/**
 * 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.streaming;

import java.io.*;
import java.net.URLDecoder;

import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.TextInputFormat;
import org.apache.hadoop.util.StringUtils;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.Writable;

/** A generic Mapper bridge.
 *  It delegates operations to an external program via stdin and stdout.
 *  @author Michel Tourn
 */
public class PipeMapper extends PipeMapRed implements Mapper {

  private boolean ignoreKey = false;
  
  String getPipeCommand(JobConf job) {
    String str = job.get("stream.map.streamprocessor");
    if (str == null) {
      return str;
    }
    try {
      return URLDecoder.decode(str, "UTF-8");
    }
    catch (UnsupportedEncodingException e) {
      System.err.println("stream.map.streamprocessor in jobconf not found");
      return null;
    }
  }

  boolean getDoPipe() {
    return true;
  }
  
  public void configure(JobConf job) {
    super.configure(job);
    String inputFormatClassName = job.getClass("mapred.input.format.class", TextInputFormat.class).getCanonicalName();
    this.ignoreKey = inputFormatClassName.equals(TextInputFormat.class.getCanonicalName());
  }

  // Do NOT declare default constructor
  // (MapRed creates it reflectively)

  public void map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) throws IOException {
    // init
    if (outThread_ == null) {
      startOutputThreads(output, reporter);
    }
    if (outerrThreadsThrowable != null) {
      mapRedFinished();
      throw new IOException ("MROutput/MRErrThread failed:"
                             + StringUtils.stringifyException(
                                                              outerrThreadsThrowable));
    }
    try {
      // 1/4 Hadoop in
      numRecRead_++;
      maybeLogRecord();
      if (debugFailDuring_ && numRecRead_ == 3) {
        throw new IOException("debugFailDuring_");
      }

      // 2/4 Hadoop to Tool
      if (numExceptions_ == 0) {
        if (!this.ignoreKey) {
          write(key);
          clientOut_.write('\t');
        }
        write(value);
        clientOut_.write('\n');
        clientOut_.flush();
      } else {
        numRecSkipped_++;
      }
    } catch (IOException io) {
      numExceptions_++;
      if (numExceptions_ > 1 || numRecWritten_ < minRecWrittenToEnableSkip_) {
        // terminate with failure
        String msg = logFailure(io);
        appendLogToJobLog("failure");
        mapRedFinished();
        throw new IOException(msg);
      } else {
        // terminate with success:
        // swallow input records although the stream processor failed/closed
      }
    }
  }

  public void close() {
    appendLogToJobLog("success");
    mapRedFinished();
  }

  @Override
  char getFieldSeparator() {
    return super.mapOutputFieldSeparator;
  }

  @Override
  int getNumOfKeyFields() {
    return super.numOfMapOutputKeyFields;
  }

}
