Emitter.java

/*
 * Emitter.java
 * Copyright (C) 2011,2012 Wannes De Smet
 * 
 * This program 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 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.xenmaster.monitoring;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import net.wgr.core.ReflectionUtils;
import net.wgr.lang.I18N;
import net.wgr.wcp.Commander;
import net.wgr.wcp.Scope;
import net.wgr.wcp.command.Command;

import org.apache.log4j.Logger;
import org.xenmaster.api.entity.Event;
import org.xenmaster.api.entity.NamedEntity;
import org.xenmaster.api.entity.Task;
import org.xenmaster.api.util.CachingFacility;
import org.xenmaster.monitoring.LogEntry.Level;

/**
 * Issues requested monitoring data "formally and with authority" 
 * @created Oct 30, 2011
 * @author double-u
 */
public class Emitter {

    protected List<EventDescriptor> descriptors;

    public Emitter() {
        descriptors = new ArrayList<>();
        buildDescriptors();
    }

    protected final void buildDescriptors() {
        try (BufferedReader br = new BufferedReader(new InputStreamReader(getClass().getResourceAsStream("/trans_" + I18N.instance().getDefaultLocale().getLanguage() + ".events")))) {
            String line;
            while ((line = br.readLine()) != null) {
                if (line.startsWith("#")) {
                    continue;
                }
                descriptors.add(EventDescriptor.fromString(line));
            }
        } catch (IOException ex) {
            Logger.getLogger(getClass()).error("Failed to read event file", ex);
        }
    }

    public void listenToEvents(EventHandler eh) {
        eh.addListener(new EventHandler.EventListener() {

            @Override
            public void eventOcurred(Event event) {
                if (event.getSnapshot() == null) {
                    return;
                }

                // Task come and go too quickly, they are mostly already gone before we can get their reference
                boolean hasValidReference = event.getOperation() == Event.Operation.MOD && !(event.getSnapshot() instanceof Task);
                String reference = event.getSnapshot().getReference(hasValidReference);
                Object cachedObject = CachingFacility.get(reference, event.getSnapshot().getClass());
                Map<String, Object> diff = ReflectionUtils.diff(cachedObject, event.getSnapshot());

                if (diff.size() < 1) {
                    // Nothing was changed?
                    return;
                }

                String title = event.getOperation().name();
                String message = "";
                ApiEventEntry.Level level = LogEntry.Level.INFORMATION;

                if (hasValidReference) {
                    diffIt:
                    for (Map.Entry<String, Object> d : diff.entrySet()) {
                        for (EventDescriptor ed : descriptors) {
                            if (event.getSnapshot() == null || d.getValue() == null) {
                                continue;
                            }

                            if (ed.match(event.getSnapshot().getClass().getSimpleName(), d.getKey(), d.getValue().toString())) {
                                title = ed.getTitle();
                                message = ed.getDescription();

                                if (NamedEntity.class.isAssignableFrom(event.getSnapshot().getClass())) {
                                    NamedEntity ne = (NamedEntity) event.getSnapshot();
                                    title = String.format(title, ne.getName(), ne.getDescription());
                                    message = String.format(message, ne.getName(), ne.getDescription());
                                    level = ed.getLevel();
                                }
                                break diffIt;
                            }
                        }
                    }
                }

                ApiEventEntry le = new ApiEventEntry(event.getSnapshot().getReference(hasValidReference), event.getEventClass(),
                        title, message, diff, event.getOperation().name(), level);
                emit(le);
            }
        }, 0);
    }

    public static void emit(LogEntry le) {
        LogEntry filledIn = le;
        filledIn.doLocalization();
        Commander.get().commandeer(new Command("log", "event", le), new Scope(Scope.Target.ALL));
    }

    protected static final class EventDescriptor {

        protected String className;
        protected String field;
        protected String newValue;
        protected String title, description;
        protected ApiEventEntry.Level level;
        protected final static Pattern EVENT_DESCRIPTOR_LINE = Pattern.compile("([^\\.]+)\\.([^:]+):([^=]+)=([^;]+);([^;]+);(.+)");

        public EventDescriptor(String className, String field, String newValue, ApiEventEntry.Level level, String title, String description) {
            this.className = className;
            this.field = field;
            this.newValue = newValue;
            this.title = title;
            this.description = description;
            this.level = level;
        }

        public boolean match(String className, String fieldName, String newValue) {
            return this.className.equals(className) && this.field.equals(fieldName) && this.newValue.equals(newValue);
        }

        public static EventDescriptor fromString(String string) {
            Matcher m = EVENT_DESCRIPTOR_LINE.matcher(string);
            if (!m.find()) {
                throw new IllegalArgumentException("Event descriptor line is not valid");
            }

            return new EventDescriptor(m.group(1).trim(), m.group(2).trim(), m.group(3).trim(), ApiEventEntry.Level.valueOf(m.group(4).trim()), m.group(5).trim(), m.group(6).trim());
        }

        public String getClassName() {
            return className;
        }

        public String getField() {
            return field;
        }

        public String getNewValue() {
            return newValue;
        }

        public String getTitle() {
            return title;
        }

        public String getDescription() {
            return description;
        }

        public Level getLevel() {
            return level;
        }
    }
}