Commit before moving targeting

src/Dodge/Euse.hs

@@ -1,5 +1,7 @@
 module Dodge.Euse where
 
+import Control.Monad
+import Data.Maybe
 import Dodge.LightSource
 import Dodge.Item.HeldOffset
 import Dodge.Wall.Create
@@ -29,6 +31,29 @@ useE eo = case eo of
     ECamouflage vis -> overCID (crCamouflage .~ vis)
     EonWristShield -> onEquipWristShield
     EoffWristShield -> onRemoveWristShield
+    EFuelSource 0 _ -> const . const id
+    EFuelSource {} -> trySiphonFuel
+
+trySiphonFuel :: Item -> Creature -> World -> World
+trySiphonFuel itm cr w = fromMaybe w $ do
+    eix <- itm ^? itLocation . ipInvID
+    hix <- cr ^? crInvSel . iselPos
+    guard (cr ^? crInvSel . iselAction == Just NoInvSelAction)
+    la <- cr ^? crInv . ix hix . itUse . heldConsumption
+    atype <- la ^? laAmmoType
+    guard (isGas atype)
+    amax <- la ^? laMax
+    acur <- la ^? laLoaded
+    guard (amax > acur)
+    return $ w & cWorld . lWorld . creatures . ix (_crID cr) . crInv %~ 
+            ( (ix hix . itUse . heldConsumption . laLoaded +~ 1)
+            . (ix eix . itUse . equipEffect . eeUse . euseFuelAmount -~ 1)
+            )
+
+isGas :: AmmoType -> Bool
+isGas a = case a of
+    GasAmmo {} -> True
+    _ -> False
 
 useMagShield :: Item -> Creature -> World -> World
 useMagShield it cr w = w & cWorld . lWorld . magnets . at mgid ?~ themagnet