Make helicopters move backwards when target is too close

'Too close' as in closer than weapons' MinRange.

OpenRA.Mods.Common/Activities/Air/HeliAttack.cs

@@ -57,6 +57,19 @@ namespace OpenRA.Mods.Common.Activities
 			if (!target.IsInRange(self.CenterPosition, attackHeli.GetMaximumRange()))
 				helicopter.SetPosition(self, helicopter.CenterPosition + helicopter.FlyStep(desiredFacing));
 
+			// Fly backwards from the target
+			// TODO: Same problem as with MaximumRange
+			if (target.IsInRange(self.CenterPosition, attackHeli.GetMinimumRange()))
+			{
+				// Facing 0 doesn't work with the following position change
+				var facing = 1;
+				if (desiredFacing != 0)
+					facing = desiredFacing;
+				else if (helicopter.Facing != 0)
+					facing = helicopter.Facing;
+				helicopter.SetPosition(self, helicopter.CenterPosition + helicopter.FlyStep(-facing));
+			}
+
 			attackHeli.DoAttack(self, target);
 
 			return this;

OpenRA.Mods.Common/Traits/Attack/AttackBase.cs

@@ -157,6 +157,15 @@ namespace OpenRA.Mods.Common.Traits
 			return Armaments.Any(a => a.Weapon.IsValidAgainst(t, self.World, self));
 		}
 
+		public WRange GetMinimumRange()
+		{
+			if (IsTraitDisabled)
+				return WRange.Zero;
+
+			return Armaments.Where(a => !a.IsTraitDisabled)
+				.Select(a => a.Weapon.MinRange).Min();
+		}
+
 		public WRange GetMaximumRange()
 		{
 			if (IsTraitDisabled)