package envoy.server.util;

import java.security.SecureRandom;

/**
 * Provides a secure token generation algorithm.
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Server v0.2-beta
 */
public final class AuthTokenGenerator {

	private static final int			TOKEN_LENGTH	= 128;
	private static final char[]			CHARACTERS		= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
	private static final char[]			BUFF			= new char[TOKEN_LENGTH];
	private static final SecureRandom	RANDOM			= new SecureRandom();

	private AuthTokenGenerator() {}

	/**
	 * Generates a random authentication token.
	 *
	 * @return a random authentication token
	 * @since Envoy Server v0.2-beta
	 */
	public static String nextToken() {
		for (int i = 0; i < BUFF.length; ++i)
			BUFF[i] = CHARACTERS[RANDOM.nextInt(CHARACTERS.length)];
		return new String(BUFF);
	}
}