Add generic transformation library to transform configs

6 files changed, 343 insertions, 0 deletions

diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/Transformation.java b/src/main/java/org/openslx/virtualization/configuration/transformation/Transformation.java
new file mode 100644
index 0000000..af0e181
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+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/Transformation.java
@@ -0,0 +1,65 @@
+package org.openslx.virtualization.configuration.transformation;
+
+/**
+ * Represents a transformation that transforms (alters) a given configuration with specified input
+ * arguments.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ *
+ * @param <T> type of the configuration which will be transformed.
+ * @param <R> type of input arguments for the transformation.
+ */
+public abstract class Transformation<T, R> implements TransformationFunction<T, R>
+{
+	/**
+	 * Name of the transformation.
+	 */
+	private final String name;
+
+	/**
+	 * State of the transformation.
+	 */
+	private boolean enabled;
+
+	/**
+	 * Creates a transformation.
+	 * 
+	 * @param name comprehensible name for the transformation.
+	 */
+	public Transformation( String name )
+	{
+		this.name = name;
+		this.setEnabled( true );
+	}
+
+	/**
+	 * Returns the name of the transformation.
+	 * 
+	 * @return name of the transformation.
+	 */
+	public String getName()
+	{
+		return this.name;
+	}
+
+	/**
+	 * Returns the state of the transformation.
+	 * 
+	 * @return state of the transformation.
+	 */
+	public boolean isEnabled()
+	{
+		return this.enabled;
+	}
+
+	/**
+	 * Sets the state for the transformation.
+	 * 
+	 * @param enabled state for the transformation.
+	 */
+	public void setEnabled( boolean enabled )
+	{
+		this.enabled = enabled;
+	}
+}
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationException.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationException.java
new file mode 100644
index 0000000..72f320d
--- /dev/null
+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationException.java
@@ -0,0 +1,25 @@
+package org.openslx.virtualization.configuration.transformation;
+
+/**
+ * An exception of a transformation error.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ */
+public class TransformationException extends Exception
+{
+	/**
+	 * Version for serialization.
+	 */
+	private static final long serialVersionUID = 7293420658901349154L;
+
+	/**
+	 * Creates a transformation exception including an error message.
+	 * 
+	 * @param errorMsg message to describe the exception.
+	 */
+	public TransformationException( String errorMsg )
+	{
+		super( errorMsg );
+	}
+}
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationFunction.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationFunction.java
new file mode 100644
index 0000000..b5be7a0
--- /dev/null
+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationFunction.java
@@ -0,0 +1,39 @@
+package org.openslx.virtualization.configuration.transformation;
+
+/**
+ * Represents a transformation operation that transforms (alters) a given configuration with
+ * specified input arguments and returns no result.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ *
+ * @param <T> type of the configuration which will be transformed.
+ * @param <R> type of input arguments for the transformation.
+ */
+@FunctionalInterface
+public interface TransformationFunction<T, R>
+{
+	/**
+	 * Transforms a given configuration with the specified input arguments.
+	 * 
+	 * @param config configuration which will be transformed.
+	 * @param args input arguments for the transformation.
+	 * 
+	 * @throws TransformationException transformation of the configuration failed.
+	 */
+	public void transform( T config, R args ) throws TransformationException;
+
+	/**
+	 * Applies the transformation function {@link #transform(Object, Object)} to the given
+	 * configuration and specified input arguments.
+	 * 
+	 * @param config configuration which will be transformed.
+	 * @param args input arguments for the transformation.
+	 * 
+	 * @throws TransformationException transformation of the configuration failed.
+	 */
+	public default void apply( T config, R args ) throws TransformationException
+	{
+		this.transform( config, args );
+	}
+}
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationGeneric.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationGeneric.java
new file mode 100644
index 0000000..4ad36c7
--- /dev/null
+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationGeneric.java
@@ -0,0 +1,25 @@
+package org.openslx.virtualization.configuration.transformation;
+
+/**
+ * Represents a generic transformation that transforms (alters) a given configuration with specified
+ * input arguments. The generic transformation does not depend on any external states of a
+ * virtualizer.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ *
+ * @param <T> type of the configuration which will be transformed.
+ * @param <R> type of input arguments for the transformation.
+ */
+public abstract class TransformationGeneric<T, R> extends Transformation<T, R>
+{
+	/**
+	 * Create a generic transformation.
+	 * 
+	 * @param name comprehensible name for the transformation.
+	 */
+	public TransformationGeneric( String name )
+	{
+		super( name );
+	}
+}
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java
new file mode 100644
index 0000000..ce0ad96
--- /dev/null
+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationManager.java
@@ -0,0 +1,146 @@
+package org.openslx.virtualization.configuration.transformation;
+
+import java.util.ArrayList;
+
+/**
+ * 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;
+
+	/**
+	 * 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 )
+	{
+		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 ) {
+			try {
+				transformation.apply( this.config, this.args );
+			} catch ( TransformationException e ) {
+				final String errorMsg = new String(
+						"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 = new String();
+		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();
+	}
+}
diff --git a/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationSpecific.java b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationSpecific.java
new file mode 100644
index 0000000..5b13f45
--- /dev/null
+++ b/src/main/java/org/openslx/virtualization/configuration/transformation/TransformationSpecific.java
@@ -0,0 +1,43 @@
+package org.openslx.virtualization.configuration.transformation;
+
+/**
+ * Represents a specific transformation that transforms (alters) a given configuration with
+ * specified input arguments. The specific transformation depends on external states of a
+ * specified virtualizer.
+ * 
+ * @author Manuel Bentele
+ * @version 1.0
+ *
+ * @param <T> type of the configuration which will be transformed.
+ * @param <R> type of input arguments for the transformation.
+ * @param <H> type of the external input source.
+ */
+public abstract class TransformationSpecific<T, R, H> extends Transformation<T, R>
+{
+	/**
+	 * Reference to virtualizer to query external states.
+	 */
+	private final H virtualizer;
+
+	/**
+	 * Create a specific transformation.
+	 * 
+	 * @param name comprehensible name for the transformation.
+	 */
+	public TransformationSpecific( String name, H virtualizer )
+	{
+		super( name );
+
+		this.virtualizer = virtualizer;
+	}
+
+	/**
+	 * Returns the referenced virtualizer of the transformation.
+	 * 
+	 * @return referenced virtualizer of the transformation.
+	 */
+	public H getVirtualizer()
+	{
+		return this.virtualizer;
+	}
+}