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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
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*/
package org.apache.griffin.measure.step.transform

import scala.collection.mutable.HashSet
import scala.concurrent.duration.Duration
import scala.concurrent.ExecutionContext
import scala.concurrent.Future

import org.apache.griffin.measure.context.DQContext
import org.apache.griffin.measure.step.DQStep
import org.apache.griffin.measure.step.DQStepStatus._
import org.apache.griffin.measure.utils.ThreadUtils

trait TransformStep extends DQStep {

  val rule: String

  val details: Map[String, Any]

  val cache: Boolean

  var status = PENDING

  val parentSteps = new HashSet[TransformStep]

  def doExecute(context: DQContext): Boolean

  def execute(context: DQContext): Boolean = {
    val threadName = Thread.currentThread().getName
    info(threadName + " bigin transform step : \n" + debugString())
    // Submit parents Steps
    val parentStepFutures = parentSteps.filter(checkAndUpdateStatus).map { parentStep =>
      Future {
        val result = parentStep.execute(context)
        parentStep.synchronized {
          if (result) {
            parentStep.status = COMPLETE
          } else {
            parentStep.status = FAILED
          }
        }
      }(TransformStep.transformStepContext)
    }
    ThreadUtils.awaitResult(
      Future.sequence(parentStepFutures)(implicitly, TransformStep.transformStepContext),
      Duration.Inf)

    parentSteps.map(step => {
      while (step.status == RUNNING) {
        Thread.sleep(1000L)
      }
    })
    val prepared = parentSteps.foldLeft(true)((ret, step) => ret && step.status == COMPLETE)
    if (prepared) {
      val res = doExecute(context)
      info(threadName + " end transform step : \n" + debugString())
      res
    } else {
      error("Parent transform step failed!")
      false
    }
  }

  def checkAndUpdateStatus(step: TransformStep): Boolean = {
    step.synchronized {
      if (step.status == PENDING) {
        step.status = RUNNING
        true
      } else {
        false
      }
    }
  }

  def debugString(level: Int = 0): String = {
    val stringBuffer = new StringBuilder
    if (level > 0) {
      for (i <- 0 to level - 1) {
        stringBuffer.append("|   ")
      }
      stringBuffer.append("|---")
    }
    stringBuffer.append(name + "\n")
    parentSteps.foreach(parentStep => stringBuffer.append(parentStep.debugString(level + 1)))
    stringBuffer.toString()
  }
}

object TransformStep {
  private[transform] val transformStepContext = ExecutionContext.fromExecutorService(
    ThreadUtils.newDaemonCachedThreadPool("transform-step"))
}