com.univapay.sdk.models.common.DateValidator Maven / Gradle / Ivy
package com.univapay.sdk.models.common;
import java.util.Calendar;
public class DateValidator {
/**
* Maximum amount of years in advance that a credit card expiration date should be trusted to be
* valid. This is mostly used if the current date is towards the end of the century and the
* expiration date is at the start of the following one.
*
* Ex. Current year is 2099, Expiration date is "01/01". The YY is "less than" the current
* year, but since the difference is less than {@code MAXIMUM_VALID_YEAR_DIFFERENCE}, it should
* still be trusted to be valid client-side.
*/
private static final int MAXIMUM_VALID_YEAR_DIFFERENCE = 20;
private static final DateValidator INSTANCE = new DateValidator(Calendar.getInstance());
private final Calendar calendar;
/**
* Used in tests to inject a custom {@link java.util.Calendar} to stabilize dates. Normal usage
* will just delegate to the actual date.
*/
protected DateValidator(Calendar calendar) {
this.calendar = calendar;
}
/**
* Helper for determining whether a date is a valid credit card expiry date.
*
* @param month Two-digit month
* @param year Two or four digit year
* @return Whether the date is a valid credit card expiry date.
*/
public static boolean isValid(int month, int year) {
return INSTANCE.isValidHelper(month, year);
}
protected boolean isValidHelper(int month, int year) {
int currentYear = getCurrentTwoDigitYear();
int twoDigitYear;
if (year >= 10 && year < 100) {
twoDigitYear = year;
} else if (year >= 1000 & year < 10000) {
twoDigitYear = year % 100;
} else {
return false;
}
if (twoDigitYear == currentYear && month < getCurrentMonth()) {
return false;
}
if (twoDigitYear < currentYear) {
// account for century-overlapping in 2-digit year representations
int adjustedYear = twoDigitYear + 100;
if (adjustedYear - currentYear > MAXIMUM_VALID_YEAR_DIFFERENCE) {
return false;
}
}
return twoDigitYear <= currentYear + MAXIMUM_VALID_YEAR_DIFFERENCE;
}
/**
* {@link java.util.Calendar#MONTH} is 0-prefixed. Add {@code 1} to align it with visualized
* expiration dates.
*/
private int getCurrentMonth() {
return calendar.get(Calendar.MONTH) + 1;
}
/**
* {@link java.util.Calendar#YEAR} is the full, 4-digit year. Take the trailing two digits to
* align it with visualized expiration dates.
*/
private int getCurrentTwoDigitYear() {
return calendar.get(Calendar.YEAR) % 100;
}
}