Decouple Gormlak AI from creatures

Decouple the definition of the Gormlak AI from the creature type itself
using generic lenses and a "HasVisionRadius" typeclass, to begin to
untangle the hs-boot web of circular dependencies. This
actually *increases* the number of hs-boot files from 1 to 2, but both
of the source imports that use them are single-instance (unlike gormlak
AI which I would expect to grow linearly with the growth of the game),
plus at least one should be able to go away once we remove collision
from the game lenses module and move it into something defined in the
entity class itself.

1 files changed, 64 insertions, 0 deletions

diff --git a/src/Xanthous/Entities/Creature/Hippocampus.hs b/src/Xanthous/Entities/Creature/Hippocampus.hs
new file mode 100644
index 000000000000..501a5b597221
--- /dev/null
+++ b/src/Xanthous/Entities/Creature/Hippocampus.hs
@@ -0,0 +1,64 @@
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE TemplateHaskell #-}
+--------------------------------------------------------------------------------
+module Xanthous.Entities.Creature.Hippocampus
+  (-- * Hippocampus
+    Hippocampus(..)
+  , initialHippocampus
+    -- ** Lenses
+  , destination
+    -- ** Destination
+  , Destination(..)
+  , destinationFromPos
+    -- *** Lenses
+  , destinationPosition
+  , destinationProgress
+  )
+where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude
+--------------------------------------------------------------------------------
+import           Data.Aeson.Generic.DerivingVia
+import           Data.Aeson (ToJSON, FromJSON)
+import           Test.QuickCheck
+import           Test.QuickCheck.Arbitrary.Generic
+--------------------------------------------------------------------------------
+import           Xanthous.Data
+import           Xanthous.Util.QuickCheck
+--------------------------------------------------------------------------------
+
+
+data Destination = Destination
+  { _destinationPosition :: !Position
+    -- | The progress towards the destination, tracked as an offset from the
+    -- creature's original position.
+    --
+    -- When this value reaches >= 1, the creature has reached their destination
+  , _destinationProgress :: !Tiles
+  }
+  deriving stock (Eq, Show, Ord, Generic)
+  deriving anyclass (NFData, CoArbitrary, Function)
+  deriving (ToJSON, FromJSON)
+       via WithOptions '[ FieldLabelModifier '[Drop 1] ]
+                       Destination
+instance Arbitrary Destination where arbitrary = genericArbitrary
+makeLenses ''Destination
+
+destinationFromPos :: Position -> Destination
+destinationFromPos _destinationPosition =
+  let _destinationProgress = 0
+  in Destination{..}
+
+data Hippocampus = Hippocampus
+  { _destination :: !(Maybe Destination)
+  }
+  deriving stock (Eq, Show, Ord, Generic)
+  deriving anyclass (NFData, CoArbitrary, Function)
+  deriving Arbitrary via GenericArbitrary Hippocampus
+  deriving (ToJSON, FromJSON)
+       via WithOptions '[ FieldLabelModifier '[Drop 1] ]
+                       Hippocampus
+makeLenses ''Hippocampus
+
+initialHippocampus :: Hippocampus
+initialHippocampus = Hippocampus Nothing