/*
 * 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.flink.table.examples.scala

import org.apache.flink.api.scala._
import org.apache.flink.streaming.api.scala.{DataStream, StreamExecutionEnvironment}
import org.apache.flink.table.api.TableEnvironment
import org.apache.flink.table.api.scala._

/**
  * Simple example for demonstrating the use of SQL on a Stream Table.
  *
  * This example shows how to:
  *  - Convert DataStreams to Tables
  *  - Register a Table under a name
  *  - Run a StreamSQL query on the registered Table
  *
  */
object StreamSQLExample {

  // *************************************************************************
  //     PROGRAM
  // *************************************************************************

  def main(args: Array[String]): Unit = {

    // set up execution environment
    val env = StreamExecutionEnvironment.getExecutionEnvironment
    val tEnv = TableEnvironment.getTableEnvironment(env)

    val orderA: DataStream[Order] = env.fromCollection(Seq(
      Order(1L, "beer", 3),
      Order(1L, "diaper", 4),
      Order(3L, "rubber", 2)))

    val orderB: DataStream[Order] = env.fromCollection(Seq(
      Order(2L, "pen", 3),
      Order(2L, "rubber", 3),
      Order(4L, "beer", 1)))

    // register the DataStreams under the name "OrderA" and "OrderB"
    tEnv.registerDataStream("OrderA", orderA, 'user, 'product, 'amount)
    tEnv.registerDataStream("OrderB", orderB, 'user, 'product, 'amount)

    // union the two tables
    val result = tEnv.sqlQuery(
      "SELECT * FROM OrderA WHERE amount > 2 UNION ALL " +
        "SELECT * FROM OrderB WHERE amount < 2")

    result.toAppendStream[Order].print()

    env.execute()
  }

  // *************************************************************************
  //     USER DATA TYPES
  // *************************************************************************

  case class Order(user: Long, product: String, amount: Int)

}