package ie.dcu.image;

import ie.dcu.matrix.*;
import ie.dcu.matrix.Matrix.Type;

/**
 * Abstract implementation of an {@link ImageOp}. Subclasses should implement
 * the {@link #processImage(MatrixProvider)} method.
 * 
 * 
 * @author Kevin McGuinness
 */
public abstract class AbstractImageOp implements ImageOp {

	private MatrixProvider inputProvider;
	private Matrix outputMatrix;
	
	/**
	 * Default constructor (does nothing).
	 */
	public AbstractImageOp() {
	}
	
	/**
	 * Returns <code>true</code> if the output matrix is available.
	 */
	public boolean isProcessingComplete() {
		return outputMatrix != null;
	}
	
	/**
	 * Returns <code>true</code> if the input {@link MatrixProvider} has been
	 * set.
	 */
	public boolean isInputProviderSet() {
		return inputProvider != null;
	}

	/**
	 * Set the input provider. Clears the output {@link Matrix}.
	 * 
	 * @see ImageOp#setInputProvider(MatrixProvider)
	 */
	public void setInputProvider(MatrixProvider provider) {
		this.inputProvider = provider;
		this.outputMatrix = null;
	}
	
	/**
	 * Returns the input {@link MatrixProvider}.
	 * 
	 * @return The input {@link MatrixProvider} or <code>null</code> if it has
	 *         not been set.
	 */
	public MatrixProvider getInputProvider() {
		return inputProvider;
	}
	
	/**
	 * Returns the output {@link Matrix}.
	 * 
	 * @return The output {@link Matrix} or <code>null</code> if it has not been
	 *         set.
	 */
	protected Matrix getOutputMatrix() {
		if (!isInputProviderSet()) {
			throw new IllegalStateException("input provider not set");
		}
		
		if (!isProcessingComplete()) {
			outputMatrix = processImage(getInputProvider());
		}
		
		return outputMatrix;
	}

	public Matrix getMatrix(boolean alwaysCopy) {
		return getMatrix(null, false);
	}

	public Matrix getMatrix(Type type, boolean alwaysCopy) {
		return getOutputMatrix().getMatrix(type, alwaysCopy);
	}
	
	/**
	 * Process the image and return the results.
	 * 
	 * @param imageProvider
	 *        A class that can be used to obtain the input image.
	 * @return The result of the image operation.
	 */
	protected abstract Matrix processImage(MatrixProvider imageProvider);

}