package lu.circl.mispbump.auxiliary;


import java.security.SecureRandom;
import java.util.Locale;
import java.util.Objects;
import java.util.Random;


public class RandomString {
    @SuppressWarnings("SpellCheckingInspection")
    private static final String upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static final String lower = upper.toLowerCase(Locale.ROOT);
    private static final String digits = "0123456789";
    private static final String alphaNum = upper + lower + digits;

    private final Random random;
    private final char[] symbols;
    private final char[] buf;

    public RandomString(int length) {
        this(length, new SecureRandom());
    }

    RandomString(int length, Random random) {
        this(length, random, alphaNum);
    }

    RandomString(int length, Random random, String symbols) {
        if (length < 1) {
            throw new IllegalArgumentException();
        }
        if (symbols.length() < 2) {
            throw new IllegalArgumentException();
        }

        this.random = Objects.requireNonNull(random);
        this.symbols = symbols.toCharArray();
        this.buf = new char[length];
    }

    public String nextString() {
        for (int idx = 0; idx < buf.length; ++idx) {
            buf[idx] = symbols[random.nextInt(symbols.length)];
        }

        return new String(buf);
    }
}