67 lines
1.7 KiB
TypeScript
67 lines
1.7 KiB
TypeScript
interface OtpServiceEntity {
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length?: number;
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}
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export class OtpService {
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private readonly otpLength: number;
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constructor({ length = 4 }: OtpServiceEntity) {
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this.otpLength = Math.max(length, 4); // Minimum of 4 digits
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}
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private hasSequentialDigits(str: string): boolean {
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for (let i = 0; i < str.length - 1; i++) {
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const current = parseInt(str[i], 10);
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const next = parseInt(str[i + 1], 10);
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if (next === current + 1 || next === current - 1) {
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return true;
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}
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}
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return false;
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}
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private hasRepeatedDigits(str: string): boolean {
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return str.split('').every((char) => char === str[0]);
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}
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private isPalindrome(str: string): boolean {
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return str === str.split('').reverse().join('');
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}
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private hasPartiallyRepeatedDigits(str: string): boolean {
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const counts: Record<string, number> = {};
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for (const char of str) {
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counts[char] = (counts[char] || 0) + 1;
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}
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// Reject if any digit appears more than twice
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return Object.values(counts).some((count) => count > 2);
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}
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private hasNoMatchLength(str: string) {
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return str.length !== this.otpLength;
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}
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private hasStartWithZero(str: string) {
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return str.split('')[0] === '0';
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}
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public generateSecureOTP(): string {
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let otp: string;
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do {
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otp = Array.from({ length: this.otpLength }, () =>
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Math.floor(Math.random() * 10).toString(),
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).join('');
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} while (
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this.hasNoMatchLength(otp) ||
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this.hasSequentialDigits(otp) ||
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this.hasRepeatedDigits(otp) ||
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this.isPalindrome(otp) ||
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this.hasPartiallyRepeatedDigits(otp) ||
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this.hasStartWithZero(otp)
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);
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return otp;
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}
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}
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