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The OpenTripPlanner multimodal journey planning system
There is a newer version: 2.5.0
package org.opentripplanner.transit.raptor.api.transit;

/**
 * The responsibility is to calculate multi-criteria value (like the generalized cost).
 * 
 * The implementation should be immutable and thread safe.
 */
public interface CostCalculator {

    /**
     * The cost is zero(0) it it is not calculated or if the cost "element" have no cost associated
     * with it.
     */
    int ZERO_COST = 0;

    /**
     * Calculate cost when on-board of a trip. The cost is only used to compare to paths on the
     * same trip - so any cost that is constant for a given trip can be dropped, but it will make
     * debugging easier if the cost can be compared with the "stop-arrival-cost". The cost must
     * incorporate the fact that 2 boarding may happen at 2 different stops.
     */
    int boardingCost(
            boolean firstBoarding,
            int prevArrivalTime,
            int boardStop,
            int boardTime,
            RaptorTripSchedule trip,
            RaptorTransferConstraint transferConstraints
    );


    /**
     * Calculate cost of boarding a trip. This should be the cost of the waiting time,
     * any board and transfer cost, and the penalty for the board stop visit. This cost should
     * NOT include the previous stop arrival cost, but the incremental cost to be added to the
     * previous stop arrival cost.
     *
     * @param boardTime          The time of boarding
     * @param transitFactorIndex The index used to look up the transit reluctance/factor
     */
    int onTripRelativeRidingCost(
            int boardTime,
            int transitFactorIndex
    );

    /**
     * Calculate the value when arriving by transit.
     *
     * @param transitFactorIndex The index used to look up the transit reluctance/factor
     */
    int transitArrivalCost(
            int boardCost,
            int alightSlack,
            int transitTime,
            int transitFactorIndex,
            int toStop
    );

    /**
     * Calculate the value, when waiting between the last transit and egress paths
     */
    int waitCost(int waitTimeInSeconds);

    /**
     * Used for estimating the remaining value for a criteria at a given stop arrival. The
     * calculated value should be a an optimistic estimate for the heuristics to work properly. So,
     * to calculate the generalized cost for given the {@code minTravelTime} and {@code
     * minNumTransfers} retuning the greatest value, which is guaranteed to be less than the
     * real value would be correct and a good choose.
     */
    int calculateMinCost(int minTravelTime, int minNumTransfers);


    /**
     * This method allows the cost calculator to add cost in addition to the generalized-cost of the
     * given egress itself. For example you might want to add a transfer cost to FLEX egress.
     *
     * @return the {@link RaptorTransfer#generalizedCost()} plus any additional board or transfer
     * cost.
     */
    int costEgress(RaptorTransfer egress);
}