StateLocatorBolt.java

package org.p7h.storm.sentimentanalysis.bolts;

import backtype.storm.task.OutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.base.BaseRichBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;
import com.google.common.base.Optional;
import org.p7h.storm.sentimentanalysis.utils.BingMapsLookup;
import org.p7h.storm.sentimentanalysis.utils.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import twitter4j.GeoLocation;
import twitter4j.Place;
import twitter4j.Status;

import java.io.IOException;
import java.util.Map;
import java.util.Properties;

/**
 * Gets the location of tweet by all 3 means and then fwds the State code with the tweet to the next Bolt.
 * There are three different objects within a tweet that we can use to determine it’s origin.
 * This Class utilizes all the three of them and prioritizes in the following order [high to low]:
 *  1. The coordinates object
 *  2. The place object
 *  3. The user object
 *
 * @author - Prashanth Babu
 */
public final class StateLocatorBolt extends BaseRichBolt {
	private static final Logger LOGGER = LoggerFactory.getLogger(StateLocatorBolt.class);
	private static final long serialVersionUID = 791846845769636712L;
	private OutputCollector _outputCollector;

	public StateLocatorBolt() {
		//No op
	}

	@Override
	public final void prepare(final Map map, final TopologyContext topologyContext,
	                          final OutputCollector outputCollector) {
		this._outputCollector = outputCollector;

		final Properties properties = new Properties();
		try {
			properties.load(StateLocatorBolt.class.getClassLoader()
					                .getResourceAsStream(Constants.CONFIG_PROPERTIES_FILE));
		} catch (final IOException ioException) {
			//Should not occur. If it does, we cant continue. So exiting the program!
			LOGGER.error(ioException.getMessage(), ioException);
			System.exit(1);
		}
		//Bolt reads the Bing Maps API Value and stores the same to BING_MAPS_API_KEY_VALUE of Constants.java so that the Bolt can use it.
		//For the lack of time I am using this Constant or else using a good Design Pattern, this can be fine-tuned.
		Constants.BING_MAPS_API_KEY_VALUE = properties.getProperty(Constants.BING_MAPS_API_KEY);
	}

	@Override
	public final void declareOutputFields(final OutputFieldsDeclarer outputFieldsDeclarer) {
		//Emit the state and also the complete tweet to the next Bolt.
		outputFieldsDeclarer.declare(new Fields("state", "tweet"));
	}

	@Override
	@SuppressWarnings("unchecked")
	public final void execute(final Tuple input) {
		final Status status = (Status) input.getValueByField("tweet");
		final Optional<String> stateOptional = getStateFromTweet(status);
		if(stateOptional.isPresent()) {
			final String state = stateOptional.get();
			//Emit the state and also the complete tweet to the next Bolt.
			this._outputCollector.emit(new Values(state, status));
		}
	}

	/**
	 * Tries to get the State of the tweet by checking first GeoLocation Object, then Place Object and finally User Object.
	 *
	 * @param status -- Status Object.
	 * @return State of the Tweet.
	 */
	private final Optional<String> getStateFromTweet(final Status status) {
		String state = getStateFromTweetGeoLocation(status);

		state = getStateFromTweetPlaceObject(status, state);

		state = getStateFromTweetUserObject(status, state);

		if(null == state || !Constants.CONSOLIDATED_STATE_CODES.contains(state)) {
//			LOGGER.info("Skipping invalid State: {}.", state);
			return Optional.absent();
		}
		LOGGER.debug("State:{}", state);
		return Optional.of(state);
	}

	/**
	 * Retrieves the State from User Object of the Tweet.
	 *
	 * @param status -- Status Object.
	 * @param state -- Current State.
	 * @return State of tweet.
	 */
	private final String getStateFromTweetUserObject(final Status status, String state) {
		String stateFromUserObject = status.getUser().getLocation();
		if(null == state && null != stateFromUserObject && 1 < stateFromUserObject.length()) {
			String stateUser = stateFromUserObject.substring(stateFromUserObject.length() - 2).toUpperCase();
			LOGGER.debug("State from User:{}", stateFromUserObject);
			//Retry to get the State of the User if the last 2 chars are US for the User's Location object.
			//This is just a pro-active check.
			//This assumes the format: NY, US
			if("US".equalsIgnoreCase(stateUser) && 5 < stateFromUserObject.length()){
				stateUser = stateFromUserObject.substring(stateFromUserObject.length() - 6, stateFromUserObject.length() - 4);
				LOGGER.debug("State from User again:{}", stateFromUserObject);
			}
			state = (2 == stateUser.length())? stateUser.toUpperCase(): null;
		}
		return state;
	}

	/**
	 * Retrieves the State from Place Object of the Tweet.
	 *
	 * @param status -- Status Object.
	 * @param state -- Current State.
	 * @return State of tweet.
	 */
	private final String getStateFromTweetPlaceObject(final Status status, String state) {
		final Place place = status.getPlace();
		if (null == state && null != place) {
			final String placeName = place.getFullName();
			if (null != placeName && 2 < placeName.length()) {
				final String stateFromPlaceObject = placeName.substring(placeName.length() - 2);
				LOGGER.debug("State from Place:{}", stateFromPlaceObject);
				state = (2 == stateFromPlaceObject.length())? stateFromPlaceObject.toUpperCase(): null;
			}
		}
		return state;
	}

	/**
	 * Retrieves the State from GeoLocation Object of the Tweet.
	 * This is considered as the primary and correct value for the State of the tweet.
	 *
	 * @param status -- Status Object.
	 * @return State of tweet.
	 */
	private final String getStateFromTweetGeoLocation(final Status status) {
		String state = null;
		final double latitude;
		final double longitude;
		final GeoLocation geoLocation = status.getGeoLocation();
		if (null != geoLocation) {
			latitude = geoLocation.getLatitude();
			longitude = geoLocation.getLongitude();
			LOGGER.debug("LatLng for BingMaps:{} and {}", latitude, longitude);
			final Optional<String> stateGeoOptional = BingMapsLookup.reverseGeocodeFromLatLong(latitude, longitude);
			if(stateGeoOptional.isPresent()){
				final String stateFromGeoLocation = stateGeoOptional.get();
				LOGGER.debug("State from BingMaps:{}", stateFromGeoLocation);
				state = (2 == stateFromGeoLocation.length())? stateFromGeoLocation.toUpperCase(): null;
			}
		}
		return state;
	}
}