/*
 * Copyright 2012, 2013 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.eclipse.internal.views;

import java.util.Map;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IToolBarManager;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.RowLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Link;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.PageBook;
import org.eclipse.ui.part.ViewPart;
import org.osgi.framework.BundleContext;

import com.redhat.thermostat.common.ApplicationService;
import com.redhat.thermostat.common.MultipleServiceTracker;
import com.redhat.thermostat.common.Timer;
import com.redhat.thermostat.common.Timer.SchedulingType;
import com.redhat.thermostat.common.config.ClientPreferences;
import com.redhat.thermostat.eclipse.internal.Activator;
import com.redhat.thermostat.eclipse.internal.controllers.ConnectDBAction;
import com.redhat.thermostat.eclipse.internal.controllers.ConnectionJobListener;
import com.redhat.thermostat.eclipse.internal.jobs.ConnectDbJob;
import com.redhat.thermostat.eclipse.internal.model.HostsVmsLabelProvider;
import com.redhat.thermostat.eclipse.internal.model.HostsVmsTreeContentProvider;
import com.redhat.thermostat.eclipse.internal.model.HostsVmsTreeRoot;
import com.redhat.thermostat.storage.core.DefaultHostsVMsLoader;
import com.redhat.thermostat.storage.core.HostsVMsLoader;
import com.redhat.thermostat.storage.dao.HostInfoDAO;
import com.redhat.thermostat.storage.dao.VmInfoDAO;

/**
 * 
 * The main class for the VM tree view of the Thermostat Eclipse client.
 * 
 */
public class HostsVmsTreeViewPart extends ViewPart {

    private Action connectAction;
    // Hosts and VMs viewer
    private TreeViewer treeViewer;
    // viewer for the connect viewing.
    private Composite connectPage;
    // Container for tree and connect
    private PageBook pageBook;
    private MultipleServiceTracker tracker;
    private ApplicationService appSvc;
    private HostInfoDAO hostInfoDAO;
    private VmInfoDAO vmInfoDAO;
    private boolean closing;
    private Timer timer;

    public HostsVmsTreeViewPart() {
        ClientPreferences clientPrefs = new ClientPreferences(Activator.getDefault().getKeyring(),
                                                              Activator.getDefault().getCommonPaths());
        Job connectJob = new ConnectDbJob(
                "Connecting to Thermostat storage...", clientPrefs);
        connectJob.setSystem(true);
        connectAction = new ConnectDBAction(connectJob);
        connectAction.setImageDescriptor(Activator
                .getImageDescriptor("icons/offline.png"));
        connectJob.addJobChangeListener(new ConnectionJobListener(connectAction));
        
        BundleContext context = Activator.getDefault().getBundle().getBundleContext();
        Class<?>[] deps = new Class<?>[] {
            ApplicationService.class,
            HostInfoDAO.class,
            VmInfoDAO.class
        };
        tracker = new MultipleServiceTracker(context, deps, new MultipleServiceTracker.Action() {
            
            @Override
            public void dependenciesAvailable(Map<String, Object> services) {
                appSvc = (ApplicationService) services.get(ApplicationService.class.getName());
                Objects.requireNonNull(appSvc);
                hostInfoDAO = (HostInfoDAO) services.get(HostInfoDAO.class.getName());
                Objects.requireNonNull(hostInfoDAO);
                vmInfoDAO = (VmInfoDAO) services.get(VmInfoDAO.class.getName());
                Objects.requireNonNull(vmInfoDAO);
                
                // Switch to Hosts/VMs page
                showHostVmsPage();
            }

            @Override
            public void dependenciesUnavailable() {
                if (!closing) {
                    // Show the user an error
                    PlatformUI.getWorkbench().getDisplay().syncExec(new Runnable() {

                        @Override
                        public void run() {
                            MessageDialog.openError(null, "Connection Error", "Unable to connect to storage");
                        }
                    });
                    // Switch to the connection page
                    showConnectionPage();
                }
            }
        });
    }
    
    @Override
    public void dispose() {
        closing = true;
        tracker.close();
        super.dispose();
    }
    
    public void showConnectionPage() {
        PlatformUI.getWorkbench().getDisplay().asyncExec(new Runnable() {
            @Override
            public void run() {
                // Stop background updates
                if (timer != null) {
                    timer.stop();
                }
                pageBook.showPage(connectPage);
            }
        });
    }

    private void showHostVmsPage() {
        final HostsVMsLoader loader = new DefaultHostsVMsLoader(hostInfoDAO,
                vmInfoDAO, true /* TODO Make configurable */);
        final HostsVmsTreeRoot root = new HostsVmsTreeRoot();

        PlatformUI.getWorkbench().getDisplay().asyncExec(new Runnable() {

            @Override
            public void run() {
                initializeTimer(root);

                treeViewer.setContentProvider(new HostsVmsTreeContentProvider(loader));
                treeViewer.setLabelProvider(new HostsVmsLabelProvider());
                treeViewer.setUseHashlookup(true);
                treeViewer.setInput(root);

                // Start background updates
                timer.start();

                pageBook.showPage(treeViewer.getControl());
            }

        });
    }

    @Override
    public void createPartControl(final Composite parent) {
        IToolBarManager mgr = getViewSite().getActionBars().getToolBarManager();
        mgr.add(connectAction);

        pageBook = new PageBook(parent, SWT.NONE);

        // Prepare Hosts/VMs tree
        treeViewer = new TreeViewer(pageBook, SWT.NONE);
        // register the tree as selection provider
        getSite().setSelectionProvider(treeViewer);

        // Prepare connect page
        RowLayout layout = new RowLayout();
        layout.wrap = true;
        connectPage = new Composite(pageBook, SWT.NONE);
        connectPage.setLayout(layout);
        Label test = new Label(connectPage, SWT.NONE);
        test.setText("Not connected... ");
        Link link = new Link(connectPage, SWT.NONE);
        // FIXME: Externalize
        link.setText("<a>Connect</a>");
        link.addListener(SWT.Selection, new Listener() {
            @Override
            public void handleEvent(Event event) {
                connectAction.run();
            }
        });
        
        showConnectionPage();
        tracker.open();
    }

    @Override
    public void setFocus() {
        pageBook.setFocus();
    }

    private void initializeTimer(final HostsVmsTreeRoot root) {
        timer = appSvc.getTimerFactory().createTimer();
        timer.setAction(new Runnable() {
            
            @Override
            public void run() {
                PlatformUI.getWorkbench().getDisplay().asyncExec(new Runnable() {
                    
                    @Override
                    public void run() {
                        if (!treeViewer.getTree().isDisposed()) {
                            // Turn off redrawing while we update to prevent flickering
                            treeViewer.getTree().setRedraw(false);
                            
                            // Preserve expanded elements
                            Object[] expandedElements = treeViewer.getExpandedElements();
                            
                            // Force update to tree
                            treeViewer.setInput(root);
                            
                            // Restore expanded elements
                            treeViewer.setExpandedElements(expandedElements);
                            
                            treeViewer.getTree().setRedraw(true);
                        }
                    }
                });
            }
        });
        timer.setInitialDelay(0);
        timer.setDelay(3);
        timer.setTimeUnit(TimeUnit.SECONDS);
        timer.setSchedulingType(SchedulingType.FIXED_RATE);
    }

}