import { ValidationOptions } from "../ValidationOptions";
import { buildMessage, ValidateBy } from "../common/ValidateBy";

export const IS_NEGATIVE = "isNegative";

/**
 * Checks if the value is a negative number smaller than zero.
 */
export function isNegative(value: unknown): boolean {
    return typeof value === "number" && value < 0;
}

/**
 * Checks if the value is a negative number smaller than zero.
 */
export function IsNegative(validationOptions?: ValidationOptions): PropertyDecorator {
    return ValidateBy(
        {
            name: IS_NEGATIVE,
            validator: {
                validate: (value, args): boolean => isNegative(value),
                defaultMessage: buildMessage(
                    (eachPrefix) => eachPrefix + "$property must be a negative number",
                    validationOptions
                )
            }
        },
        validationOptions
    );
}