I have no idea what's different

simulator/models/aircraft.py

@@ -1,5 +1,8 @@
 from django.db import models
 
+# from .flight import Flight
+from django.utils import timezone
+
 
 class AircraftBase(models.Model):
     name = models.CharField(max_length=20)
@@ -22,12 +25,12 @@ class Equipment(models.Model):
         "Aerodrome",
         on_delete=models.PROTECT,
         related_name="based_equipment",
-        help_text="Home base for this equipment",
+        help_text="Starting location for this equipment",
         null=True,
         blank=True,
     )
     cycles = models.PositiveIntegerField(
-        default=0, help_text="Total number of flight cycles (takeoff/landing pairs)"
+        default=0, help_text="Total number of flight cycles"
     )
     air_time_hours = models.DecimalField(
         max_digits=10,
@@ -42,8 +45,6 @@ class Equipment(models.Model):
     @property
     def current_location(self):
         """Get the current location of this equipment based on flight history."""
-        from .flight import Flight
-        from django.utils import timezone
 
         now = timezone.now()
 
@@ -59,5 +60,4 @@ class Equipment(models.Model):
             elif last_flight.arrival_time <= now:
                 return last_flight.destination
 
-        # No flights yet or no flights have departed, equipment is at base
         return self.base_location

simulator/models/flight.py

@@ -141,3 +141,11 @@ class Flight(models.Model):
 
 class Route(models.Model):
     """regulary scheduled flights"""
+
+    carrier = models.ForeignKey(
+        Carrier, on_delete=models.CASCADE, related_name="routes"
+    )
+    name = models.CharField()
+    days_of_week = models.JSONField(
+        default=list, help_text="[0,1,2,3,4] for weekdays, [5,6] for weekends, etc"
+    )

simulator/models/flight.py.save

@@ -0,0 +1,151 @@
+from django.db import models
+from .carrier import Carrier
+from .aircraft import Equipment
+from .aerodrome import Aerodrome
+from django.core.validators import MinValueValidator, MaxValueValidator
+from simulator.utils import haversine_nm
+from datetime import timedelta
+from django.core.exceptions import ValidationError
+from django.utils import timezone
+from decimal import Decimal
+
+
+class Flight(models.Model):
+    carrier = models.ForeignKey(
+        Carrier, on_delete=models.CASCADE, related_name="flights"
+    )
+    equipment = models.ForeignKey(
+        Equipment, on_delete=models.CASCADE, related_name="flights"
+    )
+    origin = models.ForeignKey(
+        Aerodrome, on_delete=models.CASCADE, related_name="departures"
+    )
+    destination = models.ForeignKey(
+        Aerodrome, on_delete=models.CASCADE, related_name="arrivals"
+    )
+
+    flight_number = models.PositiveIntegerField(
+        validators=[MinValueValidator(1), MaxValueValidator(9999)]
+    )
+    departure_time = models.DateTimeField()
+    canceled = models.BooleanField(default=False)
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["carrier", "flight_number"], name="unique_flight_per_carrier"
+            )
+        ]
+
+    def __str__(self):
+        return f"{self.carrier.icao}{self.flight_number} {self.origin.icao} > {self.destination.icao}"
+
+    @property
+    def distance_nm(self) -> float:
+        return haversine_nm(
+            self.origin.latitude,
+            self.origin.longitude,
+            self.destination.latitude,
+            self.destination.longitude,
+        )
+
+    @property
+    def duration(self) -> timedelta:
+        speed = self.equipment.model.cruise_speed_kt
+        hours = self.distance_nm / speed
+        return timedelta(hours=hours)
+
+    @property
+    def arrival_time(self):
+        return self.departure_time + self.duration
+
+    def clean(self):
+        if self.origin == self.destination:
+            raise ValidationError("Origin and destination airports cannot be the same.")
+
+        if self.equipment.owner != self.carrier:
+            raise ValidationError(
+                f"{self.equipment} is owned by {self.equipment.owner}, "
+                f"not {self.carrier}. Cannot assign equipment to this flight."
+            )
+
+        if self.distance_nm > self.equipment.model.range_nm:
+            raise ValidationError(
+                f"Flight distance ({self.distance_nm:.0f} nm) exceeds {self.equipment.model} "
+                f"maximum range ({self.equipment.model.range_nm} nm)."
+            )
+
+        previous_flights = Flight.objects.filter(
+            equipment=self.equipment,
+            departure_time__lt=self.departure_time,
+            canceled=False,
+        ).exclude(pk=self.pk)
+
+        previous_flight = None
+        latest_arrival = None
+        for flight in previous_flights:
+            if latest_arrival is None or flight.arrival_time > latest_arrival:
+                latest_arrival = flight.arrival_time
+                previous_flight = flight
+
+        if previous_flight:
+            if previous_flight.destination != self.origin:
+                raise ValidationError(
+                    f"{self.equipment} will be at {previous_flight.destination.icao} "
+                    f"after flight {previous_flight.carrier.icao}{previous_flight.flight_number}. "
+                    f"Cannot depart from {self.origin.icao}."
+                )
+
+            if previous_flight.arrival_time > self.departure_time:
+                raise ValidationError(
+                    f"{self.equipment} arrives at {self.origin.icao} at {previous_flight.arrival_time}. "
+                    f"Cannot depart before arrival."
+                )
+        else:
+            if (
+                self.equipment.base_location
+                and self.equipment.base_location != self.origin
+            ):
+                raise ValidationError(
+                    f"{self.equipment} is based at {self.equipment.base_location.icao}. "
+                    f"First flight must depart from base location, not {self.origin.icao}."
+                )
+
+        arrival = self.arrival_time
+
+    @property
+    def status(self):
+        if self.canceled:
+            return "Canceled"
+        now = timezone.now()
+        if now < self.departure_time:
+            return "Scheduled"
+        elif self.departure_time <= now < self.arrival_time:
+            return "In-Flight"
+        else:
+            return "Arrived"
+
+    def save(self, *args, **kwargs):
+        """Override save to update equipment cycles and air time when flight completes."""
+        is_new = self.pk is None
+        super().save(*args, **kwargs)
+
+        if not is_new and self.status == "Arrived":
+            if not hasattr(self, "_stats_updated"):
+                flight_hours = Decimal(str(self.duration.total_seconds() / 3600))
+                self.equipment.cycles += 1
+                self.equipment.air_time_hours += flight_hours
+                self.equipment.save(update_fields=["cycles", "air_time_hours"])
+                self._stats_updated = True
+
+
+class Route(models.Model):
+    """regulary scheduled flights"""
+
+    carrier = models.ForeignKey(
+        Carrier, on_delete=models.CASCADE, related_name="routes"
+    )
+    name = models.CharField()
+    days_of_week = models.JSONField(
+        default=list, help_text="[0,1,2,3,4] for weekdays, [5,6] for weekends, etc"
+    )