/*
 * 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.beam.examples.complete;

import com.google.api.services.bigquery.model.TableFieldSchema;
import com.google.api.services.bigquery.model.TableReference;
import com.google.api.services.bigquery.model.TableRow;
import com.google.api.services.bigquery.model.TableSchema;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.avro.reflect.Nullable;
import org.apache.beam.examples.common.ExampleBigQueryTableOptions;
import org.apache.beam.examples.common.ExampleOptions;
import org.apache.beam.examples.common.ExampleUtils;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.PipelineResult;
import org.apache.beam.sdk.coders.AvroCoder;
import org.apache.beam.sdk.coders.DefaultCoder;
import org.apache.beam.sdk.io.TextIO;
import org.apache.beam.sdk.io.gcp.bigquery.BigQueryIO;
import org.apache.beam.sdk.options.Default;
import org.apache.beam.sdk.options.Description;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.Combine;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.SerializableFunction;
import org.apache.beam.sdk.transforms.windowing.SlidingWindows;
import org.apache.beam.sdk.transforms.windowing.Window;
import org.apache.beam.sdk.values.KV;
import org.apache.beam.sdk.values.PBegin;
import org.apache.beam.sdk.values.PCollection;
import org.joda.time.Duration;
import org.joda.time.Instant;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

/**
 * A Beam Example that runs in both batch and streaming modes with traffic sensor data. You can
 * configure the running mode by setting {@literal --streaming} to true or false.
 *
 * <p>Concepts: The batch and streaming runners, sliding windows, use of the AvroCoder to encode a
 * custom class, and custom Combine transforms.
 *
 * <p>This example analyzes traffic sensor data using SlidingWindows. For each window, it finds the
 * lane that had the highest flow recorded, for each sensor station. It writes those max values
 * along with auxiliary info to a BigQuery table.
 *
 * <p>The pipeline reads traffic sensor data from {@literal --inputFile}.
 *
 * <p>The example is configured to use the default BigQuery table from the example common package
 * (there are no defaults for a general Beam pipeline). You can override them by using the {@literal
 * --bigQueryDataset}, and {@literal --bigQueryTable} options. If the BigQuery table do not exist,
 * the example will try to create them.
 *
 * <p>The example will try to cancel the pipelines on the signal to terminate the process (CTRL-C)
 * and then exits.
 */
@SuppressWarnings({
  "nullness" // TODO(https://issues.apache.org/jira/browse/BEAM-10402)
})
public class TrafficMaxLaneFlow {

  static final int WINDOW_DURATION = 60; // Default sliding window duration in minutes
  static final int WINDOW_SLIDE_EVERY = 5; // Default window 'slide every' setting in minutes

  /**
   * This class holds information about each lane in a station reading, along with some general
   * information from the reading.
   */
  @DefaultCoder(AvroCoder.class)
  static class LaneInfo {
    @Nullable String stationId;
    @Nullable String lane;
    @Nullable String direction;
    @Nullable String freeway;
    @Nullable String recordedTimestamp;
    @Nullable Integer laneFlow;
    @Nullable Integer totalFlow;
    @Nullable Double laneAO;
    @Nullable Double laneAS;

    public LaneInfo() {}

    public LaneInfo(
        String stationId,
        String lane,
        String direction,
        String freeway,
        String timestamp,
        Integer laneFlow,
        Double laneAO,
        Double laneAS,
        Integer totalFlow) {
      this.stationId = stationId;
      this.lane = lane;
      this.direction = direction;
      this.freeway = freeway;
      this.recordedTimestamp = timestamp;
      this.laneFlow = laneFlow;
      this.laneAO = laneAO;
      this.laneAS = laneAS;
      this.totalFlow = totalFlow;
    }

    public String getStationId() {
      return this.stationId;
    }

    public String getLane() {
      return this.lane;
    }

    public String getDirection() {
      return this.direction;
    }

    public String getFreeway() {
      return this.freeway;
    }

    public String getRecordedTimestamp() {
      return this.recordedTimestamp;
    }

    public Integer getLaneFlow() {
      return this.laneFlow;
    }

    public Double getLaneAO() {
      return this.laneAO;
    }

    public Double getLaneAS() {
      return this.laneAS;
    }

    public Integer getTotalFlow() {
      return this.totalFlow;
    }
  }

  /** Extract the timestamp field from the input string, and use it as the element timestamp. */
  static class ExtractTimestamps extends DoFn<String, String> {
    private static final DateTimeFormatter dateTimeFormat =
        DateTimeFormat.forPattern("MM/dd/yyyy HH:mm:ss");

    @ProcessElement
    public void processElement(DoFn<String, String>.ProcessContext c) throws Exception {
      String[] items = c.element().split(",", -1);

      if (items.length > 0) {
        try {
          String timestamp = items[0];
          c.outputWithTimestamp(c.element(), new Instant(dateTimeFormat.parseMillis(timestamp)));
        } catch (IllegalArgumentException e) {
          // Skip the invalid input.
        }
      }
    }
  }

  /**
   * Extract flow information for each of the 8 lanes in a reading, and output as separate tuples.
   * This will let us determine which lane has the max flow for that station over the span of the
   * window, and output not only the max flow from that calculation, but other associated
   * information. The number of lanes for which data is present depends upon which freeway the data
   * point comes from.
   */
  static class ExtractFlowInfoFn extends DoFn<String, KV<String, LaneInfo>> {

    @ProcessElement
    public void processElement(ProcessContext c) {
      String[] items = c.element().split(",", -1);
      if (items.length < 48) {
        // Skip the invalid input.
        return;
      }
      // extract the sensor information for the lanes from the input string fields.
      String timestamp = items[0];
      String stationId = items[1];
      String freeway = items[2];
      String direction = items[3];
      Integer totalFlow = tryIntParse(items[7]);
      for (int i = 1; i <= 8; ++i) {
        Integer laneFlow = tryIntParse(items[6 + 5 * i]);
        Double laneAvgOccupancy = tryDoubleParse(items[7 + 5 * i]);
        Double laneAvgSpeed = tryDoubleParse(items[8 + 5 * i]);
        if (laneFlow == null || laneAvgOccupancy == null || laneAvgSpeed == null) {
          return;
        }
        LaneInfo laneInfo =
            new LaneInfo(
                stationId,
                "lane" + i,
                direction,
                freeway,
                timestamp,
                laneFlow,
                laneAvgOccupancy,
                laneAvgSpeed,
                totalFlow);
        c.output(KV.of(stationId, laneInfo));
      }
    }
  }

  /**
   * A custom 'combine function' used with the Combine.perKey transform. Used to find the max lane
   * flow over all the data points in the Window. Extracts the lane flow from the input string and
   * determines whether it's the max seen so far. We're using a custom combiner instead of the Max
   * transform because we want to retain the additional information we've associated with the flow
   * value.
   */
  public static class MaxFlow implements SerializableFunction<Iterable<LaneInfo>, LaneInfo> {
    @Override
    public LaneInfo apply(Iterable<LaneInfo> input) {
      Integer max = 0;
      LaneInfo maxInfo = new LaneInfo();
      for (LaneInfo item : input) {
        Integer flow = item.getLaneFlow();
        if (flow != null && (flow >= max)) {
          max = flow;
          maxInfo = item;
        }
      }
      return maxInfo;
    }
  }

  /**
   * Format the results of the Max Lane flow calculation to a TableRow, to save to BigQuery. Add the
   * timestamp from the window context.
   */
  static class FormatMaxesFn extends DoFn<KV<String, LaneInfo>, TableRow> {
    @ProcessElement
    public void processElement(ProcessContext c) {

      LaneInfo laneInfo = c.element().getValue();
      TableRow row =
          new TableRow()
              .set("station_id", c.element().getKey())
              .set("direction", laneInfo.getDirection())
              .set("freeway", laneInfo.getFreeway())
              .set("lane_max_flow", laneInfo.getLaneFlow())
              .set("lane", laneInfo.getLane())
              .set("avg_occ", laneInfo.getLaneAO())
              .set("avg_speed", laneInfo.getLaneAS())
              .set("total_flow", laneInfo.getTotalFlow())
              .set("recorded_timestamp", laneInfo.getRecordedTimestamp())
              .set("window_timestamp", c.timestamp().toString());
      c.output(row);
    }

    /** Defines the BigQuery schema used for the output. */
    static TableSchema getSchema() {
      List<TableFieldSchema> fields = new ArrayList<>();
      fields.add(new TableFieldSchema().setName("station_id").setType("STRING"));
      fields.add(new TableFieldSchema().setName("direction").setType("STRING"));
      fields.add(new TableFieldSchema().setName("freeway").setType("STRING"));
      fields.add(new TableFieldSchema().setName("lane_max_flow").setType("INTEGER"));
      fields.add(new TableFieldSchema().setName("lane").setType("STRING"));
      fields.add(new TableFieldSchema().setName("avg_occ").setType("FLOAT"));
      fields.add(new TableFieldSchema().setName("avg_speed").setType("FLOAT"));
      fields.add(new TableFieldSchema().setName("total_flow").setType("INTEGER"));
      fields.add(new TableFieldSchema().setName("window_timestamp").setType("TIMESTAMP"));
      fields.add(new TableFieldSchema().setName("recorded_timestamp").setType("STRING"));
      TableSchema schema = new TableSchema().setFields(fields);
      return schema;
    }
  }

  /**
   * This PTransform extracts lane info, calculates the max lane flow found for a given station (for
   * the current Window) using a custom 'combiner', and formats the results for BigQuery.
   */
  static class MaxLaneFlow
      extends PTransform<PCollection<KV<String, LaneInfo>>, PCollection<TableRow>> {
    @Override
    public PCollection<TableRow> expand(PCollection<KV<String, LaneInfo>> flowInfo) {
      // stationId, LaneInfo => stationId + max lane flow info
      PCollection<KV<String, LaneInfo>> flowMaxes = flowInfo.apply(Combine.perKey(new MaxFlow()));

      // <stationId, max lane flow info>... => row...
      PCollection<TableRow> results = flowMaxes.apply(ParDo.of(new FormatMaxesFn()));

      return results;
    }
  }

  static class ReadFileAndExtractTimestamps extends PTransform<PBegin, PCollection<String>> {
    private final String inputFile;

    public ReadFileAndExtractTimestamps(String inputFile) {
      this.inputFile = inputFile;
    }

    @Override
    public PCollection<String> expand(PBegin begin) {
      return begin.apply(TextIO.read().from(inputFile)).apply(ParDo.of(new ExtractTimestamps()));
    }
  }

  /**
   * Options supported by {@link TrafficMaxLaneFlow}.
   *
   * <p>Inherits standard configuration options.
   */
  public interface TrafficMaxLaneFlowOptions extends ExampleOptions, ExampleBigQueryTableOptions {
    @Description("Path of the file to read from")
    @Default.String(
        "gs://apache-beam-samples/traffic_sensor/"
            + "Freeways-5Minaa2010-01-01_to_2010-02-15_test2.csv")
    String getInputFile();

    void setInputFile(String value);

    @Description("Numeric value of sliding window duration, in minutes")
    @Default.Integer(WINDOW_DURATION)
    Integer getWindowDuration();

    void setWindowDuration(Integer value);

    @Description("Numeric value of window 'slide every' setting, in minutes")
    @Default.Integer(WINDOW_SLIDE_EVERY)
    Integer getWindowSlideEvery();

    void setWindowSlideEvery(Integer value);
  }

  public static void runTrafficMaxLaneFlow(TrafficMaxLaneFlowOptions options) throws IOException {
    // Using ExampleUtils to set up required resources.
    ExampleUtils exampleUtils = new ExampleUtils(options);
    exampleUtils.setup();

    Pipeline pipeline = Pipeline.create(options);
    TableReference tableRef = new TableReference();
    tableRef.setProjectId(options.getProject());
    tableRef.setDatasetId(options.getBigQueryDataset());
    tableRef.setTableId(options.getBigQueryTable());

    pipeline
        .apply("ReadLines", new ReadFileAndExtractTimestamps(options.getInputFile()))
        // row... => <station route, station speed> ...
        .apply(ParDo.of(new ExtractFlowInfoFn()))
        // map the incoming data stream into sliding windows.
        .apply(
            Window.into(
                SlidingWindows.of(Duration.standardMinutes(options.getWindowDuration()))
                    .every(Duration.standardMinutes(options.getWindowSlideEvery()))))
        .apply(new MaxLaneFlow())
        .apply(BigQueryIO.writeTableRows().to(tableRef).withSchema(FormatMaxesFn.getSchema()));

    // Run the pipeline.
    PipelineResult result = pipeline.run();

    // ExampleUtils will try to cancel the pipeline and the injector before the program exists.
    exampleUtils.waitToFinish(result);
  }

  /**
   * Sets up and starts streaming pipeline.
   *
   * @throws IOException if there is a problem setting up resources
   */
  public static void main(String[] args) throws IOException {
    TrafficMaxLaneFlowOptions options =
        PipelineOptionsFactory.fromArgs(args).withValidation().as(TrafficMaxLaneFlowOptions.class);
    options.setBigQuerySchema(FormatMaxesFn.getSchema());

    runTrafficMaxLaneFlow(options);
  }

  private static Integer tryIntParse(String number) {
    try {
      return Integer.parseInt(number);
    } catch (NumberFormatException e) {
      return null;
    }
  }

  private static Double tryDoubleParse(String number) {
    try {
      return Double.parseDouble(number);
    } catch (NumberFormatException e) {
      return null;
    }
  }
}
