package org.simantics.db.layer0.variable;

import java.util.Map;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.adapter.AdaptException;
import org.simantics.databoard.adapter.Adapter;
import org.simantics.databoard.adapter.AdapterConstructionException;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.type.Datatype;
import org.simantics.db.Resource;
import org.simantics.db.Statement;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.request.EnumerationMap;
import org.simantics.db.common.request.IsEnumeratedValue;
import org.simantics.db.common.utils.CommonDBUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.exception.RuntimeDatabaseException;
import org.simantics.db.layer0.util.Layer0Utils;
import org.simantics.layer0.Layer0;
import org.simantics.scl.runtime.function.Function4;
import org.simantics.scl.runtime.function.FunctionImpl4;

public class VariableUtils {

	final private static Binding datatype_binding = Bindings.getBindingUnchecked(Datatype.class);
	
	public static Function4<WriteGraph, Variable, Object, Object, String> defaultInputModifier = new FunctionImpl4<WriteGraph, Variable, Object, Object, String>() {

		public String apply(WriteGraph graph, Variable variable, Object value, Object _binding) {
			try {
				return safeApply(graph, variable, value, _binding);
			} catch (DatabaseException e) {
				throw new RuntimeDatabaseException(e);
			}
		}

		public String safeApply(WriteGraph graph, Variable variable, Object value, Object _binding) throws DatabaseException {

	    	Binding binding = (Binding)_binding;
	    	
			Variable parent = variable.getParent(graph);
			Resource property = variable.getPossiblePredicateResource(graph);
			Resource container = parent.getPossibleRepresents(graph);
			if(container == null) return null;
			if(property == null) return null;

			CommonDBUtils.selectClusterSet(graph, container);

			Statement object = graph.getPossibleStatement(container, property);
			if(object == null) return null;

			Resource objectResource = object.getObject();
			if(graph.sync(new IsEnumeratedValue(objectResource))) {

				Layer0 L0 = Layer0.getInstance(graph);
				Resource type = graph.getSingleObject(objectResource, L0.PartOf);
				
				Map<String, Resource> enumMap = graph.syncRequest(new EnumerationMap(type));
				Resource newLiteral = enumMap.get(value);
				graph.deny(container, property, objectResource);
				graph.claim(container, property, newLiteral);
				
				return null;
				
			}

			Layer0 L0 = Layer0.getInstance(graph);
			Statement dt = graph.getPossibleStatement(objectResource, L0.HasDataType);
			if (dt == null) {
				throw new DatabaseException("Can't write variable " + variable.getURI(graph) + " since its literal resource " + objectResource + " does not contain a datatype statement"); 
			}

			boolean needsCustomDatatype = !dt.isAsserted(objectResource);
			Datatype correctDatatype = graph.getValue(dt.getObject(), datatype_binding);
			Binding correctBinding = Bindings.getBinding(correctDatatype);

			try {
				Adapter adapter = Bindings.getTypeAdapter(binding, correctBinding);
				Object correctValue = adapter.adapt(value);
				if (correctValue == value) {
					// Adapter is passthrough, i.e. the specified binding can be
					// considered correct for the value.
					correctBinding = binding;
				}
				value = correctValue;
			} catch (AdapterConstructionException e) {
				throw new DatabaseException("Can't adapt values from source datatype '" + binding.type().toSingleLineString() + "' to target '" + correctDatatype.toSingleLineString() + "'");
			} catch (AdaptException e) {
				throw new DatabaseException("Can't adapt value " + value + " from source datatype '" + binding.type().toSingleLineString() + "' to target '" + correctDatatype.toSingleLineString() + "'");
			}

			if (object.isAsserted(container)) {
				String sclType = needsCustomDatatype ? Layer0Utils.getSCLType(correctDatatype) : null;

				Resource type = graph.getPossibleType(objectResource, L0.Literal);
				objectResource = graph.newResource();
				graph.claim(objectResource, L0.InstanceOf, null, type);
				graph.claim(container, property, objectResource);
				if(needsCustomDatatype) {
					graph.addLiteral(objectResource, L0.HasDataType, L0.HasDataType_Inverse, L0.DataType, correctDatatype, datatype_binding);
					graph.addLiteral(objectResource, L0.HasValueType, L0.HasValueType_Inverse, L0.String, sclType, Bindings.STRING);
				}
			}
			
			graph.claimValue(objectResource, value, correctBinding);
			return null;
			
		}
		
	};

    public static String unnamedResourceName(Resource resource) {
        return "r" + resource.getResourceId();
    }
}