Stage 3

Navigation and Program Loop

Now that the database and UI are complete, it's time to build the bridge between them. In this step we will be building the navigator and program loop.

The navigator will handle navigating between pages, responding to actions returned from handle_input() on Page objects, and displaying prompts.

The program loop is responsible for running our application and continuously asking for user input until the user exits the program.

Steps

Step 1

Implementing The Navigator

A new file called navigator.rs has been added. Inside this file a Navigator Struct is defined, which contains 3 fields.

pages is a vector of Page objects. This vector is used for navigation. The user starts off on the home page and if they navigate to the Epic details page (for example) a new instance of EpicDetail will be created and pushed onto the pages vector. To navigate back to the home page we will simply pop the EpicDetail page off the pages vector (which acts like a stack). Note that the current page is always the last element in the pages vector.

prompts is an instance of the Prompts Struct. Look at the navigator tests to see how we can mock colures in the prompts Struct.

db is a JiraDatabase instance wrapped in a reference counting smart pointer so we can share ownership.

The Navigator Struct contains 2 primary functions. get_current_page() which does exactly what the name suggests and handle_action() which responds to user actions.

To complete this step finish all the TODO items in navigator.rs.

NOTE 1: Use with_context() and the anyhow! macro form the anyhow crate inside handle_action() for error handling.

NOTE 2: A method called as_any() has been added to all page objects. This was done to support down-casting, which is used in the navigator tests. For more info check out this StackOverflow post.

Step 2

The Program Loop

The program loop will be defined inside main.rs. First we will instantiate the navigator. Then inside the program loop we will get the current page, render it, wait for user input and then handle the input.

To complete this task finish the TODO items in main.rs.

NOTE 1: A new dependency called clearscreen has been added. At the top of the program loop we call clearscreen::clear(). This will clear the screen which is what we want to do before rendering the new content. Think about it like refreshing a web page... everything is wiped away and reloaded.

NOTE 2: A function called wait_for_key_press() has been added to io_utils.rs. Use this method when displaying errors. For example:

if let Err(error) = page.draw_page() {
    println!("Error rendering page: {}\nPress any key to continue...", error);
    wait_for_key_press();
};

Manual Tests

Run these manual tests (from top to bottom in order) to see if your program works as expected.

NOTE: Before running these tests, reset the database by updating data/db.json to this:

{
    "last_item_id": 0,
    "epics": {},
    "stories": {}
}

Create Epic

Steps:

cd into the root folder of the project
Run cargo run
Input c to create a new Epic
Input "New Epic name" as Epic name
Input "New Epic description" as Epic description