/**
 * 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.avro.mapred;

import java.io.IOException;
import java.io.File;
import java.io.InputStream;
import java.io.FileInputStream;
import java.io.BufferedInputStream;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.Reporter;
import org.apache.avro.Schema;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.file.DataFileStream;
import org.apache.avro.reflect.ReflectData;
import org.apache.avro.reflect.ReflectDatumWriter;
import org.apache.avro.reflect.ReflectDatumReader;
import org.junit.Test;

import static org.junit.Assert.*;

public class TestAvroMultipleInputs {

  /** The input-1 record. */
  public static class NamesRecord {
    private int id = -1;
    private CharSequence name = "";

    public NamesRecord() {}

    public NamesRecord(int id, CharSequence name) {
      this.id = id;
      this.name = name;
    }

    @Override
    public String toString() {
      return id + "\t" + name;
    }
  }

  /** The input-2 record. */
  public static class BalancesRecord {
    private int id = -1;
    private long balance = 0L;

    public BalancesRecord() {}

    public BalancesRecord(int id, long balance) {
      this.id = id;
      this.balance = balance;
    }

    @Override
    public String toString() {
      return id + "\t" + balance;
    }
  }

  /** The map output key record. */
  public static class KeyRecord {
    private int id = -1;

    public KeyRecord() {}

    public KeyRecord(int id) {
      this.id = id;
    }

    @Override
    public String toString() {
      return ((Integer) id).toString();
    }
  }

  /** The common map output value record.
   *  Carries a tag specifying what source
   *  record type was.
   */
  public static class JoinableRecord {
    private int id = -1;
    private CharSequence name = "";
    private long balance = 0L;
    private CharSequence recType = "";

    public JoinableRecord() {}

    public JoinableRecord(
        CharSequence recType,
        int id,
        CharSequence name,
        long balance) {
      this.id = id;
      this.recType = recType;
      this.name = name;
      this.balance = balance;
    }

    @Override
    public String toString() {
      return recType.toString();
    }
  }

  /** The output, combined record. */
  public static class CompleteRecord {
    private int id = -1;
    private CharSequence name = "";
    private long balance = 0L;

    public CompleteRecord() {}

    public CompleteRecord(int id, CharSequence name, long balance) {
      this.name = name;
      this.id = id;
      this.balance = balance;
    }

    void setId(int id) { this.id = id; };

    void setName(CharSequence name) { this.name = name; };

    void setBalance(long balance) { this.balance = balance; };

    @Override
    public String toString() {
      return id + "\t" + name + "\t" + balance;
    }
  }

  public static class NamesMapImpl
    extends AvroMapper<NamesRecord, Pair<KeyRecord, JoinableRecord>> {

    @Override
    public void map(
        NamesRecord nameRecord,
        AvroCollector<Pair<KeyRecord, JoinableRecord>> collector,
        Reporter reporter) throws IOException {
      collector.collect(
          new Pair<KeyRecord, JoinableRecord>(
              new KeyRecord(nameRecord.id),
              new JoinableRecord(nameRecord.getClass().getName(),
                  nameRecord.id, nameRecord.name, -1L)));
    }

  }

  public static class BalancesMapImpl
    extends AvroMapper<BalancesRecord, Pair<KeyRecord, JoinableRecord>> {

    @Override
      public void map(
          BalancesRecord balanceRecord,
          AvroCollector<Pair<KeyRecord, JoinableRecord>> collector,
          Reporter reporter) throws IOException {
      collector.collect(
          new Pair<KeyRecord, JoinableRecord>(
              new KeyRecord(balanceRecord.id),
              new JoinableRecord(balanceRecord.getClass().getName(),
                  balanceRecord.id, "", balanceRecord.balance)));
    }

  }

  public static class ReduceImpl
    extends AvroReducer<KeyRecord, JoinableRecord, CompleteRecord> {

    @Override
    public void reduce(KeyRecord ID, Iterable<JoinableRecord> joinables,
                       AvroCollector<CompleteRecord> collector,
                       Reporter reporter) throws IOException {
      CompleteRecord rec = new CompleteRecord();
      for (JoinableRecord joinable : joinables) {
        rec.setId(joinable.id);
        if (joinable.recType.toString().contains("NamesRecord")) {
          rec.setName(joinable.name);
        } else {
          rec.setBalance(joinable.balance);
        }
      }
      collector.collect(rec);
    }

  }

  @Test
  public void testJob() throws Exception {
    JobConf job = new JobConf();
    String dir = System.getProperty("test.dir", ".") +
        "target/testAvroMultipleInputs";
    Path inputPath1 = new Path(dir + "/in1");
    Path inputPath2 = new Path(dir + "/in2");
    Path outputPath = new Path(dir + "/out");

    outputPath.getFileSystem(job).delete(outputPath, true);
    inputPath1.getFileSystem(job).delete(inputPath1, true);
    inputPath2.getFileSystem(job).delete(inputPath2, true);

    writeNamesFiles(new File(inputPath1.toUri().getPath()));
    writeBalancesFiles(new File(inputPath2.toUri().getPath()));

    job.setJobName("multiple-inputs-join");
    AvroMultipleInputs.addInputPath(job, inputPath1, NamesMapImpl.class,
        ReflectData.get().getSchema(NamesRecord.class));
    AvroMultipleInputs.addInputPath(job, inputPath2, BalancesMapImpl.class,
        ReflectData.get().getSchema(BalancesRecord.class));

    Schema keySchema = ReflectData.get().getSchema(KeyRecord.class);
    Schema valueSchema = ReflectData.get().getSchema(JoinableRecord.class);
    AvroJob.setMapOutputSchema
      (job, Pair.getPairSchema(keySchema, valueSchema));
    AvroJob.setOutputSchema(job,
        ReflectData.get().getSchema(CompleteRecord.class));

    AvroJob.setReducerClass(job, ReduceImpl.class);
    job.setNumReduceTasks(1);

    FileOutputFormat.setOutputPath(job, outputPath);

    AvroJob.setReflect(job);

    JobClient.runJob(job);

    validateCompleteFile(new File(new File(dir, "out"), "part-00000.avro"));
  }

  /**
   * Writes a "names.avro" file with five sequential <id, name> pairs.
   */
  private void writeNamesFiles(File dir) throws IOException {
    DatumWriter<NamesRecord> writer = new ReflectDatumWriter<NamesRecord>();
    DataFileWriter<NamesRecord> out = new DataFileWriter<NamesRecord>(writer);
    File namesFile = new File(dir+"/names.avro");
    dir.mkdirs();
    out.create(ReflectData.get().getSchema(NamesRecord.class), namesFile);
    for (int i=0; i < 5; i++)
      out.append(new NamesRecord(i, "record"+i));
    out.close();
  }

  /**
   * Writes a "balances.avro" file with five sequential <id, balance> pairs.
   */
  private void writeBalancesFiles(File dir) throws IOException {
    DatumWriter<BalancesRecord> writer =
        new ReflectDatumWriter<BalancesRecord>();
    DataFileWriter<BalancesRecord> out =
        new DataFileWriter<BalancesRecord>(writer);
    File namesFile = new File(dir+"/balances.avro");
    dir.mkdirs();
    out.create(ReflectData.get().getSchema(BalancesRecord.class), namesFile);
    for (int i=0; i < 5; i++)
      out.append(new BalancesRecord(i, (long) i+100));
    out.close();
  }

  private void validateCompleteFile(File file) throws Exception {
    DatumReader<CompleteRecord> reader =
        new ReflectDatumReader<CompleteRecord>();
    InputStream in = new BufferedInputStream(new FileInputStream(file));
    DataFileStream<CompleteRecord> records =
        new DataFileStream<CompleteRecord>(in,reader);
    int numRecs = 0;
    for (CompleteRecord rec : records) {
      assertEquals(rec.id, numRecs);
      assertEquals(rec.balance-100, rec.id);
      assertEquals(rec.name, "record"+rec.id);
      numRecs++;
    }
    records.close();
    assertEquals(5, numRecs);
  }

}
