package org.apache.blur.mapreduce.lib.update;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;

import com.google.common.base.Splitter;

public class PrunedSequenceFileInputFormat<K, V> extends SequenceFileInputFormat<K, V> {

  private static final Log LOG = LogFactory.getLog(PrunedSequenceFileInputFormat.class);

  @Override
  public List<InputSplit> getSplits(JobContext job) throws IOException {
    List<InputSplit> splits = super.getSplits(job);
    List<InputSplit> results = new ArrayList<InputSplit>();
    Configuration configuration = job.getConfiguration();
    String table = InputSplitPruneUtil.getTable(configuration);
    for (InputSplit inputSplit : splits) {
      FileSplit fileSplit = (FileSplit) inputSplit;
      Path path = fileSplit.getPath();
      LOG.debug("Getting shard index from path [" + path + "]");
      String name = path.getName();
      int shard = getShardIndex(name);
      long rowIdUpdateFromNewDataCount = InputSplitPruneUtil.getBlurLookupRowIdUpdateFromNewDataCount(configuration,
          table, shard);
      long indexCount = InputSplitPruneUtil.getBlurLookupRowIdFromIndexCount(configuration, table, shard);
      if (rowIdUpdateFromNewDataCount == 0 || indexCount == 0) {
        LOG.info("Pruning id lookup input path [" + path + "] no overlapping ids.");
      } else if (InputSplitPruneUtil.shouldLookupExecuteOnShard(configuration, table, shard)) {
        LOG.debug("Keeping id lookup input path [" + path + "]");
        results.add(inputSplit);
      } else {
        LOG.info("Pruning id lookup input path [" + path + "]");
      }
    }
    return results;
  }

  private int getShardIndex(String name) {
    // based on file format of "part-r-00000", etc
    Iterable<String> split = Splitter.on('-').split(name);
    List<String> parts = new ArrayList<String>();
    for (String s : split) {
      parts.add(s);
    }
    return Integer.parseInt(parts.get(2));
  }

}