Process custom PreloadType to xForm (ODK Collect)

CollectQuestionPreloader.java

package org.odk.collect.android.logic;

import android.support.annotation.NonNull;

import com.google.common.base.Joiner;

import org.javarosa.core.model.data.IAnswerData;
import org.javarosa.core.model.data.LongData;
import org.javarosa.core.model.data.StringData;
import org.javarosa.core.model.instance.TreeElement;
import org.javarosa.core.model.utils.IPreloadHandler;
import org.javarosa.core.model.utils.QuestionPreloader;

import java.util.ArrayList;
import java.util.List;

/**
* Process custom xForm (ODK Collect), because no official prepared
* this rule is to record total time, with additional time-frame (time-laps)
*
* https://opendatakit.github.io/xforms-spec/#bind-attributes
* | PreloadType | Type  | Name       |Note										          |
* | ----------- | ----  | ---------- |----------------------------------------------------|
* | timer       | long  | timerTotal |total time in millis, e.g. 1000				      |
* | timer	    | string| timerLaps  |array of session recorded, e.g. 1-2;5-1000;8000-8100|
* 
* Example in xml:
* `jr:preload="timer"`
* `jr:preloadParams="timerTotal"             type="long"`
* `jr:preloadParams="timerLaps"              type="string"`
* 
* usage:
*         final FormDef formDef = createFormDefFromCacheOrXml(formPath, formXml);
*         formDef.setPreloader(new CollectQuestionPreloader());
*         
*         ..........................
*         // validate current session, sync persist data
*         getFormController().getFormDef().postProcessInstance();
*
*         // store and save new value to xForm
*         CollectQuestionPreloader.setNewTimerTotal(passTimeMilis[0]);
*         CollectQuestionPreloader.getNewTimerLaps().add(String.format("%s-%s", startTimeMilis, Calendar.getInstance().getTimeInMillis()));
*
*         // validate again to force sync current data to be stored to persist
*         getFormController().getFormDef().postProcessInstance();
**/
public class CollectQuestionPreloader extends QuestionPreloader {

    public static boolean isOldTimerTotalUpdated;
    private static long OldTimerTotal;
    private static long newTimerTotal;
    private static List<String> newTimerLaps = new ArrayList<>();
    IPreloadHandler timerLoader = new IPreloadHandler() {
        @Override
        public String preloadHandled() {
            return "timer";
        }

        @Override
        public IAnswerData handlePreload(String preloadParams) {
            return "timerTotal".equals(preloadParams)
                    ? new LongData(CollectQuestionPreloader.newTimerTotal)
                    : "timerLaps".equals(preloadParams)
                    ? new StringData(getNewTimeLapsString())
                    : null;
        }

        @Override
        public boolean handlePostProcess(TreeElement node, String params) {
            if (params.contains("timer")) {
                if ("timerLaps".equals(params)) {
                    String oldValue = node.getValue() == null
                            ? null
                            : node.getValue().getValue().toString();
                    boolean hasNewVlue = CollectQuestionPreloader.getNewTimerLaps().size() > 0;
                    String newValue = hasNewVlue
                            ? oldValue == null || oldValue.equals("")
                            ? getNewTimeLapsString()
                            : oldValue.concat(";").concat(getNewTimeLapsString())
                            : oldValue;
                    node.setAnswer(newValue == null
                            ? null
                            : new StringData(newValue));
                    CollectQuestionPreloader.getNewTimerLaps().clear();

                } else if ("timerTotal".equals(params)) {
                    long oldValue = node.getValue() == null ? 0 : (long) node.getValue().getValue();
                    CollectQuestionPreloader.OldTimerTotal = oldValue;
                    CollectQuestionPreloader.isOldTimerTotalUpdated = true;

                    long newValue = oldValue + CollectQuestionPreloader.newTimerTotal;
                    node.setAnswer(new LongData(newValue));
                    CollectQuestionPreloader.newTimerTotal = 0;
                }

                return true;
            } else {
                return false;
            }
        }

        @NonNull
        String getNewTimeLapsString() {
            return Joiner.on(";").skipNulls().join(CollectQuestionPreloader.getNewTimerLaps());
        }

    };

    /**
     *
     */
    public CollectQuestionPreloader() {
        super.addPreloadHandler(timerLoader);
    }

    public static long getOldTimerTotal() {
        return CollectQuestionPreloader.OldTimerTotal;
    }

    public static void setNewTimerTotal(long timerTotal) {
        CollectQuestionPreloader.newTimerTotal = timerTotal;
    }

    public static List<String> getNewTimerLaps() {
        return CollectQuestionPreloader.newTimerLaps;
    }

}