refactor(xanthous): Generators -> Generators.Level

I'm going to start adding generators for things like text soon, so it
makes sense to specifically sequester level generators as their own
thing

Change-Id: I175025375204fab7d75eba67dd06dab9bd2939d3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3201
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI

users/grfn/xanthous/src/Xanthous/Generators/Level/Village.hs

@@ -0,0 +1,126 @@
+--------------------------------------------------------------------------------
+module Xanthous.Generators.Level.Village
+  ( fromCave
+  ) where
+--------------------------------------------------------------------------------
+import           Xanthous.Prelude hiding (any, failing, toList)
+--------------------------------------------------------------------------------
+import           Control.Monad.Random (MonadRandom)
+import           Control.Monad.State (execStateT, MonadState, modify)
+import           Control.Monad.Trans.Maybe
+import           Control.Parallel.Strategies
+import           Data.Array.IArray
+import           Data.Foldable (any, toList)
+--------------------------------------------------------------------------------
+import           Xanthous.Data
+import           Xanthous.Data.EntityMap (EntityMap)
+import qualified Xanthous.Data.EntityMap as EntityMap
+import           Xanthous.Entities.Environment
+import           Xanthous.Generators.Level.Util
+import           Xanthous.Game.State (SomeEntity(..))
+import           Xanthous.Random
+--------------------------------------------------------------------------------
+
+fromCave :: MonadRandom m
+         => Cells -- ^ The positions of all the walls
+         -> m (EntityMap SomeEntity)
+fromCave wallPositions = execStateT (fromCave' wallPositions) mempty
+
+fromCave' :: forall m. (MonadRandom m, MonadState (EntityMap SomeEntity) m)
+          => Cells
+          -> m ()
+fromCave' wallPositions = failing (pure ()) $ do
+  Just villageRegion <-
+    choose
+    . (`using` parTraversable rdeepseq)
+    . weightedBy (\reg -> let circSize = length $ circumference reg
+                         in if circSize == 50
+                            then (1.0 :: Double)
+                            else 1.0 / (fromIntegral . abs $ circSize - 50))
+    $ regions closedHallways
+
+  let circ = setFromList . circumference $ villageRegion
+
+  centerPoints <- chooseSubset (0.1 :: Double) $ toList circ
+
+  roomTiles <- foldM
+              (flip $ const $ stepOut circ)
+              (map pure centerPoints)
+              [0 :: Int ..2]
+
+  let roomWalls = circumference . setFromList @(Set _) <$> roomTiles
+      allWalls = join roomWalls
+
+  doorPositions <- fmap join . for roomWalls $ \room ->
+    let candidates = filter (`notMember` circ) room
+    in fmap toList . choose $ ChooseElement candidates
+
+  let entryways =
+        filter (\pt ->
+                  let ncs = neighborCells pt
+                  in any ((&&) <$> (not . (wallPositions !))
+                              <*> (`notMember` villageRegion)) ncs
+                   && any ((&&) <$> (`member` villageRegion)
+                              <*> (`notElem` allWalls)) ncs)
+                  $ toList villageRegion
+
+  Just entryway <- choose $ ChooseElement entryways
+
+  for_ (filter ((&&) <$> (`notElem` doorPositions) <*> (/= entryway)) allWalls)
+    $ insertEntity Wall
+  for_ (filter (/= entryway) doorPositions) $ insertEntity unlockedDoor
+  insertEntity unlockedDoor entryway
+
+
+  where
+    insertEntity e pt = modify $ EntityMap.insertAt (ptToPos pt) $ SomeEntity e
+    ptToPos pt = _Position # (fromIntegral <$> pt)
+
+    stepOut :: Set (V2 Word) -> [[V2 Word]] -> MaybeT m [[V2 Word]]
+    stepOut circ rooms = for rooms $ \room ->
+      let nextLevels = hashNub $ toList . neighborCells =<< room
+      in pure
+         . (<> room)
+         $ filter ((&&) <$> (`notMember` circ) <*> (`notElem` join rooms))
+         nextLevels
+
+    circumference pts =
+      filter (any (`notMember` pts) . neighborCells) $ toList pts
+    closedHallways = closeHallways livePositions
+    livePositions = amap not wallPositions
+
+--------------------------------------------------------------------------------
+
+closeHallways :: Cells -> Cells
+closeHallways livePositions =
+  livePositions // mapMaybe closeHallway (assocs livePositions)
+  where
+    closeHallway (_, False) = Nothing
+    closeHallway (pos, _)
+      | isHallway pos = Just (pos, False)
+      | otherwise     = Nothing
+    isHallway pos = any ((&&) <$> not . view left <*> not . view right)
+      . rotations
+      . fmap (fromMaybe False)
+      $ arrayNeighbors livePositions pos
+
+failing :: Monad m => m a -> MaybeT m a -> m a
+failing result = (maybe result pure =<<) . runMaybeT
+
+{-
+
+import Xanthous.Generators.Village
+import Xanthous.Generators
+import Xanthous.Data
+import System.Random
+import qualified Data.Text
+import qualified Xanthous.Generators.CaveAutomata as CA
+let gi = GeneratorInput SCaveAutomata CA.defaultParams
+wallPositions <- generateFromInput gi (Dimensions 80 50) <$> getStdGen
+putStrLn . Data.Text.unpack $ showCells wallPositions
+
+import Data.Array.IArray
+let closedHallways = closeHallways . amap not $ wallPositions
+putStrLn . Data.Text.unpack . showCells $ amap not closedHallways
+
+-}