package org.gcube.gcat.utils;

import java.util.Random;

/**
 * @author Lucio Lelii (ISTI - CNR)
 * @author Luca Frosini (ISTI - CNR)
 */
public class RandomString {
	
	private static final char[] symbols;
	
	static {
		StringBuilder tmp = new StringBuilder();
		for(char ch = '0'; ch <= '9'; ++ch)
			tmp.append(ch);
		for(char ch = 'a'; ch <= 'z'; ++ch)
			tmp.append(ch);
		symbols = tmp.toString().toCharArray();
	}
	
	private final Random random = new Random();
	
	private final char[] buf;
	
	public RandomString(int length) {
		if(length < 1)
			throw new IllegalArgumentException("length < 1: " + length);
		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);
	}
}