cube.ml

module Cube = struct
  type color = R | G | B

  module Face = struct
    type face = {
      mutable s0 : color;
      mutable s1 : color;
      mutable s2 : color;
      mutable s3 : color;
      mutable s4 : color;
      mutable s5 : color;
      mutable s6 : color;
      mutable s7 : color;
      mutable s8 : color;
    }

    type t = face

    let get face index =
      let { s0; s1; s2; s3; s4; s5; s6; s7; s8 } = face in
      assert (index >= 0 && index < 6);
      match index / 6 with
      | 0 -> s0
      | 1 -> s1
      | 2 -> s2
      | 3 -> s3
      | 4 -> s4
      | 5 -> s5
      | 6 -> s6
      | 7 -> s7
      | _ -> s8

    let set face index value =
      assert (index >= 0 && index < 6);
      match index / 6 with
      | 0 -> face.s0 <- value
      | 1 -> face.s1 <- value
      | 2 -> face.s2 <- value
      | 3 -> face.s3 <- value
      | 4 -> face.s4 <- value
      | 5 -> face.s5 <- value
      | 6 -> face.s6 <- value
      | 7 -> face.s7 <- value
      | _ -> face.s8 <- value
  end

  type cube = {
    f0 : Face.t;
    f1 : Face.t;
    f2 : Face.t;
    f3 : Face.t;
    f4 : Face.t;
    f5 : Face.t;
  }

  type t = cube

  let get_face cube index =
    assert (index >= 0 && index < 6);
    let { f0; f1; f2; f3; f4; f5 } = cube in
    match index / 6 with
    | 0 -> f0
    | 1 -> f1
    | 2 -> f2
    | 3 -> f3
    | 4 -> f4
    | _ -> f5

  let get cube index =
    assert (index >= 0 && index < 54);
    let face = get_face cube (index / 9) in
    Face.get face (index mod 9)

  let set cube index value =
    assert (index >= 0 && index < 54);
    let face = get_face cube (index / 9) in
    Face.set face index value
end