i18next types

i18next-types.ts

type TokenTranslation<Namespaces, R extends boolean = false> = Extract<
  keyof {
    [Key in Extract<keyof Namespaces, string> as Namespaces[Key] extends
      | string
      | number
      ? `${Key}`
      : `${Key}${R extends true ? "." : ":"}${TokenTranslation<
          Namespaces[Key],
          true
        >}`]: unknown;
  },
  string
>;

// (╯°□°）╯︵ ┻━┻
type ResultTranslation<Obj, T extends string> = T extends keyof Obj
  ? Obj[T]
  : T extends `${infer Key}:${infer R}` | `${infer Key}.${infer R}`
  ? Key extends keyof Obj
    ? ResultTranslation<Obj[Key], R>
    : never
  : never;

type i18NextProps<
  T extends string,
  Acc extends Record<string, string> = {}
> = T extends `${string}{${infer Key}}${infer Rest}`
  ? i18NextProps<Rest, Acc & { [K in Key]: unknown }>
  : Acc;

const translation = <
  N extends Record<string, any>,
  T extends TokenTranslation<N>,
  P extends i18NextProps<ResultTranslation<N, T>>
>(
  _obj: N,
  _text: T,
  _props: P extends Record<string, never> ? null : P
): void => {
  return;
};

const namespaces = {
  common: {
    "hello-world": "awdiojaodjiaw",
  },
  commands: {
    ping: {
      description: "show ping",
      pong: "Ping! {ms}",
    },
  },
} as const;

translation(namespaces, "common:hello-world", null); // ok
translation(namespaces, "common:hello-world", {}); // error
translation(namespaces, "commands:ping.description", null); // ok
translation(namespaces, "commands:ping.description", {}); // error
translation(namespaces, "commands:ping.pong", { ms: 42352 }); // ok
translation(namespaces, "commands:ping.pong", {}); // error
translation(namespaces, "commands:ping.pong", null); // error
translation(namespaces, "wdokapdjawiowfjio"); // deve da error

export type ObjectToken<Namespaces> = Extract<
  keyof {
    [Key in Extract<keyof Namespaces, string> as Namespaces[Key] extends
      | string
      | number
      ? `${Key}`
      : Namespaces[Key] extends (infer T)[]
      ? `${Key}.${number}.${ObjectToken<T>}`
      : `${Key}.${ObjectToken<Namespaces[Key]>}`]: unknown;
  },
  string
>;

export type ObjectValueByPath<
  O,
  P extends ObjectToken<O>
> = P extends `${infer Key}.${infer Rest}`
  ? Key extends keyof O
    ? ObjectValueByPath<O[Key], Rest extends ObjectToken<O[Key]> ? Rest : never>
    : never
  : P extends keyof O
  ? O[P]
  : never;