/*****************************************************************/
/* Copyright 2013 Code Strategies                                */
/* This code may be freely used and distributed in any project.  */
/* However, please do not remove this credit if you publish this */
/* code in paper or electronic form, such as on a web site.      */
/*****************************************************************/

package avajava;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.Iterator;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Hit;
import org.apache.lucene.search.Hits;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.PhraseQuery;
import org.apache.lucene.search.Query;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.store.LockObtainFailedException;

public class LucenePhraseQueryDemo {

	public static final String FILES_TO_INDEX_DIRECTORY = "filesToIndex";
	public static final String INDEX_DIRECTORY = "indexDirectory";

	public static final String FIELD_PATH = "path";
	public static final String FIELD_CONTENTS = "contents";

	public static void main(String[] args) throws Exception {

		createIndex();

		searchIndexWithPhraseQuery("french", "fries", 0);
		searchIndexWithPhraseQuery("hamburger", "steak", 0);
		searchIndexWithPhraseQuery("hamburger", "steak", 1);
		searchIndexWithPhraseQuery("hamburger", "steak", 2);
		searchIndexWithPhraseQuery("hamburger", "steak", 3);

		searchIndexWithQueryParser("french fries"); // BooleanQuery
		searchIndexWithQueryParser("\"french fries\""); // PhaseQuery
		searchIndexWithQueryParser("\"hamburger steak\"~1"); // PhaseQuery
		searchIndexWithQueryParser("\"hamburger steak\"~2"); // PhaseQuery

	}

	public static void createIndex() throws CorruptIndexException, LockObtainFailedException, IOException {
		Analyzer analyzer = new StandardAnalyzer();
		boolean recreateIndexIfExists = true;
		IndexWriter indexWriter = new IndexWriter(INDEX_DIRECTORY, analyzer, recreateIndexIfExists);
		File dir = new File(FILES_TO_INDEX_DIRECTORY);
		File[] files = dir.listFiles();
		for (File file : files) {
			Document document = new Document();

			String path = file.getCanonicalPath();
			document.add(new Field(FIELD_PATH, path, Field.Store.YES, Field.Index.UN_TOKENIZED));

			Reader reader = new FileReader(file);
			document.add(new Field(FIELD_CONTENTS, reader));

			indexWriter.addDocument(document);
		}
		indexWriter.optimize();
		indexWriter.close();
	}

	public static void searchIndexWithQueryParser(String searchString) throws IOException, ParseException {
		System.out.println("Searching for '" + searchString + "' using QueryParser");
		Directory directory = FSDirectory.getDirectory(INDEX_DIRECTORY);
		IndexSearcher indexSearcher = new IndexSearcher(directory);

		QueryParser queryParser = new QueryParser(FIELD_CONTENTS, new StandardAnalyzer());
		Query query = queryParser.parse(searchString);
		System.out.println("Type of query: " + query.getClass().getSimpleName());
		displayQuery(query);
		Hits hits = indexSearcher.search(query);
		displayHits(hits);
	}

	public static void searchIndexWithPhraseQuery(String string1, String string2, int slop) throws IOException,
			ParseException {
		Directory directory = FSDirectory.getDirectory(INDEX_DIRECTORY);
		IndexSearcher indexSearcher = new IndexSearcher(directory);

		Term term1 = new Term(FIELD_CONTENTS, string1);
		Term term2 = new Term(FIELD_CONTENTS, string2);
		PhraseQuery phraseQuery = new PhraseQuery();
		phraseQuery.add(term1);
		phraseQuery.add(term2);
		phraseQuery.setSlop(slop);
		displayQuery(phraseQuery);
		Hits hits = indexSearcher.search(phraseQuery);
		displayHits(hits);
	}

	public static void displayHits(Hits hits) throws CorruptIndexException, IOException {
		System.out.println("Number of hits: " + hits.length());

		Iterator<Hit> it = hits.iterator();
		while (it.hasNext()) {
			Hit hit = it.next();
			Document document = hit.getDocument();
			String path = document.get(FIELD_PATH);
			System.out.println("Hit: " + path);
		}
		System.out.println();
	}

	public static void displayQuery(Query query) {
		System.out.println("Query: " + query.toString());
	}

}