/*******************************************************************************
 * Copyright (c) 2007, 2014 Association for Decentralized Information Management
 * in Industry THTH ry.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *     Semantum Oy
 *******************************************************************************/
package org.simantics.workbench.internal.contributions.search;

import java.net.URL;

import org.eclipse.swt.SWT;
import org.eclipse.swt.browser.Browser;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.part.ViewPart;
import org.simantics.Simantics;
import org.simantics.db.Session;
import org.simantics.db.layer0.genericrelation.Dependencies;
import org.simantics.db.layer0.request.ActiveModels;
import org.simantics.db.management.ISessionContext;
import org.simantics.db.management.ISessionContextChangedListener;
import org.simantics.db.management.SessionContextChangedEvent;
import org.simantics.db.service.LifecycleSupport;
import org.simantics.utils.ui.SWTUtils;
import org.simantics.workbench.search.ISearchService;
import org.simantics.workbench.search.ISearchService.ResultBrowser;
import org.simantics.workbench.search.SearchQuery;

/**
 * A very non-configurable Web browser view for search trim.
 * 
 * @author Tuukka Lehtonen
 */
public class BrowserView extends ViewPart {

    /**
     * ID of this view's plug-in extension.
     */
    public static final String ID = "org.simantics.workbench.search.browser";

    /**
     * Used as a property of this view to keep track of the last search query
     * performed with this view. This information is needed to know whether or
     * not to initialize the view with default contents after it has been
     * created. This depends on whether the creation was caused by a simple
     * activation of the view or an actual search being performed.
     */
    public static final String LAST_QUERY_PROPERTY = "org.simantics.workbench.search.browser.lastQuery";

    private Browser              browser;
    private boolean              disposed;
    private ActiveModelsListener currentListener;

    @Override
    public void createPartControl(Composite parent) {
        browser = new org.eclipse.swt.browser.Browser(parent, SWT.NONE);

        // Ensure the view receives some browser content even when no searches
        // have been performed yet.
        scheduleInitializeViewContent(false);

        // Make sure that the contents of the view are reset every time the set
        // of active models changes. This must be because what is searchable depends
        // completely on the active models. When there is no active model, the search
        // will find nothing.
        Simantics.getSessionContextProvider().addContextChangedListener(sessionListener);
        trackActiveModels(Simantics.peekSession());
    }

    private ISessionContextChangedListener sessionListener = new ISessionContextChangedListener() {
        @Override
        public void sessionContextChanged(SessionContextChangedEvent event) {
            ISessionContext ctx = event.getNewValue();
            final Session newSession = ctx != null ? ctx.peekSession() : null;
            // Synchronize session changes to the UI thread to keep threading more predictable.
            SWTUtils.asyncExec(browser, new Runnable() {
                @Override
                public void run() {
                    if (!disposed)
                        trackActiveModels(newSession);
                }
            });
        }
    };

    private void trackActiveModels(Session session) {
        if (currentListener != null) {
            currentListener.dispose();
            currentListener = null;
        }
        if (session != null) {
        	
			LifecycleSupport lfs = session.peekService(LifecycleSupport.class);
			if (lfs == null)
				return;
			if (lfs.isClosed())
				return;
        	
            ActiveModelsListener listener = new ActiveModelsListener(new Runnable() {
                @Override
                public void run() {
                    scheduleInitializeViewContent(true);
                }
            });
			
            // Make sure that the listener is disposed if the session is disposed.
            session.registerService(ActiveModelsListener.class, listener);
            session.asyncRequest(new ActiveModels(Simantics.getProjectResource()), listener);
            this.currentListener = listener;
        }
    }

    protected void scheduleInitializeViewContent(final boolean force) {
        SWTUtils.asyncExec(browser, new Runnable() {
            @Override
            public void run() {
                if (disposed)
                    return;
                // If SearchServiceImpl hasn't performed any queries yet,
                // then we shall initialize the view contents at this point.
                String lastQuery = getPartProperty(LAST_QUERY_PROPERTY);
                if (force || lastQuery == null)
                    initializeViewContent();
            }
        });
    }

    protected void initializeViewContent() {
        SearchQuery query = new SearchQuery("");
        query.setSearchFlag(Dependencies.FIELD_NAME_SEARCH, "on");
        query.setSearchFlag(Dependencies.FIELD_TYPES_SEARCH, "on");
        ISearchService searchService = (ISearchService) PlatformUI.getWorkbench().getService(ISearchService.class);
        if (searchService != null)
            searchService.performQuery(query, ResultBrowser.VIEW, false);
    }

    @Override
    public void dispose() {
        disposed = true;
        super.dispose();
    }

    public boolean isDisposed() {
        return disposed;
    }

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

    public org.eclipse.swt.browser.Browser getBrowser() {
        return browser;
    }

    public void setUrl(URL url) {
        getBrowser().setUrl(url.toString());
    }

    @Override
    public void setContentDescription(String description) {
        super.setContentDescription(description);
    }

}