/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat, Inc. and/or its affiliates or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat, Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.search.impl;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.util.Version;
import org.apache.solr.analysis.CharFilterFactory;
import org.apache.solr.analysis.TokenFilterFactory;
import org.apache.solr.analysis.TokenizerChain;
import org.apache.solr.analysis.TokenizerFactory;
import org.apache.solr.common.ResourceLoader;
import org.apache.solr.util.plugin.ResourceLoaderAware;

import org.hibernate.search.Environment;
import org.hibernate.search.annotations.AnalyzerDef;
import org.hibernate.search.annotations.CharFilterDef;
import org.hibernate.search.annotations.Parameter;
import org.hibernate.search.annotations.TokenFilterDef;
import org.hibernate.search.annotations.TokenizerDef;
import org.hibernate.search.util.impl.HibernateSearchResourceLoader;

import static org.hibernate.search.util.impl.ClassLoaderHelper.instanceFromClass;

/**
 * Instances of this class are used to build Lucene analyzers which are defined using the solr <code>TokenFilterFactory</code>.
 * To make the dependency to the solr framework optional only this class has direct dependencies to solr. Solr dependencies
 * are not supposed to be used anywhere else (except the actual configuration of the analyzers in the domain model).
 *
 * @author Emmanuel Bernard
 * @author Hardy Ferentschik
 */
final class SolrAnalyzerBuilder {
	private static final String SOLR_LUCENE_VERSION_PARAM = "luceneMatchVersion";

	private SolrAnalyzerBuilder() {
	}

	/**
	 * Builds a Lucene <code>Analyzer</code> from the specified <code>AnalyzerDef</code> annotation.
	 *
	 * @param analyzerDef The <code>AnalyzerDef</code> annotation as found in the annotated domain class.
	 * @param luceneMatchVersion The lucene version (required since Lucene 3.x)
	 * @return a Lucene <code>Analyzer</code>
	 */
	public static Analyzer buildAnalyzer(AnalyzerDef analyzerDef, Version luceneMatchVersion) {
		ResourceLoader defaultResourceLoader = new HibernateSearchResourceLoader();
		TokenizerDef token = analyzerDef.tokenizer();
		TokenizerFactory tokenFactory = instanceFromClass( TokenizerFactory.class, token.factory(), "Tokenizer factory" );
		final Map<String, String> tokenMapsOfParameters = getMapOfParameters( token.params(), luceneMatchVersion );
		tokenFactory.init( tokenMapsOfParameters );
		injectResourceLoader( tokenFactory, defaultResourceLoader, tokenMapsOfParameters );

		final int length = analyzerDef.filters().length;
		final int charLength = analyzerDef.charFilters().length;
		TokenFilterFactory[] filters = new TokenFilterFactory[length];
		CharFilterFactory[] charFilters = new CharFilterFactory[charLength];
		for ( int index = 0; index < length; index++ ) {
			TokenFilterDef filterDef = analyzerDef.filters()[index];
			filters[index] = instanceFromClass( TokenFilterFactory.class, filterDef.factory(), "Token filter factory" );
			final Map<String, String> mapOfParameters = getMapOfParameters( filterDef.params(), luceneMatchVersion );
			filters[index].init( mapOfParameters );
			injectResourceLoader( filters[index], defaultResourceLoader, mapOfParameters );
		}
		for ( int index = 0; index < charFilters.length; index++ ) {
			CharFilterDef charFilterDef = analyzerDef.charFilters()[index];
			charFilters[index] = instanceFromClass( CharFilterFactory.class, charFilterDef.factory(), "Character filter factory" );
			final Map<String, String> mapOfParameters = getMapOfParameters(
					charFilterDef.params(), luceneMatchVersion
			);
			charFilters[index].init( mapOfParameters );
			injectResourceLoader( charFilters[index], defaultResourceLoader, mapOfParameters );
		}
		return new TokenizerChain( charFilters, tokenFactory, filters );
	}

	private static void injectResourceLoader(Object processor, ResourceLoader defaultResourceLoader, Map<String, String> mapOfParameters) {
		if ( processor instanceof ResourceLoaderAware ) {
			String charset = mapOfParameters.get( Environment.RESOURCE_CHARSET );
			final ResourceLoader localResourceLoader;
			if ( charset != null ) {
				localResourceLoader = new HibernateSearchResourceLoader( charset );
			}
			else {
				localResourceLoader = defaultResourceLoader;
			}
			( ( ResourceLoaderAware ) processor ).inform( localResourceLoader );
		}
	}

	private static Map<String, String> getMapOfParameters(Parameter[] params, Version luceneMatchVersion) {
		Map<String, String> mapOfParams = new HashMap<String, String>( params.length );
		for ( Parameter param : params ) {
			mapOfParams.put( param.name(), param.value() );
		}
		mapOfParams.put( SOLR_LUCENE_VERSION_PARAM, luceneMatchVersion.toString() );
		return Collections.unmodifiableMap( mapOfParams );
	}
}