package org.simantics.db.layer0.variable;

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

import org.simantics.databoard.binding.Binding;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.uri.UnescapedChildMapOfResource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.exception.MissingVariableValueException;
import org.simantics.db.layer0.exception.NonWritableVariableException;
import org.simantics.db.layer0.variable.RVI.RVIPart;
import org.simantics.db.layer0.variable.RVI.StringRVIPart;
import org.simantics.db.layer0.variable.Variables.Role;

public abstract class AbstractChildVariable extends AbstractVariable {
	
	public AbstractChildVariable() {
		this(null);
	}
	
	public AbstractChildVariable(VariableNode node) {
		super(node);
	}

    @Override
    public Role getRole(ReadGraph graph) throws DatabaseException {
        return Role.CHILD;
    }
    
    @Override
    public <T> T getValue(ReadGraph graph) throws DatabaseException {
        throw new MissingVariableValueException("No value in child variable.");
    }
    
    @Override
    public <T> T getValue(ReadGraph graph, Binding binding) throws DatabaseException {
        throw new MissingVariableValueException("No value in child variable.");
    }
    
    @Override
    public void setValue(WriteGraph graph, Object value, Binding binding) throws DatabaseException {
        throw new NonWritableVariableException("Cannot write value to a child variable.");
    }

    
    @Override
    public Resource getRepresents(ReadGraph graph) throws DatabaseException {
        Variable parent = getParent(graph);
        if(!(parent instanceof AbstractChildVariable))
            return null;
        Resource parentRepresents = 
            ((AbstractChildVariable)parent).getRepresentsForBrowsingChildResources(graph);
        if(parentRepresents == null)
            return null;
    	Resource result = graph.syncRequest(new UnescapedChildMapOfResource(parentRepresents))
                .get(getName(graph)); 
//    	System.err.println("getRepresents " + getURI(graph) + " -> parent " + parentRepresents + " " + this + " => " + result + " " + getName(graph));
        return result; 
    }
    
    public Resource getRepresentsForBrowsingChildResources(ReadGraph graph) throws DatabaseException {
        return getRepresents(graph);
    }
    
    @Override
    public Variable getPossibleExtraProperty(ReadGraph graph, String name) throws DatabaseException {
    	return null;
    }
    
    @Override
    public void collectExtraProperties(ReadGraph graph, Map<String, Variable> properties) throws DatabaseException {
    }
    
    @Override
    protected Variable getPossibleDomainProperty(ReadGraph graph, String name) throws DatabaseException {
    	return null;
    }
    
    @Override
    public Variable getPossibleChild(ReadGraph graph, String name) throws DatabaseException {
    	return null;
    }
    
    @Override
    public Map<String, Variable> collectDomainProperties(ReadGraph graph, Map<String, Variable> map) throws DatabaseException {
    	return map;
    }
    
    @Override
    public Collection<Variable> getChildren(ReadGraph graph) throws DatabaseException {
    	return Collections.emptyList();
    }
    
    @Override
    public RVIPart getRVIPart(ReadGraph graph) throws DatabaseException {
    	return new StringRVIPart(Role.CHILD, getName(graph));
    }

    @Override
    public Set<String> getClassifications(ReadGraph graph) throws DatabaseException {
    	return Collections.emptySet();
    }

}