EDIT

// $Id$

/**

* Copyright (C) 2017 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;

import java.io.File;

import java.io.IOException;

import java.net.URL;

import java.net.URLConnection;

import java.util.Collections;

import java.util.Map;

import javax.annotation.PostConstruct;

import javax.inject.Inject;

import javax.inject.Named;

import org.eclipse.core.internal.runtime.PlatformURLPluginConnection;

import org.eclipse.core.runtime.FileLocator;

import org.eclipse.core.runtime.Platform;

import org.eclipse.e4.core.contexts.ContextInjectionFactory;

import org.eclipse.e4.core.contexts.IEclipseContext;

import org.eclipse.e4.core.services.log.Logger;

import org.eclipse.e4.ui.internal.workbench.CommandLineOptionModelProcessor;

import org.eclipse.e4.ui.internal.workbench.E4Workbench;

import org.eclipse.e4.ui.internal.workbench.E4XMIResourceFactory;

import org.eclipse.e4.ui.internal.workbench.ModelAssembler;

import org.eclipse.e4.ui.internal.workbench.URIHelper;

import org.eclipse.e4.ui.model.application.MApplication;

import org.eclipse.e4.ui.model.application.MApplicationElement;

import org.eclipse.e4.ui.model.application.commands.impl.CommandsPackageImpl;

import org.eclipse.e4.ui.model.application.impl.ApplicationPackageImpl;

import org.eclipse.e4.ui.model.application.ui.advanced.impl.AdvancedPackageImpl;

import org.eclipse.e4.ui.model.application.ui.basic.impl.BasicPackageImpl;

import org.eclipse.e4.ui.model.application.ui.impl.UiPackageImpl;

import org.eclipse.e4.ui.model.application.ui.menu.impl.MenuPackageImpl;

import org.eclipse.e4.ui.workbench.IModelResourceHandler;

import org.eclipse.e4.ui.workbench.IWorkbench;

import org.eclipse.emf.common.util.TreeIterator;

import org.eclipse.emf.common.util.URI;

import org.eclipse.emf.ecore.EObject;

import org.eclipse.emf.ecore.resource.Resource;

import org.eclipse.emf.ecore.resource.URIConverter;

import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;

import org.eclipse.emf.ecore.util.EcoreUtil;

import org.osgi.framework.Bundle;

/**

 * @author pplitzner

 * @date 07.07.2017

 *

 */

public class ModelResourceHandler implements IModelResourceHandler {

    private static final String WORKBENCH_XMI = "workbench.xmi";

    private ResourceSetImpl resourceSetImpl;

    private Resource resource;

    @Inject

    private Logger logger;

    @Inject

    private IEclipseContext context;

    @Inject

    @Named(E4Workbench.INITIAL_WORKBENCH_MODEL_URI)

    private URI applicationDefinitionInstance;

    /**

     * Dictates whether the model should be stored using EMF or with the merging algorithm.

     * https://bugs.eclipse.org/bugs/show_bug.cgi?id=295524

     *

     */

    final private boolean saveAndRestore;

    final private boolean clearPersistedState;

    /**

     * Constructor.

     *

     * @param saveAndRestore

     * @param clearPersistedState

     */

    @Inject

    public ModelResourceHandler(@Named(IWorkbench.PERSIST_STATE) boolean saveAndRestore,

            @Named(IWorkbench.CLEAR_PERSISTED_STATE) boolean clearPersistedState) {

        this.saveAndRestore = saveAndRestore;

        this.clearPersistedState = clearPersistedState;

    }

    @PostConstruct

    void init() {

        resourceSetImpl = new ResourceSetImpl();

        resourceSetImpl.getResourceFactoryRegistry().getExtensionToFactoryMap()

                .put(Resource.Factory.Registry.DEFAULT_EXTENSION, new E4XMIResourceFactory());

        resourceSetImpl.getPackageRegistry().put(ApplicationPackageImpl.eNS_URI,

                ApplicationPackageImpl.eINSTANCE);

        resourceSetImpl.getPackageRegistry().put(CommandsPackageImpl.eNS_URI,

                CommandsPackageImpl.eINSTANCE);

        resourceSetImpl.getPackageRegistry().put(UiPackageImpl.eNS_URI, UiPackageImpl.eINSTANCE);

        resourceSetImpl.getPackageRegistry()

                .put(MenuPackageImpl.eNS_URI, MenuPackageImpl.eINSTANCE);

        resourceSetImpl.getPackageRegistry().put(BasicPackageImpl.eNS_URI,

                BasicPackageImpl.eINSTANCE);

        resourceSetImpl.getPackageRegistry().put(AdvancedPackageImpl.eNS_URI,

                AdvancedPackageImpl.eINSTANCE);

        resourceSetImpl

                .getPackageRegistry()

                .put(org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicPackageImpl.eNS_URI,

                        org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicPackageImpl.eINSTANCE);

    }

    /**

     * @return {@code true} if the current application model has top-level windows.

     */

    public boolean hasTopLevelWindows() {

        return hasTopLevelWindows(resource);

    }

    /**

     * @return {@code true} if the specified application model has top-level windows.

     */

    private boolean hasTopLevelWindows(Resource applicationResource) {

        if (applicationResource == null || applicationResource.getContents() == null) {

            // If the application resource doesn't exist or has no contents, then it has no

            // top-level windows (and we are in an error state).

            return false;

        }

        MApplication application = (MApplication) applicationResource.getContents().get(0);

        return !application.getChildren().isEmpty();

    }

    @Override

    public Resource loadMostRecentModel() {

        File workbenchData = null;

        URI restoreLocation = null;

        if (saveAndRestore) {

            workbenchData = getWorkbenchSaveLocation();

            restoreLocation = URI.createFileURI(workbenchData.getAbsolutePath());

        }

        if (clearPersistedState && workbenchData != null && workbenchData.exists()) {

            workbenchData.delete();

        }

        // last stored time-stamp

        long restoreLastModified = restoreLocation == null ? 0L : new File(

                restoreLocation.toFileString()).lastModified();

        // See bug 380663, bug 381219

        // long lastApplicationModification = getLastApplicationModification();

        // boolean restore = restoreLastModified > lastApplicationModification;

        boolean restore = restoreLastModified > 0;

        boolean initialModel;

        resource = null;

        if (restore && saveAndRestore) {

            resource = loadResource(restoreLocation);

            // If the saved model does not have any top-level windows, Eclipse will exit

            // immediately, so throw out the persisted state and reinitialize with the defaults.

            if (!hasTopLevelWindows(resource)) {

                if (logger != null) {

                    logger.error(new Exception(), // log a stack trace to help debug the corruption

                            "The persisted workbench has no top-level windows, so reinitializing with defaults."); //$NON-NLS-1$

                }

                resource = null;

            }

        }

        if (resource == null) {

            Resource applicationResource = loadResource(applicationDefinitionInstance);

            MApplication theApp = (MApplication) applicationResource.getContents().get(0);

            resource = createResourceWithApp(theApp);

            context.set(E4Workbench.NO_SAVED_MODEL_FOUND, Boolean.TRUE);

            initialModel = true;

        } else {

            initialModel = false;

        }

        // Add model items described in the model extension point

        // This has to be done before commands are put into the context

        MApplication appElement = (MApplication) resource.getContents().get(0);

        this.context.set(MApplication.class, appElement);

        ModelAssembler contribProcessor = ContextInjectionFactory.make(ModelAssembler.class,

                context);

        contribProcessor.processModel(initialModel);

        if (!hasTopLevelWindows(resource) && logger != null) {

            logger.error(new Exception(), // log a stack trace to help debug the

                                            // corruption

                    "Initializing from the application definition instance yields no top-level windows! " //$NON-NLS-1$

                            + "Continuing execution, but the missing windows may cause other initialization failures."); //$NON-NLS-1$

        }

        if (!clearPersistedState) {

            CommandLineOptionModelProcessor processor = ContextInjectionFactory.make(

                    CommandLineOptionModelProcessor.class, context);

            processor.process();

        }

        return resource;

    }

    @Override

    public void save() throws IOException {

        if (saveAndRestore) {

            resource.save(null);

        }

    }

    /**

     * Creates a resource with an app Model, used for saving copies of the main app model.

     *

     * @param theApp

     *            the application model to add to the resource

     * @return a resource with a proper save path with the model as contents

     */

    @Override

    public Resource createResourceWithApp(MApplication theApp) {

        Resource res = createResource();

        res.getContents().add((EObject) theApp);

        return res;

    }

    private Resource createResource() {

        if (saveAndRestore) {

            URI saveLocation = URI.createFileURI(getWorkbenchSaveLocation().getAbsolutePath());

            return resourceSetImpl.createResource(saveLocation);

        }

        return resourceSetImpl.createResource(URI.createURI(WORKBENCH_XMI)); //$NON-NLS-1$

    }

    private File getWorkbenchSaveLocation() {

        File workbenchData = new File(getBaseLocation(), WORKBENCH_XMI); //$NON-NLS-1$

        return workbenchData;

    }

    private File getBaseLocation() {

        File baseLocation;

        try {

            baseLocation = FileLocator.getBundleFile(Platform.getBundle(TaxonomicEditorPlugin.PLUGIN_ID));

        } catch (IOException e) {

            throw new RuntimeException(e);

        }

//        baseLocation = new File(baseLocation, ".metadata"); //$NON-NLS-1$

//        baseLocation = new File(baseLocation, ".plugins"); //$NON-NLS-1$

//        baseLocation = new File(baseLocation, "org.eclipse.e4.workbench"); //$NON-NLS-1$

        return baseLocation;

    }

    // Ensures that even models with error are loaded!

    private Resource loadResource(URI uri) {

        Resource resource;

        try {

            resource = getResource(uri);

        } catch (Exception e) {

            // TODO We could use diagnostics for better analyzing the error

            logger.error(e, "Unable to load resource " + uri.toString()); //$NON-NLS-1$

            return null;

        }

        // TODO once we switch from deltas, we only need this once on the default model?

        String contributorURI = URIHelper.EMFtoPlatform(uri);

        if (contributorURI != null) {

            TreeIterator<EObject> it = EcoreUtil.getAllContents(resource.getContents());

            while (it.hasNext()) {

                EObject o = it.next();

                if (o instanceof MApplicationElement) {

                    ((MApplicationElement) o).setContributorURI(contributorURI);

                }

            }

        }

        return resource;

    }

    private Resource getResource(URI uri) throws Exception {

        Resource resource;

        if (saveAndRestore) {

            resource = resourceSetImpl.getResource(uri, true);

        } else {

            // Workaround for java.lang.IllegalStateException: No instance data can be specified

            // thrown by org.eclipse.core.internal.runtime.DataArea.assertLocationInitialized

            // The DataArea.assertLocationInitialized is called by ResourceSetImpl.getResource(URI,

            // boolean)

            resource = resourceSetImpl.createResource(uri);

            resource.load(new URL(uri.toString()).openStream(), resourceSetImpl.getLoadOptions());

        }

        return resource;

    }

    protected long getLastApplicationModification() {

        long appLastModified = 0L;

        ResourceSetImpl resourceSetImpl = new ResourceSetImpl();

        Map<String, ?> attributes = resourceSetImpl.getURIConverter().getAttributes(

                applicationDefinitionInstance,

                Collections.singletonMap(URIConverter.OPTION_REQUESTED_ATTRIBUTES,

                        Collections.singleton(URIConverter.ATTRIBUTE_TIME_STAMP)));

        Object timestamp = attributes.get(URIConverter.ATTRIBUTE_TIME_STAMP);

        if (timestamp instanceof Long) {

            appLastModified = ((Long) timestamp).longValue();

        } else if (applicationDefinitionInstance.isPlatformPlugin()) {

            try {

                java.net.URL url = new java.net.URL(applicationDefinitionInstance.toString());

                // can't just use 'url.openConnection()' as it usually returns a

                // PlatformURLPluginConnection which doesn't expose the

                // last-modification time. So we try to resolve the file through

                // the bundle to obtain a BundleURLConnection instead.

                Object[] obj = PlatformURLPluginConnection.parse(url.getFile().trim(), url);

                Bundle b = (Bundle) obj[0];

                // first try to resolve as an bundle file entry, then as a resource using

                // the bundle's classpath

                java.net.URL resolved = b.getEntry((String) obj[1]);

                if (resolved == null) {

                    resolved = b.getResource((String) obj[1]);

                }

                if (resolved != null) {

                    URLConnection openConnection = resolved.openConnection();

                    appLastModified = openConnection.getLastModified();

                }

            } catch (Exception e) {

                // ignore

            }

        }

        return appLastModified;

    }

}