measure/src/main/scala/org/apache/griffin/measure/configuration/enums/FlattenType.scala

/*
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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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with the License.  You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

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specific language governing permissions and limitations
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*/
package org.apache.griffin.measure.configuration.enums

import scala.util.matching.Regex

/**
  * the strategy to flatten metric
  */
sealed trait FlattenType {
  val idPattern: Regex
  val desc: String
}

object FlattenType {
  private val flattenTypes: List[FlattenType] = List(
    DefaultFlattenType,
    EntriesFlattenType,
    ArrayFlattenType,
    MapFlattenType
  )

  val default = DefaultFlattenType
  def apply(ptn: String): FlattenType = {
    flattenTypes.find(tp => ptn match {
      case tp.idPattern() => true
      case _ => false
    }).getOrElse(default)
  }
  def unapply(pt: FlattenType): Option[String] = Some(pt.desc)
}

/**
  * default flatten strategy
  * metrics contains 1 row -> flatten metric json map
  * metrics contains n > 1 rows -> flatten metric json array
  * n = 0: { }
  * n = 1: { "col1": "value1", "col2": "value2", ... }
  * n > 1: { "arr-name": [ { "col1": "value1", "col2": "value2", ... }, ... ] }
  * all rows
  */
 case object DefaultFlattenType extends FlattenType {
  val idPattern: Regex = "".r
  val desc: String = "default"
}

/**
  * metrics contains n rows -> flatten metric json map
  * n = 0: { }
  * n >= 1: { "col1": "value1", "col2": "value2", ... }
  * the first row only
  */
 case object EntriesFlattenType extends FlattenType {
  val idPattern: Regex = "^(?i)entries$".r
  val desc: String = "entries"
}

/**
  * metrics contains n rows -> flatten metric json array
  * n = 0: { "arr-name": [ ] }
  * n >= 1: { "arr-name": [ { "col1": "value1", "col2": "value2", ... }, ... ] }
  * all rows
  */
 case object ArrayFlattenType extends FlattenType {
  val idPattern: Regex = "^(?i)array|list$".r
  val desc: String = "array"
}

/**
  * metrics contains n rows -> flatten metric json wrapped map
  * n = 0: { "map-name": { } }
  * n >= 1: { "map-name": { "col1": "value1", "col2": "value2", ... } }
  * the first row only
  */
 case object MapFlattenType extends FlattenType {
  val idPattern: Regex = "^(?i)map$".r
  val desc: String = "map"
}