Improved heuristic for leg calculation

src/legs.rs

@@ -42,27 +42,35 @@ impl Leg {
     }
 }
 
+fn grounded_heuristic(prev_position: &Position, position: &Position) -> bool {
+    let is_flying = matches!(
+        (&prev_position, &position),
+        (Position::Flying { .. }, Position::Flying { .. })
+            | (Position::Flying { .. }, Position::Grounded { .. })
+    );
+    let lost_close_to_ground = position.datetime() - prev_position.datetime()
+        > time::Duration::minutes(5)
+        && (position.altitude() < 10000.0 || prev_position.altitude() < 10000.0);
+
+    // lost signal for more than 10h => assume it landed somewhere
+    let lost_somewhere = position.datetime() - prev_position.datetime() > time::Duration::hours(10);
+
+    is_flying && (lost_close_to_ground || lost_somewhere)
+}
+
 /// Implementation of the definition of landed in [M-4](../methodology.md).
 fn landed(prev_position: &Position, position: &Position) -> bool {
     matches!(
         (&prev_position, &position),
         (Position::Flying { .. }, Position::Grounded { .. })
-    ) || (matches!(
-        (&prev_position, &position),
-        (Position::Flying { .. }, Position::Flying { .. })
-    ) && position.datetime() - prev_position.datetime() > time::Duration::minutes(5)
-        && (position.altitude() < 10000.0 || prev_position.altitude() < 10000.0))
+    ) || grounded_heuristic(prev_position, position)
 }
 
 fn is_grounded(prev_position: &Position, position: &Position) -> bool {
     matches!(
         (&prev_position, &position),
         (Position::Grounded { .. }, Position::Grounded { .. })
-    ) || (matches!(
-        (&prev_position, &position),
-        (Position::Flying { .. }, Position::Flying { .. })
-    ) && position.datetime() - prev_position.datetime() > time::Duration::minutes(5)
-        && (position.altitude() < 10000.0 || prev_position.altitude() < 10000.0))
+    ) || grounded_heuristic(prev_position, position)
 }
 
 /// Returns a set of [`Leg`]s from a sequence of [`Position`]s.

tests/it/main.rs

@@ -103,3 +103,28 @@ async fn case_459257_2023_12_17() -> Result<(), Box<dyn Error>> {
     assert_eq!(legs.len(), 4);
     Ok(())
 }
+
+/// Case of losing signal for 2 days mid flight.
+/// https://globe.adsbexchange.com/?icao=45dd84&lat=9.613&lon=22.035&zoom=3.8&showTrace=2023-12-08
+#[tokio::test]
+async fn case_45dd84_2023_12_06() -> Result<(), Box<dyn Error>> {
+    let legs = legs(date!(2023 - 12 - 06), date!(2023 - 12 - 09), "45dd84", None).await?;
+    assert_eq!(legs.len(), 3);
+    let day = 24.0 * 60.0 * 60.0;
+    assert!(legs[0].duration().as_seconds_f32() < day);
+    assert!(legs[1].duration().as_seconds_f32() < day);
+    assert!(legs[2].duration().as_seconds_f32() < day);
+    Ok(())
+}
+
+#[tokio::test]
+async fn case_45c824_2023_12_12() -> Result<(), Box<dyn Error>> {
+    let legs = legs(date!(2023 - 12 - 12), date!(2023 - 12 - 16), "45c824", None).await?;
+
+    assert_eq!(legs.len(), 3);
+    let day = 24.0 * 60.0 * 60.0;
+    assert!(legs[0].duration().as_seconds_f32() < day);
+    assert!(legs[1].duration().as_seconds_f32() < day);
+    assert!(legs[2].duration().as_seconds_f32() < day);
+    Ok(())
+}