model.mli

(* Player id. A two-player game would have ids of 0 and 1. *)
type id = int

(* The contents of a single board space *)
type board_object =
    | Wall  | NoWall
    | Space | Player of id

(** A position type for a location on board *)
type loc = (int * int)

(** A game state.
  * Walls for an 8x8 board would only be 7x7 (in betweeen spaces) so location
  * for top left wall layout:
  * POS1 | WAL1 | POS2 | WAL
  * -------------------------
  * WAL2 | EMP0 | WAL3 | EMP0
  * -------------------------
  * POS3 | WAL4 | POS4 | WAL5
  * -------------------------
  * WAL6 | EMP0 | WAL7 | EMP0
  *
  * With POS repesenting a position on board, WAL representing a wall and
  * EMP representing an empty space that walls can pass through.
  * Coords for WAL 1 -> (1,0)
  * Coords for WAL 2 -> (0,1)
  * Coords for WAL 3 -> (2,1)
  * Coords for POS 1 -> (0,0)
  * Coords for POS 2 -> (2,0)
  * Coords for POS 3 -> (2,0)
*)
type t = {
  size : int;
  board : board_object array array;
  players : (loc * int) array
}

(** A position type for a wall (list of segment coordinates) *)
type wall = loc list

(* Represents a single move that a player is choosing to make *)
type move =
    | Move of loc
    | PlaceWall of wall

(** Create empty board state that is n * n in size (Square board) *)
val create_board : int -> t

(** [validate_move player_id move board] validates a movement or wall placement
    by a player, returning whether the move is allowed. *)
val validate_move : id -> move -> t -> bool

(** Apply the given move to the game on behalf of the given player. *)
val commit_move : id -> move -> t -> unit

(** Reverts the game to the state before the given move, assuming the player
    was in the given location. *)
val undo : id -> move -> t -> loc -> unit