path: root/src/main/rust/main.rs

mod app;
pub mod store;

use app::App;
use miette::{IntoDiagnostic, Result};
use ratatui::{
    Frame, Terminal,
    backend::Backend,
    buffer::Buffer,
    layout::Rect,
    style::Stylize,
    symbols::border,
    text::{Line, Text},
    widgets::{Block, Paragraph, Widget},
};

use ratatui::crossterm::{
    event::{
        self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode, KeyEvent, KeyEventKind,
    },
    execute,
    terminal::{EnterAlternateScreen, LeaveAlternateScreen, disable_raw_mode, enable_raw_mode},
};
use ratatui::prelude::CrosstermBackend;

#[cfg(not(tarpaulin_include))]
fn main() -> Result<()> {
    enable_raw_mode().into_diagnostic()?;
    let mut stdout = std::io::stdout();

    execute!(stdout, EnterAlternateScreen, EnableMouseCapture).into_diagnostic()?;

    let backend = CrosstermBackend::new(stdout);
    let mut term = Terminal::new(backend).into_diagnostic()?;

    let mut app = App::default();
    app.init_context()?;

    // could be error, so don't unwrap; let term restore first
    let run = run_app(&mut term, &mut app);

    // restore terminal
    disable_raw_mode().into_diagnostic()?;
    execute!(
        term.backend_mut(),
        LeaveAlternateScreen,
        DisableMouseCapture
    )
    .into_diagnostic()?;
    term.show_cursor().into_diagnostic()?;
    run?;
    Ok(())
}

fn run_app<B: Backend>(term: &mut Terminal<B>, app: &mut App) -> Result<()> {
    while !app.get_exit_status() {
        term.draw(|frame| draw(frame, app))
            .map_err(|_| std::io::Error::new(std::io::ErrorKind::Other, "idk"))
            .into_diagnostic()?;

        match event::read().into_diagnostic()? {
            // it's important to check that the event is a key press event as
            // crossterm also emits key release and repeat events on Windows.
            Event::Key(key_event) if key_event.kind == KeyEventKind::Press => {
                handle_key_event(app, key_event)?;
            }
            _ => {}
        };
    }
    Ok(())
}

fn draw(frame: &mut Frame, app: &App) {
    let run = Runtime { app };
    frame.render_widget(&run, frame.area());
}

/// Process user input and run associated app functions
fn handle_key_event(app: &mut App, key_event: KeyEvent) -> Result<()> {
    match key_event.code {
        KeyCode::Char('q') => app.exit()?,
        KeyCode::Left => app.decrement_counter()?,
        KeyCode::Right => app.increment_counter()?,
        _ => {}
    };
    Ok(())
}

struct Runtime<'a> {
    app: &'a App,
}

impl<'a> Widget for &Runtime<'a> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        let title = Line::from(" Counter App Tutorial ".bold());
        let instructions = Line::from(vec![
            " Decrement ".into(),
            "<Left>".blue().bold(),
            " Increment ".into(),
            "<Right>".blue().bold(),
            " Quit ".into(),
            "<Q> ".blue().bold(),
        ]);
        let block = Block::bordered()
            .title(title.centered())
            .title_bottom(instructions.centered())
            .border_set(border::THICK);

        let counter_text = Text::from(vec![Line::from(vec![
            "Value: ".into(),
            self.app.display_counter().yellow(),
        ])]);

        Paragraph::new(counter_text)
            .centered()
            .block(block)
            .render(area, buf);
    }
}

#[cfg(test)]
mod tests {

    use super::*;
    use app::OverflowError;
    use ratatui::style::Style;

    #[test]
    fn render() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let runtime = Runtime { app: &app };

        let mut buf = Buffer::empty(Rect::new(0, 0, 50, 4));

        runtime.render(buf.area, &mut buf);

        let mut expected = Buffer::with_lines(vec![
            "┏━━━━━━━━━━━━━ Counter App Tutorial ━━━━━━━━━━━━━┓",
            "┃                    Value: 0                    ┃",
            "┃                                                ┃",
            "┗━ Decrement <Left> Increment <Right> Quit <Q> ━━┛",
        ]);
        let title_style = Style::new().bold();
        let counter_style = Style::new().yellow();
        let key_style = Style::new().blue().bold();

        expected.set_style(Rect::new(14, 0, 22, 1), title_style);
        expected.set_style(Rect::new(28, 1, 1, 1), counter_style);
        expected.set_style(Rect::new(13, 3, 6, 1), key_style);
        expected.set_style(Rect::new(30, 3, 7, 1), key_style);
        expected.set_style(Rect::new(43, 3, 4, 1), key_style);

        assert_eq!(buf, expected);
    }

    #[test]
    fn handle_key_event_inc_dec() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let res = handle_key_event(&mut app, KeyCode::Right.into());
        assert!(res.is_ok());
        assert_eq!(app.display_counter(), "1");

        let res = handle_key_event(&mut app, KeyCode::Left.into());
        assert!(res.is_ok());
        assert_eq!(app.display_counter(), "0");
    }

    #[test]
    fn handle_key_event_inc_n() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let n = 8;

        for i in 1..=n {
            let res = handle_key_event(&mut app, KeyCode::Right.into());
            assert!(res.is_ok());
            assert_eq!(app.display_counter(), i.to_string());
        }
        assert_eq!(app.display_counter(), n.to_string());
    }

    #[test]
    fn handle_key_event_inc_n_dec() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let n = 8;

        for i in 1..=n {
            let res = handle_key_event(&mut app, KeyCode::Right.into());
            assert!(res.is_ok());
            assert_eq!(app.display_counter(), i.to_string());
        }
        assert_eq!(app.display_counter(), n.to_string());

        let res = handle_key_event(&mut app, KeyCode::Left.into());
        assert!(res.is_ok());
        assert_eq!(app.display_counter(), (n - 1).to_string());
    }

    #[test]
    fn handle_key_event_exit() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let res = handle_key_event(&mut app, KeyCode::Char('q').into());
        assert!(res.is_ok());
        assert!(app.get_exit_status());
    }

    #[test]
    fn handle_key_event_dec_error() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        let res = handle_key_event(&mut app, KeyCode::Left.into());

        assert!(res.is_err());
        let res_err = res.unwrap_err();
        let casted_val = res_err
            .downcast_ref::<OverflowError>()
            .expect("something bad occurred");

        let expected_err_msg: String = "Cannot count below 0".into();
        assert_eq!(casted_val._msg, expected_err_msg);
        assert_eq!(
            *casted_val,
            OverflowError {
                _msg: expected_err_msg,
            },
        );
    }

    #[test]
    fn handle_key_event_inc_error() {
        let mut app = App::default();
        assert!(app.init_context().is_ok());
        // no pub set_counter exposed, so we manually set this
        for _ in 0..u8::MAX {
            assert!(app.increment_counter().is_ok());
        }
        let res = handle_key_event(&mut app, KeyCode::Right.into());

        assert!(res.is_err());
        let res_err = res.unwrap_err();
        let casted_val = res_err
            .downcast_ref::<OverflowError>()
            .expect("something bad occurred");

        let expected_err_msg: String = "Cannot count above u8::MAX".into();
        assert_eq!(casted_val._msg, expected_err_msg);
        assert_eq!(
            *casted_val,
            OverflowError {
                _msg: expected_err_msg,
            },
        );
    }
}