/**
 * 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.rya.indexing.pcj.matching.provider;

import static java.util.Objects.requireNonNull;

import java.util.List;
import java.util.Map;

import org.apache.accumulo.core.client.AccumuloException;
import org.apache.accumulo.core.client.AccumuloSecurityException;
import org.apache.accumulo.core.client.Connector;
import org.apache.accumulo.core.client.TableNotFoundException;
import org.apache.hadoop.conf.Configuration;
import org.apache.log4j.Logger;
import org.apache.rya.accumulo.instance.AccumuloRyaInstanceDetailsRepository;
import org.apache.rya.api.RdfCloudTripleStoreConfiguration;
import org.apache.rya.api.instance.RyaDetailsRepository;
import org.apache.rya.api.instance.RyaDetailsRepository.RyaDetailsRepositoryException;
import org.apache.rya.indexing.accumulo.ConfigUtils;
import org.apache.rya.indexing.external.tupleSet.AccumuloIndexSet;
import org.apache.rya.indexing.external.tupleSet.ExternalTupleSet;
import org.apache.rya.indexing.pcj.storage.PrecomputedJoinStorage;
import org.apache.rya.indexing.pcj.storage.PrecomputedJoinStorage.PCJStorageException;
import org.apache.rya.indexing.pcj.storage.accumulo.AccumuloPcjStorage;
import org.apache.rya.indexing.pcj.storage.accumulo.PcjTableNameFactory;
import org.apache.rya.indexing.pcj.storage.accumulo.PcjTables;
import org.eclipse.rdf4j.query.MalformedQueryException;
import org.eclipse.rdf4j.query.QueryEvaluationException;
import org.eclipse.rdf4j.sail.SailException;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/**
 * Implementation of {@link AbstractPcjIndexSetProvider} for Accumulo.
 * This provider uses either user specified Accumulo configuration information or user a specified
 * List of ExternalTupleSets to populate an internal cache of ExternalTupleSets.  If Accumulo configuration
 * is provided, the provider connects to an instance of RyaDetails and populates the cache with
 * PCJs registered in RyaDetails.
 */
public class AccumuloIndexSetProvider extends AbstractPcjIndexSetProvider {
    private static final Logger log = Logger.getLogger(AccumuloIndexSetProvider.class);

    public AccumuloIndexSetProvider(final Configuration conf) {
        super(conf);
    }

    public AccumuloIndexSetProvider(final Configuration conf, final List<ExternalTupleSet> indices) {
        super(conf, indices);
    }

    @Override
    protected List<ExternalTupleSet> getIndices() throws PcjIndexSetException {
        requireNonNull(conf);
        try {
            final String tablePrefix = requireNonNull(conf.get(RdfCloudTripleStoreConfiguration.CONF_TBL_PREFIX));
            final Connector conn = requireNonNull(ConfigUtils.getConnector(conf));
            List<String> tables = null;

            if (conf instanceof RdfCloudTripleStoreConfiguration) {
                tables = ((RdfCloudTripleStoreConfiguration) conf).getPcjTables();
            }
            // this maps associates pcj table name with pcj sparql query
            final Map<String, String> indexTables = Maps.newLinkedHashMap();

            try(final PrecomputedJoinStorage storage = new AccumuloPcjStorage(conn, tablePrefix)) {
                final PcjTableNameFactory pcjFactory = new PcjTableNameFactory();

                final boolean tablesProvided = tables != null && !tables.isEmpty();

                if (tablesProvided) {
                    // if tables provided, associate table name with sparql
                    for (final String table : tables) {
                        indexTables.put(table, storage.getPcjMetadata(pcjFactory.getPcjId(table)).getSparql());
                    }
                } else if (hasRyaDetails(tablePrefix, conn)) {
                    // If this is a newer install of Rya, and it has PCJ Details, then
                    // use those.
                    final List<String> ids = storage.listPcjs();
                    for (final String id : ids) {
                        indexTables.put(pcjFactory.makeTableName(tablePrefix, id), storage.getPcjMetadata(id).getSparql());
                    }
                } else {
                    // Otherwise figure it out by scanning tables.
                    final PcjTables pcjTables = new PcjTables();
                    for (final String table : conn.tableOperations().list()) {
                        if (table.startsWith(tablePrefix + "INDEX")) {
                            indexTables.put(table, pcjTables.getPcjMetadata(conn, table).getSparql());
                        }
                    }
                }
            }

            // use table name sparql map (indexTables) to create {@link
            // AccumuloIndexSet}
            final List<ExternalTupleSet> index = Lists.newArrayList();
            if (indexTables.isEmpty()) {
                log.info("No Index found");
            } else {
                for (final String table : indexTables.keySet()) {
                    final String indexSparqlString = indexTables.get(table);
                    index.add(new AccumuloIndexSet(indexSparqlString, conf, table));
                }
            }

            return index;
        } catch (final PCJStorageException | AccumuloException | AccumuloSecurityException | MalformedQueryException
                | SailException | QueryEvaluationException | TableNotFoundException e) {
            throw new PcjIndexSetException("Failed to retrieve the indicies.", e);
        }
    }

    private static boolean hasRyaDetails(final String ryaInstanceName, final Connector conn) {
        final RyaDetailsRepository detailsRepo = new AccumuloRyaInstanceDetailsRepository(conn, ryaInstanceName);
        try {
            detailsRepo.getRyaInstanceDetails();
            return true;
        } catch (final RyaDetailsRepositoryException e) {
            return false;
        }
    }
}