/*
 * 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.InputFileBlockHolder
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, CodeGenerator, ExprCode, FalseLiteral}
import org.apache.spark.sql.catalyst.expressions.codegen.Block._
import org.apache.spark.sql.internal.SQLConf
import org.apache.spark.sql.types.{DataType, LongType}
import org.apache.spark.unsafe.types.UTF8String

// scalastyle:off whitespace.end.of.line
@ExpressionDescription(
  usage = "_FUNC_() - Returns the name of the file being read, or empty string if not available.",
  examples = """
    Examples:
      > SELECT _FUNC_();

  """,
  since = "1.5.0",
  group = "misc_funcs")
// scalastyle:on whitespace.end.of.line
case class InputFileName() extends LeafExpression with Nondeterministic {

  override def nullable: Boolean = false

  override def dataType: DataType = SQLConf.get.defaultStringType

  override def prettyName: String = "input_file_name"

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

  override protected def evalInternal(input: InternalRow): UTF8String = {
    InputFileBlockHolder.getInputFilePath
  }

  override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
    val className = InputFileBlockHolder.getClass.getName.stripSuffix("$")
    val typeDef = s"final ${CodeGenerator.javaType(dataType)}"
    ev.copy(code = code"$typeDef ${ev.value} = $className.getInputFilePath();",
      isNull = FalseLiteral)
  }
}


@ExpressionDescription(
  usage = "_FUNC_() - Returns the start offset of the block being read, or -1 if not available.",
  examples = """
    Examples:
      > SELECT _FUNC_();
       -1
  """,
  since = "2.2.0",
  group = "misc_funcs")
case class InputFileBlockStart() extends LeafExpression with Nondeterministic {
  override def nullable: Boolean = false

  override def dataType: DataType = LongType

  override def prettyName: String = "input_file_block_start"

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

  override protected def evalInternal(input: InternalRow): Long = {
    InputFileBlockHolder.getStartOffset
  }

  override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
    val className = InputFileBlockHolder.getClass.getName.stripSuffix("$")
    val typeDef = s"final ${CodeGenerator.javaType(dataType)}"
    ev.copy(code = code"$typeDef ${ev.value} = $className.getStartOffset();", isNull = FalseLiteral)
  }
}


@ExpressionDescription(
  usage = "_FUNC_() - Returns the length of the block being read, or -1 if not available.",
  examples = """
    Examples:
      > SELECT _FUNC_();
       -1
  """,
  since = "2.2.0",
  group = "misc_funcs")
case class InputFileBlockLength() extends LeafExpression with Nondeterministic {
  override def nullable: Boolean = false

  override def dataType: DataType = LongType

  override def prettyName: String = "input_file_block_length"

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

  override protected def evalInternal(input: InternalRow): Long = {
    InputFileBlockHolder.getLength
  }

  override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
    val className = InputFileBlockHolder.getClass.getName.stripSuffix("$")
    val typeDef = s"final ${CodeGenerator.javaType(dataType)}"
    ev.copy(code = code"$typeDef ${ev.value} = $className.getLength();", isNull = FalseLiteral)
  }
}
