/*******************************************************************************
 * Copyright (c) 2013, 2015 Obeo.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.emf.compare.diagram.internal.extensions.provider.spec;

import com.google.common.base.Preconditions;

import org.eclipse.emf.common.notify.AdapterFactory;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.compare.DifferenceKind;
import org.eclipse.emf.compare.DifferenceSource;
import org.eclipse.emf.compare.diagram.internal.extensions.DiagramDiff;
import org.eclipse.emf.compare.diagram.internal.extensions.provider.DiagramDiffItemProvider;
import org.eclipse.emf.compare.provider.AdapterFactoryUtil;
import org.eclipse.emf.compare.provider.ForwardingItemProvider;
import org.eclipse.emf.compare.provider.IItemDescriptionProvider;
import org.eclipse.emf.compare.provider.IItemStyledLabelProvider;
import org.eclipse.emf.compare.provider.ISemanticObjectLabelProvider;
import org.eclipse.emf.compare.provider.spec.OverlayImageProvider;
import org.eclipse.emf.compare.provider.utils.ComposedStyledString;
import org.eclipse.emf.compare.provider.utils.IStyledString.IComposedStyledString;
import org.eclipse.emf.compare.provider.utils.IStyledString.Style;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.edit.provider.IItemLabelProvider;
import org.eclipse.emf.edit.provider.ItemProviderAdapter;
import org.eclipse.gmf.runtime.notation.View;

/**
 * Unique item provider for every diagram differences.
 * 
 * @author <a href="mailto:cedric.notot@obeo.fr">Cedric Notot</a>
 */
public class ForwardingDiagramDiffItemProvider extends ForwardingItemProvider implements IItemStyledLabelProvider, IItemDescriptionProvider, ISemanticObjectLabelProvider {

	/** Used to describe the change. */
	protected static final String HAS_BEEN = " has been "; //$NON-NLS-1$

	/** Used to describe an illegal state exception. */
	protected static final String UNSUPPORTED = "Unsupported "; //$NON-NLS-1$

	/** Used to describe an illegal state exception. */
	protected static final String VALUE = " value: "; //$NON-NLS-1$

	/** The elide length. */
	private static final int ELIDE_LENGTH = 50;

	/** The image provider used with this item provider. */
	private OverlayImageProvider overlayProvider;

	/**
	 * Constructor.
	 * 
	 * @param delegate
	 *            Default item provider adapter.
	 */
	public ForwardingDiagramDiffItemProvider(ItemProviderAdapter delegate) {
		super(delegate);
		if (delegate instanceof DiagramDiffItemProvider) {
			overlayProvider = new OverlayImageProvider(
					((DiagramDiffItemProvider)delegate()).getResourceLocator());
		}
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.ForwardingItemProvider#hasChildren(java.lang.Object)
	 */
	@Override
	public boolean hasChildren(Object object) {
		return !getChildren(object).isEmpty();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.ForwardingItemProvider#getText(java.lang.Object)
	 */
	@Override
	public String getText(Object object) {
		return getStyledText(object).getString();
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.ForwardingItemProvider#getImage(java.lang.Object)
	 */
	@Override
	public Object getImage(Object object) {
		final DiagramDiff diagramDiff = (DiagramDiff)object;
		Object image = null;
		if (diagramDiff.getView() instanceof View) {
			image = getImage(getRootAdapterFactory(), diagramDiff.getView());
		} else {
			image = super.getImage(object);
		}
		if (overlayProvider != null && image != null) {
			Object diffImage = overlayProvider.getComposedImage(diagramDiff, image);
			return ((DiagramDiffItemProvider)delegate()).getOverlayImage(object, diffImage);
		} else {
			return image;
		}
	}

	/**
	 * Returns the image of the given <code>object</code> by adapting it to {@link IItemLabelProvider} and
	 * asking for its {@link IItemLabelProvider#getImage(Object) text}. Returns null if <code>object</code> is
	 * null.
	 * 
	 * @param adapterFactory
	 *            the adapter factory to adapt from
	 * @param object
	 *            the object from which we want a image
	 * @return the image, or null if object is null.
	 * @throws NullPointerException
	 *             if <code>adapterFactory</code> is null.
	 */
	private static Object getImage(AdapterFactory adapterFactory, Object object) {
		Preconditions.checkNotNull(adapterFactory);
		if (object != null) {
			Object adapter = adapterFactory.adapt(object, IItemLabelProvider.class);
			if (adapter instanceof IItemLabelProvider) {
				return ((IItemLabelProvider)adapter).getImage(object);
			}
		}
		return null;
	}

	/**
	 * It builds the label of the item related to the given difference.
	 * 
	 * @param diagramDiff
	 *            the difference.
	 * @return the label.
	 */
	protected String getValueText(final DiagramDiff diagramDiff) {
		return getValueText(diagramDiff.getView());
	}

	/**
	 * It builds the label of the item related to the given object.
	 * 
	 * @param view
	 *            the object.
	 * @return the label.
	 */
	protected String getValueText(EObject view) {
		EObject reference = null;
		if (view instanceof View) {
			reference = view;
		}
		String value = AdapterFactoryUtil.getText(getRootAdapterFactory(), reference);
		if (value == null) {
			value = "<null>"; //$NON-NLS-1$
		} else {
			value = org.eclipse.emf.compare.provider.spec.Strings.elide(value, ELIDE_LENGTH, "..."); //$NON-NLS-1$
		}
		return value;
	}

	/**
	 * Returns the name of the main reference or the kind of attribute change linked to the given
	 * {@link DiagramDiff}.
	 * 
	 * @param diagramDiff
	 *            the given {@link DiagramDiff}.
	 * @return the name of the main reference or the kind of attribute change linked to the given
	 *         {@link DiagramDiff}.
	 */
	protected String getReferenceText(final DiagramDiff diagramDiff) {
		return " "; //$NON-NLS-1$
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.edit.provider.ItemProviderAdapter#getForeground(java.lang.Object)
	 */
	@Override
	public Object getForeground(Object object) {
		DiagramDiff referenceChange = (DiagramDiff)object;
		switch (referenceChange.getState()) {
			case MERGED:
			case DISCARDED:
				return URI.createURI("color://rgb/156/156/156"); //$NON-NLS-1$
			default:
				return super.getForeground(object);
		}
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.IItemDescriptionProvider#getDescription(java.lang.Object)
	 */
	public String getDescription(Object object) {
		final DiagramDiff diagramDiff = (DiagramDiff)object;

		final String valueText = getValueText(diagramDiff);
		final String referenceText = getReferenceText(diagramDiff);

		String remotely = ""; //$NON-NLS-1$
		if (diagramDiff.getSource() == DifferenceSource.RIGHT) {
			remotely = "remotely "; //$NON-NLS-1$
		}

		String ret = ""; //$NON-NLS-1$
		final String hasBeen = " has been "; //$NON-NLS-1$

		switch (diagramDiff.getKind()) {
			case ADD:
				ret = valueText + hasBeen + remotely + "added to " + referenceText; //$NON-NLS-1$
				break;
			case DELETE:
				ret = valueText + hasBeen + remotely + "deleted from " + referenceText; //$NON-NLS-1$
				break;
			case CHANGE:
				ret = referenceText + " " + valueText + hasBeen + remotely + "change"; //$NON-NLS-1$ //$NON-NLS-2$
				break;
			case MOVE:
				ret = valueText + hasBeen + remotely + "moved in " + referenceText; //$NON-NLS-1$
				break;
			default:
				throw new IllegalStateException(
						UNSUPPORTED + DifferenceKind.class.getSimpleName() + VALUE + diagramDiff.getKind());
		}

		return ret;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.IItemStyledLabelProvider#getStyledText(java.lang.Object)
	 */
	public IComposedStyledString getStyledText(Object object) {
		final DiagramDiff diagramDiff = (DiagramDiff)object;

		final String valueText = getValueText(diagramDiff);

		final String referenceText = getReferenceText(diagramDiff);

		ComposedStyledString ret = new ComposedStyledString(valueText);
		ret.append(" [" + referenceText, Style.DECORATIONS_STYLER); //$NON-NLS-1$

		buildStyledText(diagramDiff.getKind(), ret);
		ret.append("]", Style.DECORATIONS_STYLER); //$NON-NLS-1$

		return ret;
	}

	/**
	 * It builds the given {@link ComposedStyledString} adding the kind of change in description.
	 * 
	 * @param kind
	 *            The kind of change.
	 * @param ret
	 *            The {@link ComposedStyledString} to build.
	 */
	protected void buildStyledText(final DifferenceKind kind, ComposedStyledString ret) {
		switch (kind) {
			case ADD:
				ret.append(" add", Style.DECORATIONS_STYLER); //$NON-NLS-1$
				break;
			case DELETE:
				ret.append(" delete", Style.DECORATIONS_STYLER); //$NON-NLS-1$
				break;
			case CHANGE:
				ret.append(" change", Style.DECORATIONS_STYLER); //$NON-NLS-1$
				break;
			case MOVE:
				ret.append(" move", Style.DECORATIONS_STYLER); //$NON-NLS-1$
				break;
			default:
				throw new IllegalStateException(
						UNSUPPORTED + DifferenceKind.class.getSimpleName() + VALUE + kind);
		}
	}

	/**
	 * {@inheritDoc}
	 * 
	 * @see org.eclipse.emf.compare.provider.ISemanticObjectLabelProvider#getSemanticObjectLabel(java.lang.Object)
	 */
	public String getSemanticObjectLabel(Object object) {
		final DiagramDiff diagramDiff = (DiagramDiff)object;
		return getValueText(diagramDiff);
	}

}