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package org.apidesign.impl.security.spi;

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

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

import java.nio.ByteBuffer;

import java.util.ServiceLoader;

import org.apidesign.spi.security.Digestor;

/**

 *

 * @author Jaroslav Tulach

 */

public class DigestorProvider implements DigestProvider {

    public DigestImplementation create(String algorithm) {

        for (Digestor<?> d : ServiceLoader.load(Digestor.class)) {

            Handler<?> h = create(d, algorithm);

            if (h != null) {

                return h;

            }

        }

        return null;

    }

    private static <Data> Handler<Data> create(Digestor<Data> dig, String algorithm) {

        Data d = DigestorAccessor.getDefault().create(dig, algorithm);

        if (d == null) {

            return null;

        } else {

            return new Handler<Data>(algorithm, dig, d);

        }

    }

    private static final class Handler<Data> extends DigestImplementation {

        private final Digestor dig;

        private final Data data;

        public Handler(String algorithm, Digestor dig, Data data) {

            super(algorithm);

            this.dig = dig;

            this.data = data;

        }

        @Override

        public void update(ByteBuffer bb) {

            DigestorAccessor.getDefault().update(dig, data, bb);

        }

        @Override

        public byte[] digest() {

            return DigestorAccessor.getDefault().digest(dig, data);

        }

    }

}