import { FormGroup } from '@angular/forms';

export const confirmValidator = (formName: string) => (group: FormGroup): { [key: string]: { formName: string } } | null => {
    const { _parent: parent } = group as any;

    if (parent) {
        if (parent.controls[formName].value === group.value) {
            return null;
        }

        checkChangeFormName(parent, formName, group);
    }

    return { confirm: { formName }  };
};

const checkChangeFormName = (parent, formName, group) => {
    parent.controls[formName].valueChanges.subscribe((value) => {
        if (value !== group.value) {
            group.setErrors({ confirm: { formName } });
        } else if (group.errors) {
            delete group.errors.confirm;

            if (!Object.keys(group.errors).length) {
                group.setErrors(null);
            }
        }
    });
};