refactor: extract loading rendering logic to crate::ui::loading_screen

The loading logic has particularities like a constant and a static mut
variable along with some unsafe code and a `terminal.draw()` call that
violates the main call at the start of the app loop.

Due to these reasons, extract all the loading rendering logic to
a dedicated module `crate::ui::loading_screen`.

Co-developed-by: Gabriel Alves <alvesgabriel@usp.br>
Signed-off-by: David Tadokoro <davidbtadokoro@usp.br>

Author: davidbtadokoro

src/ui.rs

@@ -1,34 +1,20 @@
-use std::fmt::Display;
-
 use patch_hub::patch::Patch;
 use ratatui::{
     layout::{Alignment, Constraint, Direction, Layout, Rect},
-    prelude::Backend,
     style::{Color, Modifier, Style},
     text::{Line, Span, Text},
-    widgets::{Block, Borders, HighlightSpacing, List, ListItem, ListState, Paragraph, Wrap},
-    Frame, Terminal,
+    widgets::{Block, Borders, HighlightSpacing, List, ListItem, ListState, Paragraph},
+    Frame,
 };
 
 use crate::app::{self, App};
 use app::screens::{bookmarked::BookmarkedPatchsetsState, CurrentScreen};
 
 mod details_actions;
 mod edit_config;
+pub mod loading_screen;
 mod render_patchset;
 
-const SPINNER: [char; 8] = [
-    '\u{1F311}',
-    '\u{1F312}',
-    '\u{1F313}',
-    '\u{1F314}',
-    '\u{1F315}',
-    '\u{1F316}',
-    '\u{1F317}',
-    '\u{1F318}',
-];
-static mut SPINNER_TICK: usize = 1;
-
 pub fn draw_ui(f: &mut Frame, app: &App) {
     let chunks = Layout::default()
         .direction(Direction::Vertical)
@@ -54,42 +40,6 @@ pub fn draw_ui(f: &mut Frame, app: &App) {
     render_navi_bar(f, app, chunks[2]);
 }
 
-/// This function renders a loading screen taking a `terminal` instance and a
-/// `title`.
-pub fn render_loading_screen<B: Backend>(
-    mut terminal: Terminal<B>,
-    title: impl Display,
-) -> Terminal<B> {
-    let _ = terminal.draw(|f| draw_loading_screen(f, title));
-    terminal
-}
-
-/// Gets the current spinner state and updates the tick.
-fn spinner() -> char {
-    let spinner_state = SPINNER[unsafe { SPINNER_TICK }];
-    unsafe {
-        SPINNER_TICK = (SPINNER_TICK + 1) % 8;
-    }
-    spinner_state
-}
-
-/// The actual implementation of the loading screen rendering. Currently the
-/// loading notification is static.
-fn draw_loading_screen(f: &mut Frame, title: impl Display) {
-    let loading_text = format!("{} {}", title, spinner());
-
-    let loading_par = Paragraph::new(Line::from(Span::styled(
-        loading_text,
-        Style::default().fg(Color::Green),
-    )))
-    .block(Block::default().borders(Borders::ALL))
-    .centered()
-    .wrap(Wrap { trim: true });
-
-    let loading_area = centered_rect(30, 10, f.area());
-    f.render_widget(loading_par, loading_area);
-}
-
 fn render_title(f: &mut Frame, chunk: Rect) {
     let title_block = Block::default()
         .borders(Borders::ALL)
@@ -367,7 +317,6 @@ fn render_navi_bar(f: &mut Frame, app: &App, chunk: Rect) {
     f.render_widget(keys_hint_footer, footer_chunks[1]);
 }
 
-#[allow(dead_code)]
 /// 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

src/ui/loading_screen.rs

@@ -0,0 +1,56 @@
+use std::fmt::Display;
+
+use ratatui::{
+    prelude::Backend,
+    style::{Color, Style},
+    text::{Line, Span},
+    widgets::{Block, Borders, Paragraph, Wrap},
+    Frame, Terminal,
+};
+
+use super::centered_rect;
+
+const SPINNER: [char; 8] = [
+    '\u{1F311}',
+    '\u{1F312}',
+    '\u{1F313}',
+    '\u{1F314}',
+    '\u{1F315}',
+    '\u{1F316}',
+    '\u{1F317}',
+    '\u{1F318}',
+];
+static mut SPINNER_TICK: usize = 1;
+
+/// This function renders a loading screen taking a `terminal` instance and a
+/// `title`.
+pub fn render<B: Backend>(mut terminal: Terminal<B>, title: impl Display) -> Terminal<B> {
+    let _ = terminal.draw(|f| draw_loading_screen(f, title));
+    terminal
+}
+
+/// Gets the current spinner state and updates the tick.
+fn spinner() -> char {
+    let char_to_ret = SPINNER[unsafe { SPINNER_TICK }];
+    unsafe {
+        SPINNER_TICK = (SPINNER_TICK + 1) % 8;
+    }
+    char_to_ret
+}
+
+/// The actual implementation of the loading screen rendering. Currently the
+/// loading notification is static.
+fn draw_loading_screen(f: &mut Frame, title: impl Display) {
+    let loading_text = format!("{} {}", title, spinner());
+
+    let loading_par = Paragraph::new(Line::from(Span::styled(
+        loading_text,
+        Style::default().fg(Color::Green),
+    )))
+    .block(Block::default().borders(Borders::ALL))
+    .centered()
+    .wrap(Wrap { trim: true });
+
+    let loading_area = centered_rect(30, 10, f.area());
+    f.render_widget(loading_par, loading_area);
+}

src/utils.rs

@@ -96,7 +96,7 @@ macro_rules! loading_screen {
 
             let handle = std::thread::spawn(move || {
                 while loading_clone.load(std::sync::atomic::Ordering::Relaxed) {
-                    terminal = $crate::ui::render_loading_screen(terminal, $title);
+                    terminal = $crate::ui::loading_screen::render(terminal, $title);
                     std::thread::sleep(std::time::Duration::from_millis(200));
                 }