/*
 * 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.texera.amber.engine.architecture.messaginglayer

import scala.collection.mutable

/* The abstracted FIFO/exactly-once logic */
class OrderingEnforcer[T] {

  val ofoMap = new mutable.LongMap[T]
  var current = 0L

  def setCurrent(value: Long): Unit = {
    current = value
  }

  def isDuplicated(sequenceNumber: Long): Boolean =
    sequenceNumber < current || ofoMap.contains(sequenceNumber)

  def isAhead(sequenceNumber: Long): Boolean = sequenceNumber > current

  def stash(sequenceNumber: Long, data: T): Unit = {
    ofoMap(sequenceNumber) = data
  }

  def enforceFIFO(data: T): List[T] = {
    val res = mutable.ArrayBuffer[T](data)
    current += 1
    while (ofoMap.contains(current)) {
      res.append(ofoMap(current))
      ofoMap.remove(current)
      current += 1
    }
    res.toList
  }
}
