1 files changed, 158 insertions, 0 deletions
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java
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+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java
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+package org.openslx.virtualization.configuration.transformation;
+
+import java.util.ArrayList;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * A transformation manager is a class to manage several transformations and their application.
+ * 
+ * Transformations can be registered at the transformation manager. The transformation manager has
+ * the ability to apply all registered transformations on a given configuration and specified input
+ * arguments.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ *
+ * @param <T> type of the configuration which will be transformed by all transformations.
+ * @param <R> type of input arguments for all transformations.
+ */
+public class TransformationManager<T, R>
+{
+	/**
+	 * List of registered transformations.
+	 */
+	private ArrayList<Transformation<T, R>> transformations;
+
+	/**
+	 * Reference to the configuration that will be transformed (altered).
+	 */
+	private T config;
+
+	/**
+	 * Reference to the input arguments for all registered transformations.
+	 */
+	private R args;
+
+	/**
+	 * Logger instance to log messages.
+	 */
+	private static final Logger LOGGER = LogManager.getLogger( TransformationManager.class );
+
+	/**
+	 * Create a transformation manager.
+	 * 
+	 * @param config configuration which will be transformed.
+	 * @param args input arguments for all registered transformations.
+	 */
+	public TransformationManager( T config, R args )
+	{
+		this.transformations = new ArrayList<Transformation<T, R>>();
+		this.config = config;
+		this.args = args;
+	}
+
+	/**
+	 * Registers and enables a transformation.
+	 * 
+	 * @param transformation existing transformation that will be registered and enabled.
+	 */
+	public void register( Transformation<T, R> transformation )
+	{
+		this.register( transformation, true );
+	}
+
+	/**
+	 * Registers a transformation and sets its state.
+	 * 
+	 * @param transformation existing transformation that will be registered.
+	 * @param enabled state for the existing transformation that will be set.
+	 */
+	public void register( Transformation<T, R> transformation, boolean enabled )
+	{
+		LOGGER.debug( "Register transformation '" + transformation.getName() + "' and "
+				+ ( enabled ? "enable" : "do not enable" ) + " it" );
+
+		transformation.setEnabled( enabled );
+		this.transformations.add( transformation );
+	}
+
+	/**
+	 * Registers a transformation function as a new transformation and enables the registered
+	 * transformation.
+	 * 
+	 * @param name comprehensible name for the transformation.
+	 * @param function transformation operation for the transformation.
+	 */
+	public void register( String name, TransformationFunction<T, R> function )
+	{
+		this.register( name, function, true );
+	}
+
+	/**
+	 * Registers a transformation function as a new transformation and sets the state of the
+	 * registered transformation.
+	 * 
+	 * @param name comprehensible name for the transformation.
+	 * @param function transformation operation for the transformation.
+	 * @param enabled state for the transformation.
+	 */
+	public void register( String name, TransformationFunction<T, R> function, boolean enabled )
+	{
+		this.register( new Transformation<T, R>( name ) {
+			@Override
+			public void transform( T document, R args ) throws TransformationException
+			{
+				function.apply( document, args );
+			}
+		}, enabled );
+	}
+
+	/**
+	 * Applies all registered transformations, whose state is set to <code>enabled</code>, to the
+	 * referenced configuration and input arguments.
+	 * 
+	 * @throws TransformationException transformation of the configuration failed.
+	 */
+	public void transform() throws TransformationException
+	{
+		for ( Transformation<T, R> transformation : this.transformations ) {
+			LOGGER.debug( "Apply transformation '" + transformation.getName() + "'" );
+			try {
+				transformation.apply( this.config, this.args );
+			} catch ( TransformationException e ) {
+				final String errorMsg =
+						"Error in configuration filter '" + transformation.getName() + "': " + e.getLocalizedMessage();
+				throw new TransformationException( errorMsg );
+			}
+		}
+	}
+
+	/**
+	 * Returns a human readable summary of all registered transformations.
+	 * 
+	 * @return human readable summary of all registered transformations.
+	 */
+	private String showTransformations()
+	{
+		String transformationSummary = "";
+		final int maxFilterNumCharacters = ( this.transformations.size() + 1 ) / 10;
+
+		for ( int i = 0; i < this.transformations.size(); i++ ) {
+			final Transformation<T, R> transformation = this.transformations.get( i );
+			final String paddedNumber = String.format( "%-" + maxFilterNumCharacters + "s", i + 1 );
+			final String transformationState = transformation.isEnabled() ? "[ active ]" : "[inactive]";
+			transformationSummary += paddedNumber + ": " + transformationState + " ";
+			transformationSummary += transformation.getName() + System.lineSeparator();
+		}
+
+		return transformationSummary;
+	}
+
+	@Override
+	public String toString()
+	{
+		return this.showTransformations();
+	}
+}