Add spin indicator component

2 files changed, 78 insertions, 0 deletions

diff --git a/src/core/src/components/mod.rs b/src/core/src/components/mod.rs
index 54d5837..21dd23c 100644
--- a/src/core/src/components/mod.rs
+++ b/src/core/src/components/mod.rs
@@ -4,3 +4,5 @@ pub(crate) mod edit;
 pub(crate) mod help;
 pub(crate) mod search_bar;
 mod shared;
+#[allow(dead_code)]
+pub(crate) mod spin_indicator;
diff --git a/src/core/src/components/spin_indicator/mod.rs b/src/core/src/components/spin_indicator/mod.rs
new file mode 100644
index 0000000..e73048b
--- /dev/null
+++ b/src/core/src/components/spin_indicator/mod.rs
@@ -0,0 +1,76 @@
+use std::time::{Duration, Instant};
+
+const INDICATOR_CHARACTERS: [&str; 4] = ["-", "\\", "|", "/"];
+const ANIMATE_SPEED: Duration = Duration::from_millis(100);
+
+pub(crate) struct SpinIndicator {
+	index: u8,
+	last_refreshed_at: Instant,
+}
+
+impl SpinIndicator {
+	pub(crate) fn new() -> Self {
+		Self {
+			index: 0,
+			last_refreshed_at: Instant::now(),
+		}
+	}
+
+	pub(crate) fn refresh(&mut self) {
+		if self.last_refreshed_at.elapsed() >= ANIMATE_SPEED {
+			self.last_refreshed_at = Instant::now();
+			self.index = if self.index == 3 { 0 } else { self.index + 1 }
+		}
+	}
+
+	pub(crate) fn indicator(&self) -> String {
+		format!("({})", INDICATOR_CHARACTERS[self.index as usize])
+	}
+}
+#[cfg(test)]
+mod tests {
+	use std::ops::{Add, Sub};
+
+	const SAFE_TEST_DURATION: Duration = Duration::from_secs(60);
+
+	use super::*;
+
+	#[test]
+	fn does_not_advance_if_duration_has_not_elapsed() {
+		let mut indicator = SpinIndicator::new();
+		// this test is unlikely to finish before this elapsed time
+		indicator.last_refreshed_at = Instant::now().add(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(-)");
+		indicator.refresh();
+		assert_eq!(indicator.indicator(), "(-)");
+	}
+
+	#[test]
+	fn does_not_advance_if_duration_has_elapsed() {
+		let mut indicator = SpinIndicator::new();
+		indicator.last_refreshed_at = Instant::now().sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(-)");
+		indicator.refresh();
+		assert_eq!(indicator.indicator(), "(\\)");
+	}
+
+	const INDICATOR_CHARACTERS: [&str; 4] = ["-", "\\", "|", "/"];
+	#[test]
+	fn full_animation() {
+		let mut indicator = SpinIndicator::new();
+		indicator.last_refreshed_at = Instant::now().sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(-)");
+		indicator.refresh();
+		indicator.last_refreshed_at = indicator.last_refreshed_at.sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(\\)");
+		indicator.refresh();
+		indicator.last_refreshed_at = indicator.last_refreshed_at.sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(|)");
+		indicator.refresh();
+		indicator.last_refreshed_at = indicator.last_refreshed_at.sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(/)");
+		indicator.refresh();
+		indicator.last_refreshed_at = indicator.last_refreshed_at.sub(SAFE_TEST_DURATION);
+		assert_eq!(indicator.indicator(), "(-)");
+	}
+}