import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.*;
import org.apache.lucene.store.FSDirectory;

import java.io.File;
import java.io.IOException;

public class TestMultiSearcher {

    public static void main(String[] args) throws IOException, ParseException {

        //creating file's for the FSDirectories
        File a = new File(System.getProperty("user.home"), "indexStoreA");
        File b = new File(System.getProperty("user.home"), "indexStoreB");

        //creating two directories for indices
        FSDirectory indexStoreA = FSDirectory.getDirectory(a, true);
        FSDirectory indexStoreB = FSDirectory.getDirectory(b, true);

        //creating a document to store
        Document lDoc = new Document();
        lDoc.add(Field.Text("fulltext", "Once upon a time....."));
        lDoc.add(Field.Keyword("id", "doc1"));
        lDoc.add(Field.Keyword("handle", "1"));

        //creating a document to store
        Document lDoc2 = new Document();
        lDoc2.add(Field.Text("fulltext", "in a galaxy far far away....."));
        lDoc2.add(Field.Keyword("id", "doc2"));
        lDoc2.add(Field.Keyword("handle", "1"));

        //creating a document to store
        Document lDoc3 = new Document();
        lDoc3.add(Field.Text("fulltext", "a bizarre bug manifested itself...."));
        lDoc3.add(Field.Keyword("id", "doc3"));
        lDoc3.add(Field.Keyword("handle", "1"));

        //creating an index writer for the first index
        IndexWriter writerA = new IndexWriter(indexStoreA, new StandardAnalyzer(), true);
        //creating an index writer for the second index, but writing nothing
        IndexWriter writerB = new IndexWriter(indexStoreB, new StandardAnalyzer(), true);

        //writing the documents to the first index
        writerA.addDocument(lDoc);
        writerA.addDocument(lDoc2);
        writerA.addDocument(lDoc3);
        writerA.close();
        writerA.optimize();

        //closing the second index
        writerB.close();

        //creating the query
        Query query = QueryParser.parse("handle:1", "fulltext", new StandardAnalyzer());



        //bulding the searchables
        Searcher[] searchers = new Searcher[2];
        //VITAL STEP:adding the searcher for the empty index first, before the searcher for the populated index
        searchers[0] = new IndexSearcher(indexStoreB);
        searchers[1] = new IndexSearcher(indexStoreA);
        //creating the mulitSearcher
        Searcher mSearcher = new MultiSearcher(searchers);
        //performing the search
        Hits hits = mSearcher.search(query);
        try {
            //iterating over the hit documents
            for (int i = 0; i < hits.length(); i++) {
                //false ArrayIndexOutOfBounds should happen at this point
                Document d = null;
                    d = hits.doc(i);
            }
        } catch (ArrayIndexOutOfBoundsException e) {
            e.printStackTrace(System.err);
            System.err.print("\n");
        } finally{
            mSearcher.close();
        }




        //adding one document to the empty index
        writerB = new IndexWriter(indexStoreB, new StandardAnalyzer(), false);
        writerB.addDocument(lDoc);
        writerB.optimize();
        writerB.close();


        //bulding the searchables
        Searcher[] searchers2 = new Searcher[2];
        //VITAL STEP:adding the searcher for the empty index first, before the searcher for the populated index
        searchers2[0] = new IndexSearcher(indexStoreB);
        searchers2[1] = new IndexSearcher(indexStoreA);
        //creating the mulitSearcher
        Searcher mSearcher2 = new MultiSearcher(searchers2);
        //performing same the search
        Hits hits2 = mSearcher2.search(query);
        try {
            //iterating over the hit documents
            for (int i = 0; i < hits2.length(); i++) {
                //no exceptoin should happen at this point
                Document d = null;
                    d = hits2.doc(i);
            }
        } catch (Exception e) {
            e.printStackTrace(System.err);
            System.err.print("\n");
        } finally{
            mSearcher2.close();
        }


        //deleting the document just added, this will cause a different exception to take place
        Term term = new Term("id", "doc1");
        IndexReader readerB = IndexReader.open(indexStoreB);
        readerB.delete(term);
        readerB.close();

        //optimizing the index with the writer
        writerB = new IndexWriter(indexStoreB, new StandardAnalyzer(), false);
        writerB.optimize();
        writerB.close();



        //bulding the searchables
        Searcher[] searchers3 = new Searcher[2];
        //VITAL STEP:adding the searcher for the empty index first, before the searcher for the populated index
        searchers3[0] = new IndexSearcher(indexStoreB);
        searchers3[1] = new IndexSearcher(indexStoreA);
        //creating the mulitSearcher
        Searcher mSearcher3 = new MultiSearcher(searchers3);
        //performing same the search
        Hits hits3 = mSearcher3.search(query);
        try {
            //iterating over the hit documents
            for (int i = 0; i < hits3.length(); i++) {
                //false IOException should happen at this point
                Document d = hits3.doc(i);
            }
        } catch (IOException e) {
            e.printStackTrace(System.err);
            System.err.print("\n");
        } finally{
            mSearcher3.close();
        }

    }


}