Convert generated levels to walls

Add support for converting generated levels to walls, and merge one into
the entity map at the beginning of the game.

There's nothing here that guarantees the character ends up *inside* the
level though (they almost always don't) so that'll have to be slotted
into the level generation process.

src/Xanthous/Game/Draw.hs

@@ -11,7 +11,8 @@ import Brick.Widgets.Border.Style
 import Data.List.NonEmpty(NonEmpty((:|)))
 
 import Xanthous.Data (Position(Position), x, y, loc)
-import Xanthous.Data.EntityMap
+import Xanthous.Data.EntityMap (EntityMap, atPosition)
+import qualified Xanthous.Data.EntityMap as EntityMap
 import Xanthous.Entities
 import Xanthous.Game
   ( GameState(..)
@@ -34,16 +35,19 @@ drawMessages (MessageHistory (lastMessage :| _) True) = txt lastMessage
 --   (MessageHistory _ False) -> padTop (Pad 2) $ str " "
 --   (MessageHistory (lastMessage :| _) True) -> txt lastMessage
 
-drawEntities :: (Draw a, Show a) => EntityMap a -> Widget Name
+drawEntities :: EntityMap SomeEntity -> Widget Name
 drawEntities em
   = vBox rows
   where
-    entityPositions = positions em
+    entityPositions = EntityMap.positions em
     maxY = fromMaybe 0 $ maximumOf (folded . y) entityPositions
     maxX = fromMaybe 0 $ maximumOf (folded . x) entityPositions
     rows = mkRow <$> [0..maxY]
     mkRow rowY = hBox $ renderEntityAt . flip Position rowY <$> [0..maxX]
-    renderEntityAt pos = maybe (str " ") draw $ em ^? atPosition pos . folded
+    renderEntityAt pos =
+      let neighbors = EntityMap.neighbors pos em
+      in maybe (str " ") (drawWithNeighbors neighbors)
+         $ em ^? atPosition pos . folded
 
 drawMap :: GameState -> Widget Name
 drawMap game