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diff --git a/users/grfn/xanthous/src/Xanthous/AI/Gormlak.hs b/users/grfn/xanthous/src/Xanthous/AI/Gormlak.hs
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+{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# LANGUAGE UndecidableInstances #-}
+--------------------------------------------------------------------------------
+module Xanthous.AI.Gormlak
+  ( HasVisionRadius(..)
+  , GormlakBrain(..)
+  ) where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude hiding (lines)
+--------------------------------------------------------------------------------
+import           Control.Monad.State
+import           Control.Monad.Random
+import           Data.Aeson (object)
+import qualified Data.Aeson as A
+import           Data.Generics.Product.Fields
+--------------------------------------------------------------------------------
+import           Xanthous.Data
+                 ( Positioned(..), positioned, position
+                 , diffPositions, stepTowards, isUnit
+                 , Ticks, (|*|), invertedRate
+                 )
+import           Xanthous.Data.EntityMap
+import           Xanthous.Entities.Creature.Hippocampus
+import           Xanthous.Entities.Character (Character)
+import qualified Xanthous.Entities.Character as Character
+import qualified Xanthous.Entities.RawTypes as Raw
+import           Xanthous.Entities.RawTypes (CreatureType)
+import           Xanthous.Game.State
+import           Xanthous.Game.Lenses
+                 ( entitiesCollision, collisionAt
+                 , character, characterPosition
+                 )
+import           Xanthous.Data.EntityMap.Graphics (linesOfSight, canSee)
+import           Xanthous.Random
+import           Xanthous.Monad (say)
+--------------------------------------------------------------------------------
+
+--  TODO move the following two classes to a more central location
+
+class HasVisionRadius a where visionRadius :: a -> Word
+
+type IsCreature entity =
+  ( HasVisionRadius entity
+  , HasField "_hippocampus" entity entity Hippocampus Hippocampus
+  , HasField "_creatureType" entity entity CreatureType CreatureType
+  , A.ToJSON entity
+  )
+
+--------------------------------------------------------------------------------
+
+stepGormlak
+  :: forall entity m.
+    ( MonadState GameState m, MonadRandom m
+    , IsCreature entity
+    )
+  => Ticks
+  -> Positioned entity
+  -> m (Positioned entity)
+stepGormlak ticks pe@(Positioned pos creature) = do
+  dest <- maybe (selectDestination pos creature) pure
+         $ creature ^. field @"_hippocampus" . destination
+  let progress' =
+        dest ^. destinationProgress
+        + creature ^. field @"_creatureType" . Raw.speed . invertedRate |*| ticks
+  if progress' < 1
+    then pure
+         $ pe
+         & positioned . field @"_hippocampus" . destination
+         ?~ (dest & destinationProgress .~ progress')
+    else do
+      let newPos = dest ^. destinationPosition
+          remainingSpeed = progress' - 1
+      newDest <- selectDestination newPos creature
+                <&> destinationProgress +~ remainingSpeed
+      let pe' = pe & positioned . field @"_hippocampus" . destination ?~ newDest
+      collisionAt newPos >>= \case
+        Nothing -> pure $ pe' & position .~ newPos
+        Just Stop -> pure pe'
+        Just Combat -> do
+          ents <- use $ entities . atPosition newPos
+          when (any (entityIs @Character) ents) attackCharacter
+          pure pe'
+  where
+    selectDestination pos' creature' = destinationFromPos <$> do
+      canSeeCharacter <- uses entities $ canSee (entityIs @Character) pos' vision
+      if canSeeCharacter
+        then do
+          charPos <- use characterPosition
+          if isUnit (pos' `diffPositions` charPos)
+            then attackCharacter $> pos'
+            else pure $ pos' `stepTowards` charPos
+      else do
+        lines <- map (takeWhile (isNothing . entitiesCollision . map snd . snd)
+                    -- the first item on these lines is always the creature itself
+                    . fromMaybe mempty . tailMay)
+                . linesOfSight pos' (visionRadius creature')
+                <$> use entities
+        line <- choose $ weightedBy length lines
+        pure $ fromMaybe pos' $ fmap fst . headMay =<< line
+
+    vision = visionRadius creature
+    attackCharacter = do
+      say ["combat", "creatureAttack"] $ object [ "creature" A..= creature ]
+      character %= Character.damage 1
+
+newtype GormlakBrain entity = GormlakBrain { _unGormlakBrain :: entity }
+
+instance (IsCreature entity) => Brain (GormlakBrain entity) where
+  step ticks
+    = fmap (fmap GormlakBrain)
+    . stepGormlak ticks
+    . fmap _unGormlakBrain
+  entityCanMove = const True
+
+--------------------------------------------------------------------------------
+
+-- instance Brain Creature where
+--   step = brainVia GormlakBrain
+--   entityCanMove = const True
+
+-- instance Entity Creature where
+--   blocksVision _ = False
+--   description = view $ Creature.creatureType . Raw.description
+--   entityChar = view $ Creature.creatureType . char