Todo app

original: https://gitlab.fi.muni.cz/pv281/seminar-exercises/week-03-cli-todo-list

Create a console application using clap that allows for task management.

Because of reasons, we will be using two sets of commands for this application.

• The first one is to configure how the application should start.
• The second one is to interact with the running application.

The application allows you to enter the switch -n or --name, which specifies the name of the task owner.

Upon startup, the application receives commands (always prompting with > before input).

---

Starting Commands

There is just one starting command: start (with one optional parameter).

It is invoked as follows:

cargo run -- start

The optional parameter available under the --name, -n switch allows you to specify the name of who this session belongs to.

cargo run -- start --name "John Doe"

Hint: you can use a modified version of the boilerplate available in the clap documentation

---

Interactive Commands

Those are the commands the user can enter after the application has started.

A prompt (>>>) is displayed before each command.

Use the following boilerplate to parse command from a loaded string:

/// Parses the command from the input line into the `YourInteractiveArgsStruct` struct.
/// 
/// Exits the application if the command is not recognized. The help message is printed in that case.
fn parse_to_interactive_args(line: &str) -> YourInteractiveArgsStruct {
    // assume that the command is exactly delimited by whitespace
    // you could use a more sophisticated parser here to split it more cli-like, eg `shlex`

    // need to bend the rules a bit to make this work - prepend the app name for the parser to work alright
    let line = "todo-app".to_string() + " " + line.trim();

    // parse the interactive command, exit print help and exit if it fails
    YourInteractiveArgsStruct::parse_from(line.split_whitespace())
}

exit		    terminates the application
add <name>	    creates a task, does not allow duplicates
remove <name>	removes a task (must exist)
list		    lists tasks

The format for listing tasks is:

<owner's name>'s TODOs
------------------------
<task1>
<task2>
...

Optional: Ensure that the divider between the title and the tasks is exactly the length of the title.

---

Extension - file handling

The application can be started with the switch -f or --file. If this file is specified, the output of the list command will be written to it after the exit command. If the file does not exist, it will be created.

Extension - task status

Tasks can have the status todo, in progress, and done.

Each task is set as incomplete upon creation.

The list command will display tasks in the format:

<owner's name>'s TODOs
------------------------
[<status>] <task1>
[<status>] <task2>
...

The command start <name> changes the task status from todo to in progress. The command finish <name> sets the task status to done (regardless of the previous status of the task).

Extension - priority

Add the command priority <name> <priority>, which sets the priority for a task. Only tasks with the status todo can have priority (ensure type checking to enforce this).

Tasks are sorted in the output as follows:

1. All todo tasks by priority
2. All in progress tasks
3. All done tasks

Extension - time tracking

The start command begins the timer for when work on a task starts. The finish command calculates the duration (from the start) and saves it to the respective task.

When listing tasks, completed tasks will also display the duration. The total time spent on tasks will be shown below the listings.

Extension - anything else you can think of

Add any other feature you think would be useful for a task manager.