Work on chasm rooms

src/Dodge/RoomLink.hs

@@ -21,8 +21,11 @@ module Dodge.RoomLink (
     setLinkType,
     getLinksOfType,
     swapInOutLinks,
+    isCornerLink,
+    isMidEdgeLink,
 ) where
 
+import Dodge.Base.CardinalPoint
 import Control.Lens
 import Data.List (partition)
 import qualified Data.Set as S
@@ -51,6 +54,22 @@ setOutLinks = setLinkType OutLink
 setInLinks :: (RoomLink -> Bool) -> [RoomLink] -> [RoomLink]
 setInLinks = setLinkType InLink
 
+isMidEdgeLink :: Room -> CardinalPoint -> RoomLink -> Bool
+isMidEdgeLink r x rl
+    | x == North || x == South = g West (f $ r ^?! rmType . numLinkEW)
+    | otherwise = g South (f $ r ^?! rmType . numLinkNS)
+  where
+    f y | even y = [y `div` 2]
+        | otherwise = [y `div` 2, 1 + (y `div` 2)]
+    g a = any (\y -> FromEdge a y `S.member` (rl ^. rlType))
+
+isCornerLink :: CardinalPointBetween -> RoomLink -> Bool
+isCornerLink x rl = (OnEdge a `S.member` xs && FromEdge b 0 `S.member` xs)
+    || (OnEdge b `S.member` xs && FromEdge a 0 `S.member` xs)
+  where
+    xs = rl ^. rlType
+    (a,b) = cardinalBetweenAdj x
+
 setInLinksByType :: RoomLinkType -> [RoomLink] -> [RoomLink]
 setInLinksByType lt = setInLinks (\rl -> lt `S.member` _rlType rl)