EDIT

/**

 * Copyright (C) 2018 EDIT

 * European Distributed Institute of Taxonomy

 * http://www.e-taxonomy.eu

 *

 * The contents of this file are subject to the Mozilla Public License Version 1.1

 * See LICENSE.TXT at the top of this package for the full license terms.

 */

package eu.etaxonomy.taxeditor.preference.wizard;

import java.util.Arrays;

import java.util.List;

import org.eclipse.jface.resource.JFaceResources;

import org.eclipse.jface.viewers.AbstractTreeViewer;

import org.eclipse.jface.viewers.CheckboxTreeViewer;

import org.eclipse.jface.viewers.IBaseLabelProvider;

import org.eclipse.jface.viewers.ITreeContentProvider;

import org.eclipse.jface.viewers.ITreeSelection;

import org.eclipse.swt.SWT;

import org.eclipse.swt.events.SelectionEvent;

import org.eclipse.swt.events.SelectionListener;

import org.eclipse.swt.graphics.Font;

import org.eclipse.swt.layout.GridData;

import org.eclipse.swt.layout.GridLayout;

import org.eclipse.swt.widgets.Button;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Tree;

import org.eclipse.swt.widgets.TreeItem;

import org.eclipse.swt.widgets.Widget;

import eu.etaxonomy.taxeditor.l10n.Messages;

import eu.etaxonomy.taxeditor.model.ImageResources;

/**

 * @author pplitzner

 * @since Oct 26, 2018

 *

 */

public class CheckBoxTreeComposite extends Composite implements SelectionListener {

    private static final Font FONT_DEFAULT = JFaceResources.getFontRegistry().get(JFaceResources.DEFAULT_FONT);

    private static final Font FONT_ITALIC = JFaceResources.getFontRegistry().getItalic(JFaceResources.DEFAULT_FONT);

    private static final Font FONT_BOLD = JFaceResources.getFontRegistry().getBold(JFaceResources.DEFAULT_FONT);

    private CheckboxTreeViewer viewer;

    private Button btnCollapse;

    private Button btnExpand;

    private Button btnSelectAllChildren;

    private Button btnSelectDirectChildren;

    public CheckBoxTreeComposite(Composite parent, ITreeContentProvider contentProvider, IBaseLabelProvider labelProvider, int style) {

        super(parent, style);

        GridLayout layout = new GridLayout();

        parent.setLayout(layout);

        Composite composite = new Composite(parent, SWT.NULL);

        composite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));

        GridLayout gl_composite = layout;

        gl_composite.marginHeight = 0;

        composite.setLayout(gl_composite);

        Composite toolbar = new Composite(composite, SWT.NONE);

        toolbar.setLayoutData(new GridData(SWT.RIGHT, SWT.CENTER, true, false, 1, 1));

        GridLayout gl_toolbar = new GridLayout(4, false);

        gl_toolbar.horizontalSpacing = 4;

        gl_toolbar.marginHeight = 0;

        gl_toolbar.verticalSpacing = 0;

        toolbar.setLayout(gl_toolbar);

        btnCollapse = new Button(toolbar, SWT.NONE);

        btnCollapse.addSelectionListener(this);

        btnCollapse.setImage(ImageResources.getImage(ImageResources.COLLAPSE_ALL));

        btnCollapse.setToolTipText(""); //$NON-NLS-1$

        btnExpand = new Button(toolbar, SWT.NONE);

        btnExpand.addSelectionListener(this);

        btnExpand.setImage(ImageResources.getImage(ImageResources.EXPAND));

        btnExpand.setToolTipText(""); //$NON-NLS-1$

        btnSelectDirectChildren = new Button(toolbar, SWT.NONE);

        btnSelectDirectChildren.addSelectionListener(this);

        btnSelectDirectChildren.setImage(ImageResources.getImage(ImageResources.FLAT));

        btnSelectDirectChildren.setToolTipText(Messages.CheckBoxTreeComposite_SELECT_DIRECT_CHILDREN);

                btnSelectAllChildren = new Button(toolbar, SWT.NONE);

                btnSelectAllChildren.addSelectionListener(this);

                btnSelectAllChildren.setImage(ImageResources.getImage(ImageResources.HIERARCHICAL));

                btnSelectAllChildren.setToolTipText(""); //$NON-NLS-1$

        Tree tree = new Tree(composite, SWT.BORDER | SWT.CHECK);

        tree.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));

        tree.addListener(SWT.Selection, event -> {

            if (event.detail == SWT.CHECK) {

                TreeItem item = (TreeItem) event.item;

                updateItem(item);

            }

        });

        viewer = new CheckboxTreeViewer(tree);

        viewer.setContentProvider(contentProvider);

        viewer.setLabelProvider(labelProvider);

    }

    private void updateItem(TreeItem treeItem){

        TreeItem parentItem = treeItem.getParentItem();

        if(parentItem!=null){

            updateItem(parentItem);

        }

        else{

            updateChildItems(treeItem);

        }

    }

    private void updateChildItems(TreeItem treeItem){

        treeItem.setFont(FONT_DEFAULT);

        TreeItem[] children = treeItem.getItems();

        if(children.length==0){

            return;

        }

        int checkedCount = 0;

        for (TreeItem child : children) {

            updateChildItems(child);

            if(child.getChecked()){

                if ((child.getFont().equals(FONT_BOLD)) || (child.getItems().length == 0)) {

                    checkedCount++;

                }

                //some children are checked

                treeItem.setFont(FONT_ITALIC);

            }

            else if(child.getFont().equals(FONT_ITALIC)

                    || child.getFont().equals(FONT_BOLD)){

                //some children are checked

                treeItem.setFont(FONT_ITALIC);

            }

        }

        if(checkedCount==children.length){

            //all children are checked

            treeItem.setFont(FONT_BOLD);

        }

        else if(!treeItem.getFont().equals(FONT_ITALIC)){

            if(checkedCount>0){

                //some children are checked

                treeItem.setFont(FONT_ITALIC);

            }

            else{

                //no children are checked

                treeItem.setFont(FONT_DEFAULT);

            }

        }

    }

    public CheckboxTreeViewer getViewer() {

        return viewer;

    }

    /**

     * Checks the tree items corresponding to the given elements.<br>

     * @param elements

     */

    public void setCheckedElements(Object[] elements) {

        viewer.setCheckedElements(elements);

        for (Object element: elements) {

            viewer.reveal(element);

        }

        TreeItem[] rootItems = viewer.getTree().getItems();

        for (TreeItem rootItem : rootItems) {

            updateItem(rootItem);

        }

    }

    @Override

    public void widgetSelected(SelectionEvent e) {

        ITreeSelection structuredSelection = viewer.getStructuredSelection();

        Object firstElement = structuredSelection.getFirstElement();

        if(e.widget == btnCollapse){

            viewer.collapseAll();

        }

        else if(e.widget == btnExpand){

            viewer.expandToLevel(firstElement, AbstractTreeViewer.ALL_LEVELS);

        }

        else if(e.widget == btnSelectDirectChildren){

            Widget item = viewer.testFindItem(firstElement);

            if(item instanceof TreeItem){

                viewer.expandToLevel(firstElement, 1);

                TreeItem treeItem = (TreeItem) item;

                TreeItem[] childItems = treeItem.getItems();

                List<TreeItem> childItemList = Arrays.asList(childItems);

                boolean allChecked = childItemList.stream().allMatch(childItem->childItem.getChecked());

                childItemList.stream().forEach(childItem->childItem.setChecked(!allChecked));

                TreeItem parent = getRoot(treeItem);

                updateItem(parent);

            }

        }

        else if(e.widget == btnSelectAllChildren){

            Widget item = viewer.testFindItem(firstElement);

            boolean checked = false;

            Object[] checkedElements = viewer.getCheckedElements();

            for (Object checkedElement : checkedElements) {

                if(checkedElement.equals(firstElement)){

                    checked = true;

                    break;

                }

            }

            if(item instanceof TreeItem){

                viewer.expandToLevel(firstElement, AbstractTreeViewer.ALL_LEVELS);

                viewer.setSubtreeChecked(firstElement, !checked);

                TreeItem parent = getRoot((TreeItem) item);

                updateItem(parent);

            }

        }

    }

    /**

     * @param treeItem

     * @return

     */

    private TreeItem getRoot(TreeItem treeItem) {

        TreeItem parent = treeItem;

        while(parent.getParentItem()!=null){

            parent = parent.getParentItem();

        }

        return parent;

    }

    @Override

    public void widgetDefaultSelected(SelectionEvent e) {

    }

    private enum CheckState{

        CHECKED,

        GRAYED,

        NONE

    }

}