/*******************************************************************************
  * Copyright (c) 2015-2018 Skymind, Inc.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Apache License, Version 2.0 which is available at
  * https://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.
  *
  * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/
package org.nd4s

import org.nd4j.linalg.api.ndarray.INDArray
import org.nd4j.linalg.indexing.{ NDArrayIndex, SpecifiedIndex }

class RowProjectedNDArray(val array: INDArray, val filtered: Array[Int]) {
  def this(ndarray: INDArray) {
    this(ndarray, (0 until ndarray.rows()).toArray)
  }

  def mapi(f: INDArray => INDArray): INDArray = {
    for {
      i <- filtered
    } array.putRow(i, f(array.getRow(i)))
    array.get(new SpecifiedIndex(filtered: _*), NDArrayIndex.all())
  }

  def map(f: INDArray => INDArray): INDArray =
    new RowProjectedNDArray(array.dup(), filtered).mapi(f)

  def flatMap(f: INDArray => INDArray): INDArray = map(f)

  def flatMapi(f: INDArray => INDArray): INDArray = mapi(f)

  def foreach(f: INDArray => Unit): Unit =
    for {
      i <- filtered
    } f(array.getColumn(i))

  def withFilter(f: INDArray => Boolean): RowProjectedNDArray = {
    val targets = for {
      i <- filtered
      if f(array.getRow(i))
    } yield i
    new RowProjectedNDArray(array, targets)
  }
}
