package org.simantics.db.layer0.variable;

import gnu.trove.map.hash.THashMap;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.Databoard;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.StringBinding;
import org.simantics.databoard.binding.error.BindingConstructionException;
import org.simantics.databoard.binding.error.BindingException;
import org.simantics.databoard.binding.mutable.Variant;
import org.simantics.databoard.type.Datatype;
import org.simantics.databoard.util.URIStringUtils;
import org.simantics.datatypes.literal.GUID;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.procedure.adapter.TransientCacheAsyncListener;
import org.simantics.db.common.request.PossibleIndexRoot;
import org.simantics.db.common.request.PropertyMapOfResource;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.exception.AdaptionException;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.exception.InvalidVariableException;
import org.simantics.db.layer0.exception.MissingVariableException;
import org.simantics.db.layer0.exception.MissingVariableValueException;
import org.simantics.db.layer0.request.PossibleResource;
import org.simantics.db.layer0.request.PropertyInfo;
import org.simantics.db.layer0.request.VariableRVIRequest;
import org.simantics.db.layer0.variable.RVI.GuidRVIPart;
import org.simantics.db.layer0.variable.RVI.RVIPart;
import org.simantics.db.layer0.variable.RVI.ResourceRVIPart;
import org.simantics.db.layer0.variable.RVI.StringRVIPart;
import org.simantics.db.layer0.variable.Variables.Role;
import org.simantics.layer0.Layer0;

/**
 * Abstract implementation of Variable -interface.
 * 
 * @author Hannu Niemistö
 */
public abstract class AbstractVariable implements Variable {

    @SuppressWarnings("rawtypes")
    final public VariableNode node;

    public AbstractVariable(@SuppressWarnings("rawtypes") VariableNode node) {
        this.node = node;
    }

    /**
     * Returns a variable that is not one of the standard properties listed
     * in <a href="https://www.simantics.org/wiki/index.php/Org.simantics.db.layer0.variable.Variable#Standard_required_properties">specification</a>.
     */
    protected abstract Variable getPossibleDomainProperty(ReadGraph graph, String name) throws DatabaseException;
    public abstract Variable getPossibleExtraProperty(ReadGraph graph, String name) throws DatabaseException;
    public abstract Variable getPossibleChild(ReadGraph graph, String name) throws DatabaseException;
        
    public abstract void collectExtraProperties(ReadGraph graph, Map<String, Variable> properties) throws DatabaseException;
    public abstract Map<String, Variable> collectDomainProperties(ReadGraph graph, Map<String, Variable> map) throws DatabaseException;
    public abstract Collection<Variable> getChildren(ReadGraph graph) throws DatabaseException;
    
    public abstract <T> T getValue(ReadGraph graph) throws DatabaseException;
    public abstract <T> T getValue(ReadGraph graph, Binding binding) throws DatabaseException;

    public abstract void setValue(WriteGraph graph, Object value, Binding binding) throws DatabaseException;
    public abstract String getName(ReadGraph graph) throws DatabaseException;
    //public abstract Object getSerialized(ReadGraph graph) throws DatabaseException;
    public abstract Variable getParent(ReadGraph graph) throws DatabaseException;
    public abstract Role getRole(ReadGraph graph) throws DatabaseException;
    public abstract Resource getRepresents(ReadGraph graph) throws DatabaseException;
    
    public abstract Set<String> getClassifications(ReadGraph graph) throws DatabaseException;
     
    @Override
    public PropertyInfo getPropertyInfo(ReadGraph graph) throws DatabaseException {
    	throw new DatabaseException("PropertyInfo is not available");
    }
    
    @Override
    public Resource getIndexRoot(ReadGraph graph) throws DatabaseException {
    	Resource represents = getPossibleRepresents(graph);
    	if(represents != null) return graph.syncRequest(new PossibleIndexRoot(represents));
    	Variable parent = getParent(graph);
    	if(parent == null) return null;
    	return parent.getIndexRoot(graph);
    }
    
    public void validate(ReadGraph graph) throws DatabaseException {
    }

    public String getIdentifier() {
    	return getClass().getSimpleName();
    }
    
    
    @Override
    public Role getPossibleRole(ReadGraph graph) throws DatabaseException {
    	try {
    		return getRole(graph);
    	} catch (DatabaseException e) {
    		return null;
    	}
    }
    
    protected Variable resolveChild(ReadGraph graph, Resource resource) throws DatabaseException {
    	String rName = graph.getRelatedValue(resource, Layer0.getInstance(graph).HasName, Bindings.STRING);
    	for(Variable child : browseChildren(graph)) {
    		String name = child.getPossiblePropertyValue(graph, Variables.NAME, Bindings.STRING);
    		if(rName.equals(name)) return child;
    	}
    	throw new DatabaseException("Could not resolve child " + resource);
    }
    
    protected Variable resolveChild(ReadGraph graph, GuidRVIPart part) throws DatabaseException {
    	return StandardRVIResolver.resolveChildDefault(graph, this, part);
    }
    
    protected Variable resolveProperty(ReadGraph graph, Resource resource) throws DatabaseException {
    	String rName = graph.getRelatedValue(resource, Layer0.getInstance(graph).HasName, Bindings.STRING);
    	for(Variable child : browseProperties(graph)) {
    		String name = child.getPossiblePropertyValue(graph, Variables.NAME, Bindings.STRING);
    		if(rName.equals(name)) return child;
    	}
    	throw new DatabaseException("Could not resolve child " + resource);
    }

    protected Variable resolveProperty(ReadGraph graph, GuidRVIPart part) throws DatabaseException {
    	return StandardRVIResolver.resolvePropertyDefault(graph, this, part);
    }

    protected Variable resolvePossibleChild(ReadGraph graph, Resource resource) throws DatabaseException {
        String rName = graph.getRelatedValue(resource, Layer0.getInstance(graph).HasName, Bindings.STRING);
        for(Variable child : browseChildren(graph)) {
            String name = child.getPossiblePropertyValue(graph, Variables.NAME, Bindings.STRING);
            if(rName.equals(name)) return child;
        }
        return null;
    }
    
    protected Variable resolvePossibleChild(ReadGraph graph, GuidRVIPart part) throws DatabaseException {
		Layer0 L0 = Layer0.getInstance(graph);
    	for(Variable child : browseChildren(graph)) {
    		GUID id = child.getPossiblePropertyValue(graph, L0.identifier, GUID.BINDING);
    		if(id != null) {
    			if(id.mostSignificant == part.mostSignificant && id.leastSignificant == part.leastSignificant)
    				return child;
    		}
    	}
    	return null;
    }

    protected Variable resolvePossibleProperty(ReadGraph graph, Resource resource) throws DatabaseException {
        String rName = graph.getRelatedValue(resource, Layer0.getInstance(graph).HasName, Bindings.STRING);
        for(Variable child : browseProperties(graph)) {
            String name = child.getPossiblePropertyValue(graph, Variables.NAME, Bindings.STRING);
            if(rName.equals(name)) return child;
        }
        return null;
    }

    protected Variable resolvePossibleProperty(ReadGraph graph, GuidRVIPart part) throws DatabaseException {
		Layer0 L0 = Layer0.getInstance(graph);
    	for(Variable child : browseProperties(graph)) {
    		GUID id = child.getPossiblePropertyValue(graph, L0.identifier, GUID.BINDING);
    		if(id != null) {
    			if(id.mostSignificant == part.mostSignificant && id.leastSignificant == part.leastSignificant)
    				return child;
    		}
    	}
    	return null;
    }

    public String getLabel(ReadGraph graph) throws DatabaseException { 
        return getName(graph);
    }
    
    public String getPossibleLabel(ReadGraph graph) throws DatabaseException {
    	Resource represents = getPossibleRepresents(graph);
    	if(represents == null) return null;
		return graph.getPossibleRelatedValue2(represents, graph.getService(Layer0.class).HasLabel, getParent(graph), Bindings.STRING);
    }

    public Resource getType(ReadGraph graph) throws DatabaseException {
    	
        Resource resource = getPossibleRepresents(graph);
        if(resource == null) {
        	String uri = getPossiblePropertyValue(graph, "typeURI");
        	if(uri != null) return graph.syncRequest(new org.simantics.db.common.primitiverequest.Resource(uri), TransientCacheAsyncListener.<Resource>instance());
            throw new DatabaseException("No type for " + getURI(graph));
        }
        return graph.getSingleType(resource);
        
    }
    
    public RVIPart getRVIPart(ReadGraph graph) throws DatabaseException {
        throw new UnsupportedOperationException();
    }

    @Override
    public RVI getRVI(ReadGraph graph) throws DatabaseException {
    	Databoard databoard = graph.getService( Databoard.class );
    	Binding rviBinding = databoard.getBindingUnchecked( RVI.class );
    	if(Variables.isContext(graph, this)) {
    		return RVI.empty( rviBinding );
    	} else {
    		Variable parent = getParent(graph);
    		if (parent == null)
    			// TODO: consider using a more suitable exception here to better convey the situation.
    			throw new MissingVariableException("no parent for variable " + this + " (URI=" + getPossibleURI(graph) + ")");
    		RVI base = graph.syncRequest(new VariableRVIRequest(parent));
    		RVIPart part = getRVIPart(graph);
    		return new RVIBuilder(base).append(part).toRVI();
    	}
    }
    
    protected Variable getDomainProperty(ReadGraph graph, String name) throws DatabaseException {
        Variable property = getPossibleDomainProperty(graph, name);
        if(property == null)
            throw new MissingVariableException(getIdentifier() + ": Didn't find property " + name + ".");
        return property;
    }
    
    protected void addProperty(Map<String, Variable> properties, String name, Object value, Binding binding) {
        if(value != null) {
            properties.put(name, new ConstantPropertyVariable(this, name, value, binding));
        }
    }

    protected Variable getNameVariable(ReadGraph graph) throws DatabaseException {
    	return new ConstantPropertyVariable(this, Variables.NAME, getName(graph), Bindings.STRING);
    }

    protected Variable getLabelVariable(ReadGraph graph) throws DatabaseException {
    	return new ConstantPropertyVariable(this, Variables.LABEL, getPossibleLabel(graph), Bindings.STRING);
    }

    final public Collection<Variable> browseProperties(ReadGraph graph) throws DatabaseException {
    	return getProperties(graph);
    }

    private Map<String, Variable> getPropertyMap(ReadGraph graph, String classification) throws DatabaseException {
        return collectDomainProperties(graph, classification, null);
    }

    final static class PropertyMap extends THashMap<String,Variable> {
    	
    	final private Variable variable;
    	
    	PropertyMap(Variable variable) {
    		this.variable = variable;
    	}

    	private Variable getTypeVariable() {
    		
    		return new AbstractConstantPropertyVariable(variable, Variables.TYPE, null) {

				@SuppressWarnings("unchecked")
				@Override
				public <T> T getValue(ReadGraph graph) throws DatabaseException {
					Resource represents = parent.getRepresents(graph);
					if(represents == null) return null;
					return (T)graph.getPossibleType(represents, Layer0.getInstance(graph).Entity);
				}

				@Override
				public <T> T getValue(ReadGraph graph, Binding binding) throws DatabaseException {
					return getValue(graph);
				}
    			
    		};
    	}

    	private Variable getURIVariable() {
    		
    		return new AbstractConstantPropertyVariable(variable, Variables.URI, null) {

				@SuppressWarnings("unchecked")
				@Override
				public <T> T getValue(ReadGraph graph) throws DatabaseException {
					return (T)variable.getURI(graph);
				}

				@Override
				public <T> T getValue(ReadGraph graph, Binding binding) throws DatabaseException {
					return getValue(graph);
				}
    			
    		};
    	}

    	public Variable get(Object key) {
    		Variable result = super.get(key);
    		if(result != null) return result;
    		
    		if(Variables.TYPE.equals(key)) return getTypeVariable();
    		else if(Variables.URI.equals(key)) return getURIVariable();
    		
			return null;
		}
    	
    }
    
    private Map<String, Variable> getPropertyMap(ReadGraph graph) throws DatabaseException {
    	PropertyMap properties = new PropertyMap(this);
//        Map<String, Variable> properties = new HashMap<String, Variable>();
//        try {
//            properties.put(Variables.NAME, getNameVariable(graph));
//        } catch (DatabaseException e) {
//            // A variable that has no name doesn't exist by definition.
//            // Therefore it can't have any properties.
//            return Collections.emptyMap();
//        }
//        try {
//            Variable labelVariable = getLabelVariable(graph);
//            if(labelVariable != null) properties.put(Variables.LABEL, getLabelVariable(graph));
//        } catch (DatabaseException e) {
//            // Label not absolutely mandatory.
//        }
//        addProperty(properties, Variables.TYPE, getPossibleType(graph), null);
//        addProperty(properties, Variables.URI, getPossibleURI(graph), Bindings.STRING);
        //addProperty(properties, Variables.SERIALISED, getSerialized(graph), Bindings.STRING);
        //addProperty(properties, Variables.PARENT, getParent(graph), null);
//        addProperty(properties, Variables.ROLE, getRole(graph), Bindings.STRING);
//        addProperty(properties, Variables.REPRESENTS, getPossibleRepresents(graph), null);
        collectExtraProperties(graph, properties);
        collectDomainProperties(graph, properties);
        return properties;
    }
    
    @Override
    public Collection<Variable> getProperties(ReadGraph graph) throws DatabaseException {
    	return getPropertyMap(graph).values();
    }
    
    public Collection<Variable> getProperties(ReadGraph graph, String classification) throws DatabaseException {
    	Map<String,Variable> propertyMap = getPropertyMap(graph, classification);
    	if(propertyMap == null) return Collections.emptyList();
    	else return propertyMap.values();
    }

    @Override
    public Collection<Variable> getProperties(ReadGraph graph, Resource property) throws DatabaseException {
    	return getProperties(graph, uri(graph, property));
    }

    final public Collection<Variable> browseChildren(ReadGraph graph) throws DatabaseException {
    	return getChildren(graph);
    }
    
    @Override
    public Variable getPossibleProperty(ReadGraph graph, String name)
            throws DatabaseException {
        if(Variables.NAME.equals(name)) {
        	return getNameVariable(graph);
        }
        if(Variables.LABEL.equals(name)) {
        	return getLabelVariable(graph);
        }
        if(Variables.TYPE.equals(name)) {
            Object value = getPossibleType(graph);
            if(value != null)
                return new ConstantPropertyVariable(this, name, value, null);
        }
        if(Variables.URI.equals(name)) {
            // TODO: getPossibleURI or getURI?
            Object value = getURI(graph);
            if(value != null)
                return new ConstantPropertyVariable(this, name, value, Bindings.STRING);
        }
//        if(Variables.SERIALISED.equals(name)) {
//            Object value = getSerialized(graph);
//            if(value != null)
//                return new ConstantPropertyVariable(this, name, value, Bindings.STRING);
//        }
        /*if(Variables.PARENT.equals(name)) {
            Object value = getParent(graph);
            if(value != null)
                return new ConstantPropertyVariable(this, name, value, null);
        }*/
//        if(Variables.ROLE.equals(name)) {
//            Object value = getRole(graph);
//            if(value != null)
//                return new ConstantPropertyVariable(this, name, value, null);
//        }
//        if(Variables.REPRESENTS.equals(name)) {
//            Object value = getRepresents(graph);
//            if(value != null)
//                return new ConstantPropertyVariable(this, name, value, null);
//        }
        Variable extra = getPossibleExtraProperty(graph, name);
        if(extra != null) return extra;
        return getPossibleDomainProperty(graph, name);
    }
    
    @Override
    public Variable getPossibleProperty(ReadGraph graph, Resource property) throws DatabaseException {
    	return getPossibleProperty(graph, name(graph, property));
    }

    @SuppressWarnings("unchecked")
    protected <T> T checkNull(ReadGraph graph, Object value) throws DatabaseException {
        if(value == null)
            throw new MissingVariableValueException(getClass().getSimpleName() + ": Didn't find value for " + getPossibleURI(graph));
        return (T)value;
    }

    private String name(ReadGraph graph, Resource property) throws DatabaseException {
    	return graph.getRelatedValue(property, Layer0.getInstance(graph).HasName, Bindings.STRING);
    }
    
    private String uri(ReadGraph graph, Resource property) throws DatabaseException {
    	return graph.getURI(property);
    }

    @Override
    public <T> T getPropertyValue(ReadGraph graph, String name) throws DatabaseException {
    	if(Variables.LABEL.equals(name)) return checkNull(graph, getLabel(graph));
    	Variable result = getDomainProperty(graph, name);
    	if(result != null) return result.getValue(graph);
    	if(Variables.NAME.equals(name)) return checkNull(graph, getName(graph));
    	if(Variables.TYPE.equals(name)) return checkNull(graph, getPossibleType(graph));
    	if(Variables.URI.equals(name)) return checkNull(graph, getURI(graph));
//    	if(Variables.SERIALISED.equals(name)) return checkNull(graph, getSerialized(graph));
//    	if(Variables.ROLE.equals(name)) return checkNull(graph, getRole(graph));
//    	if(Variables.REPRESENTS.equals(name)) return checkNull(graph, getRepresents(graph));
    	Variable extra = getPossibleExtraProperty(graph, name);
    	if(extra != null) return extra.getValue(graph);
    	return null;
    }    
    
    @Override
    public <T> T getPropertyValue(ReadGraph graph, Resource property) throws DatabaseException {
    	return getPropertyValue(graph, name(graph, property));
    }
    
    @SuppressWarnings("unchecked")
    @Override
    public <T> T getPossiblePropertyValue(ReadGraph graph, String name)
            throws DatabaseException {
    	
        Variable property = getPossibleDomainProperty(graph, name);
        if(property != null) return property.getPossibleValue(graph);
    	
        if(Variables.NAME.equals(name)) return (T)getName(graph);
        if(Variables.LABEL.equals(name)) return (T)getLabel(graph);
        if(Variables.TYPE.equals(name)) return (T)getPossibleType(graph);
        if(Variables.URI.equals(name)) return (T)getURI(graph);
//        if(Variables.SERIALISED.equals(name)) return (T)getSerialized(graph);
//        if(Variables.ROLE.equals(name)) return (T)getRole(graph);
//        if(Variables.REPRESENTS.equals(name)) return (T)getRepresents(graph);
        
        Variable extra = getPossibleExtraProperty(graph, name);
        if(extra != null) return extra.getPossibleValue(graph);
        
        return null;
        
    }

    @Override
    public <T> T getPossiblePropertyValue(ReadGraph graph, Resource property) throws DatabaseException {
    	return getPossiblePropertyValue(graph, name(graph, property));
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T getPropertyValue(ReadGraph graph, String name, Binding binding)
            throws DatabaseException {
        if(binding instanceof StringBinding) {
            StringBinding sb = (StringBinding)binding;
            try {
                if(Variables.NAME.equals(name)) return (T)sb.create((String)checkNull(graph, getName(graph)));
                if(Variables.LABEL.equals(name)) return (T)sb.create((String)checkNull(graph, getLabel(graph)));
                if(Variables.URI.equals(name)) return (T)sb.create((String)checkNull(graph, getURI(graph)));
//                if(Variables.SERIALISED.equals(name)) return (T)sb.create((String)checkNull(graph, getSerialized(graph)));
            } catch(BindingException e) {
                throw new DatabaseException(e);
            }
        }
        Variable property = getPossibleExtraProperty(graph, name);
        if(property != null)
            return property.getValue(graph, binding);
        property = getPossibleDomainProperty(graph, name);
        if(property == null)
            throw new MissingVariableException("Didn't find property " + name + " for " + this + ".");
        return property.getValue(graph, binding);
    }

    @Override
    public <T> T getPropertyValue(ReadGraph graph, Resource property, Binding binding) throws DatabaseException {
    	return getPropertyValue(graph, name(graph, property), binding);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T> T getPossiblePropertyValue(ReadGraph graph, String name,
            Binding binding) throws DatabaseException {
        if(binding instanceof StringBinding) {
            StringBinding sb = (StringBinding)binding;
            try {
                if(Variables.NAME.equals(name)) return (T)sb.create((String)getName(graph));
                if(Variables.LABEL.equals(name)) return (T)sb.create((String)getLabel(graph));
                if(Variables.URI.equals(name)) return (T)sb.create((String)getURI(graph));
//                if(Variables.SERIALISED.equals(name)) return (T)sb.create((String)getSerialized(graph));
            } catch(BindingException e) {
                throw new DatabaseException(e);
            }
        }
        Variable property = getPossibleExtraProperty(graph, name);
        if(property != null)
            return property.getPossibleValue(graph, binding);
        property = getPossibleDomainProperty(graph, name);
        if(property == null)
            return null;
        return property.getPossibleValue(graph, binding);
    }

    @Override
    public <T> T getPossiblePropertyValue(ReadGraph graph, Resource property, Binding binding) throws DatabaseException {
    	return getPossiblePropertyValue(graph, name(graph, property), binding);
    }

    @Override
    public void setValue(WriteGraph graph, Object value) throws DatabaseException {
    	try {
			setValue(graph, value, Bindings.getBinding(value.getClass()));
		} catch (BindingConstructionException e) {
			throw new DatabaseException(e);
		}
    }
    
    @Override
    public void setPropertyValue(WriteGraph graph, String name, Object value) throws DatabaseException {
        getProperty(graph, name).setValue(graph, value);
    }

    @Override
    public void setPropertyValue(WriteGraph graph, Resource property, Object value) throws DatabaseException {
    	setPropertyValue(graph, name(graph, property), value);
    }

    @Override
    public void setPropertyValue(WriteGraph graph, String name, Object value,
            Binding binding) throws DatabaseException {
        getProperty(graph, name).setValue(graph, value, binding);
    }

    @Override
    public void setPropertyValue(WriteGraph graph, Resource property, Object value, Binding binding) throws DatabaseException {
    	setPropertyValue(graph, name(graph, property), value, binding);
    }

    @Override
    public Variable getChild(ReadGraph graph, String name)
            throws DatabaseException {
        Variable child = getPossibleChild(graph, name);
        if(child == null)
            throw new MissingVariableException(getURI(graph) + ": didn't find child " + name + " for " + getIdentifier() + ".");
        return child;
    }    

    @Override
    public Variable getProperty(ReadGraph graph, String name)  throws DatabaseException {
        Variable result = getPossibleProperty(graph, name);
        if(result == null)
            throw new MissingVariableException(getClass().getSimpleName() + ": Didn't find property " + name + " for " + getPossibleURI(graph) + ".");
        return result;
    }
    
    @Override
    public Variable getProperty(ReadGraph graph, Resource property) throws DatabaseException {
    	return getProperty(graph, name(graph, property));
    }

    @Override
    public Variable browse(ReadGraph graph, String suffix)
            throws DatabaseException {
    	
        if(suffix.isEmpty()) 
            return this;        
        switch(suffix.charAt(0)) {
        case '.': {
            Variable parent = getParent(graph); 
            if(parent == null)
                throw new MissingVariableException("Didn't find " + suffix + " for " + this + " (" + getPossibleURI(graph) + ").");
            return parent.browse(graph, suffix.substring(1));
        }
        case '#': {
            int segmentEnd = getSegmentEnd(suffix);
            Variable property = getProperty(graph, 
                    decodeString(suffix.substring(1, segmentEnd)));
            if(property == null) 
                throw new MissingVariableException("Didn't find " + suffix + " for " + this + " (" + getPossibleURI(graph) + ").");
            return property.browse(graph, suffix.substring(segmentEnd));
        }
        case '/': {
            int segmentEnd = getSegmentEnd(suffix);
            Variable child = getChild(graph, 
                    decodeString(suffix.substring(1, segmentEnd)));
            if(child == null) 
                throw new MissingVariableException("Didn't find " + suffix + " for " + this + " (" + getPossibleURI(graph) + ").");
            return child.browse(graph, suffix.substring(segmentEnd));
        }
        default:
            throw new MissingVariableException("Didn't find " + suffix + " for " + this + " (" + getPossibleURI(graph) + ").");
        }
    	
    }

    private static int getSegmentEnd(String suffix) {
        int pos;
        for(pos=1;pos<suffix.length();++pos) {
            char c = suffix.charAt(pos);
            if(c == '/' || c == '#')
                break;
        }
        return pos;
    }
    
    @Override
    public Variable browsePossible(ReadGraph graph, String suffix)
            throws DatabaseException {
        if(suffix.isEmpty()) 
            return this;        
        switch(suffix.charAt(0)) {
        case '.': {
            Variable parent = getParent(graph); 
            if(parent == null)
                return null;
            return parent.browsePossible(graph, suffix.substring(1));
        }
        case '#': {
            int segmentEnd = getSegmentEnd(suffix);
            Variable property = getPossibleProperty(graph, 
                    decodeString(suffix.substring(1, segmentEnd)));
            if(property == null) 
                return null;
            return property.browsePossible(graph, suffix.substring(segmentEnd));
        }
        case '/': {
            int segmentEnd = getSegmentEnd(suffix);
            Variable child = getPossibleChild(graph, 
                    decodeString(suffix.substring(1, segmentEnd)));
            if(child == null) 
                return null;
            return child.browsePossible(graph, suffix.substring(segmentEnd));
        }
        default:
            return null;
        }
    }

    @Override
    public Variable browse(ReadGraph graph, Resource config)
            throws DatabaseException {
        Variable variable = browsePossible(graph, config);
        if(variable == null)
            throw new MissingVariableException("Didn't find a variable related to " + 
                    NameUtils.getSafeName(graph, config) + ".");
        return variable;
    }

    @Override
    public Variable browsePossible(ReadGraph graph, Resource config)
            throws DatabaseException {
        Layer0 l0 = Layer0.getInstance(graph);
        String name = (String)graph.getPossibleRelatedValue(config, l0.HasName, Bindings.STRING);
        if (name == null)
            return null;
        return getPossibleChild(graph, name);
    }

    @Override
    public <T> T getInterface(ReadGraph graph, Class<T> clazz)
            throws DatabaseException {
        return null;
    }

    @Override
    public String getURI(ReadGraph graph) throws DatabaseException {
    	validate(graph);
        Variable parent = getParent(graph);
        if (parent == null)
            throw new InvalidVariableException(this + " has no URI");
        return parent.getURI(graph) + getRole(graph).getIdentifier() + encodeString(getName(graph));
    }

    /**
     * For debug messages.
     * 
     * @param graph
     * @return
     * @throws DatabaseException
     */
    public String getPossibleURI(ReadGraph graph) throws DatabaseException {
        Variable parent = getParent(graph);
        if (parent == null)
            return null;
        if (parent instanceof AbstractVariable) {
            String parentUri = ((AbstractVariable) parent).getPossibleURI(graph);
            if (parentUri == null)
                return null;
            return parentUri + getRole(graph).getIdentifier() + encodeString(getName(graph));
        }
        return null;
    }

    public <T> T getPossibleValue(ReadGraph graph) throws DatabaseException {
        try {
            return getValue(graph);
        } catch(DatabaseException e) {
            return null;
        }
    }

    @Override
    public Variant getVariantValue(ReadGraph graph) throws DatabaseException {
    	Binding binding = getPossibleDefaultBinding(graph);
        if(binding != null) {
        	Object value = getValue(graph, binding);
        	return new Variant(binding, value);
        } else {
//        	System.err.println("no data type for " + getURI(graph));
    		// TODO: hackish, consider doing something else here?
    		Object value = getValue(graph);
    		try {
				binding = Bindings.OBJECT.getContentBinding(value);
			} catch (BindingException e) {
				throw new DatabaseException(e);
			}
    		return new Variant(binding, value);
        }
    }
    
    public Variant getPossibleVariantValue(ReadGraph graph) throws DatabaseException {
    	Binding binding = getPossibleDefaultBinding(graph);
        if(binding != null) {
        	Object value = getPossibleValue(graph, binding);
        	if(value == null) return null;
        	return new Variant(binding, value);
        } else {
        	Object value = getPossibleValue(graph);
        	if(value == null) return null;
        	try {
        		// TODO: hackish, consider doing something else here?
        		binding = value != null ? Bindings.getBinding(value.getClass()) : null;
        		return new Variant(binding, value);
        	} catch (BindingConstructionException e) {
        		return null;
        	}
        }
    }

    public <T> T getPossibleValue(ReadGraph graph, Binding binding) throws DatabaseException {
        try {
            return getValue(graph, binding);
        } catch(MissingVariableValueException e) {
            return null;
        }
    }

    public <T> T adapt(ReadGraph graph, Class<T> clazz) throws DatabaseException {
        throw new AdaptionException(this + " does not support adaption to " + clazz);
    }
    
    @Override
    public <T> T adaptPossible(ReadGraph graph, Class<T> clazz) throws DatabaseException {
    	try {
    		return adapt(graph, clazz);
    	} catch (AdaptionException e) {
    		return null;
    	}
    }
    
    
    public static String encodeString(String string) throws DatabaseException {
    	if (string == null || "".equals(string)) return string;
        return URIStringUtils.escape(string);
    }
    
    public static String decodeString(String string) throws DatabaseException {
        return URIStringUtils.unescape(string);
    }
    

	protected Variable getPossiblePropertyFromContext(ReadGraph graph, Resource context, String name) throws DatabaseException {

		Map<String, Resource> predicates = graph.syncRequest(new PropertyMapOfResource(context));
		Resource property = predicates.get(name);
		if(property == null) return null;
		Resource object = graph.getSingleObject(context, property);
		Variable objectAdapter = graph.getPossibleContextualAdapter(object, new ModelledVariablePropertyDescriptorImpl(this, context, property), 
				ModelledVariablePropertyDescriptor.class, Variable.class);
		if(objectAdapter != null) return objectAdapter;
		return graph.getPossibleContextualAdapter(property, new ModelledVariablePropertyDescriptorImpl(this, context, property), 
				ModelledVariablePropertyDescriptor.class, Variable.class);
		
	}
	
	protected Map<String, Variable> collectPropertiesFromContext(ReadGraph graph, Resource context, Map<String, Variable> properties) throws DatabaseException {

		for(Map.Entry<String, Resource> entry : graph.syncRequest(new PropertyMapOfResource(context)).entrySet()) {
			String name = entry.getKey();
			Resource property = entry.getValue();
			Resource object = graph.getSingleObject(context, property);
			Variable objectAdapter = graph.getPossibleContextualAdapter(object, new ModelledVariablePropertyDescriptorImpl(this, context, property), 
					ModelledVariablePropertyDescriptor.class, Variable.class);
			if(objectAdapter != null) {
				if(objectAdapter != null) {
				    if(properties == null) properties = new HashMap<String,Variable>();
				    properties.put(name, objectAdapter);
				}
			} else {
				Variable predicateAdapter = graph.getPossibleContextualAdapter(property, new ModelledVariablePropertyDescriptorImpl(this, context, property), 
						ModelledVariablePropertyDescriptor.class, Variable.class);
				if(predicateAdapter != null) {
                    if(properties == null) properties = new HashMap<String,Variable>();
				    properties.put(name, predicateAdapter);
				}
			}

		}
		
		return properties;
		
	}
	
	@Override
	public Variable resolve(ReadGraph graph, RVIPart part) throws DatabaseException {
		if(part instanceof StringRVIPart) {
			StringRVIPart srp = (StringRVIPart)part;
			if(Role.CHILD.equals(srp.getRole())) return getChild(graph, srp.string);
			else if(Role.PROPERTY.equals(srp.getRole())) return getProperty(graph, srp.string);
		} else if(part instanceof ResourceRVIPart) {
			ResourceRVIPart rrp = (ResourceRVIPart)part;
			if(Role.CHILD.equals(rrp.getRole())) return resolveChild(graph, rrp.resource);
			else if(Role.PROPERTY.equals(rrp.getRole())) return resolveProperty(graph, rrp.resource);
		} else if(part instanceof GuidRVIPart) {
			GuidRVIPart grp = (GuidRVIPart)part;
			if(Role.CHILD.equals(grp.getRole())) return resolveChild(graph, grp);
			else if(Role.PROPERTY.equals(grp.getRole())) return resolveProperty(graph, grp);
		}
		throw new DatabaseException("Unrecognized RVIPart: " + part);
	}

	@Override
	public Variable resolvePossible(ReadGraph graph, RVIPart part) throws DatabaseException {
		if(part instanceof StringRVIPart) {
			StringRVIPart srp = (StringRVIPart)part;
			if(Role.CHILD.equals(srp.getRole())) return getPossibleChild(graph, srp.string);
			else if(Role.PROPERTY.equals(srp.getRole())) return getPossibleProperty(graph, srp.string);
		} else if(part instanceof ResourceRVIPart) {
			ResourceRVIPart rrp = (ResourceRVIPart)part;
			if(Role.CHILD.equals(rrp.getRole())) return resolvePossibleChild(graph, rrp.resource);
			else if(Role.PROPERTY.equals(rrp.getRole())) return resolvePossibleProperty(graph, rrp.resource);
		} else if(part instanceof GuidRVIPart) {
			GuidRVIPart grp = (GuidRVIPart)part;
			if(Role.CHILD.equals(grp.getRole())) return resolvePossibleChild(graph, grp);
			else if(Role.PROPERTY.equals(grp.getRole())) return resolvePossibleProperty(graph, grp);
		}
		throw new DatabaseException("Unrecognized RVIPart: " + part);
	}

	@Override
	public Datatype getDatatype(ReadGraph graph) throws DatabaseException {
		throw new DatabaseException("No data type.");
	}

	public Binding getDefaultBinding(ReadGraph graph) throws DatabaseException {
		Datatype type = getDatatype(graph);
		return Bindings.getBinding(type);
	}
	
	public Binding getPossibleDefaultBinding(ReadGraph graph) throws DatabaseException {
        try {
            return getDefaultBinding(graph);
        } catch(DatabaseException e) {
            return null;
        }
	}

	@Override
	public Datatype getPossibleDatatype(ReadGraph graph) throws DatabaseException {
        try {
            return getDatatype(graph);
        } catch(DatabaseException e) {
            return null;
        }
	}
	
//	public Binding getPossibleDefaultBinding(ReadGraph graph) throws DatabaseException {
//		
//		Datatype type = getPossibleDatatype(graph);
//		if(type == null) return null;
//		return Bindings.getBinding(type);
//
//	}
//
//	@Override
//	public Datatype getPossibleDatatype(ReadGraph graph) throws DatabaseException {
//		
//		Variant vt = getVariantValue(graph);
//		if(vt == null) return null;
//		Binding binding = vt.getBinding();
//		if(binding == null) return null;
//		return binding.type();
//
//	}

	@Override
	public Variable getPredicate(ReadGraph graph) throws DatabaseException {
		throw new DatabaseException(getClass().getSimpleName() + ": No predicate property for " + getPossibleURI(graph));
	}

	@Override
	public Variable getPossiblePredicate(ReadGraph graph) throws DatabaseException {
		try {
            return getPredicate(graph);
        } catch(DatabaseException e) {
            return null;
        }
	}
	
	@Override
	public Resource getPredicateResource(ReadGraph graph) throws DatabaseException {
		Variable predicate = getPredicate(graph);
		if(predicate == null) throw new DatabaseException(getClass().getSimpleName() + ": No predicate property for " + getPossibleURI(graph));
		return predicate.getRepresents(graph);
	}
	
	@Override
	public Resource getPossiblePredicateResource(ReadGraph graph) throws DatabaseException {
		Variable predicate = getPossiblePredicate(graph);
		if(predicate == null) return null;
		else return predicate.getPossibleRepresents(graph);
	}

	@Override
	public Resource getPossibleRepresents(ReadGraph graph) throws DatabaseException {
        try {
            return getRepresents(graph);
        } catch(DatabaseException e) {
            return null;
        }
	}

	@Override
	public Resource getPossibleType(ReadGraph graph) throws DatabaseException {
        Resource resource = getPossibleRepresents(graph);
        if(resource == null) {
        	String uri = getPossiblePropertyValue(graph, "typeURI");
        	if(uri != null) return graph.syncRequest(new PossibleResource(uri), TransientCacheAsyncListener.<Resource>instance());
            return null;
        }
        return graph.getPossibleObject(resource, Layer0.getInstance(graph).InstanceOf);
	}

    public Resource getType(ReadGraph graph, Resource baseType) throws DatabaseException {
        Resource resource = getPossibleRepresents(graph);
        if(resource == null) {
        	String uri = getPossiblePropertyValue(graph, "typeURI");
        	if(uri != null) return graph.syncRequest(new org.simantics.db.common.primitiverequest.Resource(uri), TransientCacheAsyncListener.<Resource>instance());
            throw new DatabaseException("No type for " + getURI(graph));
        }
        return graph.getSingleType(resource, baseType);
    }

	@Override
	public Resource getPossibleType(ReadGraph graph, Resource baseType) throws DatabaseException {
        Resource resource = getPossibleRepresents(graph);
        if(resource == null) {
        	String uri = getPossiblePropertyValue(graph, "typeURI");
        	if(uri != null) {
        		Resource type = graph.syncRequest(new PossibleResource(uri), TransientCacheAsyncListener.<Resource>instance());
        		if(type == null) return null;
        		if(graph.isInheritedFrom(type, baseType)) return type;
        		else return null;
        	}
            return null;
        }
        return graph.getPossibleType(resource, baseType);
	}

    public Map<String, Variable> collectDomainProperties(ReadGraph graph, String classification, Map<String, Variable> map) throws DatabaseException {
    	Map<String,Variable> all = collectDomainProperties(graph, null);
    	for(Map.Entry<String, Variable> entry : all.entrySet()) {
    		Set<String> classifications = entry.getValue().getClassifications(graph);
    		if(classifications.contains(classification)) {
    			if(map == null) map = new HashMap<String,Variable>();
    			map.put(entry.getKey(), entry.getValue());
    		}
    	}
    	return map;
    }
    
    @Override
    public RVI getPossibleRVI(ReadGraph graph) throws DatabaseException {
        try {
            return getRVI(graph);
        } catch(DatabaseException e) {
            return null;
        }
    }

}