the NameContainsKeywordPredicate and runs the test method to check each file and verify that it fulfils the predicate. This is so that the model can update itself to present the list of files that the user wishes to view.
The test method invokes classes from the external Apache PDFBox library, namely PDDocument and PDFTextStripper to extract the contents of the existing files.
The extracted content is then checked to verify if it contains the keyword input by the user.
Further checks are also done to confirm if each file’s name contains the keyword as well.
The model then updates itself and stores the current action in the history object.
Finally, the FindCommand returns a CommandResult back to the LogicManager for follow up action.

This is a brief explanation of the inner workings of the FindCommmand and its execution method.

4.12.3. Considerations

Our application also implements several security features such as the ability of users to Encrypt and Decrypt their files. Hence, a major security concern was to prevent the FindCommand from searching through the contents of files that are previously encrypted. This is crucial to prevent the leakage of data as malicious users might simply utilize the FindCommand to extract information from the tracked files.

4.12.4. Future Implementation

The main issue with the current implementation of the FindCommand is its slow speeds with respect to large files or files that contain a large string of text files. Hence, a possible consideration you might wish to improve upon is to "upgrade" this feature by improving its speed of this feature.
Yet another enhancement to this feature you might wish to implement is the use of Optical Image Recognition, otherwise known as OCR. This will allow the application to translate images within the file to words which would further improve the ability of the application to look through content even if they are images.

4.13. Filter feature

4.13.1. Current Implementation

The filter feature is facilitated by FilterCommand and FilterCommandParser. This feature is similar to Find feature in that it lists a subset of all the files in the application, except that it will list the files based on the tag of the file.

The filter feature has the following syntax:

Format: filter t/<TAG> …

<TAG> refers to a tag that is valid, i.e. a tag that was previously set on a file.
All tags need to have the prefix /t to differentiate between each tag.

4.13.2. Feature Breakdown

Figure 27. Filter Command Activity Diagram

The inner workings of FilterCommand can be explained in the following steps should you need to modify it. Given that they are extremely similar to that of the Find Feature, you may refer to that should you need more information.

The LogicManager component invokes a PdfBookParser to parse the input command.
- An input command such as filter t/school t/lecture.
The PdfBookParser then decodes the instruction by identifying the keyword, which is select and creates a new FilterCommandParser to parse the necessary parameters.
- These parameters are mainly each tag specified as t/TAG
- The FilterCommandParser creates a predicate TagContainsKeywordsPredicate which tests each file if it contains the specified tags.
The FilterCommandParser then parses the parameter, FilterCommand object that is returned to the LogicManager to execute.
The LogicManager supplies the FilterCommand with the existing application model and command history and executes it.
The execution of the FilterCommand mainly contains the following step.
- Provides model with the newly formed TagContainsKeyworkdsPredicate to update the list of files with only those that contain the input tags.
- This change causes the invocation of the UI component to display the selected item to the user.
Finally, upon successful execution, a CommandResult is returned to the LogicManager for other operations.
- If any errors occur mid-execution, a CommandException is thrown. These errors may occur due to:
  - Invalid parameter inputs.

4.14. Select feature

4.14.1. Current Implementation

The select feature is facilitated by SelectCommand and SelectCommandParser. This allows users to select a file and view more information pertaining to that selected file. They are able to view features such as its size, any deadlines assigned to it, its name, and directory.

The Select feature has the following syntax: Format: select INDEX

4.14.2. Feature Breakdown

The inner workings of SelectCommand can be explained in the following steps should you need to modify it.

The LogicManager component invokes a PdfBookParser to parse the input command.
- An input command such as select 1.
The PdfBookParser then decodes the instruction by identifying the keyword, which is select and creates a new SelectCommandParser to parse the necessary parameters.
The SelectCommandParser then parses the parameter, in this case 1 and creates a new SelectCommand object that is returned to the LogicManager to execute.
The LogicManager supplies the SelectCommand with the existing application model and command history and executes it.
The execution of the SelectCommand sets the selectedPdf property of the model.
- This change causes the invocation of the UI component to display the selected item to the user.
Finally, upon successful execution, a CommandResult is returned to the LogicManager for other operations.
- If any errors occur mid-execution, a CommandException is thrown. These errors may occur due to:
  - Invalid parameter inputs.

4.15. Sort feature

4.15.1. Current Implementation

The sort feature is facilitated by SortCommand and SortCommandParser. The sort command allows the user to arrange the list of files tracked by the application in a specified order & criteria. The order can be ascending (up) or descending (down) while the criteria can be name, deadline or size.

The Sort feature has the following syntax: Format: sort CRITERIA ORDER Example:

sort deadline up
sort name down

4.15.2. Feature Breakdown

Listed below is a brief explanation of the inner workings of the sort feature.

The LogicManager component invokes a PdfBookParser to parse the input command.
- An input command such as sort deadline up.
The PdfBookParser then decodes the instruction by identifying the keyword, which is select and creates a new SortCommandParser to parse the necessary parameters.
The SortCommandParser then parses both parameters and creates a SortCommand object that is returned to the LogicManager to execute.
- The parameters are the CRITERIA and ORDER specified by the user.
The LogicManager supplies the SortCommand with the existing application model and command history and executes it.
The execution of the SortCommand contains the following steps:
- The list of existing files are obtained from the Model component
- This list is sorted with the given CRITERIA and ORDER.
- The sorted list is set as the new default list of the Model component.
This change causes the invocation of the UI component to display the new list of files to the user.
Finally, upon successful execution, a CommandResult is returned to the LogicManager for other operations.
- If any errors occur mid-execution, a CommandException is thrown. These errors may occur due to:
  - Invalid parameter inputs such as invalid CRITERIA or ORDER.

All other operations carried out after sort that require an INDEX to be supplied must follow the newly set indexes of the files tracked by the application.

4.16. Tag feature

4.16.1. Current Implementation

The tag feature is facilitated by TagCommand and the TagCommandParser. This allows users to set tags to files that are tracked by the application that allows them to easily organize and view these files with other operations supported by our application such as the Filter Feature. In order to perform the Tag Command the user needs to specify a PREFIX that is denoted by -a or r to signify the addition or removal of a tag. The INDEX that refers to the file that the user wishes to interact with and the tags themselves that are represented in the t/TAG format where TAG text that the user wishes to use as a tag.

The Tag feature has the following syntax: Format: tag PREFIX INDEX t/TAG…

Example: * tag 1 -a t/SEROCKS * tag 1 -r t/SEROCKS * tag 2 -a t/Urgent t/Resume

4.16.2. Feature Breakdown

The inner workings of TagCommand can be briefly explained in the following steps should you need to modify it.

The LogicManager component invokes a PdfBookParser to parse the input command.
- An input command such as tag 1 -a t/SEROCKS.
The PdfBookParser then decodes the instruction by identifying the keyword, which is select and creates a new TagCommandParser to parse the necessary parameters.
The TagCommandParser then parses the relevant parameters and creates a new SortCommand object that is returned to the LogicManager to execute. The parsed parameters include:
- PREFIX which, as mentioned above, indicates if the tag is to be added or removed from the file.
- INDEX which indicates to the command which file that the user wishes to interact with.
- t/TAG which contain the name of the tag(s) that the user wishes to add to the specified file.
The LogicManager supplies the TagCommand with the existing application model and command history and executes it.
The execution of the TagCommand contains the following steps:
- The file that the user wishes to add the tags to is obtained from the model.
- The parsed tag(s) are added to the chosen file.
- The model is then updated with the newly modified file.
- Changes are reflected in the UI component by new labels forming under the name of the file.
Finally, upon successful execution, a CommandResult is returned to the LogicManager for other operations.
- If any errors occur mid-execution, a CommandException is thrown. These errors may occur due to:
  - Invalid parameter inputs.

The Tag Feature only allows for tags that do not contain spaces and are alphanumeric.

4.17. History feature

4.17.1. Current Implementation

The history feature is facilitated by HistoryCommand. This feature displays the previous commands entered since the start of the current session of the application; each time the application is closed, the command history will be erased.

The history feature has the following syntax:

history

When there is no command history, a message will be shown to notify the user.

4.18. File Protection

PDF++ has a robust in-built file protection system which allows you to encrypt or decrypt any PDF files you want. These features utilises the Apache PDFBox® library, specifically the PDDocument, AccessPermission, and StandardProtectionPolicy.

An encrypted file is a file that is protected with a password. The terms protect and encrypt will be used interchangeably.

You can visit Section 4.18.1, “Encryption feature” and Section 4.18.2, “Decryption feature” to understand more about the respective feature.

4.18.1. Encryption feature

Current Implementation

The encrypt feature is facilitated by both EncryptCommand and EncryptCommandParser.

The implementation of the EncryptCommand execution is summarised in the following activity diagram:

Figure 28. Encrypt Command Activity Diagram

The provided index is checked for validity i.e. referring to a specific Pdf in PdfBook.
1. If the index is invalid, a CommandException will be thrown and the execution ends.
The Pdf specified via the index is retrieved from the PdfBook.
A File object is created for the Pdf.
The File will be loaded as PDDocument, which is an indicator that the File is a PDF document that is uncorrupted and not protected with a password.
1. Error in loading Pdf as PDDocument would throw an IOException. Common reasons for error are:
  1. File not found in location
  2. Lack of user permissions to open File
  3. Protected File
  4. Corrupted File
2. Thrown IOException is intercepted, a CommandException will be thrown and the execution ends.
AccessPermission, and StandardProtectionPolicy are created. The password specified will be passed to StandardProtectionPolicy for the purpose of setting security settings for the PDDocument.
A protected Pdf will be saved and closed.
1. Error in encrypting the file will throw an IOException. Common reasons for error are:
  1. Excessive long password
  2. Empty password
2. Thrown IOException is intercepted, a CommandException will be thrown and the execution ends.
The Pdf is recorded in the Section 3.4, “Model component” and the changes are saved.
A CommandResult is returned upon successful exception of EncryptCommand.

This sequence diagram demonstrates the [main-success-scenario] from the LogicManager to the end of EncryptCommand execution:

Figure 29. Encrypt Command Sequence Diagram

Design Considerations

Edit password of an encrypted file

Alternative 1 (current choice): Execute DecryptCommand then EncryptCommand
- Due to security reasons, it was decided to focus on encrypting an unprotected Pdf. You will need to use Section 4.18.2, “Decryption feature” before encrypting it with a new password. This is to ensure your intent in changing the password, as the current version PDF++ does not support Forget Password feature.
- However, this process is inefficient as you will need to enter 2 commands instead of 1.
Alternative 2: Change the password of an encrypted file
- This minimised the number of commands to be executed, but there are several security concerns as mentioned above.

A sophisticated protection system

Multiple adjustments to protect your interest
1. Section 4.17, “History feature” will not show the executed EncryptCommand which includes the password of the file.
2. The Section 4.19, “Undo/Redo feature [Coming in v2.0]” is temporarily disabled until a solution that will not comprise your privacy has been found.
3. Pressing up in the command box will not show the EncryptCommand that was previously executed.

Future Implementation

There are concerns of accidental encryption of a file with a wrong password. In PDF++ v2.0, the EncryptCommand will prompt you to re-enter the password as a form of confirmation message. If there is a mismatch of the two passwords entered, the command will not be executed.

4.18.2. Decryption feature

Current Implementation

The current Implementation of DecryptCommand is very similar to Section 4.18.1, “Encryption feature”. The part where it is implemented differently will be specifically marked with a * for your convenience.

The decrypt feature is facilitated by both DecryptCommand and DecryptCommandParser.

The implementation of the DecryptCommand execution is summarised in the following activity diagram.

Figure 30. Decrypt Command Activity Diagram

The provided index is checked for validity i.e. referring to a specific Pdf in PdfBook.
1. If the index is invalid, a CommandException will be thrown and the execution ends.
The Pdf specified via the index is retrieved from the PdfBook.
A File object is created for the Pdf.
The File will be loaded as PDDocument with the specified password, which is an indicator that the File is a PDF document that is uncorrupted, protected and the password provided is valid *.
1. Error in loading Pdf as PDDocument would throw an IOException and invalid password would throw a CommandException. Common reasons for error are:
  1. File not found in location
  2. Lack of user permissions to open File
  3. Unprotected File *
  4. Corrupted File
  5. Wrong password *
2. Thrown IOException is intercepted, a CommandException will be thrown and the execution ends.
Upon success loading of the PDDocument, the security will be removed. *
An unprotected * Pdf will be saved and closed.
The Pdf is recorded in the Section 3.4, “Model component” and the changes are saved.
A CommandResult is returned upon successful exception of DecryptCommand.

This sequence diagram demonstrates the [main-success-scenario] from the LogicManager to the end of DecryptCommand execution:

Figure 31. Decrypt Command Sequence Diagram

Design Considerations

A sophisticated protection system

Multiple adjustments to protect your interest
1. Section 4.17, “History feature” will not show the executed EncryptCommand which includes the password of the file.
2. The Section 4.19, “Undo/Redo feature [Coming in v2.0]” is temporarily disabled until a solution that will not comprise your privacy has been found.
3. Pressing up in the command box will not show the EncryptCommand that was previously executed.

Future Implementation

If unauthorised personnel obtained the password of your files through illegal means, they can potentially set the file with a new password. This will hinder your access to your files.

However, With 2-Factor Authentication, there is an additional layer of protection that prevents these personnel from changing the passwords of your files. This ensures that only you/any authorised personnel can decrypt your files.

In PDF++ v2.0, the DecryptCommand will support for the 2FA feature as mentioned above. If this feature is highly demanded, this feature will be implemented to EncryptCommand too.

4.19. Undo/Redo feature [Coming in v2.0]

4.19.1. Current Implementation

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

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

These operations are exposed in the Model interface as Model#commitPdfBook(), Model#undoPdfBook() and Model#redoPdfBook() 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 VersionedPdfBook will be initialized with the initial pdf book state, and the currentStatePointer pointing to that single pdf book state.

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

Step 3. The user executes add n/David … to add a new pdf. The add command also calls Model#commitPdfBook(), causing another modified pdf book state to be saved into the pdfBookStateList.

If a command fails its execution, it will not call Model#commitPdfBook(), so the pdf book state will not be saved into the pdfBookStateList.

Step 4. The user now decides that adding the pdf was a mistake, and decides to undo that action by executing the undo command. The undo command will call Model#undoPdfBook(), which will shift the currentStatePointer once to the left, pointing it to the previous pdf book state, and restores the pdf book to that state.

If the currentStatePointer is at index 0, pointing to the initial pdf book state, then there are no previous pdf book states to restore. The undo command uses Model#canUndoPdfBook() 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#redoPdfBook(), which shifts the currentStatePointer once to the right, pointing to the previously undone state, and restores the pdf book to that state.

If the currentStatePointer is at index pdfBookStateList.size() - 1, pointing to the latest pdf book state, then there are no undone pdf book states to restore. The redo command uses Model#canRedoPdfBook() 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 pdf book, such as list, will usually not call Model#commitPdfBook(), Model#undoPdfBook() or Model#redoPdfBook(). Thus, the pdfBookStateList remains unchanged.

Step 6. The user executes clear, which calls Model#commitPdfBook(). Since the currentStatePointer is not pointing at the end of the pdfBookStateList, all pdf book 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:

4.19.2. Design Considerations

Aspect: How undo & redo executes

Alternative 1 (current choice): Saves the entire pdf 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 pdf 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 pdf 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 VersionedPdfBook.
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.

4.20. 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 4.21, “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 are not usually noteworthy but may be useful in debugging e.g. print the actual list instead of just its size

4.21. Configuration

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

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 32. 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.pdf.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.pdf.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.pdf.storage.StorageManagerTest
3. Hybrids of unit and integration tests. These tests are checking multiple code units as well as how they are connected together.
  e.g. seedu.pdf.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, Pdf Book depends on the Jackson library for JSON parsing. Managing these dependencies can be automated using Gradle. For example, Gradle can download the dependencies automatically, which is better than these alternatives:

Include those libraries in the repo (this bloats the repo size)
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 pdfs 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).
  
  PdfBookParser is responsible for analyzing command words.
- Solution
  
  Modify the switch statement in PdfBookParser#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 pdf book, but the model API does not support such 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 pdf book.
- Hints
  
  The Model and the PdfBook 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 PdfBook and Pdf classes can be used to implement the tag removal logic. PdfBook allows you to update a pdf, and Pdf allows you to update the tags.
- Solution
  
  Implement a removeTag(Tag) method in PdfBook. Loop through each pdf, and remove the tag from each pdf.
  
  Add a new API method deleteTag(Tag) in ModelManager. Your ModelManager should call PdfBook#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 pdf 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 pdf 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 pdf cards. For example, friends tags can be all in brown, and colleagues tags can be all in yellow.

Before

Figure 33. UI Before Tag

After

Figure 34. UI After Tag
- Hints
  
  The tag labels are created inside the PdfCard 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 PdfCard '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

Figure 35. Ui Before Result

After

Figure 36. UI After Result
- 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 PdfBookSystemTest#assertCommandBoxShowsDefaultStyle() and PdfBookSystemTest#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 pdf book.

Before

Figure 37. UI Before Status

After

Figure 38. UI After Status
- 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 pdf book is updated.
- Solution
  
  Modify the constructor of StatusBarFooter to take in the number of pdfs when the application just started.
  
  Use StatusBarFooter#handlePdfBookChangedEvent(PdfBookChangedEvent) to update the number of pdfs whenever there are new changes to the pdfbook.
  
  For tests, modify StatusBarFooterHandle by adding a state-saving functionality for the total number of people status, just like what we did for save directory and sync status.
  
  For system tests, modify PdfBookSystemTest to also verify the new total number of pdfs 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 pdf book to the cloud. However, the current implementation of the application constantly saves the pdf 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 pdf book storage.

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

Add a new method backupPdfBook(ReadOnlyPdfBook), so that the pdf book can be saved in a fixed temporary directory.
- Hint
  
  Add the API method in PdfBookStorage interface.
  
  Implement the logic in StorageManager and JsonPdfBookStorage 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 pdfbook, 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 pdf specified in the INDEX.
Format: remark INDEX r/[REMARK]

Examples:

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

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 PdfBookParser to accept a RemarkCommand.

Tests:

Add RemarkCommandTest that tests that execute() throws an Exception.
Add new test method to PdfBookParserTest, 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 PdfBookParser 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 PdfBookParserTest to test that the correct command is generated according to the user input.

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

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

Main:

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

Tests:

Modify PdfCardHandle 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 Pdf 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 Directory, 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 `Pdf` to support a `Remark` field

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

Main:

Add getRemark() in Pdf.
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 pdf will be created without a remark).
Modify SampleDataUtil to add remarks for the sample data (delete your data/pdfbook.json so that the application will load the sample data when you launch it.)

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

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

Main:

Add a new JSON field for Remark.

Tests:

Fix invalidAndValidPdfPdfBook.json, typicalPdfsPdfBook.json, validPdfBook.json etc., such that the JSON tests will not fail due to a missing remark field.

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

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

Tests:

Add a new method withRemark() for PdfBuilder. This method will create a new Remark for the pdf that it is currently building.
Try and use the method on any sample Pdf in TypicalPdfs.

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

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

Main:

Modify PdfCard's constructor to bind the Remark field to the Pdf 's remark.

Tests:

Modify GuiTestAssert#assertCardDisplaysPdf(…) 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 pdf.

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:

has a need to manage a significant number of contacts
prefers desktop app over other types
can type fast
prefers typing over mouse input
is reasonably comfortable using CLI apps

Value proposition: manage contacts 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…
`* * *`	new user	see usage instructions	refer to instructions when I forget how to use the App
`* * *`	organized student	rename the PDFs to any valid name supported by the operating system	keep my PDFs organized
`* * *`	lazy user	filter my PDFs based on the tags	so that I can see all the files with the same tag in the app
`* * *`	user	delete a pdf	remove entries that I no longer need
`* * *`	user	find a pdf by name	locate details of PDFs without having to go through the entire list
`* * *`	user with different tasks and deadlines	set due dates for my PDFs	be notified of upcoming deadlines and know the files required for that task
`* *`	student	view my productivity analysis and estimate time to get work done	allocate sufficient time to finish my homework & assignments before deadlines
`*`	user	view clashing tasks/appointments	be notified and make changes
`*`	class tutor	obtain the statistics of the exam	evaluate the performance of the exam
`*`	teacher	create new exam paper	create formatted online exam paper easily
`*`	NUS student	submit my files to LumiNUS with command lines	submit files without using an internet browsers

* * *

new user

see usage instructions

refer to instructions when I forget how to use the App

* * *

organized student

rename the PDFs to any valid name supported by the operating system

keep my PDFs organized

* * *

lazy user

filter my PDFs based on the tags

so that I can see all the files with the same tag in the app

* * *

user

delete a pdf

remove entries that I no longer need

* * *

user

find a pdf by name

locate details of PDFs without having to go through the entire list

* * *

user with different tasks and deadlines

set due dates for my PDFs

be notified of upcoming deadlines and know the files required for that task

* *

student

view my productivity analysis and estimate time to get work done

allocate sufficient time to finish my homework & assignments before deadlines

*

user

view clashing tasks/appointments

be notified and make changes

*

class tutor

obtain the statistics of the exam

evaluate the performance of the exam

*

teacher

create new exam paper

create formatted online exam paper easily

*

NUS student

submit my files to LumiNUS with command lines

submit files without using an internet browsers

Appendix D: Use Cases

Use case: Add new PDF file

System: PDF++
Actor: Student
MSS

User types add f/FILEPATH into the CLI Input.
User presses enter.
PDF++ makes a record of the relevant attributes of the selected PDF.

Use case ends.

Extensions
3a. User loads an invalid file (not a pdf).

3a1. PDF++ shows an error message to user.
3a2. User repeats Step 1 and 2 to add a valid pdf into PDF++.
Use Case resumes at step 3.

Use case: Find keyword in files within PDF++

System: PDF++
Actor: Student
MSS

User types find KEYWORD.
User presses enter.
PDF++ Returns a list of files that contain the keyword in its names or content.
Use case ends.

Extensions
2a. User input invalid data.

2a1. PDF++ throws an exception to alert the user.
2a2. User repeats Step 1 to 3 to search till a valid KEYWORD is entered.

2b. User inputs a KEYWORD that is not in any of the files.

2b1. PDF++ Returns an empty list.
Use Case ends.

Use case: Delete PDF file within PDF++

System: PDF++
Actor: Student
MSS

User requests to list pdfs
PdfBook shows a list of pdfs
User requests to delete a specific pdf in the list
PdfBook deletes the pdf

Use case ends.

Extensions

2a. The list is empty.

Use case ends.
3a. The given index is invalid.
- 3a1. PdfBook shows an error message.
  
  Use case resumes at step 2.

Use case: Merge PDF files within PDF++

System: PDF++
Actor: Student
MSS

User types list in CLI to list all pdfs.
PdfBook shows a list of pdfs.
User types merge [INDEXES] in CLI where INDEXES refer to displayed list index of pdfs to be merged in their desired order.
PdfBook merges the specified pdfs into new pdf.
PdfBook updates the list to show the merged pdf.

Use case ends.

Extensions

3a. One of the indexes provided is invalid.

3a1. PDF++ throws an exception to alert the user.
3a2. User repeats Step 1 to 3 to merge with valid indexes provided.
Use case ends.

4a. One or more of the files referenced by indexes provided are encrypted.

4a1. PDF++ throws an exception to alert the user.
4a2. User removes encryption on files to be merged before restarting from Step 1.
Use case ends.

4b. One or more of the files fail to be opened or merged, throwing a Java FileIOException.

4b1. PDF++ throws an exception to alert the user.
4b2. User ensures that files to be merged are working before restarting from Step 1.
Use case ends.

Appendix E: Non Functional Requirements

Technical requirements

The software should work on both 32-bit and 64-bit environments.
Platform compatibility

The software should work on Windows, Linux and OS-X platforms.
Response time

The software should respond within two seconds.
Cost

The software is free of charge. However, we do appreciate any contributions to our coffee fund.
Privacy

The software should work entirely offline and should not collect user personal data for any purposes.
Licensing

The software is free, open-source does not require installation.
Portability

The software should not require any installer; it should be able to run without installing any additional software.
Extensibility

The software should take future growth into consideration e.g. adding features, carry-forward of customizations at next major version upgrade.
Testability

The software should not have features that are hard to test both manual and automated testing.
Data requirements

The data that is stored locally should be editable by user. In other words, expert users can open the file without using the application and edit it for his or her liking.

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
Encrypted file: A file that is protected with a password
Main Success Scenario: The expected sequence of events assuming that nothing goes wrong

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 directory. Close the window.
2. Re-launch the app by double-clicking the jar file.
  Expected: The most recent window size and directory is retained.

G.2. Adding a pdf

Adding an actual pdf file that is on the local device
1. Prerequisites:
  1. Have Read, Write and Execute permissions to access the file.
  2. The file must be an unencrypted and uncorrupted pdf file.
2. Test case: add f/C:\Users\WeiTang\Desktop\test\validPdfFile.pdf
  1. Please make sure that your command is of this format: add f/VALIDFILEPATH.pdf. Note that the file path various for Operating Systems and devices.
  2. Expected: The pdf is added to the last index of the list. Details of the added pdf shown in the status message. Timestamp in the status bar is updated.
3. Test case: add f/invalidFilePath
  1. Expected: No pdf is added. Error details are shown in the status message. Status bar remains the same.

G.3. Sorting the list of pdf

Sorting the list of pdfs in a specified order
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system. The sort command works even for an empty list.
2. Test case: sort name up
  Expected: The list of pdfs will be sorted according to name in ascending order.
3. Other correct sort commands to try: sort name down (sort the list by name in descending order), sort size up (sort the list by size in ascending order), sort size down (sort the list by size in descending order), sort deadline up (sort the list by deadline in ascending order), sort deadline down (sort the list by deadline in descending order).
4. Test case: sort invalidOperation up
  Expected: The list of pdfs is not sorted. Error details are shown in the status message. Status bar remains the same.
5. Other incorrect sort commands to try: sort name wrongCriteria (the order is wrong), sort name (sort order is not specified), sort up (sort order is not specified).
Moving a pdf to a new specified directory
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: move 1
  Expected: A GUI will show to allow you to select the directory that you want to move the first pdf to.
  1. If the directory indicated is different from the current directory of pdf
    Expected: The pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
  2. If the directory indicated is same from the current directory of the pdf
    Expected: The first pdf is not moved. Error details are shown in the status message. Status bar remains the same.
3. Test case: move 1 d/validPathToDirectory
  1. If the directory indicated is different from the current directory of pdf
    Expected: The pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
  2. If the directory indicated is same from the current directory of the pdf
    Expected: The first pdf is not moved. Error details are shown in the status message. Status bar remains the same. Expected: The first pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
4. Test case: move d/validPathToDirectory Expected: No pdf is moved. Error details are shown in the status message. Status bar remains the same.
5. Other incorrect move commands to try: move, move 1 d/ (no directory specified), move 1 validPathToDirectory (no directory prefix), move 1 d/NotADirectory.pdf (not directory path specified)
  Expected: Similar to previous.

G.4. Open

Open the pdf by the specified index in the list.
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: open 1
  Expected: The first pdf is opened using the system default PDFReader. Details of the updated pdf shown in the status message. Timestamp in the status bar is updated.
3. open 0
  Expected: No pdf is open. Error details are shown in the status message. Status bar remains the same.
4. Other incorrect open commands to try: open, open x (where x is larger than the list size), open y (where y is any negative number)
  Expected: Similar to previous.

G.5. Rename a pdf file

Prerequisites: The pdfs in the list are uncorrupted and they exist in the system.
Test case: rename 1 n/newName.pdf
Expected: First pdf is renamed to newName.pdf. Details of the updated pdf shown in the status message. Timestamp in the status bar is updated.
Test case: rename 1 n/pdf
Expected: First pdf is not renamed. Error details are shown in the status message. Status bar remains the same.
Other incorrect rename commands to try: rename 1 validName.pdf (no prefix), rename x n/validName.pdf(where x is larger than the list size), rename y n/validName.pdf (where y is any negative number), rename n/validName.pdf (no index), rename 1 wrong/validName.pdf (wrong prefix)
Expected: Similar to previous.

G.6. Tagging a pdf

Tagging a pdf that is in the list.
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: tag 1 -a t/SEROCKS
  Expected: First pdf is tagged with SEROCKS. Details of the updated pdf shown in the status message. Timestamp in the status bar is updated. The first file in the file section GUI has the SEROCKS tag.
3. Other correct tag commands to try: tag 1 -a t/SEROCKS t/CS2103T (as tag supports for adding of multiple tags)
  Expected: Similar to previous.
4. Test case: tag 1 -r t/SEROCKS
  1. If the tag does not exists:
    Expected: The pdf is not tagged. Error details are shown in the status message. Status bar remains the same.
  2. If the tag exists:
    Expected: First pdf’s tag is removed. Details of the updated pdf shown in the status message. Timestamp in the status bar is updated.
5. Test case: tag 1 -r SEROCKS
  Expected: The pdf is not tagged. Error details are shown in the status message. Status bar remains the same.
6. Other incorrect tag commands to try: tag 1 -x t/SEROCKS (invalid operation), tag 1 -a t/ (no tag specified)
  Expected: Similar to previous.

G.7. Deleting a pdf

Deleting a pdf while all pdfs are listed
1. Prerequisites: List all pdfs using the list command. Multiple pdfs in the list.
2. Test case: delete 1
  Expected: First pdf is deleted from the list. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
3. Test case: delete 0
  Expected: No pdf is deleted. Error details are 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), delete y (where y is any negative number)
  Expected: Similar to previous.

G.8. Move

Moving a pdf to a new specified directory
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: move 1
  Expected: A GUI will show to allow you to select the directory that you want to move the first pdf to.
  1. If the directory indicated is different from the current directory of pdf
    Expected: The pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
  2. If the directory indicated is same from the current directory of the pdf
    Expected: The first pdf is not moved. Error details are shown in the status message. Status bar remains the same.
3. Test case: move 1 d/validPathToDirectory
  1. If the directory indicated is different from the current directory of pdf
    Expected: The pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
  2. If the directory indicated is same from the current directory of the pdf
    Expected: The first pdf is not moved. Error details are shown in the status message. Status bar remains the same. Expected: The first pdf is moved to the new directory. Details of the deleted pdf shown in the status message. Timestamp in the status bar is updated.
4. Test case: move d/validPathToDirectory Expected: No pdf is moved. Error details are shown in the status message. Status bar remains the same.
5. Other incorrect move commands to try: move, move 1 d/ (no directory specified), move 1 validPathToDirectory (no directory prefix), move 1 d/NotADirectory.pdf (not directory path specified)
  Expected: Similar to previous.

G.9. Deadline

Setting deadline of the pdf
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: deadline 1 date/14-4-2019
  Expected: The first pdf is set with deadline 14-4-2019. Details of the edited pdf shown in the status message. Timestamp in the status bar is updated.
3. Other correct deadline commands to try: deadline 1 done (set that the task has been completed), deadline 1 remove (remove the deadline)
4. Test case: deadline 1 date/20-20-2019
  Expected: No deadline is set to the first pdf. Error details are shown in the status message. Status bar remains the same.
5. Other incorrect deadline commands to try: deadline x date/4-4-2019 (where x is larger than the list size), deadline y date/4-4-2019 (where y is any negative number), deadline 1 date/ (no date specified), deadline 1 d (wrong prefix), deadline date (no index specified)

G.10. Filter

Filters the list of pdfs by the specified tag
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: filter t/SEROCKS
  Expected: All pdfs with the same tag will be shown in the filtered list. Details of the number of pdf is shown in the status message. Timestamp in the status bar is updated.
3. Other correct filter commands to try: filter t/SEROCKS t/CS2103T (more than 1 tag specified) Expected: All pdfs with either of the tags will be shown in the filtered list.
4. Test case: filter t/
  Expected: An empty list will be displayed.

G.11. Find

Finds the list of pdfs with the specified keyword(s)
1. Prerequisites: The pdf files in the list are uncorrupted and they exist in the system.
2. Test case: find algorithm
  Expected: All pdfs with the keyword as the name and in the file will be shown in the filtered list. Details of the the number of pdf listed is shown in the status message. Timestamp in the status bar is updated.
3. Other correct find commands to try: find algorithm SEROCK (more than one keyword)
  Expected: All pdfs with at least one of the keywords as the name and in the file will be shown in the filtered list.
4. Test case: find
  Expected: No pdf is filtered. Error details are shown in the status message. Status bar remains the same.

G.12. Encrypt

Encrypts the pdf by the specified index of the list with the specified password
1. Prerequisites: The pdf files in the list are uncorrupted, unencrypted and they exist in the system.
2. Test case: encrypt 1 password/anyValidPassword
  Expected: The first pdf will be encrypted with the password anyValidPassword. Details of the encryption is shown in the status message. Timestamp in the status bar is updated.
3. Test case: encrypt 1 password/
  Expected: The first pdf is not encrypted. Error details are shown in the status message. Status bar remains the same.
4. Other incorrect encrypt commands to try: encrypt 1 anyValidPassword (no prefix), encrypt 1 p/anyValidPassword (wrong prefix), encrypt password/anyValidPassword (no index) Expected: Similar to previous.

G.13. Decrypt

Decrypts the pdf by the specified index of the list with the specified password.
1. Prerequisites: The pdf files in the list are uncorrupted, protected and they exist in the system.
2. Test case: decrypt 1 password/anyValidPassword
  Expected: The first pdf will be encrypted with the password anyValidPassword. Details of the decryption is shown in the status message. Timestamp in the status bar is updated.
3. Test case: decrypt 1 password/
  Expected: The first pdf is not encrypted. Error details are shown in the status message. Status bar remains the same.
4. Other incorrect decrypt commands to try: decrypt 1 anyValidPassword (no prefix), decrypt 1 p/anyValidPassword (wrong prefix), decrypt password/anyValidPassword (no index) Expected: Similar to previous.

G.14. Merge

Merge 2 or more pdfs into 1 and adds the merged pdf to the back of the list.
1. Prerequisites: The pdf files in the list are uncorrupted, unprotected and they exist in the system, and at least 2 indexes are specified.
2. Test case: merge 1 2
  Expected: The first and second pdfs are merged into one pdf and put at the back of the list. Details of the merge is shown in the status message. Timestamp in the status bar is updated.
3. Other correct merge commands to try: merge 1 1 1 1 1
  Expected: The first pdf is merged 5 times into 1 pdf and the merged pdf is added to the back of the list.
4. Test case: merge 0
  Expected: No merged pdf is produced. Error details are shown in the status message. Status bar remains the same.
5. Other incorrect merge commands to try: merge 1, (only 1 index is specified), merge 1 x (where x is larger than the list size), merge 1 y (where y is any negative number)
  Expected: Similar to previous.

G.15. Saving data

Dealing with missing/corrupted data files
1. When you have a corrupted data files in the application. You can follow the steps below:
  1. Enter open INDEX to test that the file is really uncorrupted and cannot be accessed from the application
  2. Enter delete INDEX to remove the file from the application
  3. Enter add f/PATHTOFILE.pdf to add the file from the system to the application.

PDF++ - Developer Guide

How the architecture components interact with each other

Logic component

Model component

Ui component

Storage component

Use case: Add new PDF file

Use case: Find keyword in files within PDF++

Use case: Delete PDF file within PDF++

Use case: Merge PDF files within PDF++

`Logic` component

`Model` component

`Ui` component

`Storage` component