import type { Int } from ".";
import type { Args, Fn } from "../../HKT";
import type { Every } from "../../List/Every";
import type IsDigitFn from "../../Str/IsDigit";
import type { ToChars } from "../../Str/ToChars";
import type { AssertInt } from "../../helpers";
import type { Abs } from "../Abs";

/**
 * Parse a string to an {@link Int}. Return `never` if the string is not a valid integer.
 *
 * Type safety is **not guaranteed**.
 *
 * Sig: `(s: string) => Int`
 */
export type FromStrUnsafe<S extends string> = AssertInt<
  string extends S ? Int
  : S extends `${infer N extends number}` ?
    Every<IsDigitFn, ToChars<`${Abs<N>}`>> extends true ?
      N
    : never
  : never
>;

/**
 * [Fn] Parse a string to an {@link Int}. Return `never` if the string is not a valid integer.
 *
 * Type safety is **not guaranteed**.
 *
 * Sig: `(s: string) => Int`
 */
export default interface FromStrUnsafeFn extends Fn<[string], Int> {
  def: ([s]: Args<this>) => FromStrUnsafe<typeof s>;
}