source: PerfectFit/Dialog/src/main/java/tudelft/mentalhealth/perfectfit/updatefuncs/TimeDifference.java

package tudelft.mentalhealth.perfectfit.updatefuncs;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

import tudelft.dialogmanager.parameters.DoubleValue;
import tudelft.dialogmanager.parameters.Parameters;
import tudelft.dialogmanager.updatefunctions.UpdateFunction;

/**
 * Function to get difference between two timestamps (in seconds since 1970).
 *
 */
public class TimeDifference implements UpdateFunction {

        private final String previousTimeFieldname;
        private final String differenceFieldname;

        /**
         * 
         * @param previousTimeFieldname the name of the parameter containing the
         *                              previous time
         * @param differenceFieldname   the parameter name that will be filled with
         *                              the difference (seconds) between now and
         *                              previous time.
         */
        @JsonCreator
        public TimeDifference(
                        @JsonProperty("previousTimeFieldname") String previousTimeFieldname,
                        @JsonProperty("differenceFieldname") String differenceFieldname)
                        throws IOException {
                this.previousTimeFieldname = previousTimeFieldname;
                this.differenceFieldname = differenceFieldname;
        }

        @Override
        public Parameters call(Parameters parameters) {
                return parameters.with(differenceFieldname,
                                new DoubleValue(System.currentTimeMillis() / 1000d
                                                - parameters.getDouble(previousTimeFieldname)));
        }

        @Override
        public List<String> getAssignedParameters() {
                return Arrays.asList(differenceFieldname);
        }

}