/*
 *  Copyright 2012 Anyware Services
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.ametys.plugins.newsletter.workflow;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URISyntaxException;
import java.net.URL;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.avalon.framework.context.Context;
import org.apache.avalon.framework.context.ContextException;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.cocoon.Constants;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.ametys.core.util.I18nUtils;
import org.ametys.plugins.newsletter.category.Category;
import org.ametys.plugins.newsletter.category.CategoryProviderExtensionPoint;
import org.ametys.plugins.newsletter.ga.GAUriBuilder;
import org.ametys.plugins.repository.metadata.CompositeMetadata;
import org.ametys.web.repository.content.WebContent;
import org.ametys.web.site.SiteConfigurationExtensionPoint;

/**
 * Send a google analytics event for every newsletter e-mail sent.
 */
public class SendGAEventsEngine implements Runnable
{
    
    private static final Logger _LOGGER = LoggerFactory.getLogger(SendGAEventsEngine.class);
    
    private static final DateFormat _DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd");
    
    /** The avalon context. */
    protected Context _context;
    
    /** The cocoon environment context. */
    protected org.apache.cocoon.environment.Context _environmentContext;
    
    /** The service manager. */
    protected ServiceManager _manager;
    
    /** Is the engine initialized ? */
    protected boolean _initialized;
    
    /** The google analytics URI builder. */
    protected GAUriBuilder _gaUriBuilder;
    
    /** The category provider extension point. */
    protected CategoryProviderExtensionPoint _categoryProviderEP;
    
    /** The site configuration extension point. */
    protected SiteConfigurationExtensionPoint _siteConf;
    
    /** The i18n utils component. */
    protected I18nUtils _i18nUtils;
    
    private boolean _parametrized;
    
    private String _siteName;
    
    private Date _newsletterDate;
    private long _newsletterNumber;
    private String _newsletterTitle;
    
    private Category _category;
    
    private int _eventCount;
    
    /**
     * Initialize the engine.
     * @param manager the avalon service manager.
     * @param context the avalon context.
     * @throws ContextException if an error occurred during initialization
     * @throws ServiceException if an error occurred during initialization
     */
    public void initialize(ServiceManager manager, Context context) throws ContextException, ServiceException
    {
        _manager = manager;
        _context = context;
        _environmentContext = (org.apache.cocoon.environment.Context) context.get(Constants.CONTEXT_ENVIRONMENT_CONTEXT);
        
        // Lookup the needed components.
        _gaUriBuilder = (GAUriBuilder) manager.lookup(GAUriBuilder.ROLE);
        _categoryProviderEP = (CategoryProviderExtensionPoint) manager.lookup(CategoryProviderExtensionPoint.ROLE);
        _siteConf = (SiteConfigurationExtensionPoint) manager.lookup(SiteConfigurationExtensionPoint.ROLE);
        _i18nUtils = (I18nUtils) manager.lookup(I18nUtils.ROLE);
        
        _initialized = true;
    }
    
    /**
     * Parametrize engine
     * @param siteName The site name
     * @param newsletterContent the newsletter content
     * @param category the newsletter category
     * @param eventCount the number of events
     */
    public void parametrize(String siteName, WebContent newsletterContent, Category category, int eventCount)
    {
        _siteName = siteName;
        _category = category;
        _eventCount = eventCount;
        
        CompositeMetadata meta = newsletterContent.getMetadataHolder();
        _newsletterDate = meta.getDate("newsletter-date", null);
        _newsletterNumber = meta.getLong("newsletter-number", 0);
        _newsletterTitle = meta.getString("title", "");
        
        _parametrized = true;
    }
    
    private void _checkInitialization()
    {
        if (!_initialized)
        {
            String message = "The GA events engine has to be properly initialized before it's run.";
            _LOGGER.error(message);
            throw new IllegalStateException(message);
        }
        if (!_parametrized)
        {
            String message = "The GA events engine has to be parametrized before it's run.";
            _LOGGER.error(message);
            throw new IllegalStateException(message);
        }
    }
    
    public void run()
    {
        _checkInitialization();
        
        if (_LOGGER.isInfoEnabled())
        {
            _LOGGER.info("Starting to send GA newsletter events.");
        }
        
        boolean trackingEnabled = _siteConf.getValueAsBoolean(_siteName, "newsletter-enable-tracking");
        String gaWebId = _siteConf.getValueAsString(_siteName, "google-web-property-id");
        
        if (trackingEnabled && StringUtils.isNotBlank(gaWebId))
        {
            sendEvents(gaWebId);
        }
        
        if (_LOGGER.isInfoEnabled())
        {
            _LOGGER.info("All mails are sent at " + new Date());
        }
    }
    
    /**
     * Send GA events for a given GA user account.
     * @param gaWebId the google web ID.
     */
    protected void sendEvents(String gaWebId)
    {
        // Compute the event identifier.
        String eventIdentifier = computeEventIdentifier();
        
        for (int i = 0; i < _eventCount; i++)
        {
            try
            {
                if (i > 0)
                {
                    Thread.sleep(1100);
                }
                
                // Build the URI and send the request.
                String uri = _gaUriBuilder.getEventGifUri(gaWebId, eventIdentifier, false);
                sendEvent(uri);
            }
            catch (IOException e)
            {
                _LOGGER.error("IO error sending the event.", e);
            }
            catch (InterruptedException e)
            {
                _LOGGER.error("Error while waiting for sending mails.", e);
            }
        }
    }
    
    /**
     * Send the event request, given the full GIF URL.
     * @param eventUrl the full event GIF URL (with parameters).
     * @throws IOException if an error occurs sending the GIF HTTP request.
     */
    protected void sendEvent(String eventUrl) throws IOException
    {
        URL url = new URL(eventUrl);
        
        // Use a custom user agent to avoid 
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestProperty("User-Agent", "Ametys/3 (compatible; MSIE 6.0)");
        connection.setRequestMethod("GET");
        connection.connect();
        
        int responseCode = connection.getResponseCode();
        
        if (responseCode != HttpURLConnection.HTTP_OK)
        {
            _LOGGER.error("Google analytics image request returned with error (code: " + responseCode + ").");
        }
        else
        {
            // Quietly consume the stream, ignoring errors.
            consumeQuietly(connection.getInputStream());
        }
    }
    
    /**
     * Compute the event identifier for the newsletter sending.
     * @return the event identifier.
     */
    protected String computeEventIdentifier()
    {
        String newsletterTitle = _i18nUtils.translate(_category.getTitle(), _category.getLang());
        
        String category = "Newsletters / " + newsletterTitle;
        String action = "Sending";
        
        StringBuilder label = new StringBuilder();
        label.append(_newsletterTitle);
        if (_newsletterNumber > 0)
        {
            label.append(" / ").append(_newsletterNumber);
        }
        if (_newsletterDate != null)
        {
            label.append(" / ").append(_DATE_FORMAT.format(_newsletterDate));
        }
        
        try
        {
            return _gaUriBuilder.getEventIdentifier(category, action, label.toString());
        }
        catch (URISyntaxException e)
        {
            // Should never happen.
            _LOGGER.error("Unsupported encoding.", e);
        }
        
        return "";
    }
    
    /**
     * Consume a stream, reading all its data and ignoring errors. 
     * @param input the input stream to consume.
     */
    protected void consumeQuietly(InputStream input)
    {
        try
        {
            byte[] buffer = new byte[256];
            while (input.read(buffer) != -1)
            {
                // Ignore.
            }
        }
        catch (IOException e)
        {
            // Ignore.
        }
        finally
        {
            IOUtils.closeQuietly(input);
        }
    }
    
}