EDIT

// $Id$

/**

* 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.workbench.handler;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import javax.inject.Named;

import org.apache.logging.log4j.LogManager;import org.apache.logging.log4j.Logger;

import org.eclipse.core.runtime.CoreException;

import org.eclipse.core.runtime.IConfigurationElement;

import org.eclipse.core.runtime.IExtensionRegistry;

import org.eclipse.core.runtime.Platform;

import org.eclipse.e4.core.di.annotations.Execute;

import org.eclipse.e4.ui.services.IServiceConstants;

import org.eclipse.jface.preference.IPreferencePage;

import org.eclipse.jface.preference.PreferenceDialog;

import org.eclipse.jface.preference.PreferenceManager;

import org.eclipse.jface.preference.PreferenceNode;

import org.eclipse.swt.widgets.Shell;

/**

 * Scans all extension for extension point <code>eu.etaxonomy.taxeditor.store.preferencePage</code> and

 * creates the tree of preference nodes according to the <code>category</code> attribute of the

 * extension point.<br>

 * <b>Note:</b> If, for a given category, no parent node can be found then this page will not be

 * added to the preferences

 * @author pplitzner

 * @date 14.02.2018

 *

 */

public class OpenPreferencesHandler {

    private static final String ATT_NAME = "name"; //$NON-NLS-1$

    private static final String ATT_ID = "id"; //$NON-NLS-1$

    private static final String ATT_CATEGORY = "category"; //$NON-NLS-1$

    private static final String ATT_CLASS = "class"; //$NON-NLS-1$

    private static final String EXTENSION_ELEMENT_PAGE = "page"; //$NON-NLS-1$

    private static final String EXTENSION_POINT_ID = "eu.etaxonomy.taxeditor.store.preferencePage"; //$NON-NLS-1$

    private Logger logger = LogManager.getLogger(OpenPreferencesHandler.class);

    @Execute

    public void execute(@Named(IServiceConstants.ACTIVE_SHELL)Shell shell) {

        List<PageWrapper> pagesYetToBeAdded = new ArrayList<>();

        List<PageWrapper> rootPages = new ArrayList<>();

        Map<String, PreferenceNode> idToNodeMap = new HashMap<>();

        PreferenceManager manager = new PreferenceManager('/');

        IExtensionRegistry reg = Platform.getExtensionRegistry();

        IConfigurationElement[] extensions = reg

                .getConfigurationElementsFor(EXTENSION_POINT_ID); //$NON-NLS-1$

        for (IConfigurationElement configElement : extensions) {

            if(configElement.getName().equals(EXTENSION_ELEMENT_PAGE)){ //$NON-NLS-1$

                Object o;

                try {

                    o = configElement.createExecutableExtension(ATT_CLASS);

                    if(o instanceof IPreferencePage){

                        IPreferencePage page = (IPreferencePage) o;

                        String category = configElement.getAttribute(ATT_CATEGORY);

                        String id = configElement.getAttribute(ATT_ID);

                        String name = configElement.getAttribute(ATT_NAME);

                        page.setTitle(name);

                        //add all root nodes

                        if(category==null){

                            rootPages.add(new PageWrapper(page, category, id, name));

                        }

                        //child nodes will be handled later

                        else{

                            pagesYetToBeAdded.add(new PageWrapper(page, category, id, name));

                        }

                    }

                } catch (CoreException e) {

                    logger.error(String.format("Failed to initialize preference page for config element: %s", configElement), e); //$NON-NLS-1$

                }

            }

        }

        //sort root nodes

        Collections.sort(rootPages, new PreferenceNodeComparator());

        //add root nodes

        rootPages.forEach(pageWrapper->{

            PreferenceNode node = new PreferenceNode(pageWrapper.id, pageWrapper.page);

            manager.addToRoot(node);

            idToNodeMap.put(pageWrapper.id, node);

        });

        //sort child nodes

        Collections.sort(pagesYetToBeAdded, new PreferenceNodeComparator());

        //add child nodes

        int size = pagesYetToBeAdded.size();

        while(!pagesYetToBeAdded.isEmpty()){

            Iterator<PageWrapper> iterator = pagesYetToBeAdded.iterator();

            while(iterator.hasNext()){

                PageWrapper pageWrapper = iterator.next();

                if(addPage(pageWrapper, idToNodeMap)){

                    iterator.remove();

                }

            }

            if(size==pagesYetToBeAdded.size()){

                //avoid potential endless loop

                break;

            }

            size = pagesYetToBeAdded.size();

        }

        PreferenceDialog dialog = new PreferenceDialog(shell, manager);

        dialog.create();

        dialog.getTreeViewer().expandToLevel(2);

        dialog.open();

    }

    private boolean addPage(PageWrapper pageWrapper, Map<String, PreferenceNode> idToNodeMap){

        PreferenceNode node = new PreferenceNode(pageWrapper.id, pageWrapper.page);

        PreferenceNode parent = idToNodeMap.get(pageWrapper.category);

        if(parent!=null){

            idToNodeMap.put(pageWrapper.id, node);

            parent.add(node);

            return true;

        }

        return false;

    }

    private class PreferenceNodeComparator implements Comparator<PageWrapper>{

        @Override

        public int compare(PageWrapper o1, PageWrapper o2) {

            return o1.name.compareTo(o2.name);

        }

    }

    private class PageWrapper{

        IPreferencePage page;

        String category;

        String id;

        String name;

        public PageWrapper(IPreferencePage page, String category, String id, String name) {

            super();

            this.page = page;

            this.category = category;

            this.id = id;

            this.name = name;

        }

    }

}