EDIT

/**

 * Copyright (C) 2015 EDIT

 * European Distributed Institute of Taxonomy

 * http://www.e-taxonomy.eu

 *

 * The contents of this file are subject to the Mozilla Public License Version 1.1

 * See LICENSE.TXT at the top of this package for the full license terms.

 */

package eu.etaxonomy.cdm.api.cache;

import java.io.File;

import java.util.UUID;

import org.apache.logging.log4j.LogManager;

import org.apache.logging.log4j.Logger;

import org.springframework.beans.factory.annotation.Autowired;

import eu.etaxonomy.cdm.api.application.CdmApplicationState;

import eu.etaxonomy.cdm.api.config.EhCacheConfiguration;

import eu.etaxonomy.cdm.cache.CacheLoader;

import eu.etaxonomy.cdm.cache.CdmEntityCacheKey;

import eu.etaxonomy.cdm.cache.CdmTransientEntityCacher;

import eu.etaxonomy.cdm.config.ConfigFileUtil;

import eu.etaxonomy.cdm.model.common.CdmBase;

import eu.etaxonomy.cdm.model.term.DefinedTermBase;

import eu.etaxonomy.cdm.model.term.Representation;

import eu.etaxonomy.cdm.model.term.TermBase;

import eu.etaxonomy.taxeditor.service.RemoteInvocationTermCacher;

import eu.etaxonomy.taxeditor.session.CdmEntitySession;

import eu.etaxonomy.taxeditor.session.ICdmEntitySession;

import eu.etaxonomy.taxeditor.session.ICdmEntitySessionManager;

import eu.etaxonomy.taxeditor.session.ICdmEntitySessionManagerObserver;

import net.sf.ehcache.CacheManager;

import net.sf.ehcache.config.CacheConfiguration;

import net.sf.ehcache.config.DiskStoreConfiguration;

import net.sf.ehcache.config.SizeOfPolicyConfiguration;

/**

 * Class which uses CDM services to cache cdm entities

 *

 * FIXME: Currently only handles term entities. It would be

 *        interesting to have a generic method which finds the

 *        correct service to load / cache the entity.

 * TODO by AM: compare with {@link CdmTermCacher} and merge if possible

 *

 * @author cmathew

 */

public class CdmServiceCachingProxy

        extends CdmPermanentCacheBase

        implements ICdmEntitySessionManagerObserver {

    private static final Logger logger = LogManager.getLogger();

    private ICdmEntitySessionManager cdmEntitySessionManager;

    private CdmTransientEntityCacher cdmTransientEntityCacher;

    private CacheLoader cacheLoader;

    //NOTE AM: this is currently not used

    @Autowired

    private ConfigFileUtil configFileUtil = null;

    public CdmServiceCachingProxy() {

        super();

    }

    @Override

    protected void setup() {

        setUpCacheManager();

        DefinedTermBase.setCacher(this);

        CdmTransientEntityCacher.setPermanentCacher(this);

        RemoteInvocationTermCacher.setDefaultCacher(this);

        cacheLoader = new CacheLoader(this);

    }

    private void setUpCacheManager() {

        DiskStoreConfiguration diskStoreConfiguration = new DiskStoreConfiguration();

        File ehcacheFolder = null;

        if(configFileUtil != null){

            try {

                ehcacheFolder = configFileUtil.getCdmHomeSubDir("taxeditor-ehcache");

            } catch (Exception e){

                logger.warn("Cannot determine CdmHomeSubDir for ./taxeditor-ehcache, will use fallback method.", e);

            }

        }

        if(ehcacheFolder == null){

            ehcacheFolder = ConfigFileUtil.getCdmHomeSubDirFallback("taxeditor-ehcache");

        }

        // FIXME use subfolder per taxeditor version to allow running multiple

        //   installations in parallel

        // String taxEditorVersion = ..;

        // File ehcacheFolder = new File(ehcacheFolder, taxEditorVersion);

        diskStoreConfiguration.setPath(ehcacheFolder.getAbsolutePath());

        EhCacheConfiguration cacheConfig = new EhCacheConfiguration();

        cacheConfig.setDiskStoreConfiguration(diskStoreConfiguration);

        CacheManager cacheManager = cacheConfig.cacheManager();

        setCacheManager(cacheManager);

    }

    @Override

    protected CacheConfiguration getPermanentCacheConfiguration() {

        // For a better understanding on how to size caches, refer to

        // http://ehcache.org/documentation/configuration/cache-size

        SizeOfPolicyConfiguration sizeOfConfig = new SizeOfPolicyConfiguration();

        sizeOfConfig.setMaxDepth(100);

        sizeOfConfig.setMaxDepthExceededBehavior("abort");

        return new CacheConfiguration(PERMANENT_CACHE_NAME, 0)

        	.eternal(true)

        	.sizeOfPolicy(sizeOfConfig)

        	.overflowToOffHeap(false);

    }

    @Override

    protected CdmBase findByUuid(UUID uuid) {

        CdmBase term = CdmApplicationState.getCurrentAppConfig().getTermService().findWithoutFlush(uuid);

        return load(term);

    }

    /**

     * <code>true</code> if the parameter is a term or a representation

     */

    @Override

    public boolean isCachable(CdmBase cdmEntity) {

     	if(cdmEntity == null){

     	    return false;

     	}else if (cdmEntity instanceof TermBase || cdmEntity instanceof Representation){

            return true;

        }else{

            return false;

        }

    }

    public void setCdmEntitySessionManager(ICdmEntitySessionManager cdmEntitySessionManager) {

        this.cdmEntitySessionManager = cdmEntitySessionManager;

        if(cdmEntitySessionManager != null) {

            cdmEntitySessionManager.addSessionObserver(this);

        }

    }

    public CdmTransientEntityCacher getCurrentCacher() {

        ICdmEntitySession cdmEntitySession = cdmEntitySessionManager.getActiveSession();

        if(cdmEntitySession != null && cdmEntitySession instanceof CdmEntitySession) {

            return ((CdmEntitySession) cdmEntitySession).getCacher();

        }

        return null;

    }

    @Override

    public <T extends CdmBase> T  getFromCache(T cdmBase) {

        T cachedCdmEntity = null;

        // first we check in the active session cache if the

        // entity has been loaded there

        // FIXME:Remoting do we really need the cdmTransientEntityCacher

        // here. Is it not guaranteed that every entity which 'isCachable'

        // by this cacher is cached only in this cacher ?

        if(!isCachable(cdmBase) && cdmTransientEntityCacher != null) {

            CdmEntityCacheKey<T> key = CdmTransientEntityCacher.generateKey(cdmBase);

            cachedCdmEntity = cdmTransientEntityCacher.getFromCache(key);

        }

        if(cachedCdmEntity == null) {

            cachedCdmEntity = super.getFromCache(cdmBase);

        }

        return cachedCdmEntity;

    }

    @Override

    public <T extends CdmBase> T load(T cdmEntity) {

        @SuppressWarnings("unchecked")

        T cachedCdmEntity = (T)getFromCache(cdmEntity.getUuid());

        if(isCachable(cdmEntity) && cachedCdmEntity == null) {

            cachedCdmEntity = cacheLoader.load(cdmEntity, false, true);

        }

        return cachedCdmEntity;

    }

    @Override

    public void changed() {

        ICdmEntitySession cdmEntitySession = cdmEntitySessionManager.getActiveSession();

        if(cdmEntitySession != null && cdmEntitySession instanceof CdmEntitySession) {

            this.cdmTransientEntityCacher = ((CdmEntitySession) cdmEntitySession).getCacher();

        } else {

            this.cdmTransientEntityCacher = null;

        }

    }

}