/*
 * 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.mahout.h2o.common

import scala.reflect.ClassTag
import org.apache.hadoop.io._
import java.util.Arrays

class DrmMetadata(

    /** Writable  key type as a sub-type of Writable */
    val keyTypeWritable: Class[_],

    /** Value writable type, as a sub-type of Writable */
    val valueTypeWritable: Class[_]

    ) {

  import DrmMetadata._

  val (

      /** Actual drm key class tag once converted out of writable */
      keyClassTag: ClassTag[_],

      /** Conversion from Writable to value type of the DRM key */
      keyW2ValFunc: ((Writable) => Any)

      ) = keyTypeWritable match {
    case cz if cz == classOf[IntWritable] => ClassTag.Int -> w2int _
    case cz if cz == classOf[LongWritable] => ClassTag.Long -> w2long _
    case cz if cz == classOf[DoubleWritable] => ClassTag.Double -> w2double _
    case cz if cz == classOf[FloatWritable] => ClassTag.Float -> w2float _
    case cz if cz == classOf[Text] => ClassTag(classOf[String]) -> w2string _
    case cz if cz == classOf[BooleanWritable] => ClassTag(classOf[Boolean]) -> w2bool _
    case cz if cz == classOf[BytesWritable] => ClassTag(classOf[Array[Byte]]) -> w2bytes _
    case _ => throw new IllegalArgumentException(s"Unsupported DRM key type:${keyTypeWritable.getName}")
  }

}

object DrmMetadata {

  private[common] def w2int(w: Writable) = w.asInstanceOf[IntWritable].get()

  private[common] def w2long(w: Writable) = w.asInstanceOf[LongWritable].get()

  private[common] def w2double(w: Writable) = w.asInstanceOf[DoubleWritable].get()

  private[common] def w2float(w: Writable) = w.asInstanceOf[FloatWritable].get()

  private[common] def w2string(w: Writable) = w.asInstanceOf[Text].toString()

  private[common] def w2bool(w: Writable) = w.asInstanceOf[BooleanWritable].get()

  private[common] def w2bytes(w: Writable) = Arrays.copyOf(w.asInstanceOf[BytesWritable].getBytes(),
                                                           w.asInstanceOf[BytesWritable].getLength())
}
