package eu.dnetlib.iis.collapsers.basic;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import eu.dnetlib.iis.common.citations.schemas.Citation;
import eu.dnetlib.iis.common.citations.schemas.CitationEntry;

/**
 * Collapses {@link Citation} records by position field by merging all fields 
 * taking confidenceLevel into account when handling destinationDocumentId.
 * 
 * It is expected sourceDocumentId is the same for all {@link Citation} objects.
 * 
 * @author mhorst
 */
public class GenericCitationCollapser extends SimpleCollapser<Citation> {

    @Override
    protected List<Citation> collapseNonEmpty(List<Citation> objects) {
		Map<Integer, List<Citation>> citationsByPositionMap = new HashMap<Integer, List<Citation>>();
		for (Citation citation : objects) {
			List<Citation> list = citationsByPositionMap.get(citation.getEntry().getPosition());
			if (list==null) {
				citationsByPositionMap.put(citation.getEntry().getPosition(), 
						list = new ArrayList<Citation>());
			}
			list.add(citation);
		}
		List<Citation> results = new ArrayList<Citation>(citationsByPositionMap.size());
		for (List<Citation> citationsByPosition : citationsByPositionMap.values()) {
			results.add(collapseForPosition(citationsByPosition));
		}
		return results;
    }

    /**
     * Collapses citations for the same sourceDocumentId and position.
     * @param objects
     * @return collapsed citation or null when nothing to collapse
     */
    Citation collapseForPosition(List<Citation> objects) {
    	if (objects==null || objects.size()==0) {
    		return null;
    	} else if (objects.size()==1) {
    		return objects.get(0);
    	} else {
    		Citation resultCandidate = objects.get(0);
    		for (int i=1; i<objects.size(); i++) {
    			resultCandidate = merge(resultCandidate, objects.get(i).getEntry());
    		}
    		return resultCandidate;
    	}
    }
    
    /**
     * Merges existing citation with new citation entry details.
     * @param existingCitation
     * @param newCitationEntry
     * @return existing citation supplemented with new citation entry details
     */
    Citation merge(Citation existingCitation, CitationEntry newCitationEntry) {
    	if (newCitationEntry != null) {
    		if (newCitationEntry.getDestinationDocumentId()!=null && newCitationEntry.getConfidenceLevel()!=null) {
//    			setting only when not set or when confidence level higher than already stored
//    			important assumption is based on schema assurance: confidenceLevel is always set when destinationDocumentId was set
    			if (existingCitation.getEntry().getDestinationDocumentId()==null ||
    					existingCitation.getEntry().getConfidenceLevel() == null ||
    					existingCitation.getEntry().getConfidenceLevel() < newCitationEntry.getConfidenceLevel()) {
    				existingCitation.getEntry().setDestinationDocumentId(newCitationEntry.getDestinationDocumentId());
    				existingCitation.getEntry().setConfidenceLevel(newCitationEntry.getConfidenceLevel());
    			}
    		}
//    		according to schema externalDestinationDocumentIds cannot be null
    		if (!newCitationEntry.getExternalDestinationDocumentIds().isEmpty()) {
				existingCitation.getEntry().getExternalDestinationDocumentIds().putAll(
						newCitationEntry.getExternalDestinationDocumentIds());
    		}
    		if (newCitationEntry.getRawText()!=null && newCitationEntry.getRawText().length()>0) {
    			existingCitation.getEntry().setRawText(newCitationEntry.getRawText());
    		}
    	}		
    	return existingCitation;
    }
}