package snake
package life

import LifeModel.*

/** m13 life rules: the next generation is a function of the whole old board, and nothing else. */
object LifeRules:

  /**
   * One generation of Conway's Life on the LW x LH board (B3/S23), from a canonical list of live cells to a canonical
   * list (sorted row-major: by `y`, then `x`; no duplicates).
   * - A live cell with 2 or 3 live neighbours stays alive; a dead cell with exactly 3 live neighbours is born;
   *   every other cell is dead in the next generation.
   * - The neighbours of a cell are the up to 8 cells around it that are on the board: the edges are dead,
   *   nothing wraps around.
   * - Every cell is judged by the *old* board only.
   */
  def lifeStep(cells: List[Point]): List[Point] = ???

  /**
   * The one function that says how the world changes: `(state, action) => state`.
   * - `Frame`: when running, the next generation (`lifeStep`) and `generation + 1`; when paused, unchanged.
   * - `Step`: when paused, the next generation and `generation + 1`; when running, unchanged.
   * - `TogglePause`: `running` flips.
   * - `Toggle(cell)`: a dead cell becomes alive, a live one dead, whether the world runs or not; `cells` stays canonical
   *   (insert the new cell at its row-major place). A cell off the board changes nothing. `generation` is unchanged.
   * - `Clear`: no live cells, generation 0; `running` and `seed` are kept.
   * - `Randomize`: draw `Random.intBelow(4)` (Module 4) once for every cell of the board, in row-major order
   *   (y = 0 until LH, and within a row x = 0 until LW), threading the seed from `state.seed`; a cell is alive when its
   *   draw is 0. The state gets those cells, the seed after the last draw, and generation 0; `running` is kept.
   *   1200 draws: thread the seed with a fold, not with deep recursion.
   */
  def lifeUpdate(state: LifeState, action: LifeAction): LifeState = ???