/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.percolator;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.index.IndexOptions;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.index.memory.MemoryIndex;
import org.apache.lucene.util.CloseableThreadLocal;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.index.engine.Engine;
import org.elasticsearch.index.mapper.ParsedDocument;
import org.elasticsearch.index.mapper.internal.UidFieldMapper;

import java.io.IOException;

/**
 * Implementation of {@link PercolatorIndex} that can only hold a single Lucene document
 * and is optimized for that
 */
class SingleDocumentPercolatorIndex implements PercolatorIndex {

    private final CloseableThreadLocal<MemoryIndex> cache;

    SingleDocumentPercolatorIndex(CloseableThreadLocal<MemoryIndex> cache) {
        this.cache = cache;
    }

    @Override
    public void prepare(PercolateContext context, ParsedDocument parsedDocument) {
        MemoryIndex memoryIndex = cache.get();
        for (IndexableField field : parsedDocument.rootDoc().getFields()) {
            if (field.fieldType().indexOptions() == IndexOptions.NONE && field.name().equals(UidFieldMapper.NAME)) {
                continue;
            }
            try {
                Analyzer analyzer = context.mapperService().documentMapper(parsedDocument.type()).mappers().indexAnalyzer();
                // TODO: instead of passing null here, we can have a CTL<Map<String,TokenStream>> and pass previous,
                // like the indexer does
                try (TokenStream tokenStream = field.tokenStream(analyzer, null)) {
                    if (tokenStream != null) {
                        memoryIndex.addField(field.name(), tokenStream, field.boost());
                    }
                 }
            } catch (Exception e) {
                throw new ElasticsearchException("Failed to create token stream for [" + field.name() + "]", e);
            }
        }
        context.initialize(new DocEngineSearcher(memoryIndex), parsedDocument);
    }

    private class DocEngineSearcher extends Engine.Searcher {

        private final MemoryIndex memoryIndex;

        public DocEngineSearcher(MemoryIndex memoryIndex) {
            super("percolate", memoryIndex.createSearcher());
            this.memoryIndex = memoryIndex;
        }

        @Override
        public void close() {
            try {
                this.reader().close();
                memoryIndex.reset();
            } catch (IOException e) {
                throw new ElasticsearchException("failed to close percolator in-memory index", e);
            }
        }
    }
}