smarkdown 0.1.0

use crate::app::{App, Mode, Prompt};
use crate::highlight::{highlight_line, highlight_line_preview};
use ratatui::layout::{Constraint, Direction, Layout, Rect};
use ratatui::style::{Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, BorderType, Borders, Paragraph};
use ratatui::Frame;

pub fn draw(frame: &mut Frame, app: &mut App) {
    let root = Layout::default()
        .direction(Direction::Vertical)
        .constraints([Constraint::Length(1), Constraint::Min(3), Constraint::Length(1)])
        .split(frame.area());

    draw_titlebar(frame, app, root[0]);
    draw_editor(frame, app, root[1]);
    draw_statusbar(frame, app, root[2]);
}

fn draw_titlebar(frame: &mut Frame, app: &App, area: Rect) {
    let name = app
        .buffer
        .path
        .as_ref()
        .and_then(|p| p.file_name())
        .and_then(|n| n.to_str())
        .unwrap_or("untitled");
    let dirty = if app.buffer.dirty { " ●" } else { "" };
    let mode_tag = match app.mode {
        Mode::Edit => "EDIT",
        Mode::Preview => "PREVIEW",
    };
    let title = format!(" 📓 Smarkdown — {name}{dirty}   [{mode_tag}] ");
    let line = Line::from(Span::styled(
        title,
        Style::default().fg(app.config.theme.accent.resolve()).add_modifier(Modifier::BOLD),
    ));
    frame.render_widget(Paragraph::new(line), area);
}

fn draw_editor(frame: &mut Frame, app: &mut App, area: Rect) {
    let theme = &app.config.theme;
    let is_preview = app.mode == Mode::Preview;
    let block = Block::default()
        .borders(Borders::ALL)
        .border_type(BorderType::Rounded)
        .border_style(Style::default().fg(theme.quote.resolve()));
    let inner = block.inner(area);
    frame.render_widget(block, area);

    let height = inner.height as usize;
    app.buffer.ensure_visible(height.max(1));

    let total = app.buffer.lines.len();
    let num_width = total.to_string().len().max(3) as u16;
    let show_gutter = app.config.editor.show_line_numbers && !is_preview;
    let show_margin = app.config.editor.notebook_margin && !is_preview;
    let mut gutter_w = 0u16;
    if show_gutter {
        gutter_w += num_width + 1;
    }
    if show_margin {
        gutter_w += 2;
    }

    let mut rendered: Vec<Line> = Vec::with_capacity(height);
    let scroll = app.buffer.scroll;
    for row in scroll..(scroll + height).min(total) {
        let mut spans = Vec::new();
        if show_gutter {
            spans.push(Span::styled(
                format!("{:>width$} ", row + 1, width = num_width as usize),
                Style::default().fg(theme.line_number.resolve()),
            ));
        }
        if show_margin {
            spans.push(Span::styled("│ ", Style::default().fg(theme.margin_line.resolve())));
        }
        if is_preview {
            spans.extend(highlight_line_preview(&app.buffer.lines[row], theme));
        } else {
            spans.extend(highlight_line(&app.buffer.lines[row], theme));
        }
        rendered.push(Line::from(spans));
    }

    frame.render_widget(Paragraph::new(rendered), inner);

    if !is_preview {
        let cursor_x = inner.x
            + gutter_w
            + display_width(&app.buffer.lines[app.buffer.cursor_row], app.buffer.cursor_col);
        let cursor_y = inner.y + (app.buffer.cursor_row - scroll) as u16;
        frame.set_cursor_position((cursor_x, cursor_y));
    }
}

fn display_width(line: &str, col: usize) -> u16 {
    use unicode_width::UnicodeWidthChar;
    line.chars()
        .take(col)
        .map(|c| c.width().unwrap_or(1) as u16)
        .sum()
}

fn draw_statusbar(frame: &mut Frame, app: &App, area: Rect) {
    let theme = &app.config.theme;
    let style = Style::default().fg(theme.status_bar_fg.resolve()).bg(theme.status_bar_bg.resolve());

    let text = match &app.prompt {
        Prompt::Open(input) => format!(" Open file: {input}_"),
        Prompt::SaveAs(input) => format!(" Save as: {input}_"),
        Prompt::ConfirmQuit => " Discard unsaved changes? [y/N] ".to_string(),
        Prompt::None => {
            let pos = format!(
                " {}:{} ",
                app.buffer.cursor_row + 1,
                app.buffer.cursor_col + 1
            );
            let words = format!("{} words ", app.buffer.word_count());
            let hint = " ^Tab preview  ^S save  ^O open  ^N new  ^Q quit ";
            let msg = app.status_msg.clone().unwrap_or_default();
            format!("{pos}│ {words}│ {msg}{hint}")
        }
    };

    frame.render_widget(Paragraph::new(Line::from(Span::styled(text, style))), area);
}