game.ml

open! Base

type t =
  { mutable snake : Snake.t
  ; mutable apple : Apple.t
  ; mutable game_state : Game_state.t
  ; height : int
  ; width : int
  ; amount_to_grow : int
  }
[@@deriving sexp_of]

(* TODO: Implement [in_bounds]. *)
let in_bounds t position = failwith "For you to implement"

(* TODO: Implement [create].

   Make sure that the game returned by [create] is in a valid state. In particular, we
   should fail with the message "unable to create initial apple" if [Apple.create] is
   unsuccessful, and "unable to create initial snake" if the initial snake is invalid
   (i.e. goes off the board). *)
let create ~height ~width ~initial_snake_length ~amount_to_grow =
  failwith "For you to implement"
;;

let snake t = t.snake
let apple t = t.apple
let game_state t = t.game_state

(* TODO: Implement [set_direction]. *)
let set_direction t direction = ()

(* TODO: Implement [step].

   [step] should:
   - move the snake forward one square
   - check for collisions (end the game with "Wall collision" or "Self collision")
   - if necessary:
     -- consume apple
     -- if apple cannot be regenerated, win game; otherwise, grow the snake *)
let step t = ()

module For_testing = struct
  let create_apple_force_location_exn ~height ~width ~location =
    let invalid_locations =
      List.init height ~f:(fun row ->
          List.init width ~f:(fun col -> { Position.row; col }))
      |> List.concat
      |> List.filter ~f:(fun pos -> not ([%compare.equal: Position.t] location pos))
    in
    match Apple.create ~height ~width ~invalid_locations with
    | None -> failwith "[Apple.create] returned [None] when [Some _] was expected!"
    | Some apple -> apple
  ;;

  let create_apple_and_update_game_exn t ~apple_location =
    let apple =
      create_apple_force_location_exn
        ~height:t.height
        ~width:t.width
        ~location:apple_location
    in
    t.apple <- apple
  ;;

  let create_game_with_apple_exn
      ~height
      ~width
      ~initial_snake_length
      ~amount_to_grow
      ~apple_location
    =
    let t = create ~height ~width ~initial_snake_length ~amount_to_grow in
    create_apple_and_update_game_exn t ~apple_location;
    t
  ;;
end