//$Id: CacheFactory.java,v 1.5 2005/02/12 07:19:08 steveebersole Exp $
package org.hibernate.cache;

import java.util.Properties;

import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.cfg.Settings;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * @author Gavin King
 */
public final class CacheFactory {
	
	private static final Log log = LogFactory.getLog(CacheFactory.class);
	
	private CacheFactory() {}
	
	public static final String READ_ONLY = "read-only";
	public static final String READ_WRITE = "read-write";
	public static final String NONSTRICT_READ_WRITE = "nonstrict-read-write";
	public static final String TRANSACTIONAL = "transactional";
	
	public static CacheConcurrencyStrategy createCache(
		final String concurrencyStrategy, 
		String regionName, 
		final boolean mutable, 
		final Settings settings,
		final Properties properties) 
	throws HibernateException {
		
		if ( concurrencyStrategy==null || !settings.isSecondLevelCacheEnabled() ) return null; //no cache
		
		String prefix = settings.getCacheRegionPrefix();
		if ( prefix!=null ) regionName = prefix + '.' + regionName;
		
		if ( log.isDebugEnabled() ) log.debug("instantiating cache region: " + regionName + " usage strategy: " + concurrencyStrategy);
		
		final CacheConcurrencyStrategy ccs;
		if ( concurrencyStrategy.equals(READ_ONLY) ) {
			if (mutable) log.warn( "read-only cache configured for mutable class: " + regionName );
			ccs = new ReadOnlyCache();
		}
		else if ( concurrencyStrategy.equals(READ_WRITE) ) {
			ccs = new ReadWriteCache();
		}
		else if ( concurrencyStrategy.equals(NONSTRICT_READ_WRITE) ) {
			ccs = new NonstrictReadWriteCache();
		}
		else if ( concurrencyStrategy.equals(TRANSACTIONAL) ) {
			ccs = new TransactionalCache();
		}
		else {
			throw new MappingException("cache usage attribute should be read-write, read-only, nonstrict-read-write or transactional");
		}
		
		final Cache impl;
		try {
			impl = settings.getCacheProvider().buildCache(regionName, properties);
		}
		catch (CacheException e) {
			throw new HibernateException( "Could not instantiate cache implementation", e );
		}
		ccs.setCache(impl);
		
		return ccs;
	}
		
}
