// Copyright (c) 2023-2024 Onur Cinar.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
// https://github.com/cinar/checker

package v2

import (
	"reflect"
	"unicode"
)

const (
	// nameDigits is the name of the digits check.
	nameDigits = "digits"
)

var (
	// ErrNotDigits indicates that the given value is not a valid digits string.
	ErrNotDigits = NewCheckError("NOT_DIGITS")
)

// IsDigits checks if the value contains only digit characters.
func IsDigits(value string) (string, error) {
	for _, r := range value {
		if !unicode.IsDigit(r) {
			return value, ErrNotDigits
		}
	}
	return value, nil
}

// checkDigits checks if the value contains only digit characters.
func checkDigits(value reflect.Value) (reflect.Value, error) {
	_, err := IsDigits(value.Interface().(string))
	return value, err
}

// makeDigits makes a checker function for the digits checker.
func makeDigits(_ string) CheckFunc[reflect.Value] {
	return checkDigits
}