Wave function collapse SQUARE

import scala.collection.mutable.{ArrayBuffer, Buffer}
import scala.util.Random

class Square(grid: WaveFunctionCollapse, val location: GridPos):
  var tile: Option[String] = None
  val boundary       = Buffer.fill[Option[Char]](8)(None)
  var plausibleTiles = ArrayBuffer[String]() ++ AllTiles.allStrings


  /**
    * Fixes a single element in the boundary and removes incompatible tiles.
    * @param placeOnBoundary index of the element on the boundary
    * @param value value to be set in the boundary
    */
  def fix(placeOnBoundary: Int, value: Char): Unit =
    this.boundary(placeOnBoundary) = Some(value)
    this.plausibleTiles = this.plausibleTiles.filter( _(placeOnBoundary) == value)
  end fix

  /**
   * Calculates the entropy of the tile, that is - the number of plausible tiles.
   * @return the number of plausible tiles
   */
  def entropy: Int = plausibleTiles.size

  /**
  * Selects a random tile from all plausible tiles. Updates neighboring tiles if necessary.
  */
  def collapse(): Unit =
    val chosenTile = Random.shuffle(this.plausibleTiles).head
    this.tile = Some(chosenTile)
    var index = 0
    while index <= 7 do
      propagateChange(index, this.tile.get(index))
      index += 1

  end collapse

  /**
   * Propagates the change in this square's boundary to boundaries and plausible tiles of neighboring squares.
   * @param boundaryIndex index in this squares boundary
   * @param fixedValue the value to be set in the boundary
   */

  def propagateChange(boundaryIndex: Int, fixedValue: Char): Unit =
    for neighbor <- neighborBoundaries do
      if neighbor.mine == boundaryIndex && !(this.location.x == 0 && neighbor.dir == West) && !(this.location.x == 9 && neighbor.dir == East) && !(this.location.y == 0 && neighbor.dir == North) && !(this.location.y == 9 && neighbor.dir == South) then
        this.grid.elementAt(this.location.neighbor(neighbor.dir)).fix(neighbor.theirs, fixedValue)
  end propagateChange

end Square