/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.vxquery.runtime.functions.index;

import org.apache.hyracks.data.std.api.IPointable;
import org.apache.hyracks.data.std.primitive.UTF8StringPointable;
import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
import org.apache.hyracks.dataflow.common.comm.util.ByteBufferInputStream;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.vxquery.datamodel.accessors.TaggedValuePointable;
import org.apache.vxquery.datamodel.builders.sequence.SequenceBuilder;
import org.apache.vxquery.datamodel.values.ValueTag;
import org.apache.vxquery.exceptions.ErrorCode;
import org.apache.vxquery.exceptions.SystemException;
import org.apache.vxquery.index.IndexDocumentBuilder;
import org.apache.vxquery.runtime.functions.index.updateIndex.MetaFileUtil;
import org.apache.vxquery.runtime.functions.index.updateIndex.XmlMetadata;
import org.apache.vxquery.runtime.functions.util.FunctionHelper;
import org.apache.vxquery.xmlparser.IParser;
import org.apache.vxquery.xmlparser.ITreeNodeIdProvider;
import org.apache.vxquery.xmlparser.XMLParser;

import javax.xml.bind.JAXBException;
import java.io.DataInputStream;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.file.Paths;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.concurrent.ConcurrentHashMap;

public class IndexConstructorUtil {
    static boolean isMetaFilePresent = false;
    static MetaFileUtil metaFileUtil;
    static ConcurrentHashMap<String, XmlMetadata> metadataMap = new ConcurrentHashMap<>();

    public static void evaluate(TaggedValuePointable[] args, IPointable result, UTF8StringPointable stringp,
            ByteBufferInputStream bbis, DataInputStream di, SequenceBuilder sb, ArrayBackedValueStorage abvs,
            ITreeNodeIdProvider nodeIdProvider, ArrayBackedValueStorage abvsFileNode, TaggedValuePointable nodep,
            boolean isElementPath, String nodeId) throws SystemException, JAXBException {
        String collectionFolder;
        String indexFolder;
        TaggedValuePointable collectionTVP = args[0];
        TaggedValuePointable indexTVP = args[1];

        if (collectionTVP.getTag() != ValueTag.XS_STRING_TAG || indexTVP.getTag() != ValueTag.XS_STRING_TAG) {
            throw new SystemException(ErrorCode.FORG0006);
        }

        try {
            // Get the list of files.
            collectionTVP.getValue(stringp);
            bbis.setByteBuffer(ByteBuffer.wrap(Arrays.copyOfRange(stringp.getByteArray(), stringp.getStartOffset(),
                    stringp.getLength() + stringp.getStartOffset())), 0);
            collectionFolder = di.readUTF();

            // Get the index folder
            indexTVP.getValue(stringp);
            bbis.setByteBuffer(ByteBuffer.wrap(Arrays.copyOfRange(stringp.getByteArray(), stringp.getStartOffset(),
                    stringp.getLength() + stringp.getStartOffset())), 0);
            indexFolder = di.readUTF();

            metaFileUtil = MetaFileUtil.create(indexFolder);
            isMetaFilePresent = metaFileUtil.isMetaFilePresent();
            metaFileUtil.setCollectionForIndex(indexFolder, collectionFolder);

        } catch (IOException e) {
            throw new SystemException(ErrorCode.SYSE0001, e);
        }
        File collectionDirectory = new File(collectionFolder);
        if (!collectionDirectory.exists()) {
            throw new RuntimeException("The collection directory (" + collectionFolder + ") does not exist.");
        }

        try {
            abvs.reset();
            sb.reset(abvs);

            Directory dir = FSDirectory.open(Paths.get(indexFolder));
            Analyzer analyzer = new CaseSensitiveAnalyzer();
            IndexWriterConfig iwc = new IndexWriterConfig(analyzer);

            // Create will overwrite the index everytime
            iwc.setOpenMode(OpenMode.CREATE);

            //Create an index writer
            IndexWriter writer = new IndexWriter(dir, iwc);

            //Add files to index
            indexXmlFiles(collectionDirectory, writer, isElementPath, nodep, abvsFileNode, nodeIdProvider, sb, bbis, di,
                    nodeId);

            if (!isMetaFilePresent) {
                // Write metadata map to a file.
                metaFileUtil.updateMetadataMap(metadataMap, indexFolder);
                metaFileUtil.writeMetadataToFile();
            }

            //This makes write slower but search faster.
            writer.forceMerge(1);

            writer.close();

            sb.finish();
            result.set(abvs);
        } catch (IOException e) {
            throw new SystemException(ErrorCode.SYSE0001, e);
        }
    }

    /*This function goes recursively one file at a time. First it turns the file into an ABVS document node, then
     * it indexes that document node.
     */
    public static void indexXmlFiles(File collectionDirectory, IndexWriter writer, boolean isElementPath,
            TaggedValuePointable nodep, ArrayBackedValueStorage abvsFileNode, ITreeNodeIdProvider nodeIdProvider,
            SequenceBuilder sb, ByteBufferInputStream bbis, DataInputStream di, String nodeId)
            throws SystemException, IOException {

        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy, HH:mm:ss");

        for (File file : collectionDirectory.listFiles()) {

            if (readableXmlFile(file.getPath())) {
                abvsFileNode.reset();

                IndexDocumentBuilder ibuilder = getIndexBuilder(file, writer, nodep, abvsFileNode, nodeIdProvider, bbis,
                        di, nodeId);

                ibuilder.printStart();
                if (!isMetaFilePresent) {
                    XmlMetadata xmlMetadata = new XmlMetadata();
                    xmlMetadata.setPath(file.getCanonicalPath());
                    xmlMetadata.setFileName(file.getName());
                    xmlMetadata.setLastModified(sdf.format(file.lastModified()));
                    try {
                        xmlMetadata.setMd5(metaFileUtil.generateMD5(file));
                    } catch (NoSuchAlgorithmException e) {
                        throw new SystemException(ErrorCode.SYSE0001, e);
                    }
                    metadataMap.put(file.getCanonicalPath(), xmlMetadata);
                }

            } else if (file.isDirectory()) {
                // Consider all XML file in sub directories.
                indexXmlFiles(file, writer, isElementPath, nodep, abvsFileNode, nodeIdProvider, sb, bbis, di, nodeId);
            }
        }
    }

    public static boolean readableXmlFile(String path) {
        return (path.toLowerCase().endsWith(".xml") || path.toLowerCase().endsWith(".xml.gz"));
    }

    /**
     * Separated from create index method so that it could be used as a helper function in IndexUpdater
     */
    public static IndexDocumentBuilder getIndexBuilder(File file, IndexWriter writer, TaggedValuePointable nodep,
            ArrayBackedValueStorage abvsFileNode, ITreeNodeIdProvider nodeIdProvider, ByteBufferInputStream bbis,
            DataInputStream di, String nodeId) throws IOException {

        //Get the document node
        IParser parser = new XMLParser(false, nodeIdProvider, nodeId);
        FunctionHelper.readInDocFromString(file.getPath(), bbis, di, abvsFileNode, parser);

        nodep.set(abvsFileNode.getByteArray(), abvsFileNode.getStartOffset(), abvsFileNode.getLength());

        //Add the document to the index
        //Creates one lucene doc per file
        return new IndexDocumentBuilder(nodep, writer, file.getCanonicalPath());
    }
}