/**
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* luhn.js
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*
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*/
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import {terminal} from "./dfhi.js";
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const checkLuhnNumber = (n) => {
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let sumEvent = 0n;
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let sumOdd = 0n;
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while(n > 0) {
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sumOdd += (n % 10n); // modulo division base 10 to get the last digit
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n = n/10n; // integer division base 10 to shift credit number one digit to right
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let rest = n % 10n; // get the second-last digit
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let p = rest*2n;
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sumEvent += (p > 9n) ? (p - 9n) : p;
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n = n/10n;
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}
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return (sumEvent + sumOdd) % 10n;
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}
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window.main = (...argv) => {
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try {
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let credit = argv[0];
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let n = BigInt(credit.replace(/[-_\s+]/g, ''));
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const sum = checkLuhnNumber(n);
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if (sum === 0n) {
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terminal.printl(`${credit} may be a valid credit number`);
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} else {
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terminal.printl(`${credit} is not a valid credit number`);
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}
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}catch (e) {
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terminal.printl("Die eingegebene Zeichenkette ist keine Credit Nummer");
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terminal.printl("Erlaubten Zeichen sind Ziffer, Leerzeichen und Bindenstrich");
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}
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};
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