package org.simantics.db.layer0.variable;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.Datatypes;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.error.DatatypeConstructionException;
import org.simantics.databoard.type.Datatype;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.util.Layer0Utils;
import org.simantics.layer0.Layer0;

abstract public class StandardExpressionGraphPropertyVariable extends StandardGraphPropertyVariable {
	
    final public String expressionText;
	
	transient private int hash = 0;

	public StandardExpressionGraphPropertyVariable(ReadGraph graph, Variable parent, Resource property, String expressionText) throws DatabaseException {
	    super(graph, parent, null, property);
		assert parent != null;
		assert property != null;
		assert expressionText != null;
		this.expressionText = expressionText;
	}

	@Override
	public void validate(ReadGraph graph) throws DatabaseException {
	}

	@Override
	public String getName(ReadGraph graph) throws DatabaseException {
		return graph.getRelatedValue(property.predicate, graph.getService(Layer0.class).HasName, Bindings.STRING);
	}

	@Override
	public String getLabel(ReadGraph graph) throws DatabaseException {
		return graph.getRelatedValue2(property.predicate, graph.getService(Layer0.class).HasLabel, parent);
	}

	@Override
	public Variable getParent(ReadGraph graph) throws DatabaseException {
		return parent;
	}

	@Override
	public <T> T getValue(ReadGraph graph) throws DatabaseException {
		
		assertAlive(graph);
		
		return (T)getValueAccessor(graph).getValue(graph, this);
	}

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

		return (T)getValueAccessor(graph).getValue(graph, this, binding);
	}
	
	@Override
	public Resource getRepresents(ReadGraph graph) throws DatabaseException {
		
		assertAlive(graph);
		
		return null;
		
	}

	@Override
	public Resource getPossibleRepresents(ReadGraph graph) throws DatabaseException {
		
		assertAlive(graph);
		
		return null;
		
	}

	@Override
	public void setValue(WriteGraph graph, Object value, Binding binding) throws DatabaseException {
		assertAlive(graph);
		throw new UnsupportedOperationException("Procedural expression variable cannot be set.");
	}
	
	@Override
	public void setValue(WriteGraph graph, Object value) throws DatabaseException {
		assertAlive(graph);
		throw new UnsupportedOperationException("Procedural expression variable cannot be set.");
	}

	@Override
	public Datatype getDatatype(ReadGraph graph) throws DatabaseException {
		try {
			return Layer0Utils.getDatatype(graph, this);
		} catch (DatabaseException e) {
			return null;
		}
	}
	
	@Override
	public String getUnit(ReadGraph graph) throws DatabaseException {
		try {
			return Layer0Utils.getUnit(graph, this);
		} catch (DatabaseException e) {
			return null;
		}
	}
	
	@Override
	public Resource getContainerResource(ReadGraph graph) throws DatabaseException {
		return null;
	}

    @Override
    public Collection<Variable> getChildren(ReadGraph graph) throws DatabaseException {

        Map<String, Variable> result = new HashMap<String, Variable>();
        VariableMap map = getPossibleChildVariableMap(graph);
        if(map != null) map.getVariables(graph, this, result);
        return result.values();
        
    }
    
    @Override
    public Variable getPossibleChild(ReadGraph graph, String name) throws DatabaseException {

        VariableMap map = getPossibleChildVariableMap(graph);
        if(map == null) return null;
        try {
            return map.getVariable(graph, this, name);
        } catch (DatabaseException e) {
            return null;
        }
        
    }
	
	@Override
	protected Variable getPossibleDomainProperty(ReadGraph graph, String name) throws DatabaseException {

		VariableMap valueMap = getPossiblePropertyVariableMap(graph);
		if(valueMap == null) return null;
		try {
			return valueMap.getVariable(graph, this, name);
		} catch (DatabaseException e) {
			return null;
		}
		
	}
	
	@Override
	public Map<String, Variable> collectDomainProperties(ReadGraph graph, Map<String, Variable> properties) throws DatabaseException {

		VariableMap valueMap = getPossiblePropertyVariableMap(graph);
		if(valueMap == null) return properties;
		return valueMap.getVariables(graph, this, properties);
		
	}
	
	@Override
	public Variable getPredicate(ReadGraph graph) throws DatabaseException {
		return Variables.getVariable(graph, graph.getURI(property.predicate));
	}
	
	@Override
	public Resource getPredicateResource(ReadGraph graph) throws DatabaseException {
		return property.predicate;
	}
	
	@Override
	public Resource getPossiblePredicateResource(ReadGraph graph) throws DatabaseException {
		return property.predicate;
	}

	@Override
	public int hashCode() {
		if(hash == 0) {
			final int prime = 31;
			int result = 1;
			result = prime * result + parent.hashCode();
			result = prime * result + property.hashCode();
			result = prime * result + expressionText.hashCode();
			hash =result;
		}
		return hash;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		StandardExpressionGraphPropertyVariable other = (StandardExpressionGraphPropertyVariable) obj;
		if (!expressionText.equals(other.expressionText))
			return false;
		return super.equals(other);
	}

	@Override
	protected Variable getNameVariable(ReadGraph graph) throws DatabaseException {
		Layer0 L0 = Layer0.getInstance(graph);
		return new StandardGraphPropertyVariable(graph, this, L0.HasName);
	}
	
	private void assertAlive(ReadGraph graph) throws DatabaseException {
	}
	
	protected ValueAccessor getValueAccessor(ReadGraph graph) throws DatabaseException {
	    return new ValueAccessor() {
            
            @Override
            public void setValue(WriteGraph graph, Variable context, Object value, Binding binding) throws DatabaseException {
                throw new UnsupportedOperationException();
            }
            
            @Override
            public void setValue(WriteGraph graph, Variable context, Object value) throws DatabaseException {
                throw new UnsupportedOperationException();
            }
            
            @Override
            public Object getValue(ReadGraph graph, Variable context, Binding binding) throws DatabaseException {
            	return compute(graph, context, binding);
            }
            
            @Override
            public Object getValue(ReadGraph graph, Variable context) throws DatabaseException {
            	return compute(graph, context);
            }

			@Override
			public Datatype getDatatype(ReadGraph graph, Variable context) throws DatabaseException {
				try {
					Object value = compute(graph, context);
					return Datatypes.getDatatype(value.getClass());
				} catch (DatatypeConstructionException e) {
					throw new DatabaseException(e);
				}
			}
        };
	}
	
	abstract protected Object compute(ReadGraph graph, Variable context) throws DatabaseException;
	abstract protected Object compute(ReadGraph graph, Variable context, Binding binding) throws DatabaseException;
	
	protected VariableMap getPossibleChildVariableMap(ReadGraph graph) throws DatabaseException {
        return graph.getPossibleRelatedValue2(property.predicate, Layer0.getInstance(graph).domainChildren, this);
	}

	protected VariableMap getPossiblePropertyVariableMap(ReadGraph graph) throws DatabaseException {
		return graph.getPossibleRelatedValue2(property.predicate, Layer0.getInstance(graph).domainProperties, this);
	}
	
	public Set<String> getClassifications(ReadGraph graph) throws DatabaseException {
		ArrayList<String> value = getPropertyValue(graph, "classifications"); 
		return new HashSet<String>(value);
	}
	
}