package org.apidesign.impl.security.extension;

import org.apidesign.api.security.Digest;

import java.nio.ByteBuffer;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.security.Provider;

import java.security.Security;

import java.util.Collections;

import java.util.List;

import java.util.Map;

/**

 *

 * @author Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 */

// BEGIN: day.end.bridges.BridgeToOld

public final class BridgeToOld extends Provider {

    public BridgeToOld() {

        super("spi.Digestor", 1.0, "");

        Security.addProvider(this);

    }

    // BEGIN: day.end.bridges.cycle

    private ThreadLocal<Boolean> searching = new ThreadLocal<Boolean>();

    final boolean isSearching() {

        return Boolean.TRUE.equals(searching.get());

    }

    @Override

    public synchronized Service getService(String type, String algorithm) {

        Boolean prev = searching.get();

        try {

            searching.set(Boolean.TRUE);

            if ("MessageDigest".equals(type)) {

                Digest dig = Digest.getInstance(algorithm);

                if (dig != null) {

                    return new ServiceImpl(

                        dig, this, type, algorithm, "", 

                        Collections.<String>emptyList(), 

                        Collections.<String,String>emptyMap());

                }

            }

            return null;

        } finally {

            searching.set(prev);

        }

    }

    // END: day.end.bridges.cycle

    private static class ServiceImpl<Data> extends Service {

        Digest dig;

        public ServiceImpl(Digest dig, Provider provider, 

            String type, String algorithm, String className, 

            List<String> aliases, Map<String, String> attributes

        ) {

            super(provider, type, algorithm, className, aliases, attributes);

            this.dig = dig;

        }

        @Override

        public Object newInstance(Object constructorParameter) 

        throws NoSuchAlgorithmException {

            return new MessageDigest(getAlgorithm()) {

                private byte[] res;

                @Override

                protected void engineUpdate(byte input) {

                    ByteBuffer bb = ByteBuffer.wrap(new byte[] { input });

                    res = dig.digest(bb);

                }

                @Override

                protected void engineUpdate(

                    byte[] input, int offset, int len

                ) {

                    ByteBuffer bb = ByteBuffer.wrap(input);

                    bb.position(offset);

                    bb.limit(offset + len);

                    res = dig.digest(bb);

                }

                @Override

                protected byte[] engineDigest() {

                    return res;

                }

                @Override

                protected void engineReset() {

                    dig = Digest.getInstance(getAlgorithm());

                }

            };

        }

    }

}

// END: day.end.bridges.BridgeToOld