Implement the start of creature AI

Add a Brain class, which determines for an entity the set of moves it
makes every step of the game, and begin to implement that for gormlaks.
The idea here is that every step of the game, a gormlak will move
towards the furthest-away wall it can see.

6 files changed, 38 insertions, 7 deletions

diff --git a/src/Xanthous/Entities/Arbitrary.hs b/src/Xanthous/Entities/Arbitrary.hs
index 2d1890f787a3..8ba6447933b2 100644
--- a/src/Xanthous/Entities/Arbitrary.hs
+++ b/src/Xanthous/Entities/Arbitrary.hs
@@ -12,6 +12,7 @@ import           Xanthous.Entities.Character
 import           Xanthous.Entities.Item
 import           Xanthous.Entities.Creature
 import           Xanthous.Entities.Environment
+import           Xanthous.AI.Gormlak ()
 --------------------------------------------------------------------------------
 
 instance Arbitrary SomeEntity where
diff --git a/src/Xanthous/Entities/Character.hs b/src/Xanthous/Entities/Character.hs
index 9423f2dc96b0..1c7d1bbe82a6 100644
--- a/src/Xanthous/Entities/Character.hs
+++ b/src/Xanthous/Entities/Character.hs
@@ -41,6 +41,9 @@ instance Draw Character where
       rloc = Location (negate scrollOffset, negate scrollOffset)
       rreg = (2 * scrollOffset, 2 * scrollOffset)
 
+-- the character does not (yet) have a mind of its own
+instance Brain Character where step = brainVia Brainless
+
 instance Entity Character where
   blocksVision _ = False
   description _ = "yourself"
diff --git a/src/Xanthous/Entities/Creature.hs b/src/Xanthous/Entities/Creature.hs
index 5151f78b3061..accf0c42e2ad 100644
--- a/src/Xanthous/Entities/Creature.hs
+++ b/src/Xanthous/Entities/Creature.hs
@@ -8,6 +8,7 @@ module Xanthous.Entities.Creature
   , newWithType
   , damage
   , isDead
+  , visionRadius
   ) where
 --------------------------------------------------------------------------------
 import           Xanthous.Prelude
@@ -17,8 +18,7 @@ import           Data.Aeson.Generic.DerivingVia
 import           Data.Aeson (ToJSON, FromJSON)
 --------------------------------------------------------------------------------
 import           Xanthous.Entities.RawTypes hiding (Creature, description)
-import qualified Xanthous.Entities.RawTypes as Raw
-import           Xanthous.Entities (Draw(..), Entity(..), DrawRawChar(..))
+import           Xanthous.Entities (Draw(..), DrawRawChar(..))
 --------------------------------------------------------------------------------
 
 data Creature = Creature
@@ -35,9 +35,7 @@ makeLenses ''Creature
 instance Arbitrary Creature where
   arbitrary = genericArbitrary
 
-instance Entity Creature where
-  blocksVision _ = False
-  description = view $ creatureType . Raw.description
+--------------------------------------------------------------------------------
 
 newWithType :: CreatureType -> Creature
 newWithType _creatureType =
@@ -52,3 +50,6 @@ damage amount = hitpoints %~ \hp ->
 
 isDead :: Creature -> Bool
 isDead = views hitpoints (== 0)
+
+visionRadius :: Creature -> Word
+visionRadius = const 12 -- TODO
diff --git a/src/Xanthous/Entities/Environment.hs b/src/Xanthous/Entities/Environment.hs
index 4ef67a577dbb..e8190cd42a92 100644
--- a/src/Xanthous/Entities/Environment.hs
+++ b/src/Xanthous/Entities/Environment.hs
@@ -13,7 +13,15 @@ import Brick (str)
 import Brick.Widgets.Border.Style (unicode)
 import Brick.Types (Edges(..))
 --------------------------------------------------------------------------------
-import Xanthous.Entities (Draw(..), entityIs, Entity(..), SomeEntity)
+import Xanthous.Entities
+       ( Draw(..)
+       , entityIs
+       , Entity(..)
+       , SomeEntity
+       , Brain(..)
+       , Brainless(..)
+       , brainVia
+       )
 import Xanthous.Entities.Draw.Util
 import Xanthous.Data
 --------------------------------------------------------------------------------
@@ -22,6 +30,9 @@ data Wall = Wall
   deriving stock (Show, Eq, Ord, Generic, Enum)
   deriving anyclass (CoArbitrary, Function)
 
+-- deriving via Brainless Wall instance Brain Wall
+instance Brain Wall where step = brainVia Brainless
+
 instance Entity Wall where
   blocksVision _ = True
   description _ = "a wall"
@@ -64,6 +75,9 @@ instance Draw Door where
       horizDoor = '␣'
       vertDoor = '['
 
+-- deriving via Brainless Door instance Brain Door
+instance Brain Door where step = brainVia Brainless
+
 instance Entity Door where
   blocksVision = not . view open
   description _ = "a door"
diff --git a/src/Xanthous/Entities/Item.hs b/src/Xanthous/Entities/Item.hs
index 6b50f50ad83c..832f0d4d62b3 100644
--- a/src/Xanthous/Entities/Item.hs
+++ b/src/Xanthous/Entities/Item.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE StandaloneDeriving #-}
 --------------------------------------------------------------------------------
 module Xanthous.Entities.Item
   ( Item(..)
@@ -13,7 +14,14 @@ import           Data.Aeson.Generic.DerivingVia
 --------------------------------------------------------------------------------
 import           Xanthous.Entities.RawTypes hiding (Item, description)
 import qualified Xanthous.Entities.RawTypes as Raw
-import           Xanthous.Entities (Draw(..), Entity(..), DrawRawChar(..))
+import           Xanthous.Entities
+                 ( Draw(..)
+                 , Entity(..)
+                 , DrawRawChar(..)
+                 , Brain(..)
+                 , Brainless(..)
+                 , brainVia
+                 )
 --------------------------------------------------------------------------------
 
 data Item = Item
@@ -27,6 +35,9 @@ data Item = Item
                        Item
 makeLenses ''Item
 
+-- deriving via (Brainless Item) instance Brain Item
+instance Brain Item where step = brainVia Brainless
+
 instance Arbitrary Item where
   arbitrary = Item <$> arbitrary
 
diff --git a/src/Xanthous/Entities/Raws.hs b/src/Xanthous/Entities/Raws.hs
index e1bb429a0f0d..9b7d63c6c4c5 100644
--- a/src/Xanthous/Entities/Raws.hs
+++ b/src/Xanthous/Entities/Raws.hs
@@ -17,6 +17,7 @@ import           Xanthous.Entities.RawTypes
 import           Xanthous.Entities
 import qualified Xanthous.Entities.Creature as Creature
 import qualified Xanthous.Entities.Item as Item
+import           Xanthous.AI.Gormlak ()
 --------------------------------------------------------------------------------
 rawRaws :: [(FilePath, ByteString)]
 rawRaws = $(embedDir "src/Xanthous/Entities/Raws")