/*
    *
    * 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.hadoop.hbase.rest;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.DoNotRetryIOException;
  import org.apache.hadoop.hbase.KeyValue;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Get;
  import org.apache.hadoop.hbase.client.NeedUnmanagedConnectionException;
  import org.apache.hadoop.hbase.client.Result;
  import org.apache.hadoop.hbase.client.Table;
  import org.apache.hadoop.hbase.filter.Filter;
  import org.apache.hadoop.util.StringUtils;
  
  @InterfaceAudience.Private
  public class RowResultGenerator extends ResultGenerator {
    private static final Log LOG = LogFactory.getLog(RowResultGenerator.class);
  
    private Iterator<Cell> valuesI;
    private Cell cache;
  
    public RowResultGenerator(final String tableName, final RowSpec rowspec,
        final Filter filter, final boolean cacheBlocks)
        throws IllegalArgumentException, IOException {
      try (Table table = RESTServlet.getInstance().getTable(tableName)) {
        Get get = new Get(rowspec.getRow());
        if (rowspec.hasColumns()) {
          for (byte[] col : rowspec.getColumns()) {
            byte[][] split = KeyValue.parseColumn(col);
            if (split.length == 1) {
              get.addFamily(split[0]);
            } else if (split.length == 2) {
              get.addColumn(split[0], split[1]);
            } else {
              throw new IllegalArgumentException("Invalid column specifier.");
            }
          }
        }
        get.setTimeRange(rowspec.getStartTime(), rowspec.getEndTime());
        get.setMaxVersions(rowspec.getMaxVersions());
        if (filter != null) {
          get.setFilter(filter);
        }
        get.setCacheBlocks(cacheBlocks);
        Result result = table.get(get);
        if (result != null && !result.isEmpty()) {
          valuesI = result.listCells().iterator();
        }
      } catch (DoNotRetryIOException | NeedUnmanagedConnectionException e) {
        // Warn here because Stargate will return 404 in the case if multiple
        // column families were specified but one did not exist -- currently
        // HBase will fail the whole Get.
        // Specifying multiple columns in a URI should be uncommon usage but
        // help to avoid confusion by leaving a record of what happened here in
        // the log.
        LOG.warn(StringUtils.stringifyException(e));
      }
    }
  
    public void close() {
    }
  
    public boolean hasNext() {
      if (cache != null) {
        return true;
      }
      if (valuesI == null) {
        return false;
      }
      return valuesI.hasNext();
    }
  
    public Cell next() {
      if (cache != null) {
        Cell kv = cache;
        cache = null;
       return kv;
     }
     if (valuesI == null) {
       return null;
     }
     try {
       return valuesI.next();
     } catch (NoSuchElementException e) {
       return null;
     }
   }
 
   public void putBack(Cell kv) {
     this.cache = kv;
   }
 
   public void remove() {
     throw new UnsupportedOperationException("remove not supported");
   }
 }