use crate::app::App;
use miette::ErrReport;
use ratatui::{
    Frame,
    layout::{Constraint, Direction, Layout, Rect},
    style::{Style, Stylize},
    symbols::border,
    text::{Line, Span, Text},
    widgets::{Block, Clear, Paragraph, Widget},
};

pub fn draw(frame: &mut Frame, app: &App) {
    let rect = draw_layout(app);
    frame.render_widget(rect, frame.area());

    if let Some(error) = app.get_error() {
        let popup = error_popup(error);

        let area = centered_rect(40, 25, frame.area());
        frame.render_widget(Clear, area);
        frame.render_widget(popup, area);
    }
}

fn draw_layout(app: &App) -> impl Widget {
    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(),
        app.display_counter().yellow(),
    ])]);

    Paragraph::new(counter_text).centered().block(block)
}

/// helper function to create a centered rect using up certain percentage of the available rect `r`
fn centered_rect(percent_x: u16, percent_y: u16, r: Rect) -> Rect {
    // Cut the given rectangle into three vertical pieces
    let popup_layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Percentage((100 - percent_y) / 2),
            Constraint::Percentage(percent_y),
            Constraint::Percentage((100 - percent_y) / 2),
        ])
        .split(r);
    // Then cut the middle vertical piece into three width-wise pieces
    Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Percentage((100 - percent_x) / 2),
            Constraint::Percentage(percent_x),
            Constraint::Percentage((100 - percent_x) / 2),
        ])
        .split(popup_layout[1])[1] // Return the middle chunk
}

fn error_popup(error: &ErrReport) -> impl Widget {
    let title = Line::from("Error").bold();
    let popup = Block::bordered()
        .title(title.centered())
        .border_set(border::DOUBLE);

    let error_text = error_text(error);

    Paragraph::new(error_text).block(popup)
}

fn error_text(error: &ErrReport) -> Text<'_> {
    let errname_spans = vec![
        Span::raw("Error   "),
        Span::styled("x", Style::new().red()),
        Span::raw(" "),
        Span::raw(error.to_string()),
    ];

    let line1 = Line::default().spans(errname_spans);
    let help_spans = vec![
        Span::styled("  help: ", Style::new().cyan()),
        Span::raw(error.help().map_or("".into(), |x| x.to_string())),
    ];
    let line2 = Line::default().spans(help_spans);

    Text::from(vec![line1, line2])
}

#[cfg(test)]
mod tests {

    use super::*;
    use ratatui::{buffer::Buffer, layout::Rect, style::Style};

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

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

        let res = draw_layout(&app);
        res.render(rect, &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);
    }
}