net.datafaker.idnumbers.NricNumber Maven / Gradle / Ivy

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package net.datafaker.idnumbers;

import net.datafaker.providers.base.BaseProviders;
import net.datafaker.service.RandomService;

import java.util.EnumMap;
import java.util.Map;

/**
 * Generate number of UIN/FIN for Singapore.
 * Algorithm is given from http://www.ngiam.net/NRIC/
 */
public class NricNumber implements IdNumbers {

    public enum Type {SINGAPOREAN_TWENTIETH_CENTURY, FOREIGNER_TWENTIETH_CENTURY, SINGAPOREAN_TWENTY_FIRST_CENTURY, FOREIGNER_TWENTY_FIRST_CENTURY}

    private record NricType(char firstLetter, String matchLetters, int[] code, int initialValue) {

        public String format(int[] digits) {
                int value = initialValue;
                StringBuilder id = new StringBuilder(String.valueOf(firstLetter));
                for (int i = 0; i < digits.length; i++) {
                    value += digits[i] * code[i];
                    id.append(digits[i]);
                }
                value %= 11;
                id.append(matchLetters.charAt(value));
                return id.toString();
            }
        }

    private static final int[] CODE = {0, 2, 7, 6, 5, 4, 3, 2};
    private static final String FIN_LETTERS = "XWUTRQPNMLK";
    private static final String UIN_LETTERS = "JZIHGFEDCBA";
    private static final Map INITIALIZER = new EnumMap<>(Type.class);

    static {
        INITIALIZER.put(Type.SINGAPOREAN_TWENTIETH_CENTURY, new NricType('S', UIN_LETTERS, CODE, 0));
        INITIALIZER.put(Type.FOREIGNER_TWENTIETH_CENTURY, new NricType('F', FIN_LETTERS, CODE, 0));
        INITIALIZER.put(Type.SINGAPOREAN_TWENTY_FIRST_CENTURY, new NricType('T', UIN_LETTERS, CODE, 4));
        INITIALIZER.put(Type.FOREIGNER_TWENTY_FIRST_CENTURY, new NricType('G', FIN_LETTERS, CODE, 4));
    }

    public static String getValidFIN(BaseProviders f, Type type) {
        final RandomService random = f.random();
        final int[] number = new int[7];
        for (int i = 0; i < number.length; i++) {
            number[i] = random.nextInt(0, 9);
        }
        return INITIALIZER.get(type).format(number);
    }

}