TicTacToe in typescript types

game.ts

// Game setup

type BoardPosition = [number, number];

type Space<Location extends BoardPosition, X extends BoardPosition[], Y extends BoardPosition[]> = Location extends X[number] ? 1 : Location extends Y[number] ? 2 : 0;

type Board<X extends BoardPosition[], Y extends BoardPosition[]> = [
    [Space<[0,0], X, Y>,Space<[0,1], X, Y>,Space<[0,2], X, Y>],
    [Space<[1,0], X, Y>,Space<[1,1], X, Y>,Space<[1,2], X, Y>],
    [Space<[2,0], X, Y>,Space<[2,1], X, Y>,Space<[2,2], X, Y>]
];

// Validation

type HasValidRow<M extends BoardPosition[], R extends number> = [R, 0] extends M[number]
 ? [R, 1] extends M[number]
 ? [R, 2] extends M[number]
 ? true
 : false
 : false
 : false;

type HasValidCol<M extends BoardPosition[], R extends number> = [0, R] extends M[number]
 ? [1, R] extends M[number]
 ? [2, R] extends M[number]
 ? true
 : false
 : false
 : false;

 type HasValidForwardSlash<M extends BoardPosition[]> = [0,0] extends M[number]
 ? [1, 1] extends M[number]
 ? [2, 2] extends M[number]
 ? true
 : false
 : false
 : false;

 type HasValidBackwardSlash<M extends BoardPosition[]> = [0,2] extends M[number]
 ? [1, 1] extends M[number]
 ? [2, 0] extends M[number]
 ? true
 : false
 : false
 : false;

 type ValidateBoardForUsersMoves<M extends BoardPosition[]> = HasValidRow<M, 0> extends false
    ? HasValidRow<M, 1> extends false 
    ? HasValidRow<M, 2> extends false
    ? HasValidCol<M, 0> extends false
    ? HasValidCol<M, 1> extends false
    ? HasValidCol<M, 2> extends false
    ? HasValidForwardSlash<M> extends false
    ? HasValidBackwardSlash<M> extends false
    ? false
    : true
    : true
    : true
    : true
    : true
    : true
    : true
    : true;

type ValidateBoard<X extends BoardPosition[] = [], Y extends BoardPosition[] = []> = 
    ValidateBoardForUsersMoves<X> extends true
    ? 'X'
    : ValidateBoardForUsersMoves<Y> extends true
    ? 'Y'
    : null;

// Convert string of moves to a board position array
type ToNumber<S extends string> = S extends `${infer N extends number}` ? N : never
type GreaterThan<
  N1 extends number,
  N2 extends number,
  A extends unknown[] = [],
> = A['length'] extends N1
  ? false
  : A['length'] extends N2
  ? true
  : GreaterThan<N1, N2, [0, ...A]>;
type HasValue<T extends string, C extends String> = T extends C ? true : false;
type RemoveUndefined<T extends unknown[]> = T extends [infer A, ...infer rest] ? [...(A extends undefined ? [] : [A]), ...RemoveUndefined<rest>] : [];

type StringToGrid<T extends string[], C extends string> = RemoveUndefined<{
    [index in keyof T]: GreaterThan<ToNumber<`${index}`>, 5> extends true
    ? GreaterThan<ToNumber<`${index}`>, 7> extends true
    ? HasValue<T[index], C> extends true ? [2,2] : undefined
    : GreaterThan<ToNumber<`${index}`>, 6> extends true
    ? HasValue<T[index], C> extends true ? [2,1] : undefined
    : HasValue<T[index], C> extends true ? [2,0] : undefined
    : GreaterThan<ToNumber<`${index}`>, 2> extends true
    ? GreaterThan<ToNumber<`${index}`>, 4> extends true
    ? HasValue<T[index], C> extends true ? [1,2] : undefined
    : GreaterThan<ToNumber<`${index}`>, 3> extends true
    ? HasValue<T[index], C> extends true ? [1,1] : undefined
    : HasValue<T[index], C> extends true ? [1,0] : undefined
    : GreaterThan<ToNumber<`${index}`>, 1> extends true
    ? HasValue<T[index], C> extends true ? [0,2] : undefined
    : GreaterThan<ToNumber<`${index}`>, 0> extends true
    ? HasValue<T[index], C> extends true ? [0,1] : undefined
    : HasValue<T[index], C> extends true ? [0,0] : undefined
}>

type ToBoardPosition<T extends unknown> = T extends BoardPosition[] ? T : never;

// Game helpers
type TicTacToe<Game extends string[]> = ValidateBoard<ToBoardPosition<StringToGrid<Game, 'x'>>, ToBoardPosition<StringToGrid<Game, 'y'>>> extends 'X' ? 'X has won!' : ValidateBoard<ToBoardPosition<StringToGrid<Game, 'x'>>, ToBoardPosition<StringToGrid<Game, 'y'>>> extends 'Y' ? 'Y has won!' : 'No winner';



type Result = TicTacToe<[
    'x','','y',
    'y','y','',
    '','x','x'
]>