fn print_diff()

in crates/q_chat/src/tools/fs_write.rs [363:467]
94 lines of code
6 McCabe index (conditional complexity)

fn print_diff(
    updates: &mut impl Write,
    old_str: &StylizedFile,
    new_str: &StylizedFile,
    start_line: usize,
) -> Result<()> {
    let diff = similar::TextDiff::from_lines(&old_str.content, &new_str.content);

    // First, get the gutter width required for both the old and new lines.
    let (mut max_old_i, mut max_new_i) = (1, 1);
    for change in diff.iter_all_changes() {
        if let Some(i) = change.old_index() {
            max_old_i = i + start_line;
        }
        if let Some(i) = change.new_index() {
            max_new_i = i + start_line;
        }
    }
    let old_line_num_width = terminal_width_required_for_line_count(max_old_i);
    let new_line_num_width = terminal_width_required_for_line_count(max_new_i);

    // Now, print
    fn fmt_index(i: Option<usize>, start_line: usize) -> String {
        match i {
            Some(i) => (i + start_line).to_string(),
            _ => " ".to_string(),
        }
    }
    for change in diff.iter_all_changes() {
        // Define the colors per line.
        let (text_color, gutter_bg_color, line_bg_color) = match (change.tag(), new_str.truecolor) {
            (similar::ChangeTag::Equal, true) => (style::Color::Reset, new_str.gutter_bg, new_str.line_bg),
            (similar::ChangeTag::Delete, true) => (
                style::Color::Reset,
                style::Color::Rgb { r: 79, g: 40, b: 40 },
                style::Color::Rgb { r: 36, g: 25, b: 28 },
            ),
            (similar::ChangeTag::Insert, true) => (
                style::Color::Reset,
                style::Color::Rgb { r: 40, g: 67, b: 43 },
                style::Color::Rgb { r: 24, g: 38, b: 30 },
            ),
            (similar::ChangeTag::Equal, false) => (style::Color::Reset, new_str.gutter_bg, new_str.line_bg),
            (similar::ChangeTag::Delete, false) => (style::Color::Red, new_str.gutter_bg, new_str.line_bg),
            (similar::ChangeTag::Insert, false) => (style::Color::Green, new_str.gutter_bg, new_str.line_bg),
        };
        // Define the change tag character to print, if any.
        let sign = match change.tag() {
            similar::ChangeTag::Equal => " ",
            similar::ChangeTag::Delete => "-",
            similar::ChangeTag::Insert => "+",
        };

        let old_i_str = fmt_index(change.old_index(), start_line);
        let new_i_str = fmt_index(change.new_index(), start_line);

        // Print the gutter and line numbers.
        queue!(updates, style::SetBackgroundColor(gutter_bg_color))?;
        queue!(
            updates,
            style::SetForegroundColor(text_color),
            style::Print(sign),
            style::Print(" ")
        )?;
        queue!(
            updates,
            style::Print(format!(
                "{:>old_line_num_width$}",
                old_i_str,
                old_line_num_width = old_line_num_width
            ))
        )?;
        if sign == " " {
            queue!(updates, style::Print(", "))?;
        } else {
            queue!(updates, style::Print("  "))?;
        }
        queue!(
            updates,
            style::Print(format!(
                "{:>new_line_num_width$}",
                new_i_str,
                new_line_num_width = new_line_num_width
            ))
        )?;
        // Print the line.
        queue!(
            updates,
            style::SetForegroundColor(style::Color::Reset),
            style::Print(":"),
            style::SetForegroundColor(text_color),
            style::SetBackgroundColor(line_bg_color),
            style::Print(" "),
            style::Print(change),
            style::ResetColor,
        )?;
    }
    queue!(
        updates,
        crossterm::terminal::Clear(crossterm::terminal::ClearType::UntilNewLine),
        style::Print("\n"),
    )?;

    Ok(())
}