/*
 * 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.index.query;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.join.BitSetProducer;
import org.apache.lucene.search.similarities.Similarity;
import org.apache.lucene.util.SetOnce;
import org.elasticsearch.Version;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.client.Client;
import org.elasticsearch.common.CheckedFunction;
import org.elasticsearch.common.ParsingException;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
import org.elasticsearch.common.lucene.search.Queries;
import org.elasticsearch.common.xcontent.NamedXContentRegistry;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.IndexSettings;
import org.elasticsearch.index.analysis.IndexAnalyzers;
import org.elasticsearch.index.cache.bitset.BitsetFilterCache;
import org.elasticsearch.index.fielddata.IndexFieldData;
import org.elasticsearch.index.mapper.ContentPath;
import org.elasticsearch.index.mapper.DocumentMapper;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.mapper.Mapper;
import org.elasticsearch.index.mapper.MapperService;
import org.elasticsearch.index.mapper.ObjectMapper;
import org.elasticsearch.index.mapper.TextFieldMapper;
import org.elasticsearch.index.query.support.NestedScope;
import org.elasticsearch.index.similarity.SimilarityService;
import org.elasticsearch.script.ScriptService;
import org.elasticsearch.search.lookup.SearchLookup;
import org.elasticsearch.transport.RemoteClusterAware;

import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.LongSupplier;

import static java.util.Collections.unmodifiableMap;

/**
 * Context object used to create lucene queries on the shard level.
 */
public class QueryShardContext extends QueryRewriteContext {

    private final ScriptService scriptService;
    private final IndexSettings indexSettings;
    private final MapperService mapperService;
    private final SimilarityService similarityService;
    private final BitsetFilterCache bitsetFilterCache;
    private final BiFunction<MappedFieldType, String, IndexFieldData<?>> indexFieldDataService;
    private final int shardId;
    private final IndexReader reader;
    private final String clusterAlias;
    private String[] types = Strings.EMPTY_ARRAY;
    private boolean cachable = true;
    private final SetOnce<Boolean> frozen = new SetOnce<>();
    private final Index fullyQualifiedIndex;

    public void setTypes(String... types) {
        this.types = types;
    }

    public String[] getTypes() {
        return types;
    }

    private final Map<String, Query> namedQueries = new HashMap<>();
    private boolean allowUnmappedFields;
    private boolean mapUnmappedFieldAsString;
    private NestedScope nestedScope;
    private boolean isFilter;

    public QueryShardContext(int shardId, IndexSettings indexSettings, BitsetFilterCache bitsetFilterCache,
                             BiFunction<MappedFieldType, String, IndexFieldData<?>> indexFieldDataLookup, MapperService mapperService,
                             SimilarityService similarityService, ScriptService scriptService, NamedXContentRegistry xContentRegistry,
                             NamedWriteableRegistry namedWriteableRegistry, Client client, IndexReader reader, LongSupplier nowInMillis,
                             String clusterAlias) {
        super(xContentRegistry, namedWriteableRegistry,client, nowInMillis);
        this.shardId = shardId;
        this.similarityService = similarityService;
        this.mapperService = mapperService;
        this.bitsetFilterCache = bitsetFilterCache;
        this.indexFieldDataService = indexFieldDataLookup;
        this.allowUnmappedFields = indexSettings.isDefaultAllowUnmappedFields();
        this.nestedScope = new NestedScope();
        this.scriptService = scriptService;
        this.indexSettings = indexSettings;
        this.reader = reader;
        this.clusterAlias = clusterAlias;
        this.fullyQualifiedIndex = new Index(RemoteClusterAware.buildRemoteIndexName(clusterAlias, indexSettings.getIndex().getName()),
            indexSettings.getIndex().getUUID());
    }

    public QueryShardContext(QueryShardContext source) {
        this(source.shardId, source.indexSettings, source.bitsetFilterCache, source.indexFieldDataService, source.mapperService,
                source.similarityService, source.scriptService, source.getXContentRegistry(), source.getWriteableRegistry(),
                source.client, source.reader, source.nowInMillis, source.clusterAlias);
        this.types = source.getTypes();
    }

    private void reset() {
        allowUnmappedFields = indexSettings.isDefaultAllowUnmappedFields();
        this.lookup = null;
        this.namedQueries.clear();
        this.nestedScope = new NestedScope();
        this.isFilter = false;
    }

    public IndexAnalyzers getIndexAnalyzers() {
        return mapperService.getIndexAnalyzers();
    }

    public Similarity getSearchSimilarity() {
        return similarityService != null ? similarityService.similarity(mapperService) : null;
    }

    public List<String> defaultFields() {
        return indexSettings.getDefaultFields();
    }

    public boolean queryStringLenient() {
        return indexSettings.isQueryStringLenient();
    }

    public boolean queryStringAnalyzeWildcard() {
        return indexSettings.isQueryStringAnalyzeWildcard();
    }

    public boolean queryStringAllowLeadingWildcard() {
        return indexSettings.isQueryStringAllowLeadingWildcard();
    }

    public BitSetProducer bitsetFilter(Query filter) {
        return bitsetFilterCache.getBitSetProducer(filter);
    }

    public <IFD extends IndexFieldData<?>> IFD getForField(MappedFieldType fieldType) {
        return (IFD) indexFieldDataService.apply(fieldType, fullyQualifiedIndex.getName());
    }

    public void addNamedQuery(String name, Query query) {
        if (query != null) {
            namedQueries.put(name, query);
        }
    }

    public Map<String, Query> copyNamedQueries() {
        // This might be a good use case for CopyOnWriteHashMap
        return unmodifiableMap(new HashMap<>(namedQueries));
    }

    /**
     * Return whether we are currently parsing a filter or a query.
     */
    public boolean isFilter() {
        return isFilter;
    }

    /**
     * Public for testing only!
     *
     * Sets whether we are currently parsing a filter or a query
     */
    public void setIsFilter(boolean isFilter) {
        this.isFilter = isFilter;
    }

    /**
     * Returns all the fields that match a given pattern. If prefixed with a
     * type then the fields will be returned with a type prefix.
     */
    public Collection<String> simpleMatchToIndexNames(String pattern) {
        return mapperService.simpleMatchToFullName(pattern);
    }

    public MappedFieldType fieldMapper(String name) {
        return failIfFieldMappingNotFound(name, mapperService.fullName(name));
    }

    public ObjectMapper getObjectMapper(String name) {
        return mapperService.getObjectMapper(name);
    }

    /**
     * Returns s {@link DocumentMapper} instance for the given type.
     * Delegates to {@link MapperService#documentMapper(String)}
     */
    public DocumentMapper documentMapper(String type) {
        return mapperService.documentMapper(type);
    }

    /**
     * Gets the search analyzer for the given field, or the default if there is none present for the field
     * TODO: remove this by moving defaults into mappers themselves
     */
    public Analyzer getSearchAnalyzer(MappedFieldType fieldType) {
        if (fieldType.searchAnalyzer() != null) {
            return fieldType.searchAnalyzer();
        }
        return getMapperService().searchAnalyzer();
    }

    /**
     * Gets the search quote analyzer for the given field, or the default if there is none present for the field
     * TODO: remove this by moving defaults into mappers themselves
     */
    public Analyzer getSearchQuoteAnalyzer(MappedFieldType fieldType) {
        if (fieldType.searchQuoteAnalyzer() != null) {
            return fieldType.searchQuoteAnalyzer();
        }
        return getMapperService().searchQuoteAnalyzer();
    }

    public void setAllowUnmappedFields(boolean allowUnmappedFields) {
        this.allowUnmappedFields = allowUnmappedFields;
    }

    public void setMapUnmappedFieldAsString(boolean mapUnmappedFieldAsString) {
        this.mapUnmappedFieldAsString = mapUnmappedFieldAsString;
    }

    MappedFieldType failIfFieldMappingNotFound(String name, MappedFieldType fieldMapping) {
        if (fieldMapping != null || allowUnmappedFields) {
            return fieldMapping;
        } else if (mapUnmappedFieldAsString) {
            TextFieldMapper.Builder builder = new TextFieldMapper.Builder(name);
            return builder.build(new Mapper.BuilderContext(indexSettings.getSettings(), new ContentPath(1))).fieldType();
        } else {
            throw new QueryShardException(this, "No field mapping can be found for the field with name [{}]", name);
        }
    }

    /**
     * Returns the narrowed down explicit types, or, if not set, all types.
     */
    public Collection<String> queryTypes() {
        String[] types = getTypes();
        if (types == null || types.length == 0 || (types.length == 1 && types[0].equals("_all"))) {
            DocumentMapper mapper = getMapperService().documentMapper();
            return mapper == null ? Collections.emptyList() : Collections.singleton(mapper.type());
        }
        return Arrays.asList(types);
    }

    private SearchLookup lookup = null;

    public SearchLookup lookup() {
        if (lookup == null) {
            lookup = new SearchLookup(getMapperService(),
                mappedFieldType -> indexFieldDataService.apply(mappedFieldType, fullyQualifiedIndex.getName()), types);
        }
        return lookup;
    }

    public NestedScope nestedScope() {
        return nestedScope;
    }

    public Version indexVersionCreated() {
        return indexSettings.getIndexVersionCreated();
    }

    public ParsedQuery toFilter(QueryBuilder queryBuilder) {
        return toQuery(queryBuilder, q -> {
            Query filter = q.toFilter(this);
            if (filter == null) {
                return null;
            }
            return filter;
        });
    }

    public ParsedQuery toQuery(QueryBuilder queryBuilder) {
        return toQuery(queryBuilder, q -> {
            Query query = q.toQuery(this);
            if (query == null) {
                query = Queries.newMatchNoDocsQuery("No query left after rewrite.");
            }
            return query;
        });
    }

    private ParsedQuery toQuery(QueryBuilder queryBuilder, CheckedFunction<QueryBuilder, Query, IOException> filterOrQuery) {
        reset();
        try {
            QueryBuilder rewriteQuery = Rewriteable.rewrite(queryBuilder, this, true);
            return new ParsedQuery(filterOrQuery.apply(rewriteQuery), copyNamedQueries());
        } catch(QueryShardException | ParsingException e ) {
            throw e;
        } catch(Exception e) {
            throw new QueryShardException(this, "failed to create query: {}", e, queryBuilder);
        } finally {
            reset();
        }
    }

    public Index index() {
        return indexSettings.getIndex();
    }

    /** Return the script service to allow compiling scripts. */
    public final ScriptService getScriptService() {
        failIfFrozen();
        return scriptService;
    }

    /**
     * if this method is called the query context will throw exception if methods are accessed
     * that could yield different results across executions like {@link #getClient()}
     */
    public final void freezeContext() {
        this.frozen.set(Boolean.TRUE);
    }

    /**
     * This method fails if {@link #freezeContext()} is called before on this
     * context. This is used to <i>seal</i>.
     *
     * This methods and all methods that call it should be final to ensure that
     * setting the request as not cacheable and the freezing behaviour of this
     * class cannot be bypassed. This is important so we can trust when this
     * class says a request can be cached.
     */
    protected final void failIfFrozen() {
        this.cachable = false;
        if (frozen.get() == Boolean.TRUE) {
            throw new IllegalArgumentException("features that prevent cachability are disabled on this context");
        } else {
            assert frozen.get() == null : frozen.get();
        }
    }

    @Override
    public void registerAsyncAction(BiConsumer<Client, ActionListener<?>> asyncAction) {
        failIfFrozen();
        super.registerAsyncAction(asyncAction);
    }

    @Override
    public void executeAsyncActions(ActionListener listener) {
        failIfFrozen();
        super.executeAsyncActions(listener);
    }

    /**
     * Returns <code>true</code> iff the result of the processed search request is cachable. Otherwise <code>false</code>
     */
    public final boolean isCachable() {
        return cachable;
    }

    /**
     * Returns the shard ID this context was created for.
     */
    public int getShardId() {
        return shardId;
    }

    @Override
    public final long nowInMillis() {
        failIfFrozen();
        return super.nowInMillis();
    }

    public Client getClient() {
        failIfFrozen(); // we somebody uses a terms filter with lookup for instance can't be cached...
        return client;
    }

    public QueryBuilder parseInnerQueryBuilder(XContentParser parser) throws IOException {
        return AbstractQueryBuilder.parseInnerQueryBuilder(parser);
    }

    @Override
    public final QueryShardContext convertToShardContext() {
        return this;
    }

    /**
     * Returns the index settings for this context. This might return null if the
     * context has not index scope.
     */
    public IndexSettings getIndexSettings() {
        return indexSettings;
    }

    /**
     * Return the MapperService.
     */
    public MapperService getMapperService() {
        return mapperService;
    }

    /** Return the current {@link IndexReader}, or {@code null} if no index reader is available,
     *  for instance if this rewrite context is used to index queries (percolation). */
    public IndexReader getIndexReader() {
        return reader;
    }

    /**
     * Returns the fully qualified index including a remote cluster alias if applicable, and the index uuid
     */
    public Index getFullyQualifiedIndex() {
        return fullyQualifiedIndex;
    }
}
