/*
 * 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.arrow.flight.perf;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.apache.arrow.flight.BackpressureStrategy;
import org.apache.arrow.flight.FlightDescriptor;
import org.apache.arrow.flight.FlightEndpoint;
import org.apache.arrow.flight.FlightInfo;
import org.apache.arrow.flight.FlightProducer;
import org.apache.arrow.flight.FlightServer;
import org.apache.arrow.flight.Location;
import org.apache.arrow.flight.NoOpFlightProducer;
import org.apache.arrow.flight.Ticket;
import org.apache.arrow.flight.perf.impl.PerfOuterClass.Perf;
import org.apache.arrow.flight.perf.impl.PerfOuterClass.Token;
import org.apache.arrow.memory.BufferAllocator;
import org.apache.arrow.util.AutoCloseables;
import org.apache.arrow.util.Preconditions;
import org.apache.arrow.vector.BigIntVector;
import org.apache.arrow.vector.VectorSchemaRoot;
import org.apache.arrow.vector.types.Types.MinorType;
import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.Schema;

import com.google.common.collect.ImmutableList;
import com.google.protobuf.InvalidProtocolBufferException;

public class PerformanceTestServer implements AutoCloseable {

  private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(PerformanceTestServer.class);

  private final FlightServer flightServer;
  private final Location location;
  private final BufferAllocator allocator;
  private final PerfProducer producer;
  private final boolean isNonBlocking;

  public PerformanceTestServer(BufferAllocator incomingAllocator, Location location) {
    this(incomingAllocator, location, new BackpressureStrategy() {
      private FlightProducer.ServerStreamListener listener;

      @Override
      public void register(FlightProducer.ServerStreamListener listener) {
        this.listener = listener;
      }

      @Override
      public WaitResult waitForListener(long timeout) {
        while (!listener.isReady() && !listener.isCancelled()) {
          // busy wait
        }
        return WaitResult.READY;
      }
    }, false);
  }

  public PerformanceTestServer(BufferAllocator incomingAllocator, Location location, BackpressureStrategy bpStrategy,
                               boolean isNonBlocking) {
    this.allocator = incomingAllocator.newChildAllocator("perf-server", 0, Long.MAX_VALUE);
    this.location = location;
    this.producer = new PerfProducer(bpStrategy);
    this.flightServer = FlightServer.builder(this.allocator, location, producer).build();
    this.isNonBlocking = isNonBlocking;
  }

  public Location getLocation() {
    return flightServer.getLocation();
  }

  public PerformanceTestServer start() throws IOException {
    flightServer.start();
    return this;
  }

  @Override
  public void close() throws Exception {
    AutoCloseables.close(flightServer, allocator);
  }

  private final class PerfProducer extends NoOpFlightProducer {
    private final BackpressureStrategy bpStrategy;

    private PerfProducer(BackpressureStrategy bpStrategy) {
      this.bpStrategy = bpStrategy;
    }

    @Override
    public void getStream(CallContext context, Ticket ticket,
        ServerStreamListener listener) {
      bpStrategy.register(listener);
      final Runnable loadData = () -> {
        VectorSchemaRoot root = null;
        try {
          Token token = Token.parseFrom(ticket.getBytes());
          Perf perf = token.getDefinition();
          Schema schema = Schema.deserializeMessage(perf.getSchema().asReadOnlyByteBuffer());
          root = VectorSchemaRoot.create(schema, allocator);
          BigIntVector a = (BigIntVector) root.getVector("a");
          BigIntVector b = (BigIntVector) root.getVector("b");
          BigIntVector c = (BigIntVector) root.getVector("c");
          BigIntVector d = (BigIntVector) root.getVector("d");
          listener.setUseZeroCopy(true);
          listener.start(root);
          root.allocateNew();

          int current = 0;
          long i = token.getStart();
          while (i < token.getEnd()) {
            if (listener.isCancelled()) {
              root.clear();
              return;
            }

            if (TestPerf.VALIDATE) {
              a.setSafe(current, i);
            }

            i++;
            current++;
            if (i % perf.getRecordsPerBatch() == 0) {
              root.setRowCount(current);

              bpStrategy.waitForListener(0);
              if (listener.isCancelled()) {
                root.clear();
                return;
              }
              listener.putNext();
              current = 0;
              root.allocateNew();
            }
          }

          // send last partial batch.
          if (current != 0) {
            root.setRowCount(current);
            listener.putNext();
          }
          listener.completed();
        } catch (InvalidProtocolBufferException e) {
          throw new RuntimeException(e);
        } finally {
          try {
            AutoCloseables.close(root);
          } catch (Exception e) {
            throw new RuntimeException(e);
          }
        }
      };

      if (!isNonBlocking) {
        loadData.run();
      } else {
        final ExecutorService service = Executors.newSingleThreadExecutor();
        service.submit(loadData);
        service.shutdown();
      }
    }

    @Override
    public FlightInfo getFlightInfo(CallContext context,
        FlightDescriptor descriptor) {
      try {
        Preconditions.checkArgument(descriptor.isCommand());
        Perf exec = Perf.parseFrom(descriptor.getCommand());

        final Schema pojoSchema = new Schema(ImmutableList.of(
            Field.nullable("a", MinorType.BIGINT.getType()),
            Field.nullable("b", MinorType.BIGINT.getType()),
            Field.nullable("c", MinorType.BIGINT.getType()),
            Field.nullable("d", MinorType.BIGINT.getType())
            ));

        Token token = Token.newBuilder().setDefinition(exec)
            .setStart(0)
            .setEnd(exec.getRecordsPerStream())
            .build();
        final Ticket ticket = new Ticket(token.toByteArray());

        List<FlightEndpoint> endpoints = new ArrayList<>();
        for (int i = 0; i < exec.getStreamCount(); i++) {
          endpoints.add(new FlightEndpoint(ticket, getLocation()));
        }

        return new FlightInfo(pojoSchema, descriptor, endpoints, -1,
            exec.getRecordsPerStream() * exec.getStreamCount());
      } catch (InvalidProtocolBufferException e) {
        throw new RuntimeException(e);
      }
    }
  }
}



