package edu.harvard.iq.dataverse.harvest.server.xoai;
import com.lyncode.xoai.dataprovider.handlers.helpers.ResumptionTokenHelper;
import com.lyncode.xoai.model.oaipmh.ResumptionToken;
import static java.lang.Math.round;
import static com.google.common.base.Predicates.isNull;
/**
*
* @author Leonid Andreev
* Dataverse's own version of the XOAI ResumptionTokenHelper
* Fixes the issue with the offset cursor: the OAI validation spec
* insists that it starts with 0, while the XOAI implementation uses 1
* as the initial offset.
*/
public class XresumptionTokenHelper {
private ResumptionToken.Value current;
private long maxPerPage;
private Long totalResults;
public XresumptionTokenHelper(ResumptionToken.Value current, long maxPerPage) {
this.current = current;
this.maxPerPage = maxPerPage;
}
public XresumptionTokenHelper withTotalResults(long totalResults) {
this.totalResults = totalResults;
return this;
}
public ResumptionToken resolve (boolean hasMoreResults) {
if (isInitialOffset() && !hasMoreResults) return null;
else {
if (hasMoreResults) {
ResumptionToken.Value next = current.next(maxPerPage);
return populate(new ResumptionToken(next));
} else {
ResumptionToken resumptionToken = new ResumptionToken();
resumptionToken.withCursor(round((current.getOffset()) / maxPerPage));
if (totalResults != null)
resumptionToken.withCompleteListSize(totalResults);
return resumptionToken;
}
}
}
private boolean isInitialOffset() {
return isNull().apply(current.getOffset()) || current.getOffset() == 0;
}
private ResumptionToken populate(ResumptionToken resumptionToken) {
if (totalResults != null)
resumptionToken.withCompleteListSize(totalResults);
resumptionToken.withCursor(round((resumptionToken.getValue().getOffset() - maxPerPage)/ maxPerPage));
return resumptionToken;
}
}