snake

package o1.snake

import o1._
import scala.util.Random
import SnakeGame._


// This companion object provides aConstants and an utility function.
object SnakeGame {

  // The height and width of the game area, measured in squares that can hold
  // a single segment of a snake.
  val SizeInSquares = 40

  // Randomly returns the position of a single square on the grid, excluding the
  // very edges (where no food can appear and which kill the snake if it enters).
  def randomLocationOnGrid() = {
    new GridPos(Random.nextInt(SizeInSquares - 2) + 1,
                Random.nextInt(SizeInSquares - 2) + 1)
  }

}



// Represents games of Snake. A SnakeGame object is mutable: it tracks the
// position and heading of a snake as well as the position of a food item that
// is available for the snake to eat next.
class SnakeGame(initialPos: GridPos, initialHeading: CompassDir) {

  private var segments = Vector(initialPos) // container: the locations of every segment of the snake, in order from head to tail
  var snakeHeading = initialHeading         // most-recent holder (the direction most recently set for the snake)
  var nextFood = randomLocationOnGrid()     // most-recent holder (a changing random location for the next available food item)

  def snakeSegments = this.segments

  def isOver: Boolean = {
    val head = this.segments.head
    val validCoords = 1 until SizeInSquares
    val collidedWithWall = (!validCoords.contains(head.x) || !validCoords.contains(head.y))
    val pom = segments.drop(1).exists(_==segments(0))
    val result = (collidedWithWall || pom)
    result
  }
   //val pom = segments.drop(1).exists(_==segments(0))
    //val result = (collidedWithWall && pom)
    //result

  // This gets repeatedly called as the game progresses. It advances the snake by
  // one square in its current heading. In case the snake finds food, it grows by
  // one segment, the current nextFood vanishes and new food is placed in a random location.
  def advance() = {
    if(segments(0).neighbor(snakeHeading)==nextFood)
    {
      segments = segments(0).neighbor(snakeHeading) +: segments
      nextFood=randomLocationOnGrid()
    }
    else
    {
     // segments(0) = segments(0).neighbor(snakeHeading)
    //  for (i <- 1 to segments.size-2 )
    //  {
    //    segments(i)=segments(i+1)
    //  }
      var pom = segments.init
      pom = segments(0).neighbor(snakeHeading) +: pom
      segments=pom
    }
  }


}