package org.aksw.sparqlify.sparqlview;


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

import org.aksw.jena_sparql_api.restriction.RestrictionManagerImpl;
import org.aksw.jena_sparql_api.views.IViewDef;
import org.aksw.jena_sparql_api.views.ViewInstance;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ListMultimap;

/***
 * A complete binding consists of a list of views and an overall binding
 *
 * Can be seen as a conjunction of views
 *
 * @author raven
 *
 */
public class ViewInstanceJoin<T extends IViewDef>
{
    //private List<T> viewInstances;		// Maybe set of views???

    /**
     * The multimap data structure groups view instances by their parent view,
     * which enables more efficient self join elimination
     * (There can only be self joins if the instance's parent views are the same)
     */
    private ListMultimap<String, ViewInstance<T>> nameToInstances = ArrayListMultimap.create();


    private RestrictionManagerImpl restrictions;

    //private TwoWayBinding completeBinding; // Not sure if that is needed - maybe the restrictions already contain all information

    public List<String> getViewNames() {
        Collection<ViewInstance<T>> viewInstances = getViewInstances();

        List<String> result = new ArrayList<String>(viewInstances.size());

        for(ViewInstance<T> instance : viewInstances) {
            result.add(instance.getViewDefinition().getName());
        }

        return result;
    }

    public static <T extends IViewDef> ListMultimap<String, ViewInstance<T>> toMap(Collection<ViewInstance<T>> viewInstances) {
        ListMultimap<String, ViewInstance<T>> result = ArrayListMultimap.create();

        for(ViewInstance<T> viewInstance : viewInstances) {
            String viewName = viewInstance.getViewDefinition().getName();
            result.put(viewName, viewInstance);
        }

        return result;
    }

    public ListMultimap<String, ViewInstance<T>> getInstancesGroupedByParent() {
        return nameToInstances;
    }

    public ViewInstanceJoin(List<ViewInstance<T>> viewInstances,
            RestrictionManagerImpl restrictions)
    {
        this(toMap(viewInstances), restrictions);
    }

    public ViewInstanceJoin(ListMultimap<String, ViewInstance<T>> nameToInstances,
            RestrictionManagerImpl restrictions)
    {
        super();
        this.nameToInstances = nameToInstances;
        this.restrictions = restrictions;
        //this.completeBinding = completeBinding;
    }


    public Collection<ViewInstance<T>> getViewInstances()
    {
        return nameToInstances.values();
    }

    public RestrictionManagerImpl getRestrictions() {
        return restrictions;
    }

    @Override
    public String toString()
    {
        return "" + getViewInstances();
    }
}