val board = Array.ofDim[Int](3,3)

def printBoard() {
  println(
    board.map(_.map {
      case 1 => 'X'
      case -1 => 'O'
      case 0 => '.'
    }.mkString).mkString("\n")
  )
}

def isFullRow(elems: Int*) = elems.head != 0 && elems.forall(_ == elems.head)

def threeInRow() = {
  isFullRow(board(0)(0), board(0)(1), board(0)(2)) ||
  isFullRow(board(1)(0), board(1)(1), board(1)(2)) ||
  isFullRow(board(2)(0), board(2)(1), board(2)(2)) ||
  isFullRow(board(0)(0), board(1)(0), board(2)(0)) ||
  isFullRow(board(0)(1), board(1)(1), board(2)(1)) ||
  isFullRow(board(0)(2), board(1)(2), board(2)(2)) ||
  isFullRow(board(0)(0), board(1)(1), board(2)(2)) ||
  isFullRow(board(0)(2), board(1)(1), board(2)(0))
}

def boardIsFull() = board.forall(_.forall(_ != 0))

//determines if player a wins for sure if he plays perfectly
//b - player who's turn it is
def win(a: Int, b: Int, yPos: Int, xPos: Int): Boolean = {
  var result = if(a == b) true else false
  board(yPos)(xPos) = b
  if(threeInRow()) {
    if(a == b) result = true
    else result = false
  } else if(boardIsFull()) {
    result = false
  } else {
    for(y <- 0 until 3; x <- 0 until 3) {
      if(board(y)(x) == 0) {
        if(a == b) result = result && win(a, -b, y, x)
        else result = result || win(a, -b, y, x)
      }
    }
  }
  board(yPos)(xPos) = 0
  result
}

val rand = new util.Random

printBoard()
println()

while(!threeInRow() && !boardIsFull()) { 
  println("make your move")
  var (x,y) = (-1,-1)
  do {
    try {
      print("x: ")
      x = readInt()
      print("y: ")
      y = readInt()
    } catch {
      case _: NumberFormatException => x = -1; y = -1
    }
  } while(x < 0 || x > 2 || y < 0 || y > 2 || board(y)(x) != 0)
  
  board(y)(x) = 1
  if(!threeInRow() && !boardIsFull()) {
    val possibleMoves = for(y <- 0 until 3; x <- 0 until 3 if(board(y)(x) == 0)) yield (y,x)
    val moveNotLoose = possibleMoves.filterNot(coord => win(1, -1, coord._1, coord._2))
    val moveWin = possibleMoves.filter(coord => win(-1, -1, coord._1, coord._2))
    val move = rand.shuffle(if(moveWin.isEmpty) moveNotLoose else moveWin).head
    
    board(move._1)(move._2) = -1
  }
  println()
  printBoard()
  println()
}