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package com.octo.android.robospice.persistence;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;

import roboguice.util.temp.Ln;

import com.octo.android.robospice.persistence.exception.CacheCreationException;
import com.octo.android.robospice.persistence.exception.CacheLoadingException;
import com.octo.android.robospice.persistence.exception.CacheSavingException;

/**
 * An entity responsible for loading/saving data from/to cache. It implements a
 * Chain of Responsibility pattern, delegating loading and saving operations to
 * {@link ObjectPersister} or {@link ObjectPersisterFactory} elements. The chain
 * of responsibility is ordered. This means that the order used to register
 * elements matters. All elements in the chain of responsibility are questioned
 * in order. The first element that can handle a given class for persistence
 * will be used to persist data of this class.
 * @author sni
 */
/*
 * Note to maintainers : concurrency must be taken care of as persister can be
 * created by factories at any time. Thx to Henri Tremblay from EasyMock for
 * peer review and concurrency checks.
 */
@SuppressWarnings("deprecation")
public class CacheManager implements ICacheManager {

    /** The Chain of Responsibility list of all {@link Persister}. */
    private Collection listPersister = new ArrayList();
    private Map>> mapFactoryToPersister = new HashMap>>();

    /** {@inheritDoc} */
    @Override
    public void addPersister(Persister persister) {
        listPersister.add(persister);
        if (persister instanceof ObjectPersisterFactory) {
            // will lead the list to be copied whenever we add a persister to it
            // but there won't be any overhead while iterating through the list.
            mapFactoryToPersister.put((ObjectPersisterFactory) persister, new CopyOnWriteArrayList>());
        } else if (!(persister instanceof ObjectPersister)) {
            throw new RuntimeException(getClass().getSimpleName() + " only supports " + ObjectPersister.class.getSimpleName() + " or " + ObjectPersisterFactory.class.getSimpleName() + " instances.");
        }
    }

    /** {@inheritDoc} */
    @Override
    public void removePersister(Persister persister) {
        listPersister.remove(persister);
        if (persister instanceof ObjectPersisterFactory) {
            mapFactoryToPersister.remove(persister);
        }
    }

    /**
     * {@inheritDoc}
     * @throws CacheCreationException
     */
    @Override
    public  T loadDataFromCache(Class clazz, Object cacheKey, long maxTimeInCacheBeforeExpiry) throws CacheLoadingException, CacheCreationException {
        return getObjectPersister(clazz).loadDataFromCache(cacheKey, maxTimeInCacheBeforeExpiry);
    }

    @Override
    @SuppressWarnings("unchecked")
    /** {@inheritDoc}*/
    public  T saveDataToCacheAndReturnData(T data, Object cacheKey) throws CacheSavingException, CacheCreationException {
        // http://stackoverflow.com/questions/4460580/java-generics-why-someobject-getclass-doesnt-return-class-extends-t
        ObjectPersister classCacheManager = getObjectPersister((Class) data.getClass());
        return classCacheManager.saveDataToCacheAndReturnData(data, cacheKey);
    }

    /**
     * {@inheritDoc}
     * @throws CacheCreationException
     */
    @Override
    public boolean isDataInCache(Class clazz, Object cacheKey, long maxTimeInCacheBeforeExpiry) throws CacheCreationException {
        return getObjectPersister(clazz).isDataInCache(cacheKey, maxTimeInCacheBeforeExpiry);
    }

    /**
     * {@inheritDoc}
     * @throws CacheLoadingException
     * @throws CacheCreationException
     */
    @Override
    public Date getDateOfDataInCache(Class clazz, Object cacheKey) throws CacheLoadingException, CacheCreationException {
        return new Date(getObjectPersister(clazz).getCreationDateInCache(cacheKey));
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean removeDataFromCache(Class clazz, Object cacheKey) {
        try {
            return getObjectPersister(clazz).removeDataFromCache(cacheKey);
        } catch (CacheCreationException e) {
            Ln.e(e);
            return false;
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void removeAllDataFromCache(Class clazz) {
        try {
            getObjectPersister(clazz).removeAllDataFromCache();
        } catch (CacheCreationException e) {
            Ln.e(e);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public  List