import { FormControl, ValidationErrors } from '@angular/forms';
import { NgModule } from '@angular/core';

/**
 * Base static class for all validators
 */
export class OibValidator {
    /**
     * Angular 4.x.x Reactive Forms Validator function
     * @param {FormControl} control Angular FormControl thats used for oib input
     * @returns {ValidationErrors} Returns Validations Errors with name validateOIB that can be used to bind errors in html
     */
    public static check(control: FormControl): ValidationErrors {

        let valid: boolean = false;
        if (control !== null && control.value !== null) {
            valid = OibValidator.checkOib(control.value);
        }

        return valid ? null : {
            validateOib: {
                valid: valid
            }
        };
    }

    /**
     * Checks if the entered OIB is valid
     * @param {string} oib OIB (Osobni Identifikacijski Broj) is a unique number assigned to citizens and companies in Croatia
     * @returns {boolean} Returns boolean indicating if OIB is valid
     */
    public static checkOib(oib: string): boolean {
        if (oib === null) return false;
        if (oib.length !== 11) return false;

        let b: number = parseInt(oib, 10);
        if (isNaN(b)) return false;

        let a: number = 10;
        for (let i: number = 0; i < 10; i++) {
            a = a + parseInt(oib.substr(i, 1), 10);
            a = a % 10;
            if (a === 0) a = 10;
            a *= 2;
            a = a % 11;
        }
        let controlNumber: number = 11 - a;
        if (controlNumber === 10) controlNumber = 0;

        return controlNumber === parseInt(oib.substr(10, 1));
    }
}