import { AsNumber, Reverse } from "../../string";
import { Unreachable } from "../../type";
import { StripLeadingZeros } from "../string";
import { ValidatePosInt, ValidateNonnegInt, ValidateInt } from "./_validate";
import { _Inc } from ".";
type SubtractionDigitMap = [
    9,
    0,
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8
];
/**
 * "decrements" a positive integer in reverse serialized form `S`
 * e.g. `__Dec<"01"> = "90"` since `"01"` represents `10` and `"09"` represents `9`
 */
type __Dec<S extends string> = S extends `${infer D extends number}${infer T}` ? D extends 0 ? `9${__Dec<T>}` : `${SubtractionDigitMap[D]}${T}` : Unreachable;
/**
 * decrements positive integer `N`
 *
 * @warning you probably want to use `DecPos` instead. this type does not enforce type constraints past `number`.
 *
 * @since 0.0.2
 */
export type _DecPos<N extends number> = AsNumber<StripLeadingZeros<Reverse<__Dec<Reverse<`${N}`>>>>>;
/**
 * decrements nonnegative integer `N`
 *
 * @warning you probably want to use `DecNonneg` instead. this type does not enforce type constraints past `number`.
 *
 * @since 0.0.2
 */
export type _DecNonneg<N extends number> = N extends 0 ? -1 : _DecPos<N>;
/**
 * decrements integer `N`
 *
 * @warning you probably want to use `Dec` instead. this type does not enforce type constraints past `number`.
 *
 * @since 0.0.2
 */
export type _Dec<N extends number> = `${N}` extends `-${infer Abs extends number}` ? AsNumber<`-${_Inc<Abs>}`> : _DecNonneg<N>;
/**
 * decrements positive integer `N`
 *
 * validates that `N` is in fact a positive integer
 *
 * @since 0.0.2
 */
export type DecPos<N extends ValidatePosInt<N>> = ValidatePosInt<N> extends number ? N extends (infer N extends number) ? _DecPos<N> : Unreachable : never;
/**
 * decrements nonnegative integer `N`
 *
 * validates that `N` is in fact a nonnegative integer
 *
 * @since 0.0.2
 */
export type DecNonneg<N extends ValidateNonnegInt<N>> = ValidateNonnegInt<N> extends number ? N extends (infer N extends number) ? _DecNonneg<N> : Unreachable : never;
/**
 * decrements integer `N`
 *
 * validates that `N` is in fact an integer
 *
 * @since 0.0.2
 */
export type Dec<N extends ValidateInt<N>> = ValidateInt<N> extends number ? N extends (infer N extends number) ? _Dec<N> : Unreachable : never;
export {};
//# sourceMappingURL=dec.d.ts.map