/*
 * 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.spark.sql.catalyst.expressions

import org.apache.spark.rdd.InputFileNameHolder
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode}
import org.apache.spark.sql.types.{DataType, StringType}
import org.apache.spark.unsafe.types.UTF8String

/**
 * Expression that returns the name of the current file being read.
 */
@ExpressionDescription(
  usage = "_FUNC_() - Returns the name of the current file being read if available.")
case class InputFileName() extends LeafExpression with Nondeterministic {

  override def nullable: Boolean = false

  override def dataType: DataType = StringType

  override def prettyName: String = "input_file_name"

  override protected def initializeInternal(partitionIndex: Int): Unit = {}

  override protected def evalInternal(input: InternalRow): UTF8String = {
    InputFileNameHolder.getInputFileName()
  }

  override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
    ev.copy(code = s"final ${ctx.javaType(dataType)} ${ev.value} = " +
      "org.apache.spark.rdd.InputFileNameHolder.getInputFileName();", isNull = "false")
  }
}
