game: added single player

Integrated the engine into the playable game.
Created a menu to choose between single player and hotseat.
Added a way to choose difficulty and color in single player.

src/game.nim

@@ -1,7 +1,10 @@
-import ./chess
+import parseutils
 
-proc runGame*(): void =
-  ## Initializes and runs a game of chess.
+import ./chess.nim
+import ./engine.nim
+
+proc runGameHotseat*(): void =
+  ## Initializes and runs a game of chess as hotseat.
   var game = initGame()
   var draw: string
   game.echoBoard(game.toMove)
@@ -23,4 +26,66 @@ proc runGame*(): void =
   if game.isStalemate(game.toMove):
     echo "Stalemate"
 
-runGame()
+proc runGameSolo*(color: Color, difficulty: int): void =
+  ## Initializes and runs a solo game of chess.
+  ## The player plays as `color`.
+  var game = initGame()
+  var draw: string
+  while not game.isCheckmate(game.toMove) and not game.isStalemate(game.toMove):
+    if (game.toMove == color):
+      game.echoBoard(color)
+      echo "Make a move"
+      var hMove = readLine(stdin)
+      while not game.checkedMove(notationToMove(hMove, game.toMove)):
+        hMove = readLine(stdin)
+      game.echoBoard(color)
+      if (game.isDrawClaimable):
+        echo "Do you want to claim a draw? (y/N)"
+        draw = readLine(stdin)
+        if (draw == "y"):
+          echo "Draw claimed"
+          break
+    else:
+      var cMove = bestMove(game, 3)
+      game.checkedMove(cMove)
+  if game.isCheckmate(game.toMove):
+    echo $game.toMove & " was checkmated"
+  if game.isStalemate(game.toMove):
+    echo "Stalemate"
+
+proc menu(): void =
+  ## Presents choices on what to play.
+  echo("\nWelcome to YchESs!\n\n\n")
+  var input: string
+  var playerCount: int
+  while true:
+    echo("How many players? (1/2)")
+    input = readLine(stdin)
+    discard parseInt(input, playerCount, 0)
+    if (playerCount == 1 or playerCount == 2):
+      break
+  if playerCount == 1:
+    var color: string
+    var difficulty: int
+    while true:
+      echo("Choose the difficulty for the engine (1-10)")
+      input = readLine(stdin)
+      discard parseInt(input, difficulty, 0)
+      if (difficulty >= 1 and difficulty <= 10):
+        break
+    while true:
+      echo("Do you want to play Black or White? (B/W)")
+      color = readLine(stdin)
+      if (color == "B"):
+        echo("\n\n\n")
+        runGameSolo(Color.Black, difficulty)
+        break
+      elif (color == "W"):
+        echo("\n\n\n")
+        runGameSolo(Color.White, difficulty)
+        break
+  else:
+    echo("\n\n\n")
+    runGameHotseat()
+
+menu()