/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.apache.cxf.sts.cache;

import java.io.Closeable;
import java.io.IOException;
import java.net.URL;
import java.security.Principal;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.management.JMException;
import javax.management.ObjectName;

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.config.CacheConfiguration;

import org.apache.cxf.Bus;
import org.apache.cxf.buslifecycle.BusLifeCycleListener;
import org.apache.cxf.buslifecycle.BusLifeCycleManager;
import org.apache.cxf.common.classloader.ClassLoaderUtils;
import org.apache.cxf.common.logging.LogUtils;
import org.apache.cxf.management.InstrumentationManager;
import org.apache.cxf.management.ManagedComponent;
import org.apache.cxf.management.ManagementConstants;
import org.apache.cxf.management.annotation.ManagedOperation;
import org.apache.cxf.management.annotation.ManagedResource;
import org.apache.cxf.resource.ResourceManager;
import org.apache.cxf.sts.IdentityMapper;
import org.apache.cxf.ws.security.cache.EHCacheManagerHolder;
import org.apache.cxf.ws.security.tokenstore.TokenStoreFactory;
import org.apache.ws.security.CustomTokenPrincipal;

/**
 * A EH-Cache based cache to cache identities in different realms where
 * the relationship is of type FederateIdentity.
 */
@ManagedResource()
public class EHCacheIdentityCache 
    implements IdentityCache, IdentityMapper, Closeable, BusLifeCycleListener, ManagedComponent {
    
    private static final Logger LOG = LogUtils.getL7dLogger(EHCacheIdentityCache.class);
    
    private IdentityMapper identityMapper;
    private MemoryIdentityCacheStatistics statistics;
    private Ehcache cache;
    private Bus bus;
    private CacheManager cacheManager;
    
    
    public EHCacheIdentityCache(
        IdentityMapper identityMapper, Bus b
    ) {
        this(identityMapper, EHCacheIdentityCache.class.getName(), b, null);
    }
    
    public EHCacheIdentityCache(
        IdentityMapper identityMapper, String key, Bus b, URL configFileURL
    ) {
        this.identityMapper = identityMapper;
        
        bus = b;
        if (bus != null) {
            b.getExtension(BusLifeCycleManager.class).registerLifeCycleListener(this);
            InstrumentationManager im = b.getExtension(InstrumentationManager.class);
            if (im != null) {
                try {
                    im.register(this);
                } catch (JMException e) {
                    LOG.log(Level.WARNING, "Registering EHCacheIdentityCache failed.", e);
                }
            }
        }

        if (configFileURL != null) {
            cacheManager = EHCacheManagerHolder.getCacheManager(bus, configFileURL);
        } else {
            cacheManager = EHCacheManagerHolder.getCacheManager(bus, getDefaultConfigFileURL());
        }
        CacheConfiguration cc = EHCacheManagerHolder.getCacheConfiguration(key, cacheManager);
        
        Ehcache newCache = new Cache(cc);
        cache = cacheManager.addCacheIfAbsent(newCache);
    }
    
    public MemoryIdentityCacheStatistics getStatistics() {
        
        if (statistics == null) {
            this.statistics = new MemoryIdentityCacheStatistics(bus, this);
        }
        return statistics;
    }

    public void setStatistics(MemoryIdentityCacheStatistics stats) {
        this.statistics = stats;
    }

    @Override
    public void add(String user, String realm, Map<String, String> identities) {
        cache.put(new Element(user + "@" + realm, identities));
    }

    @SuppressWarnings("unchecked")
    @ManagedOperation()
    @Override
    public Map<String, String> get(String user, String realm) {
        Element element = cache.get(user + "@" + realm);
        if (element != null && !cache.isExpired(element)) {
            return (Map<String, String>)element.getObjectValue();
        }
        return null;
    }

    @Override
    public void remove(String user, String realm) {
        cache.remove(user + "@" + realm);       
    }
    
    @ManagedOperation()
    @Override
    public void clear() {
        cache.removeAll();
    }
    
    @ManagedOperation()
    @Override
    public int size() {
        return cache.getSize();
    }
    
    @ManagedOperation()
    public String getContent() {
        return this.cache.toString();
    }

    @Override
    public Principal mapPrincipal(String sourceRealm,
            Principal sourcePrincipal, String targetRealm) {
        
        Principal targetPrincipal = null;
        Map<String, String> identities = this.get(sourcePrincipal.getName(), sourceRealm);
        if (identities != null) {
            if (LOG.isLoggable(Level.FINE)) {
                LOG.fine("Identities found for '" + sourcePrincipal.getName() + "@" + sourceRealm + "'");
            }
            // Identities object found for key sourceUser@sourceRealm
            String targetUser = identities.get(targetRealm);
            if (targetUser == null) {
                getStatistics().increaseCacheMiss();
                if (LOG.isLoggable(Level.FINE)) {
                    LOG.fine("No mapping found for realm " + targetRealm + " of user '"
                             + sourcePrincipal.getName() + "@" + sourceRealm + "'");
                }
                // User identity of target realm not cached yet
                targetPrincipal = this.identityMapper.mapPrincipal(
                        sourceRealm, sourcePrincipal, targetRealm);
                // Add the identity for target realm to the cached entry 
                identities.put(targetRealm, targetPrincipal.getName());
                
                // Verify whether target user has cached some identities already
                Map<String, String> cachedItem = this.get(targetPrincipal.getName(), targetRealm);
                if (cachedItem != null) {
                    if (LOG.isLoggable(Level.FINE)) {
                        LOG.fine("Merging mappings for '" + sourcePrincipal.getName() + "@" + sourceRealm + "'");
                    }
                    //Identites already cached for targetUser@targetRealm key pair
                    //Merge into identities object
                    this.mergeMap(identities, cachedItem);
                }
                this.add(targetPrincipal.getName(), targetRealm, identities);
            } else {
                getStatistics().increaseCacheHit();
                if (LOG.isLoggable(Level.INFO)) {
                    LOG.info("Mapping '" + sourcePrincipal.getName() + "@" + sourceRealm + "' to '"
                             + targetUser + "@" + targetRealm + "' cached");
                }
                targetPrincipal = new CustomTokenPrincipal(targetUser);
            }
            
        } else {
            if (LOG.isLoggable(Level.FINE)) {
                LOG.fine("No mapping found for realm " + targetRealm + " of user '"
                        + sourcePrincipal.getName() + "@" + sourceRealm + "'");
            }
            getStatistics().increaseCacheMiss();
            
            // Identities object NOT found for key sourceUser@sourceRealm
            targetPrincipal = this.identityMapper.mapPrincipal(
                    sourceRealm, sourcePrincipal, targetRealm);
            identities = new HashMap<String, String>();
            identities.put(sourceRealm, sourcePrincipal.getName());
            identities.put(targetRealm, targetPrincipal.getName());
            this.add(targetPrincipal.getName(), targetRealm, identities);
            this.add(sourcePrincipal.getName(), sourceRealm, identities);
        }
        return targetPrincipal;
    }
    
    
    
    private void mergeMap(Map<String, String> to, Map<String, String> from) {
        for (String key : from.keySet()) {
            to.put(key, from.get(key));
        }
        for (String key : to.keySet()) {
            from.put(key, to.get(key));
        }
    }
    
    public void close() {
        if (cacheManager != null) {
            // this step is especially important for global shared cache manager
            if (cache != null) {
                cacheManager.removeCache(cache.getName());
            }

            EHCacheManagerHolder.releaseCacheManger(cacheManager);
            cacheManager = null;
            cache = null;
            if (bus != null) {
                bus.getExtension(BusLifeCycleManager.class).unregisterLifeCycleListener(this);
            }
        }
    }

    public void initComplete() {
    }

    public void preShutdown() {
        close();
    }

    public void postShutdown() {
        close();
    }
    
    private URL getDefaultConfigFileURL() {
        URL url = null;
        ResourceManager rm = bus.getExtension(ResourceManager.class);
        url = rm.resolveResource("sts-ehcache.xml", URL.class);
        try {
            if (url == null) {
                url = ClassLoaderUtils.getResource("sts-ehcache.xml", TokenStoreFactory.class);
            }
            if (url == null) {
                url = new URL("sts-ehcache.xml");
            }
            return url;
        } catch (IOException e) {
            // Do nothing
        }
        return null;
    }

    public ObjectName getObjectName() throws JMException {
        StringBuilder buffer = new StringBuilder();
        buffer.append(ManagementConstants.DEFAULT_DOMAIN_NAME).append(':');
        buffer.append(ManagementConstants.BUS_ID_PROP).append('=').append(bus.getId()).append(',');
        buffer.append(ManagementConstants.TYPE_PROP).append('=').append("EHCacheIdentityCache").append(',');
        buffer.append(ManagementConstants.NAME_PROP).append('=')
            .append("EHCacheIdentityCache-" + System.identityHashCode(this));
        return new ObjectName(buffer.toString());
    }
}

