EDIT

/**

* Copyright (C) 2017 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.cache;

import java.beans.PropertyDescriptor;

import java.io.PrintStream;

import java.lang.reflect.InvocationTargetException;

import java.util.ArrayList;

import java.util.Collection;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import org.apache.commons.beanutils.BeanUtilsBean;

import org.apache.commons.beanutils.PropertyUtils;

import org.apache.commons.beanutils.PropertyUtilsBean;

import org.apache.commons.lang.builder.HashCodeBuilder;

import org.apache.log4j.Logger;

import org.hibernate.Hibernate;

import org.hibernate.collection.internal.AbstractPersistentCollection;

import org.hibernate.envers.internal.entities.mapper.relation.lazy.proxy.CollectionProxy;

import org.hibernate.envers.internal.entities.mapper.relation.lazy.proxy.MapProxy;

import org.hibernate.envers.internal.entities.mapper.relation.lazy.proxy.SortedMapProxy;

import eu.etaxonomy.cdm.hibernate.HibernateProxyHelper;

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

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

import eu.etaxonomy.cdm.model.reference.INomenclaturalReference;

import eu.etaxonomy.cdm.persistence.dao.initializer.AbstractBeanInitializer;

/**

 * @author a.kohlbecker

 * @since 08.11.2017

 *

 */

public class CdmEntityCache implements EntityCache {

    private final static Logger logger = Logger.getLogger(CdmEntityCache.class);

    protected static final String COPY_ENTITY = "!";

    protected Set<CdmBase> entities = new HashSet<>();

    private Map<EntityKey, CdmBase> entityyMap = new HashMap<>();

    private List<String> entityPathList = new ArrayList<>();

    private Map<EntityKey, List<String>> entityPathsMap = new HashMap<>();

    private Set<EntityKey> copyEntitiyKeys = new HashSet<>();

    private Set<Object> objectsSeen = new HashSet<>();

    protected CdmEntityCache(){

    }

    /**

     * @param entity the first entity to be cached. can be <code>null</code>.

     *      Further entities can be added to the cache with {@link CdmEntityCache#add(CdmBase)}

     */

    public CdmEntityCache(CdmBase entity){

        if(entity != null){

            this.entities.add(entity);

            update();

        }

    }

    @Override

    public boolean update() {

        entityPathList.clear();

        entityPathsMap.clear();

        objectsSeen.clear();

        copyEntitiyKeys.clear();

        for(CdmBase entity : entities){

            analyzeEntity(entity, "");

        }

        return copyEntitiyKeys.isEmpty();

    }

    /**

     *

     */

    protected void analyzeEntity(CdmBase bean, String propertyPath) {

        if(bean == null){

            return;

        }

        CdmBase proxyBean = bean;

        bean = HibernateProxyHelper.deproxy(proxyBean, CdmBase.class);

        EntityKey entityKey = new EntityKey(bean);

        propertyPath += "[" + entityKey;

        String flags = "";

        CdmBase mappedEntity = entityyMap.put(entityKey, proxyBean);

        if(mappedEntity != null && mappedEntity != bean) {

            copyEntitiyKeys.add(entityKey);

            flags += COPY_ENTITY + bean.hashCode();

        }

        flags = analyzeMore(bean, entityKey, flags, mappedEntity);

        if(!flags.isEmpty()){

            propertyPath += "(" + flags + ")";

        }

        propertyPath += "]";

        logger.debug(propertyPath);

        entityPathList.add(propertyPath);

        if(!entityPathsMap.containsKey(entityKey)){

            entityPathsMap.put(entityKey, new ArrayList<>());

        }

        entityPathsMap.get(entityKey).add(propertyPath);

        if(!objectsSeen.add(bean)){

            // avoid cycles, do not recurse into properties of objects that have been analyzed already

            return;

        }

        Set<PropertyDescriptor> properties = AbstractBeanInitializer.getProperties(bean, null);

        for(PropertyDescriptor prop : properties){

            try {

                Object propertyValue = PropertyUtils.getProperty(bean, prop.getName());

                if(propertyValue == null){

                    continue;

                }

                String propertyPathSuffix = "." + prop.getName();

                logger.debug("\t\tproperty:" + propertyPathSuffix);

                if(Hibernate.isInitialized(propertyValue)) {

                    if(CdmBase.class.isAssignableFrom(prop.getPropertyType())

                            || INomenclaturalReference.class.equals(prop.getPropertyType())

                            ){

                        analyzeEntity(HibernateProxyHelper.deproxy(propertyValue, CdmBase.class), propertyPath + propertyPathSuffix);

                        continue;

                    }

                    Collection<CdmBase> collection = null;

                    if(propertyValue instanceof AbstractPersistentCollection){

                        if (propertyValue  instanceof Collection) {

                            collection = (Collection<CdmBase>) propertyValue;

                        } else if (propertyValue instanceof Map) {

                            collection = ((Map<?,CdmBase>)propertyValue).values();

                        } else {

                            logger.error("unhandled subtype of AbstractPersistentCollection");

                        }

                    } else if (propertyValue instanceof CollectionProxy

                                || propertyValue instanceof MapProxy<?, ?>

                                || propertyValue instanceof SortedMapProxy<?, ?>){

                            //hibernate envers collections

                            // FIXME this won't work!!!!

                            collection = (Collection<CdmBase>)propertyValue;

                    }

                    if(collection != null){

                        for(CdmBase collectionItem : collection){

                            analyzeEntity(HibernateProxyHelper.deproxy(collectionItem, CdmBase.class), propertyPath + propertyPathSuffix);

                        }

                    } else {

                        // logger.error("Unhandled property type " + propertyValue.getClass().getName());

                    }

                }

            } catch (IllegalAccessException e) {

                String message = "Illegal access on property " + prop;

                logger.error(message);

                throw new RuntimeException(message, e);

            } catch (InvocationTargetException e) {

                String message = "Cannot invoke property " + prop + " not found";

                logger.error(message);

                throw new RuntimeException(message, e);

            } catch (NoSuchMethodException e) {

                String message = "Property " + prop.getName() + " not found for class " + bean.getClass();

                logger.error(message);

            }

        }

    }

    /**

     * Empty method which can be implemented by subclasses which do further analysis.

     *

     * @param bean

     * @param entityKey

     * @param flags

     * @param mappedEntity

     * @return

     */

    protected String analyzeMore(CdmBase bean, EntityKey entityKey, String flags, CdmBase mappedEntity) {

        return flags;

    }

    public void printEntityGraph(PrintStream printStream){

        printLegend(printStream);

        for(String path : entityPathList) {

            printStream.println(path);

        }

    }

    public void printCopyEntities(PrintStream printStream){

        printStream.println("-------------- Copy Entities --------------");

        printLegend(printStream);

        for(EntityKey key : copyEntitiyKeys){

            for(String path : entityPathsMap.get(key)) {

                printStream.println(path);

            }

        }

    }

    /**

     * @param printStream

     */

    protected void printLegend(PrintStream printStream) {

        printStream.println(this.getClass().getSimpleName() + " legend: ");

        printStream.println("    - '!{objectHash}': detected copy entity, followed by object hash");

    }

    public class EntityKey {

        Class type;

        int id;

        public EntityKey(Class type, int id){

            this.type = type;

            this.id = id;

        }

        public EntityKey(CdmBase entity){

            type = entity.getClass();

            id = entity.getId();

        }

        /**

         * @return the type

         */

        public Class getType() {

            return type;

        }

        /**

         * @return the id

         */

        public int getId() {

            return id;

        }

        /**

         * {@inheritDoc}

         */

        @Override

        public int hashCode() {

            return new HashCodeBuilder(15, 33)

                    .append(type)

                    .append(id)

                    .toHashCode();

        }

        @Override

        public boolean equals(Object obj) {

            EntityKey other = (EntityKey)obj;

            return this.id == other.id && this.type == other.type;

        }

        @Override

        public String toString() {

            return type.getSimpleName() + "#" + getId();

        }

    }

    /**

     *

     * @return the entities in this cache

     */

    public Set<CdmBase> getEntities(){

        return entities;

    }

    /**

     * {@inheritDoc}

     * <p>

     * In case the cached bean is a HibernateProxy it will be unproxied

     * before returning it.

     */

    @Override

    public <CDM extends CdmBase> CDM find(CDM value) {

        if(value != null){

            EntityKey entityKey = new EntityKey(HibernateProxyHelper.deproxy(value));

            CDM cachedBean = (CDM) entityyMap.get(entityKey);

            if(cachedBean != null){

                return (CDM) HibernateProxyHelper.deproxy(cachedBean, CdmBase.class);

            }

        }

        return null;

    }

    private <CDM extends CdmBase> CDM findProxy(CDM value) {

        if(value != null){

            EntityKey entityKey = new EntityKey(HibernateProxyHelper.deproxy(value));

            return (CDM) entityyMap.get(entityKey);

        }

        return null;

    }

    /**

     * {@inheritDoc}

     * <p>

     * In case the cached bean is a HibernateProxy it will be unproxied

     * before returning it.

     */

    @Override

    public <CDM extends CdmBase> CDM find(Class<CDM> type, int id) {

        EntityKey entityKey = new EntityKey(type, id);

        CDM cachedBean = (CDM) entityyMap.get(entityKey);

        if(cachedBean != null){

            return (CDM) HibernateProxyHelper.deproxy(cachedBean, CdmBase.class);

        }

        return null;

    }

    @Override

    public <CDM extends CdmBase> CDM findAndUpdate(CDM value){

        CDM cachedBean = findProxy(value);

        if(cachedBean != null && VersionableEntity.class.isAssignableFrom(cachedBean.getClass())){

            updatedCachedIfEarlier((VersionableEntity)cachedBean, (VersionableEntity)value);

        }

        if(cachedBean != null){

            return (CDM) HibernateProxyHelper.deproxy(cachedBean, CdmBase.class);

        }

        return null;

    }

    /**

     * @param cachedValue

     * @param value

     */

    private <CDM extends VersionableEntity> void updatedCachedIfEarlier(CDM cachedValue, CDM value) {

       if(cachedValue != null && value != null && value.getUpdated() != null){

           if(cachedValue.getUpdated() == null || value.getUpdated().isAfter(cachedValue.getUpdated())){

               try {

                copyProperties(cachedValue, value);

            } catch (IllegalAccessException e) {

                /* should never happen */

                e.printStackTrace();

            } catch (InvocationTargetException e) {

                /* critical! re-throw as runtime exception, which is ok in the context of a vaadin app */

                throw new RuntimeException(e);

            }

           }

       }

    }

    /**

     * partially copy of {@link BeanUtilsBean#copyProperties(Object, Object)}

     */

    private <CDM extends VersionableEntity> void copyProperties(CDM dest, CDM orig) throws IllegalAccessException, InvocationTargetException {

        PropertyUtilsBean propertyUtils = BeanUtilsBean.getInstance().getPropertyUtils();

        PropertyDescriptor[] origDescriptors =

                propertyUtils.getPropertyDescriptors(orig);

            for (int i = 0; i < origDescriptors.length; i++) {

                String name = origDescriptors[i].getName();

                if ("class".equals(name)) {

                    continue; // No point in trying to set an object's class

                }

                if (propertyUtils.isReadable(orig, name) &&

                        propertyUtils.isWriteable(dest, name)) {

                    try {

                        if(CdmBase.class.isAssignableFrom(propertyUtils.getPropertyType(dest, name))){

                            CdmBase origValue = (CdmBase)propertyUtils.getSimpleProperty(orig, name);

                            if(!Hibernate.isInitialized(origValue)){

                                // ignore uninitialized entities

                                continue;

                            }

                            // only copy entities if origValue either is a completely different entity (A)

                            // or if origValue is updated (B).

                            CdmBase destValue = (CdmBase)propertyUtils.getSimpleProperty(dest, name);

                            if(destValue == null && origValue == null){

                                continue;

                            }

                            if(

                                    origValue != null && destValue == null ||

                                    origValue == null && destValue != null ||

                                    origValue.getId() != destValue.getId() ||

                                    origValue.getClass() != destValue.getClass() ||

                                    origValue.getUuid() != destValue.getUuid()){

                                // (A)

                                BeanUtilsBean.getInstance().copyProperty(dest, name, origValue);

                            } else {

                                // (B) recurse into findAndUpdate

                                findAndUpdate(origValue);

                            }

                        } else {

                                Object value = propertyUtils.getSimpleProperty(orig, name);

                                BeanUtilsBean.getInstance().copyProperty(dest, name, value);

                        }

                    } catch (NoSuchMethodException e) {

                        // Should not happen

                    }

                }

            }

    }

    /**

     * {@inheritDoc}

     */

    @Override

    public <CDM extends CdmBase> void add(CDM value) {

        entities.add(value);

        analyzeEntity(value, "");

    }

}