/*
 * 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 phrasecount.query;

import java.util.Iterator;
import java.util.Map.Entry;

import com.google.common.collect.Iterators;
import org.apache.accumulo.core.client.ClientConfiguration;
import org.apache.accumulo.core.client.Connector;
import org.apache.accumulo.core.client.RowIterator;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.client.ZooKeeperInstance;
import org.apache.accumulo.core.client.security.tokens.PasswordToken;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Mutation;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.fluo.api.config.FluoConfiguration;
import org.apache.hadoop.io.Text;
import phrasecount.pojos.Counts;
import phrasecount.pojos.PhraseAndCounts;

/**
 * All of the code for dealing with the Accumulo table that Fluo is exporting to
 */
public class PhraseCountTable implements Iterable<PhraseAndCounts> {

  static final String STAT_CF = "stat";

  // name of column qualifier used to store phrase count across all documents
  static final String TOTAL_PC_CQ = "totalCount";

  // name of column qualifier used to store number of documents containing a phrase
  static final String DOC_PC_CQ = "docCount";

  public static Mutation createMutation(String phrase, long seq, Counts pc) {
    Mutation mutation = new Mutation(phrase);

    // use the sequence number for the Accumulo timestamp, this will cause older updates to fall
    // behind newer ones
    if (pc.totalPhraseCount == 0) {
      mutation.putDelete(STAT_CF, TOTAL_PC_CQ, seq);
    } else {
      mutation.put(STAT_CF, TOTAL_PC_CQ, seq, pc.totalPhraseCount + "");
    }

    if (pc.docPhraseCount == 0) {
      mutation.putDelete(STAT_CF, DOC_PC_CQ, seq);
    } else {
      mutation.put(STAT_CF, DOC_PC_CQ, seq, pc.docPhraseCount + "");
    }

    return mutation;
  }

  private Connector conn;
  private String table;

  public PhraseCountTable(FluoConfiguration fluoConfig, String table) throws Exception {
    ZooKeeperInstance zki = new ZooKeeperInstance(
        new ClientConfiguration().withZkHosts(fluoConfig.getAccumuloZookeepers())
            .withInstance(fluoConfig.getAccumuloInstance()));
    this.conn = zki.getConnector(fluoConfig.getAccumuloUser(),
        new PasswordToken(fluoConfig.getAccumuloPassword()));
    this.table = table;
  }

  public PhraseCountTable(Connector conn, String table) {
    this.conn = conn;
    this.table = table;
  }


  public Counts getPhraseCounts(String phrase) throws Exception {
    Scanner scanner = conn.createScanner(table, Authorizations.EMPTY);
    scanner.setRange(new Range(phrase));

    int sum = 0;
    int docCount = 0;

    for (Entry<Key, Value> entry : scanner) {
      String cq = entry.getKey().getColumnQualifierData().toString();
      if (cq.equals(TOTAL_PC_CQ)) {
        sum = Integer.valueOf(entry.getValue().toString());
      }

      if (cq.equals(DOC_PC_CQ)) {
        docCount = Integer.valueOf(entry.getValue().toString());
      }
    }

    return new Counts(docCount, sum);
  }

  @Override
  public Iterator<PhraseAndCounts> iterator() {
    try {
      Scanner scanner = conn.createScanner(table, Authorizations.EMPTY);
      scanner.fetchColumn(new Text(STAT_CF), new Text(TOTAL_PC_CQ));
      scanner.fetchColumn(new Text(STAT_CF), new Text(DOC_PC_CQ));

      RowTransform transform = new RowTransform();
      return Iterators.transform(new RowIterator(scanner), transform::apply);
    } catch (RuntimeException e) {
      throw e;
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
}