package snake

/** A grid cell. Two points with the same `x` and `y` are `==` (case classes compare structurally). */
final case class Point(x: Int, y: Int)

enum Direction:
  case Up, Down, Left, Right

enum Status:
  case Playing, Paused, GameOver, Won

/** Everything that can happen to the game, as data. */
enum Action:
  case Tick
  case Turn(dir: Direction)
  case TogglePause
  case Restart
  case Frame

/** The whole game. `snake` is head first; `seed` is the unsigned 32-bit random seed (0 until 2^32). */
final case class GameState(
    width: Int,
    height: Int,
    snake: List[Point],
    dir: Direction,
    nextDir: Direction,
    apple: Option[Point],
    seed: Long,
    score: Int,
    status: Status,
    frame: Int
)

/** m02 model: the data the whole game is built from. Case classes and enums are immutable. */
object Model:

  def delta(dir: Direction): Point = dir match
    case Direction.Up    => Point(0, -1)
    case Direction.Down  => Point(0, 1)
    case Direction.Left  => Point(-1, 0)
    case Direction.Right => Point(1, 0)

  def opposite(dir: Direction): Direction = dir match
    case Direction.Up    => Direction.Down
    case Direction.Down  => Direction.Up
    case Direction.Left  => Direction.Right
    case Direction.Right => Direction.Left

  def initialState(seed: Long): GameState = GameState(
    width = 20,
    height = 20,
    snake = List(Point(10, 10), Point(9, 10), Point(8, 10)),
    dir = Direction.Right,
    nextDir = Direction.Right,
    apple = None,
    seed = seed,
    score = 0,
    status = Status.Playing,
    frame = 0
  )