Complete TUI coverage and security audit

apps/tui/src/ui.rs

@@ -18,6 +18,29 @@ use crate::{
 const MINIMUM_WIDTH: u16 = 40;
 const MINIMUM_HEIGHT: u16 = 8;
 
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum ColorCapability {
+    Color,
+    Monochrome,
+}
+
+impl ColorCapability {
+    pub fn detect() -> Self {
+        Self::from_environment(
+            std::env::var_os("TERM").as_deref(),
+            std::env::var_os("NO_COLOR").is_some(),
+        )
+    }
+
+    fn from_environment(term: Option<&std::ffi::OsStr>, no_color: bool) -> Self {
+        if no_color || term.is_some_and(|term| term == "dumb") {
+            Self::Monochrome
+        } else {
+            Self::Color
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub enum LayoutClass {
     TooSmall,
@@ -39,6 +62,19 @@ pub fn layout_class(area: Rect) -> LayoutClass {
 }
 
 pub fn draw(frame: &mut Frame, app: &App) {
+    draw_with_color_capability(frame, app, ColorCapability::Color);
+}
+
+pub fn draw_with_color_capability(frame: &mut Frame, app: &App, capability: ColorCapability) {
+    draw_inner(frame, app);
+    if capability == ColorCapability::Monochrome {
+        for cell in &mut frame.buffer_mut().content {
+            cell.set_fg(Color::Reset).set_bg(Color::Reset);
+        }
+    }
+}
+
+fn draw_inner(frame: &mut Frame, app: &App) {
     let area = frame.area();
     if layout_class(area) == LayoutClass::TooSmall {
         frame.render_widget(
@@ -77,7 +113,8 @@ fn render_content(frame: &mut Frame, app: &App, area: Rect) {
         return;
     }
 
-    if let Some(matrix) = app.qr_popup() {
+    if let Some(popup) = app.qr_popup() {
+        let matrix = popup.matrix();
         let padded_width = matrix.width() + 8;
         let needed_width =
             u16::try_from(padded_width.saturating_mul(2).saturating_add(2)).unwrap_or(u16::MAX);
@@ -98,7 +135,7 @@ fn render_content(frame: &mut Frame, app: &App, area: Rect) {
         };
         frame.render_widget(
             Paragraph::new(text)
-                .block(Block::bordered().title("OTP QR — Esc closes"))
+                .block(Block::bordered().title(format!("{} — Esc closes", popup.title())))
                 .wrap(Wrap { trim: false }),
             area,
         );
@@ -654,6 +691,8 @@ fn prompt_line(app: &App) -> Paragraph<'static> {
 
 #[cfg(test)]
 mod tests {
+    use std::ffi::OsStr;
+
     use ratatui::{Terminal, backend::TestBackend};
 
     use super::*;
@@ -685,6 +724,49 @@ mod tests {
         assert_eq!(layout_class(Rect::new(0, 0, 140, 20)), LayoutClass::Wide);
     }
 
+    #[test]
+    fn color_capability_has_a_complete_monochrome_fallback() {
+        assert_eq!(
+            ColorCapability::from_environment(Some(OsStr::new("xterm-256color")), false),
+            ColorCapability::Color
+        );
+        assert_eq!(
+            ColorCapability::from_environment(Some(OsStr::new("dumb")), false),
+            ColorCapability::Monochrome
+        );
+        assert_eq!(
+            ColorCapability::from_environment(Some(OsStr::new("xterm")), true),
+            ColorCapability::Monochrome
+        );
+
+        let app = App::new();
+        let backend = TestBackend::new(100, 20);
+        let mut terminal = Terminal::new(backend).expect("test terminal");
+        terminal
+            .draw(|frame| draw_with_color_capability(frame, &app, ColorCapability::Monochrome))
+            .expect("monochrome draw");
+        assert!(
+            terminal
+                .backend()
+                .buffer()
+                .content
+                .iter()
+                .all(|cell| { cell.fg == Color::Reset && cell.bg == Color::Reset })
+        );
+
+        terminal
+            .draw(|frame| draw_with_color_capability(frame, &app, ColorCapability::Color))
+            .expect("color draw");
+        assert!(
+            terminal
+                .backend()
+                .buffer()
+                .content
+                .iter()
+                .any(|cell| { cell.fg != Color::Reset || cell.bg != Color::Reset })
+        );
+    }
+
     #[test]
     fn minimum_size_message_is_clear() {
         let output = render(39, 8, &App::new());