package org.simantics.structural2;

import java.util.Collection;
import java.util.LinkedList;

import org.simantics.databoard.Databoard;
import org.simantics.databoard.binding.Binding;
import org.simantics.datatypes.literal.GUID;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.adapter.Instances;
import org.simantics.db.layer0.exception.MissingVariableException;
import org.simantics.db.layer0.variable.RVI;
import org.simantics.db.layer0.variable.RVI.GuidRVIPart;
import org.simantics.db.layer0.variable.RVI.RVIPart;
import org.simantics.db.layer0.variable.RVIBuilder;
import org.simantics.db.layer0.variable.StandardRVIResolver;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.layer0.variable.Variables;
import org.simantics.layer0.Layer0;
import org.simantics.simulation.ontology.SimulationResource;
import org.simantics.structural.stubs.StructuralResource2;

public class StructuralRVIResolver extends StandardRVIResolver {

    protected boolean isRVIBase(ReadGraph graph, Variable variable) throws DatabaseException {
        if (Variables.isContext(graph, variable)) return true;
        StructuralResource2 STR = StructuralResource2.getInstance(graph);
        Resource represents = variable.getRepresents(graph);
        if (represents == null) return false;
        if (graph.isInstanceOf(represents, STR.Composite)) return false;
        return true;
    }
    
    @Override
    public RVI getRVI(ReadGraph graph, Variable variable) throws DatabaseException {
        if (Variables.isContext(graph, variable)) {
            Databoard databoard = graph.getService( Databoard.class );
            Binding rviBinding = databoard.getBindingUnchecked( RVI.class );
            return RVI.empty(rviBinding);
        }
        else {
            Variable base = variable.getParent(graph);
            while(!isRVIBase(graph, base)) base = base.getParent(graph);
            RVIPart part = getRVIPart(graph, variable);
            return new RVIBuilder(base.getRVI(graph)).append(part).toRVI();
        }
    }
    
    @Override
    public RVI getPossibleRVI(ReadGraph graph, Variable variable) throws DatabaseException {
        if (Variables.isContext(graph, variable)) {
            Databoard databoard = graph.getService( Databoard.class );
            Binding rviBinding = databoard.getBindingUnchecked( RVI.class );
            return RVI.empty(rviBinding);
        }
        else {
            Variable base = variable.getParent(graph);
            if(base == null) return null;
            while(!isRVIBase(graph, base)) {
                base = base.getParent(graph);
                if(base == null) return null;
            }
            RVIPart part = getRVIPart(graph, variable);
            if(part == null) return null;
            RVI baseRVI = base.getPossibleRVI(graph);
            if(baseRVI == null) return null;
            return new RVIBuilder(baseRVI).append(part).toRVI();
        }
    }

    protected boolean isPartOfComponentType(ReadGraph graph, Resource resource)
            throws DatabaseException {
        Layer0 L0 = Layer0.getInstance(graph);
        StructuralResource2 STR = StructuralResource2.getInstance(graph);
        Resource container = graph.getPossibleObject(resource, L0.PartOf);
        if(container != null && graph.isInstanceOf(container, STR.Composite)) {
            return graph.hasStatement(container, STR.Defines);
        }
        return false;
    }

    protected Resource getBase(ReadGraph graph, Variable variable, Resource resource) throws DatabaseException {
        Layer0 L0 = Layer0.getInstance(graph);
        SimulationResource SIMU = SimulationResource.getInstance(graph);
        Resource represents = variable.getPossibleRepresents(graph);
        if(represents != null && graph.isInstanceOf(represents, SIMU.Run)) return Variables.getPossibleConfigurationContextResource(graph, represents);
        else if(isPartOfComponentType(graph, resource)) return graph.getPossibleObject(resource, L0.PartOf);
        return represents;
    }

    protected Collection<Resource> getRVIPath(ReadGraph graph, Variable variable, Resource resource)
            throws DatabaseException {
        Resource base = getBase(graph, variable, resource);
        if (base == null)
            return null;
        LinkedList<Resource> result = new LinkedList<Resource>();
        result.add(resource);
        Layer0 L0 = Layer0.getInstance(graph);
        resource = graph.getPossibleObject(resource, L0.PartOf);
        if(resource == null) return null;
        while(!base.equals(resource)) {
            result.addFirst(resource);
            resource = graph.getPossibleObject(resource, L0.PartOf);
            if(resource == null) return null;
        }
        return result;
    }
    
    protected Collection<Resource> getRVIPath(ReadGraph graph, Variable variable, GuidRVIPart part)
            throws DatabaseException {

    	if(part.resource != null) {
    		return getRVIPath(graph, variable, part.resource);
    	} else {
	    	Resource indexRoot = variable.getIndexRoot(graph);
	        Instances instances = graph.adapt(Layer0.getInstance(graph).Entity, Instances.class);
	        GUID guid = new GUID(part.mostSignificant, part.leastSignificant);
	        Collection<Resource> queryResult = instances.find(graph, indexRoot, "GUID:"+guid.indexString());
	        if(queryResult.size() != 1) return null;
	        return getRVIPath(graph, variable, queryResult.iterator().next());
    	}
    	
    }

    @Override
    protected Variable resolveChild(ReadGraph graph, Variable variable, Resource resource) throws DatabaseException {
        Collection<Resource> path = getRVIPath(graph, variable, resource);
        if (path == null)
            throw new MissingVariableException("Didn't find a variable related to " + resource + ".", resource);
        for (Resource r : path)
            variable = variable.browse(graph, r);
        return variable;
    }

    @Override
    protected Variable resolveChild(ReadGraph graph, Variable variable, GuidRVIPart part) throws DatabaseException {
        Collection<Resource> path = getRVIPath(graph, variable, part);
        if (path == null)
            throw new MissingVariableException("Didn't find a variable related to " + part + ".", variable.getPossibleRepresents(graph));
        for (Resource r : path)
            variable = variable.browse(graph, r);
        return variable;
    }

}