src/model/boat.rs

@@ -1,5 +1,6 @@
 use std::ops::DerefMut;
 
+use chrono::NaiveDateTime;
 use itertools::Itertools;
 use rocket::serde::{Deserialize, Serialize};
 use rocket::FromForm;
@@ -391,6 +392,39 @@ ORDER BY amount_seats DESC
         .await
         .ok()
     }
+
+    pub async fn on_water_between(
+        &self,
+        db: &mut Transaction<'_, Sqlite>,
+        dep: NaiveDateTime,
+        arr: NaiveDateTime,
+    ) -> bool {
+        let dep = dep.format("%Y-%m-%dT%H:%M").to_string();
+        let arr = arr.format("%Y-%m-%dT%H:%M").to_string();
+
+        sqlx::query!(
+            "SELECT COUNT(*) AS overlap_count
+FROM logbook
+WHERE boat_id = ?
+  AND (
+    (departure <= ? AND arrival >= ?)  -- Existing entry covers the entire new period
+    OR (departure >= ? AND departure < ?)  -- Existing entry starts during the new period
+    OR (arrival > ? AND arrival <= ?)  -- Existing entry ends during the new period
+  );",
+            self.id,
+            arr,
+            arr,
+            dep,
+            dep,
+            dep,
+            arr
+        )
+        .fetch_one(db.deref_mut())
+        .await
+        .unwrap()
+        .overlap_count
+            > 0
+    }
 }
 
 #[cfg(test)]

src/model/logbook.rs

@@ -142,6 +142,7 @@ pub enum LogbookUpdateError {
     TooFast(i64, i64),
     AlreadyFinalized,
     ExternalSteeringPersonMustSteerOrShipmaster,
+    BoatAlreadyOnWater,
 }
 
 #[derive(Debug, PartialEq)]
@@ -196,6 +197,7 @@ impl From<LogbookUpdateError> for LogbookCreateError {
             LogbookUpdateError::ExternalSteeringPersonMustSteerOrShipmaster => {
                 LogbookCreateError::ExternalSteeringPersonMustSteerOrShipmaster
             }
+            LogbookUpdateError::BoatAlreadyOnWater => LogbookCreateError::BoatAlreadyOnWater,
         }
     }
 }
@@ -573,6 +575,12 @@ ORDER BY departure DESC
             return Err(LogbookUpdateError::ArrivalNotAfterDeparture);
         }
 
+        if !boat.external {
+            if boat.on_water_between(db, dep, arr).await {
+                return Err(LogbookUpdateError::BoatAlreadyOnWater);
+            };
+        }
+
         let duration_in_mins = (arr.and_utc().timestamp() - dep.and_utc().timestamp()) / 60;
         // Not possible to row < 1 min / 500 m = < 2 min / km
         let possible_distance_km = duration_in_mins / 2;

src/tera/log.rs

@@ -347,6 +347,7 @@ async fn home_logbook(
         Err(LogbookUpdateError::TooFast(km, min)) => Flash::error(Redirect::to("/log"), format!("KM zu groß für die eingegebene Dauer ({km} km in {min} Minuten). Bitte überprüfe deine Start- und Endzeit und versuche es erneut.")),
         Err(LogbookUpdateError::AlreadyFinalized) => Flash::error(Redirect::to("/log"), "Logbucheintrag wurde bereits abgeschlossen."),
         Err(LogbookUpdateError::ExternalSteeringPersonMustSteerOrShipmaster) => Flash::error(Redirect::to("/log"), "Wenn du eine 'Externe Steuerperson' hinzufügst, muss diese steuern oder Schiffsführer sein!"),
+        Err(LogbookUpdateError::BoatAlreadyOnWater) => Flash::error(Redirect::to("/log"), "Das Boot war in diesem Zeitraum schon am Wasser. Bitte überprüfe das Datum und die Zeit."),
         Err(e) => Flash::error(
             Redirect::to("/log"),
             format!("Eintrag {logbook_id} konnte nicht abgesendet werden (Fehler: {e:?})!"),