/*
 * 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.griffin.measure.step.read

import org.apache.spark.sql._
import scala.util.Try

import org.apache.griffin.measure.context.DQContext
import org.apache.griffin.measure.step.DQStep

trait ReadStep extends DQStep {

  val config: Map[String, Any]

  val cache: Boolean

  def execute(context: DQContext): Try[Boolean] = Try {
    info(s"read data source [$name]")
    read(context) match {
      case Some(df) =>
//        if (needCache) context.dataFrameCache.cacheDataFrame(name, df)
        context.runTimeTableRegister.registerTable(name, df)
        true
      case _ =>
        warn(s"read data source [$name] fails")
        false
    }
  }

  def read(context: DQContext): Option[DataFrame]

}