/**
 * Copyright 2012 Twitter, Inc.
 *
 * <p>Licensed 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
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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 fr.ens.biologie.genomique.eoulsan.modules.mapping.hadoop.hadoopbamcli;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Counter;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.JobID;
import org.apache.hadoop.mapreduce.MapContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.StatusReporter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.TaskInputOutputContext;

/*
 * This is based on ContextFactory.java from hadoop-2.0.x sources.
 */

/**
 * Utility methods to allow applications to deal with inconsistencies between MapReduce Context
 * Objects API between hadoop-0.20 and later versions.
 */
public class ContextUtil {

  private static final boolean useV21;

  private static final Constructor<?> JOB_CONTEXT_CONSTRUCTOR;
  private static final Constructor<?> TASK_CONTEXT_CONSTRUCTOR;
  private static final Constructor<?> MAP_CONTEXT_CONSTRUCTOR;
  private static final Constructor<?> MAP_CONTEXT_IMPL_CONSTRUCTOR;
  private static final Constructor<?> GENERIC_COUNTER_CONSTRUCTOR;

  private static final Field READER_FIELD;
  private static final Field WRITER_FIELD;
  private static final Field OUTER_MAP_FIELD;
  private static final Field WRAPPED_CONTEXT_FIELD;

  private static final Method GET_CONFIGURATION_METHOD;
  private static final Method GET_COUNTER_METHOD;
  private static final Method INCREMENT_COUNTER_METHOD;

  static {
    boolean v21 = true;
    final String PACKAGE = "org.apache.hadoop.mapreduce";
    try {
      Class.forName(PACKAGE + ".task.JobContextImpl");
    } catch (ClassNotFoundException cnfe) {
      v21 = false;
    }
    useV21 = v21;
    Class<?> jobContextCls;
    Class<?> taskContextCls;
    Class<?> taskIOContextCls;
    Class<?> mapCls;
    Class<?> mapContextCls;
    Class<?> innerMapContextCls;
    Class<?> genericCounterCls;
    try {
      if (v21) {
        jobContextCls = Class.forName(PACKAGE + ".task.JobContextImpl");
        taskContextCls = Class.forName(PACKAGE + ".task.TaskAttemptContextImpl");
        taskIOContextCls = Class.forName(PACKAGE + ".task.TaskInputOutputContextImpl");
        mapContextCls = Class.forName(PACKAGE + ".task.MapContextImpl");
        mapCls = Class.forName(PACKAGE + ".lib.map.WrappedMapper");
        innerMapContextCls = Class.forName(PACKAGE + ".lib.map.WrappedMapper$Context");
        genericCounterCls = Class.forName(PACKAGE + ".counters.GenericCounter");
      } else {
        jobContextCls = Class.forName(PACKAGE + ".JobContext");
        taskContextCls = Class.forName(PACKAGE + ".TaskAttemptContext");
        taskIOContextCls = Class.forName(PACKAGE + ".TaskInputOutputContext");
        mapContextCls = Class.forName(PACKAGE + ".MapContext");
        mapCls = Class.forName(PACKAGE + ".Mapper");
        innerMapContextCls = Class.forName(PACKAGE + ".Mapper$Context");
        genericCounterCls = Class.forName("org.apache.hadoop.mapred.Counters$Counter");
      }
    } catch (ClassNotFoundException e) {
      throw new IllegalArgumentException("Can't find class", e);
    }
    try {
      JOB_CONTEXT_CONSTRUCTOR = jobContextCls.getConstructor(Configuration.class, JobID.class);
      JOB_CONTEXT_CONSTRUCTOR.setAccessible(true);
      TASK_CONTEXT_CONSTRUCTOR =
          taskContextCls.getConstructor(Configuration.class, TaskAttemptID.class);
      TASK_CONTEXT_CONSTRUCTOR.setAccessible(true);
      GENERIC_COUNTER_CONSTRUCTOR =
          genericCounterCls.getDeclaredConstructor(String.class, String.class, Long.TYPE);
      GENERIC_COUNTER_CONSTRUCTOR.setAccessible(true);

      if (useV21) {
        MAP_CONTEXT_CONSTRUCTOR = innerMapContextCls.getConstructor(mapCls, MapContext.class);
        MAP_CONTEXT_IMPL_CONSTRUCTOR =
            mapContextCls.getDeclaredConstructor(
                Configuration.class,
                TaskAttemptID.class,
                RecordReader.class,
                RecordWriter.class,
                OutputCommitter.class,
                StatusReporter.class,
                InputSplit.class);
        MAP_CONTEXT_IMPL_CONSTRUCTOR.setAccessible(true);
        WRAPPED_CONTEXT_FIELD = innerMapContextCls.getDeclaredField("mapContext");
        WRAPPED_CONTEXT_FIELD.setAccessible(true);
        Method get_counter_method;
        try {
          get_counter_method =
              Class.forName(PACKAGE + ".TaskAttemptContext")
                  .getMethod("getCounter", String.class, String.class);
        } catch (Exception e) {
          get_counter_method =
              Class.forName(PACKAGE + ".TaskInputOutputContext")
                  .getMethod("getCounter", String.class, String.class);
        }
        GET_COUNTER_METHOD = get_counter_method;
      } else {
        MAP_CONTEXT_CONSTRUCTOR =
            innerMapContextCls.getConstructor(
                mapCls,
                Configuration.class,
                TaskAttemptID.class,
                RecordReader.class,
                RecordWriter.class,
                OutputCommitter.class,
                StatusReporter.class,
                InputSplit.class);
        MAP_CONTEXT_IMPL_CONSTRUCTOR = null;
        WRAPPED_CONTEXT_FIELD = null;
        GET_COUNTER_METHOD = taskIOContextCls.getMethod("getCounter", String.class, String.class);
      }
      MAP_CONTEXT_CONSTRUCTOR.setAccessible(true);
      READER_FIELD = mapContextCls.getDeclaredField("reader");
      READER_FIELD.setAccessible(true);
      WRITER_FIELD = taskIOContextCls.getDeclaredField("output");
      WRITER_FIELD.setAccessible(true);
      OUTER_MAP_FIELD = innerMapContextCls.getDeclaredField("this$0");
      OUTER_MAP_FIELD.setAccessible(true);
      GET_CONFIGURATION_METHOD =
          Class.forName(PACKAGE + ".JobContext").getMethod("getConfiguration");
      INCREMENT_COUNTER_METHOD =
          Class.forName(PACKAGE + ".Counter").getMethod("increment", Long.TYPE);
    } catch (SecurityException e) {
      throw new IllegalArgumentException("Can't run constructor ", e);
    } catch (NoSuchMethodException e) {
      throw new IllegalArgumentException("Can't find constructor ", e);
    } catch (NoSuchFieldException e) {
      throw new IllegalArgumentException("Can't find field ", e);
    } catch (ClassNotFoundException e) {
      throw new IllegalArgumentException("Can't find class", e);
    }
  }

  /**
   * Creates JobContext from a JobConf and jobId using the correct constructor for based on Hadoop
   * version. <code>jobId</code> could be null.
   *
   * @param conf Hadoop configuration
   * @param jobId job ID
   * @return a JobContext object
   */
  public static JobContext newJobContext(Configuration conf, JobID jobId) {
    try {
      return (JobContext) JOB_CONTEXT_CONSTRUCTOR.newInstance(conf, jobId);
    } catch (InstantiationException e) {
      throw new IllegalArgumentException("Can't instantiate JobContext", e);
    } catch (IllegalAccessException e) {
      throw new IllegalArgumentException("Can't instantiate JobContext", e);
    } catch (InvocationTargetException e) {
      throw new IllegalArgumentException("Can't instantiate JobContext", e);
    }
  }

  /**
   * Creates TaskAttempContext from a JobConf and jobId using the correct constructor for based on
   * Hadoop version.
   *
   * @param conf Hadoop configuration
   * @param taskAttemptId task attempt ID
   * @return a TaskAttemptContext object
   */
  public static TaskAttemptContext newTaskAttemptContext(
      Configuration conf, TaskAttemptID taskAttemptId) {
    try {
      return (TaskAttemptContext) TASK_CONTEXT_CONSTRUCTOR.newInstance(conf, taskAttemptId);
    } catch (InstantiationException e) {
      throw new IllegalArgumentException("Can't instantiate TaskAttemptContext", e);
    } catch (IllegalAccessException e) {
      throw new IllegalArgumentException("Can't instantiate TaskAttemptContext", e);
    } catch (InvocationTargetException e) {
      throw new IllegalArgumentException("Can't instantiate TaskAttemptContext", e);
    }
  }

  /**
   * Create a new generic counter.
   *
   * @param name name of the counter
   * @param displayName display name
   * @param value the counter value
   * @return with Hadoop 2 : <code>new GenericCounter(args)</code>,<br>
   *     with Hadoop 1 : <code>new Counter(args)</code>
   */
  public static Counter newGenericCounter(String name, String displayName, long value) {
    try {
      return (Counter) GENERIC_COUNTER_CONSTRUCTOR.newInstance(name, displayName, value);
    } catch (InstantiationException e) {
      throw new IllegalArgumentException("Can't instantiate Counter", e);
    } catch (IllegalAccessException e) {
      throw new IllegalArgumentException("Can't instantiate Counter", e);
    } catch (InvocationTargetException e) {
      throw new IllegalArgumentException("Can't instantiate Counter", e);
    }
  }

  /**
   * Invoke getConfiguration() method on JobContext. Works with both Hadoop 1 and 2.
   *
   * @param context job context
   * @return a Configuration object
   */
  public static Configuration getConfiguration(JobContext context) {
    try {
      return (Configuration) GET_CONFIGURATION_METHOD.invoke(context);
    } catch (IllegalAccessException e) {
      throw new IllegalArgumentException("Can't invoke method", e);
    } catch (InvocationTargetException e) {
      throw new IllegalArgumentException("Can't invoke method", e);
    }
  }

  /**
   * Get counter.
   *
   * @param context task context
   * @param groupName group name
   * @param counterName counter name
   * @return a Counter object
   */
  public static Counter getCounter(
      TaskInputOutputContext<?, ?, ?, ?> context, String groupName, String counterName) {
    return (Counter) invoke(GET_COUNTER_METHOD, context, groupName, counterName);
  }

  /** Invokes a method and rethrows any exception as runtime exceptions. */
  private static Object invoke(Method method, Object obj, Object... args) {
    try {
      return method.invoke(obj, args);
    } catch (IllegalAccessException e) {
      throw new IllegalArgumentException("Can't invoke method " + method.getName(), e);
    } catch (InvocationTargetException e) {
      throw new IllegalArgumentException("Can't invoke method " + method.getName(), e);
    }
  }

  /**
   * Increment counter.
   *
   * @param counter counter to increment
   * @param increment increment of the counter
   */
  public static void incrementCounter(Counter counter, long increment) {
    invoke(INCREMENT_COUNTER_METHOD, counter, increment);
  }
}
