001/*
002 * Copyright (c) 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the Eclipse Public License v1.0
006 * which accompanies this distribution, and is available at
007 * http://www.eclipse.org/legal/epl-v10.html
008 *
009 * Contributors:
010 *     Florent Guillaume
011 */
012package org.nuxeo.ecm.core.api.pathsegment;
013
014import java.util.LinkedList;
015
016import org.apache.commons.logging.Log;
017import org.apache.commons.logging.LogFactory;
018import org.nuxeo.ecm.core.api.DocumentModel;
019import org.nuxeo.ecm.core.api.NuxeoException;
020import org.nuxeo.runtime.model.ComponentContext;
021import org.nuxeo.runtime.model.ComponentInstance;
022import org.nuxeo.runtime.model.DefaultComponent;
023
024/**
025 * Central service for the generation of a path segment for a document.
026 */
027public class PathSegmentComponent extends DefaultComponent implements PathSegmentService {
028
029    private static final Log log = LogFactory.getLog(PathSegmentComponent.class);
030
031    public static final String XP = "pathSegmentService";
032
033    protected LinkedList<Class<? extends PathSegmentService>> contribs;
034
035    protected PathSegmentService service;
036
037    protected boolean recompute;
038
039    @Override
040    public void activate(ComponentContext context) {
041        contribs = new LinkedList<Class<? extends PathSegmentService>>();
042        recompute = true;
043        service = null;
044    }
045
046    @Override
047    public void deactivate(ComponentContext context) {
048        contribs.clear();
049        service = null;
050    }
051
052    @Override
053    @SuppressWarnings("unchecked")
054    public void registerContribution(Object contrib, String xp, ComponentInstance contributor) {
055        if (!XP.equals(xp)) {
056            log.error("Unknown extension point " + xp);
057            return;
058        }
059        if (!(contrib instanceof PathSegmentServiceDescriptor)) {
060            log.error("Invalid contribution: " + contrib.getClass().getName());
061            return;
062        }
063        PathSegmentServiceDescriptor desc = (PathSegmentServiceDescriptor) contrib;
064        Class<?> klass;
065        try {
066            klass = Class.forName(desc.className);
067        } catch (ClassNotFoundException e) {
068            log.error("Invalid contribution class: " + desc.className);
069            return;
070        }
071        if (!PathSegmentService.class.isAssignableFrom(klass)) {
072            log.error("Invalid contribution class: " + desc.className);
073            return;
074        }
075        contribs.add((Class<PathSegmentService>) klass);
076        log.info("Registered path segment service: " + desc.className);
077        recompute = true;
078    }
079
080    @Override
081    public void unregisterContribution(Object contrib, String xp, ComponentInstance contributor) {
082        if (!XP.equals(xp)) {
083            return;
084        }
085        if (!(contrib instanceof PathSegmentServiceDescriptor)) {
086            return;
087        }
088        PathSegmentServiceDescriptor desc = (PathSegmentServiceDescriptor) contrib;
089        Class<?> klass;
090        try {
091            klass = Class.forName(desc.className);
092        } catch (ClassNotFoundException e) {
093            return;
094        }
095        if (!klass.isAssignableFrom(PathSegmentService.class)) {
096            return;
097        }
098        contribs.remove(klass);
099        log.info("Unregistered path segment service: " + desc.className);
100        recompute = true;
101    }
102
103    @Override
104    public String generatePathSegment(DocumentModel doc) {
105        if (recompute) {
106            recompute();
107            recompute = false;
108        }
109        return service.generatePathSegment(doc);
110    }
111
112    protected void recompute() {
113        Class<? extends PathSegmentService> klass;
114        if (contribs.isEmpty()) {
115            klass = PathSegmentServiceDefault.class;
116        } else {
117            klass = contribs.getLast();
118        }
119        if (service == null || klass != service.getClass()) {
120            try {
121                service = klass.newInstance();
122            } catch (ReflectiveOperationException e) {
123                throw new NuxeoException(e);
124            }
125        } // else keep old service instance
126    }
127
128    @Override
129    public String generatePathSegment(String s) {
130        if (recompute) {
131            recompute();
132            recompute = false;
133        }
134        return service.generatePathSegment(s);
135    }
136
137    @Override
138    public int getMaxSize() {
139        if (recompute) {
140            recompute();
141            recompute = false;
142        }
143        return service.getMaxSize();
144    }
145}