Add revealTile function

src/Lib.hs

@@ -1,5 +1,6 @@
 module Lib
   ( flagTile
+  , revealTile
   , printBoard
   , Board(..)
   , Tile(..)
@@ -18,15 +19,15 @@ data Tile
   deriving (Eq, Show)
 
 data TileState
-  = Revealed
+  = Hidden
   | Flagged
-  | Hidden
+  | Revealed
   deriving (Eq, Show)
 
 type Coordinates = (Int, Int)
 
-flagTile :: Board -> Coordinates -> Board
-flagTile (Board board) (x, y) =
+flagTile :: Coordinates -> Board -> Board
+flagTile (x, y) (Board board) =
   case findTile (Board board) (x, y) of
     (Just tile) -> flagHiddenTile tile
     Nothing     -> Board board
@@ -35,6 +36,31 @@ flagTile (Board board) (x, y) =
     flagHiddenTile (Bomb Hidden) = replaceTile (Board board) (x, y) (Bomb Flagged)
     flagHiddenTile _ = Board board
 
+revealTile :: Coordinates -> Board -> Board
+revealTile (x, y) (Board board) =
+  case findTile (Board board) (x, y) of
+    (Just tile) -> revealHiddenTile tile
+    Nothing     -> Board board
+  where
+    revealHiddenTile (Value 0 Hidden) =
+      revealTile (x - 1, y - 1) .
+      revealTile (x, y - 1) .
+      revealTile (x + 1, y - 1) .
+      revealTile (x - 1, y) .
+      revealTile (x + 1, y) . revealTile (x - 1, y + 1) . revealTile (x, y + 1) . revealTile (x + 1, y + 1) $
+      replaceTile (Board board) (x, y) (Value 0 Revealed)
+    revealHiddenTile (Value value Hidden) = replaceTile (Board board) (x, y) (Value value Revealed)
+    revealHiddenTile (Bomb Hidden) = revealAll (Board board)
+    revealHiddenTile _ = Board board
+
+revealAll :: Board -> Board
+revealAll (Board board) = Board $ map revealLine board
+  where
+    revealLine = map revealSingleTile
+    revealSingleTile (Value value Hidden) = Value value Revealed
+    revealSingleTile (Bomb Hidden)        = Bomb Revealed
+    revealSingleTile tile                 = tile
+
 replaceTile :: Board -> Coordinates -> Tile -> Board
 replaceTile (Board board) (x, y) tile =
   let (firstRows, line:lastRows) = splitAt y board
@@ -58,9 +84,9 @@ printBoard :: Board -> String
 printBoard (Board board) = concatMap printLine board
   where
     printLine line = concatMap printTile line ++ "\n"
-    printTile (Bomb Hidden) = "#"
-    printTile (Bomb Revealed) = "B"
-    printTile (Value _ Hidden) = "#"
+    printTile (Bomb Hidden)      = "#"
+    printTile (Bomb Revealed)    = "B"
+    printTile (Value _ Hidden)   = "#"
     printTile (Value x Revealed) = show x
-    printTile (Bomb Flagged) = "F"
-    printTile (Value _ Flagged) = "F"
+    printTile (Bomb Flagged)     = "F"
+    printTile (Value _ Flagged)  = "F"