EDIT

/**

 *

 */

package eu.etaxonomy.taxeditor.ui.section;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.Comparator;

import java.util.EnumSet;

import java.util.List;

import java.util.Observable;

import java.util.Observer;

import org.eclipse.jface.action.Action;

import org.eclipse.jface.action.IAction;

import org.eclipse.jface.action.ToolBarManager;

import org.eclipse.jface.resource.ImageDescriptor;

import org.eclipse.swt.SWT;

import org.eclipse.swt.events.DisposeEvent;

import org.eclipse.swt.events.DisposeListener;

import org.eclipse.swt.events.SelectionAdapter;

import org.eclipse.swt.events.SelectionEvent;

import org.eclipse.swt.events.SelectionListener;

import org.eclipse.swt.graphics.Color;

import org.eclipse.swt.graphics.ImageData;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Control;

import org.eclipse.swt.widgets.Label;

import org.eclipse.ui.forms.events.ExpansionEvent;

import org.eclipse.ui.forms.events.IExpansionListener;

import org.eclipse.ui.forms.widgets.ExpandableComposite;

import eu.etaxonomy.cdm.api.conversation.ConversationHolder;

import eu.etaxonomy.cdm.common.CdmUtils;

import eu.etaxonomy.cdm.model.common.CdmBase;

import eu.etaxonomy.cdm.model.permission.CRUD;

import eu.etaxonomy.taxeditor.model.AbstractUtility;

import eu.etaxonomy.taxeditor.model.ImageResources;

import eu.etaxonomy.taxeditor.preference.IPreferenceKeys;

import eu.etaxonomy.taxeditor.preference.PreferencesUtil;

import eu.etaxonomy.taxeditor.preference.Resources;

import eu.etaxonomy.taxeditor.store.CdmStore;

import eu.etaxonomy.taxeditor.store.LoginManager;

import eu.etaxonomy.taxeditor.store.StoreUtil;

import eu.etaxonomy.taxeditor.ui.element.AbstractFormSection;

import eu.etaxonomy.taxeditor.ui.element.CdmFormFactory;

import eu.etaxonomy.taxeditor.ui.element.ICdmFormElement;

/**

 * This class visualizes an CDM entity of type ENTITY and additionally provides the functionality to add

 * other elements of type ELEMENT to them.

 *

 * @param <ENTITY> A CDM entity which should be visualized by this section.

 * @param <ELEMENT> An element that can be added (multiple times) to this entity.

 *

 * @author n.hoffmann

 */

public abstract class AbstractEntityCollectionSection<ENTITY, ELEMENT> extends AbstractFormSection<ENTITY> implements IExpansionListener, Observer {

    private static final EnumSet<CRUD> UPDATE = EnumSet.of(CRUD.UPDATE);

    protected Composite container;

	private Label label_empty;

	private String title;

    private AbstractEntityCollectionElement<ENTITY> entityCollectionElement;

	public AbstractEntityCollectionSection(CdmFormFactory formFactory, ConversationHolder conversation, ICdmFormElement parentElement, String title, int style) {

		super(formFactory, parentElement, ExpandableComposite.CLIENT_INDENT | style);

		this.title = title;

		this.setText(getTitleString());

		updateToolbar();

		addExpansionListener(this);

		CdmStore.getLoginManager().addObserver(this);

		addDisposeListener(new DisposeListener() {

            @Override

            public void widgetDisposed(DisposeEvent e) {

                CdmStore.getLoginManager().deleteObserver(AbstractEntityCollectionSection.this);

            }

        });

	}

	protected Control createToolbar() {

		ToolBarManager toolBarManager = new ToolBarManager(SWT.FLAT);

		Action addAction = new Action("Add", IAction.AS_PUSH_BUTTON){

			@Override

			public void run() {

			    ELEMENT element = createNewElement();

			    if(element != null){

			        addElement(element);

			        if(! getSection().isExpanded()) {

			            getSection().setExpanded(true);

			        }

			        internalUpdateSection(true);

			    }

			}

		};

		addAction.setImageDescriptor(new ImageDescriptor() {

			@Override

			public ImageData getImageData() {

				return ImageResources.getImage(ImageResources.ADD_ICON).getImageData();

			}

		});

		addAction.setToolTipText(getTooltipString());

		Action browseAction = null;

		if(allowAddExisting()){

		    browseAction = new Action("Browse", IAction.AS_PUSH_BUTTON){

		        @Override

		        public void run() {

		            ELEMENT element = addExisting();

		            if(element != null){

		                addElement(element);

		                if(! getSection().isExpanded()) {

		                    getSection().setExpanded(true);

		                }

		                internalUpdateSection(true);

		            }

		        }

		    };

		    browseAction.setImageDescriptor(new ImageDescriptor() {

		        @Override

		        public ImageData getImageData() {

		            return ImageResources.getImage(ImageResources.BROWSE_ICON).getImageData();

		        }

		    });

		    browseAction.setToolTipText("Browse");

		}

		toolBarManager.add(addAction);

		if(browseAction!=null){

		    toolBarManager.add(browseAction);

		}

		addAction(toolBarManager);

		return toolBarManager.createControl(this);

	}

    protected void addAction(ToolBarManager toolBarManager) {

        // default implementation empty

    }

    /**

	 * using this method is discouraged, use updateToolBar() instead

	 */

	public void showToolbar(){

		setTextClient(createToolbar());

	}

    /**

     * using this method is discouraged, use updateToolBar() instead

     */

	public void removeToolbar(){

		setTextClient(null);

	}

	@Override

	public void setEntity(ENTITY entity) {

		if(entity != null){

			super.setEntity(entity);

			internalUpdateSection(false);

		}

		setSectionTitle();

		updateToolbar();

		layout();

	}

	/**

	 * Sets the title for the section. Adds a "+" sign if the collection is not empty for this section.

	 * Override in subclasses if you want to have a different behaviour.

	 */

	protected void setSectionTitle() {

		Collection<ELEMENT> collection = getCollection(getEntity());

		if(collection != null && collection.size() > 0){

			this.setText(getTitleString() + " +");

		}else{

			this.setText(getTitleString());

		}

	}

	/**

	 * Removes all content from the container

	 */

	private void destroyDynamicContent(){

		if(label_empty != null){

			label_empty.dispose();

			label_empty = null;

		}

		removeElements();

	}

	/**

	 * Call this method after dynamically changing the client area.

	 * If the options changed is set to <code>true</code>, will also fire a state changed

	 * event to inform the user of unsaved changes.

	 *

	 * @param changed a boolean.

	 */

	protected void internalUpdateSection(boolean changed){

	    setSectionTitle();

		destroyDynamicContent();

		if(isExpanded() || expandSectionWhenContentAvailable()) {

            renderContent(isExpanded());

        }

		if(changed) {

            firePropertyChangeEvent(this);

        }

	}

	/**

	 * Create the elements to be shown in this section client area

	 */

	private void renderContent(boolean forceExpansion)

	{

		Collection<ELEMENT> collection = getCollection(getEntity());

		if(collection == null || collection.isEmpty()){

			createEmptyContent();

		}else{

		    List<ELEMENT> elements = new ArrayList<>(collection);

		    Collections.sort(elements, getComparator());

			createDynamicContents(elements);

			forceExpansion = true;

		}

		this.setExpanded(forceExpansion);

		reflow();

	}

	protected void createEmptyContent(){

		label_empty = formFactory.createLabel(getLayoutComposite(), getEmptyString());

	}

	/**

	 * Creates the widgets for the collection

	 *

	 * @param elements a {@link java.util.Collection} object.

	 */

	protected void createDynamicContents(Collection<ELEMENT> elements)

	{

		int i = 0;

		for(final ELEMENT element : elements){

			SelectionAdapter removeListener = new SelectionAdapter(){

				@Override

				public void widgetSelected(SelectionEvent e) {

					removeElement(element);

					internalUpdateSection(true);

				}

			};

			boolean modulo = i++%2 == 0;

			String colorResource = modulo ? Resources.COLOR_LIST_EVEN : Resources.COLOR_LIST_ODD;

			createElementComposite(element, removeListener, AbstractUtility.getColor(colorResource));

		}

	}

	/**

	 * Create the specific widget for the element

	 *

	 * @param element a ELEMENT object.

	 * @param removeListener a {@link org.eclipse.swt.events.SelectionListener} object.

	 * @param backgroundColor a {@link org.eclipse.swt.graphics.Color} object.

	 */

	protected void createElementComposite(ELEMENT element, SelectionListener removeListener, Color backgroundColor){

		entityCollectionElement = formFactory.createEntityCollectionElement(this, element, removeListener, backgroundColor, SWT.NULL);

	}

	/** {@inheritDoc} */

	@Override

	public void setBackground(Color color) {

		if(label_empty != null && !label_empty.isDisposed()){

			label_empty.setBackground(color);

		}

		super.setBackground(color);

	}

	/**

	 * <p>getTitleString</p>

	 *

	 * @return a {@link java.lang.String} object.

	 */

	public String getTitleString() {

		return CdmUtils.Nz(title);

	}

	/**

	 * <p>setTitleString</p>

	 *

	 * @param title a {@link java.lang.String} object.

	 */

	public void setTitleString(String title){

		this.title = title;

		setSectionTitle();

		layout();

	}

	/** {@inheritDoc} */

	@Override

    public void expansionStateChanging(ExpansionEvent e) {

//		logger.warn("Expansion State Changing");

	}

	/** {@inheritDoc} */

	@Override

    public void expansionStateChanged(ExpansionEvent e) {

		if(isExpanded()){

			renderContent(isExpanded());

		}else{

			destroyDynamicContent();

		}

	}

	private boolean expandSectionWhenContentAvailable(){

		return PreferencesUtil.getBooleanValue(IPreferenceKeys.SHOULD_EXPAND_SECTION_WHEN_DATA_AVAILABLE, true);

	}

	/**

	 * Remove an element from the entities collection and update the section

	 *

	 * @param element a ELEMENT object.

	 */

	public void removeElementAndUpdate(ELEMENT element) {

		removeElement(element);

		internalUpdateSection(true);

	}

	@Override

    public void update(Observable o, Object arg){

	    if(o instanceof LoginManager){

	        updateToolbar();

	    }

	}

    protected void updateToolbar() {

        if( !(getEntity() instanceof CdmBase) || (getEntity() != null && CdmStore.currentAuthentiationHasPermission(StoreUtil.getCdmEntity(getEntity()), UPDATE)) ){

            showToolbar();

        } else {

            removeToolbar();

        }

    }

    public AbstractEntityCollectionElement<ENTITY> getEntityCollectionElement() {

        return entityCollectionElement;

    }

    /**

     * Returns the {@link Comparator} specific for the ELEMENTs

     * which is used to sort the elements

     * @return the comparator for ELEMENT

     */

    public abstract Comparator<ELEMENT> getComparator();

	/**

	 * Get the specific collection of this entity

	 *

	 * @param entity a ENTITY object.

	 * @return a {@link java.util.Collection} object.

	 */

	public abstract Collection<ELEMENT> getCollection(ENTITY entity);

	/**

	 * Create a new Element for this collection

	 *

	 * @return a ELEMENT object.

	 */

	public abstract ELEMENT createNewElement();

	/**

	 * Add an element to the entities collection

	 *

	 * @param element a ELEMENT object.

	 */

	public abstract void addElement(ELEMENT element);

	/**

	 * Add an existing element to the entities collection.

	 * @return the existing element

	 */

	public abstract ELEMENT addExisting();

	/**

	 * If <code>true</code> the section will also display

	 * a browse icon to choose from existing elements.

	 * <br>

	 * <b>Note:</b> when returning true you have to make sure

	 * to implement the {@link #addExisting()} method

	 * @return true if existing entities can be added;

	 * false otherwise

	 */

	public abstract boolean allowAddExisting();

	/**

	 * Remove an element from the entities collection

	 *

	 * @param element a ELEMENT object.

	 */

	public abstract void removeElement(ELEMENT element);

	/**

	 * String to display when the collection is empty

	 *

	 * @return a {@link java.lang.String} object.

	 */

	public abstract String getEmptyString();

	/**

	 * <p>getTooltipString</p>

	 *

	 * @return String to display when hovering the add button

	 */

	protected abstract String getTooltipString();

}