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Artifact for providing chaos symmetric encryption.
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// /////////////////////////////////////////////////////////////////////////////
// REFCODES.ORG
// /////////////////////////////////////////////////////////////////////////////
// This code is copyright (c) by Siegfried Steiner, Munich, Germany, distributed
// on an "AS IS" BASIS WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, and licen-
// sed under the following (see "http://en.wikipedia.org/wiki/Multi-licensing")
// licenses:
// -----------------------------------------------------------------------------
// GNU General Public License, v3.0 ("http://www.gnu.org/licenses/gpl-3.0.html")
// -----------------------------------------------------------------------------
// Apache License, v2.0 ("http://www.apache.org/licenses/LICENSE-2.0")
// -----------------------------------------------------------------------------
// Please contact the copyright holding author(s) of the software artifacts in
// question for licensing issues not being covered by the above listed licenses,
// also regarding commercial licensing models or regarding the compatibility
// with other open source licenses.
// /////////////////////////////////////////////////////////////////////////////

package org.refcodes.security.alt.chaos;

import org.refcodes.numerical.NumericalUtility;

/**
 * The {@link ChaosOptionsImpl} provides means to create a {@link ChaosOptions}
 * instance.
 */
public class ChaosOptionsImpl implements ChaosOptions {

	// /////////////////////////////////////////////////////////////////////////
	// VARIABLES:
	// /////////////////////////////////////////////////////////////////////////

	private boolean _isXorNext;
	private boolean _isMutateS;
	private boolean _isSalted;
	private short _rndPrefixSize;

	// /////////////////////////////////////////////////////////////////////////
	// CONSTRUCTORS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Instantiates the {@link ChaosOptions} by reversing the result of the
	 * {@link #getEncoded()} operation where the byte array contains the values
	 * of the options. The values use a big endian representation. The byte
	 * array being passed is to be of the size as returned by
	 * {@link ChaosOptions#getEncodedLength()}. The meaning of the bits in the
	 * encoded byte are defined as in {@link #OPTIONS_BIT_MUTATE_S},
	 * {@link #OPTIONS_BIT_XOR_NEXT} and {@link #OPTIONS_BIT_SALTED}.
	 * 
	 * @param aEncoded The encoded representation of the options.
	 */
	public ChaosOptionsImpl( byte[] aEncoded ) {
		if ( !NumericalUtility.isBitSetAt( aEncoded[0], OPTIONS_BIT_RND_PREFIX ) && Byte.toUnsignedInt( aEncoded[1] ) != 0 ) {
			throw new IllegalArgumentException( "The PREFIX option has been set to false though the prefix size is set to <" + Byte.toUnsignedInt( aEncoded[1] ) + "> which is ambigous!" );
		}
		_isMutateS = NumericalUtility.isBitSetAt( aEncoded[0], OPTIONS_BIT_MUTATE_S );
		_isXorNext = NumericalUtility.isBitSetAt( aEncoded[0], OPTIONS_BIT_XOR_NEXT );
		_isSalted = NumericalUtility.isBitSetAt( aEncoded[0], OPTIONS_BIT_SALTED );
		_rndPrefixSize = NumericalUtility.isBitSetAt( aEncoded[0], OPTIONS_BIT_RND_PREFIX ) ? (short) ( Byte.toUnsignedInt( aEncoded[1] ) + 1 ) : 0;
	}

	/**
	 * Constructs the {@link ChaosOptionsImpl} with the given values.
	 * 
	 * @param isMutateS Enables or disables the {@link #isMutateS()} option.
	 * @param isXorNext Enables or disables the {@link #isXorNext()} option.
	 * @param isSalted Enables or disables the {@link #isSalted()} option.
	 */
	public ChaosOptionsImpl( boolean isMutateS, boolean isXorNext, boolean isSalted ) {
		_isMutateS = isMutateS;
		_isXorNext = isXorNext;
		_isSalted = isSalted;
		_rndPrefixSize = 0;
	}

	/**
	 * Constructs the {@link ChaosOptionsImpl} with the given values.
	 * 
	 * @param isMutateS Enables or disables the {@link #isMutateS()} option.
	 * @param isXorNext Enables or disables the {@link #isXorNext()} option.
	 * @param isSalted Enables or disables the {@link #isSalted()} option.
	 * @param aRndPrefixSize The number of bytes to prefix with random bytes.
	 */
	public ChaosOptionsImpl( boolean isMutateS, boolean isXorNext, boolean isSalted, short aRndPrefixSize ) {
		_isMutateS = isMutateS;
		_isXorNext = isXorNext;
		_isSalted = isSalted;
		_rndPrefixSize = aRndPrefixSize;
	}

	private ChaosOptionsImpl( Builder builder ) {
		_isMutateS = builder.isMutateS;
		_isXorNext = builder.isXorNext;
		_isSalted = builder.isSalted;
		_rndPrefixSize = builder.rndPrefixSize;
	}

	// /////////////////////////////////////////////////////////////////////////
	// METHODS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean isXorNext() {
		return _isXorNext;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean isMutateS() {
		return _isMutateS;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean isSalted() {
		return _isSalted;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public short getRndPrefixSize() {
		return _rndPrefixSize;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public String toString() {
		return getClass().getSimpleName() + " [isMutateS=" + _isMutateS + ", isXorNext=" + _isXorNext + ", ( isSalted=" + _isSalted + " | hasRndPrefix=" + hasRndPrefix() + " [rndPrefixSize=" + _rndPrefixSize + "]) := isFixedLength=" + isFixedLength() + "]";
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ( _isMutateS ? 1231 : 1237 );
		result = prime * result + ( _isSalted ? 1231 : 1237 );
		result = prime * result + ( _isXorNext ? 1231 : 1237 );
		result = prime * result + _rndPrefixSize;
		return result;
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean equals( Object obj ) {
		if ( this == obj ) {
			return true;
		}
		if ( obj == null ) {
			return false;
		}
		if ( !( obj instanceof ChaosOptions ) ) {
			return false;
		}
		final ChaosOptions other = (ChaosOptions) obj;
		if ( _isMutateS != other.isMutateS() ) {
			return false;
		}
		if ( _isSalted != other.isSalted() ) {
			return false;
		}
		if ( _isXorNext != other.isXorNext() ) {
			return false;
		}
		if ( _rndPrefixSize != other.getRndPrefixSize() ) {
			return false;
		}
		return true;
	}

	/**
	 * Creates builder to build {@link ChaosOptionsImpl}.
	 * 
	 * @return created builder
	 */
	public static Builder builder() {
		return new Builder();
	}

	// /////////////////////////////////////////////////////////////////////////
	// INNER CLASSES:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Builder to build {@link ChaosOptions} instances.
	 */
	public static final class Builder {

		private boolean isXorNext;
		private boolean isMutateS;
		private boolean isSalted;
		public short rndPrefixSize;

		private Builder() {}

		/**
		 * Enables or disables the {@link #isXorNext()} option.
		 * 
		 * @param isXorNext True in case XOR obfuscation is to be applied.
		 *
		 * @return This builder as of the builder pattern.
		 */
		public Builder withXorNext( boolean isXorNext ) {
			this.isXorNext = isXorNext;
			return this;
		}

		/**
		 * Enables or disables the {@link #isMutateS()} option.
		 * 
		 * @param isMutateS True in case MUTATION obfuscation is to be applied.
		 * 
		 * @return This builder as of the builder pattern.
		 */
		public Builder withMutateS( boolean isMutateS ) {
			this.isMutateS = isMutateS;
			return this;
		}

		/**
		 * Enables or disables the {@link #isSalted()} option.
		 *
		 * @param isSalted True in case MUTATION obfuscation is to be applied.
		 * 
		 * @return This builder as of the builder pattern.
		 */
		public Builder withSalted( boolean isSalted ) {
			this.isSalted = isSalted;
			return this;
		}

		/**
		 * Sets the prefix size for the {@link #getRndPrefixSize} option. Valid
		 * values range from {1..256} representable by one byte as of
		 * {0x00..0xFF}.
		 *
		 * @param aRndPrefixSize The size of the random bytes in case the PREFIX
		 *        option is to be applied.
		 * 
		 * @return This builder as of the builder pattern.
		 */
		public Builder withRndPrefixSize( short aRndPrefixSize ) {
			if ( aRndPrefixSize < 1 || aRndPrefixSize > 256 ) {
				throw new IllegalArgumentException( "The RND prefix size <" + aRndPrefixSize + "> is out of range, valid values range from {1..256} representable by one byte as of {0x00..0xFF}." );
			}
			this.rndPrefixSize = aRndPrefixSize;
			return this;
		}

		/**
		 * Determines whether an ADD operation of the {@link ChaosKey}'s S value
		 * is to be applied with the current byte value (using signed bytes -128
		 * to +127).
		 *
		 * @return the chaos metrics builder
		 */
		public ChaosOptionsImpl build() {
			return new ChaosOptionsImpl( this );
		}
	}
}