package org.apidesign.api.security;

import java.nio.ByteBuffer;

import org.apidesign.impl.security.friendapi.DigestImplementation;

import org.apidesign.impl.security.friendapi.DigestProvider;

import java.util.ServiceLoader;

/** MessageDigest extends MessageDigestSpi, that means the javadoc

 *

 * @author Jaroslav Tulach

 */

// BEGIN: day.end.bridges.Digest

public final class Digest {

    private final DigestImplementation impl;

    /** Factory method is better than constructor */

    private Digest(DigestImplementation impl) {

        this.impl = impl;

    }

    /** Factory method to create digest for an algorithm.

     */

    public static Digest getInstance(String algorithm) {

        for (DigestProvider dp : ServiceLoader.load(DigestProvider.class)) {

            DigestImplementation impl = dp.create(algorithm);

            if (impl != null) {

                return new Digest(impl);

            }

        }

        throw new IllegalArgumentException(algorithm);

    }

    //

    // these methods are kept the same as in original MessageDigest,

    // but for simplicity choose just some from the original API

    //

    public byte[] digest(ByteBuffer bb) {

        impl.update(bb);

        return impl.digest();

    }

}

// END: day.end.bridges.Digest