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The OpenTripPlanner multimodal journey planning system
There is a newer version: 2.5.0
package org.opentripplanner.model.transfer;

import javax.annotation.Nullable;
import org.opentripplanner.model.Route;
import org.opentripplanner.model.Trip;

/**
 * This interface is used to represent a point or location where a transfer start from or end.
 *
 * There are 4 different Transfer points:
 * 

 *   
 *     {@link StopTransferPoint} This apply to all trip stopping at the given stop.
 *
 *     This is the least specific type, and is overridden if a more specific type exist.
 *   
 *   
 *     {@link StationTransferPoint} This applies to all trips stopping at a stop part of the given
 *     station.
 *     The specificity-ranking is above {@link StationTransferPoint}s and less than
 *     {@link RouteStationTransferPoint}.
 *   
 *   
 *     A {@link RouteStationTransferPoint} is a from/to point for a Route at the given stop. This
 *     only exists in GTFS, not in the Nordic NeTex profile.
 *
 *     The specificity-ranking is above {@link StopTransferPoint}s and less than
 *     {@link RouteStopTransferPoint}.
 *   
 *   
 *     A {@link RouteStopTransferPoint} is a from/to point for a Route at the given station. This
 *     only exists in GTFS, not in the Nordic NeTex profile.
 *
 *     The specificity-ranking is above {@link RouteStationTransferPoint}s and less than
 *     {@link TripTransferPoint}.
 *   
 *   
 *     {@link TripTransferPoint} A transfer from/to a Trip at the given stop position(not stop).
 *     The GTFS Transfers may specify a transfer from/to a trip and stop/station. But in OTP we
 *     map the stop to a stop position in pattern. The OTP model {@link TripTransferPoint} does NOT
 *     reference the stop/station, but the {@code stopPositionInPattern} instead. There is two
 *     reasons for this. In NeTEx the an interchange is from a trip and stop-point, so this model
 *     fits better with NeTEx. The second reason is that real-time updates could invalidate the
 *     trip-transfer-point, since the stop could change to another platform(common for railway
 *     stations). To account for this the RT-update would need to patch the trip-transfer-point.
 *     We simplify the RT-updates by converting the stop to a stop-position-in-pattern.
 *     
 *     This is the most specific point type.
 *   
 * 
 * 
 */
public interface TransferPoint {

  /** Return {@code true} if this transfer point apply to all trips in pattern */
  boolean appliesToAllTrips();

  /**
   * 
   * Specificity of a transfer
   * 
   */
  int getSpecificityRanking();

  /** is a Trip specific transfer point */
  default boolean isTripTransferPoint() { return false; }

  default TripTransferPoint asTripTransferPoint() { return (TripTransferPoint) this; }

  /** is a Route specific transfer point */
  default boolean isRouteStationTransferPoint() { return false; }

  default RouteStationTransferPoint asRouteStationTransferPoint() {
    return (RouteStationTransferPoint) this;
  }

  /** is a Route specific transfer point */
  default boolean isRouteStopTransferPoint() { return false; }

  default RouteStopTransferPoint asRouteStopTransferPoint() {
    return (RouteStopTransferPoint) this;
  }

  /** is a Stop specific transfer point (no Trip or Route) */
  default boolean isStopTransferPoint() { return false; }

  default StopTransferPoint asStopTransferPoint() { return (StopTransferPoint) this; }

  /** is a Station specific transfer point (no Trip or Route) */
  default boolean isStationTransferPoint() { return false; }

  default StationTransferPoint asStationTransferPoint() { return (StationTransferPoint) this; }


  /**
   * Utility method witch can be used in APIs to get the trip, if it exists, from a transfer point.
   */
  @Nullable
  static Trip getTrip(TransferPoint point) {
    return point.isTripTransferPoint() ? point.asTripTransferPoint().getTrip() : null;
  }

  /**
   * Utility method witch can be used in APIs to get the route, if it exists, from a transfer point.
   */
  @Nullable
  static Route getRoute(TransferPoint point) {
    if(point.isTripTransferPoint()) {
      return point.asTripTransferPoint().getTrip().getRoute();
    }
    if(point.isRouteStopTransferPoint()) {
      return point.asRouteStopTransferPoint().getRoute();
    }
    if(point.isRouteStationTransferPoint()) {
      return point.asRouteStationTransferPoint().getRoute();
    }
    return null;
  }
}