/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the "Elastic License
 * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
 * Public License v 1"; you may not use this file except in compliance with, at
 * your election, the "Elastic License 2.0", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.deps.lucene;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.IntPoint;
import org.apache.lucene.document.SortedDocValuesField;
import org.apache.lucene.document.StoredField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.StoredFieldVisitor;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.FieldDoc;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.store.ByteBuffersDirectory;
import org.apache.lucene.store.Directory;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.common.lucene.Lucene;
import org.elasticsearch.test.ESTestCase;

import java.io.IOException;
import java.util.ArrayList;

import static org.hamcrest.Matchers.equalTo;

public class SimpleLuceneTests extends ESTestCase {
    public void testSortValues() throws Exception {
        try (
            Directory dir = new ByteBuffersDirectory();
            IndexWriter indexWriter = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER))
        ) {
            for (int i = 0; i < 10; i++) {
                Document document = new Document();
                String text = new String(new char[] { (char) (97 + i), (char) (97 + i) });
                document.add(new TextField("str", text, Field.Store.YES));
                document.add(new SortedDocValuesField("str", new BytesRef(text)));
                indexWriter.addDocument(document);
            }
            try (IndexReader reader = DirectoryReader.open(indexWriter)) {
                IndexSearcher searcher = newSearcher(reader);
                TopFieldDocs docs = searcher.search(new MatchAllDocsQuery(), 10, new Sort(new SortField("str", SortField.Type.STRING)));
                for (int i = 0; i < 10; i++) {
                    FieldDoc fieldDoc = (FieldDoc) docs.scoreDocs[i];
                    assertThat(
                        (BytesRef) fieldDoc.fields[0],
                        equalTo(new BytesRef(new String(new char[] { (char) (97 + i), (char) (97 + i) })))
                    );
                }
            }
        }
    }

    public void testSimpleNumericOps() throws Exception {
        try (
            Directory dir = new ByteBuffersDirectory();
            IndexWriter indexWriter = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER))
        ) {
            Document document = new Document();
            document.add(new TextField("_id", "1", Field.Store.YES));
            document.add(new IntPoint("test", 2));
            document.add(new StoredField("test", 2));
            indexWriter.addDocument(document);

            try (IndexReader reader = DirectoryReader.open(indexWriter)) {
                IndexSearcher searcher = newSearcher(reader);
                TopDocs topDocs = searcher.search(new TermQuery(new Term("_id", "1")), 1);
                Document doc = searcher.storedFields().document(topDocs.scoreDocs[0].doc);
                IndexableField f = doc.getField("test");
                assertThat(f.numericValue(), equalTo(2));

                topDocs = searcher.search(IntPoint.newExactQuery("test", 2), 1);
                doc = searcher.storedFields().document(topDocs.scoreDocs[0].doc);
                f = doc.getField("test");
                assertThat(f.stringValue(), equalTo("2"));
            }
        }
    }

    /**
     * Here, we verify that the order that we add fields to a document counts, and not the lexi order
     * of the field. This means that heavily accessed fields that use field selector should be added
     * first (with load and break).
     */
    public void testOrdering() throws Exception {
        try (
            Directory dir = new ByteBuffersDirectory();
            IndexWriter indexWriter = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER))
        ) {
            Document document = new Document();
            document.add(new TextField("_id", "1", Field.Store.YES));
            document.add(new TextField("#id", "1", Field.Store.YES));
            indexWriter.addDocument(document);

            try (IndexReader reader = DirectoryReader.open(indexWriter)) {
                IndexSearcher searcher = newSearcher(reader);
                TopDocs topDocs = searcher.search(new TermQuery(new Term("_id", "1")), 1);
                final ArrayList<String> fieldsOrder = new ArrayList<>();
                searcher.storedFields().document(topDocs.scoreDocs[0].doc, new StoredFieldVisitor() {
                    @Override
                    public Status needsField(FieldInfo fieldInfo) throws IOException {
                        fieldsOrder.add(fieldInfo.name);
                        return Status.YES;
                    }
                });

                assertThat(fieldsOrder.size(), equalTo(2));
                assertThat(fieldsOrder.get(0), equalTo("_id"));
                assertThat(fieldsOrder.get(1), equalTo("#id"));
            }
        }
    }

    public void testNRTSearchOnClosedWriter() throws Exception {
        try (
            Directory dir = new ByteBuffersDirectory();
            IndexWriter indexWriter = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER));
            DirectoryReader reader = DirectoryReader.open(indexWriter)
        ) {
            for (int i = 0; i < 100; i++) {
                Document document = new Document();
                TextField field = new TextField("_id", Integer.toString(i), Field.Store.YES);
                document.add(field);
                indexWriter.addDocument(document);
            }
            try (DirectoryReader refreshedReader = refreshReader(reader)) {
                for (LeafReaderContext leaf : refreshedReader.leaves()) {
                    leaf.reader().terms("_id").iterator().next();
                }
            }
        }
    }

    private static DirectoryReader refreshReader(DirectoryReader reader) throws IOException {
        DirectoryReader oldReader = reader;
        reader = DirectoryReader.openIfChanged(reader);
        if (reader != oldReader) {
            oldReader.close();
        }
        return reader;
    }
}