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 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
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package org.apache.cayenne.crypto.cipher;

import java.security.NoSuchAlgorithmException;
import java.util.Map;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;

import org.apache.cayenne.crypto.CayenneCryptoException;
import org.apache.cayenne.crypto.CryptoConstants;
import org.apache.cayenne.di.Inject;

/**
 * Creates and returns a new {@link Cipher} configured using properties from
 * {@link CryptoConstants#PROPERTIES_MAP}.
 * 
 * @since 4.0
 */
public class DefaultCipherFactory implements CipherFactory {

    protected String transformation;
    protected int blockSize;

    public DefaultCipherFactory(@Inject(CryptoConstants.PROPERTIES_MAP) Map<String, String> properties) {
        String algorithm = properties.get(CryptoConstants.CIPHER_ALGORITHM);

        if (algorithm == null) {
            throw new CayenneCryptoException("Cipher algorithm is not set. Property name: "
                    + CryptoConstants.CIPHER_ALGORITHM);
        }

        String mode = properties.get(CryptoConstants.CIPHER_MODE);
        if (mode == null) {
            throw new CayenneCryptoException("Cipher mode is not set. Property name: " + CryptoConstants.CIPHER_MODE);
        }

        String padding = properties.get(CryptoConstants.CIPHER_PADDING);
        if (padding == null) {
            throw new CayenneCryptoException("Cipher padding is not set. Property name: "
                    + CryptoConstants.CIPHER_PADDING);
        }

        this.transformation = algorithm + "/" + mode + "/" + padding;
    }

    @Override
    public Cipher cipher() {
        try {
            return Cipher.getInstance(transformation);
        } catch (NoSuchAlgorithmException e) {
            throw new CayenneCryptoException("Error instantiating a cipher - no such algorithm: " + transformation, e);
        } catch (NoSuchPaddingException e) {
            throw new CayenneCryptoException("Error instantiating a cipher - no such padding: " + transformation, e);
        }
    }

    @Override
    public int blockSize() {

        // lazy init to prevent Cipher initialization in constructor.
        // synchronization is not required - if we do it multiple times ,
        // shouldn't be a big deal...
        if (blockSize == 0) {
            this.blockSize = cipher().getBlockSize();
        }

        return blockSize;
    }
}