/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */

package org.apache.isis.core.metamodel.facets.properties.defaults.method;

import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.apache.isis.core.commons.exceptions.UnknownTypeException;
import org.apache.isis.core.metamodel.adapter.ObjectAdapter;
import org.apache.isis.core.metamodel.adapter.ObjectAdapterProvider;
import org.apache.isis.core.metamodel.facetapi.FacetHolder;
import org.apache.isis.core.metamodel.facets.ImperativeFacet;
import org.apache.isis.core.metamodel.facets.properties.defaults.PropertyDefaultFacetAbstract;
import org.apache.isis.core.metamodel.spec.ObjectSpecification;
import org.apache.isis.core.metamodel.specloader.SpecificationLoader;

public class PropertyDefaultFacetViaMethod extends PropertyDefaultFacetAbstract implements ImperativeFacet {

    private final Method method;
    private final SpecificationLoader specificationLoader;
    private final ObjectAdapterProvider adapterProvider;

    public PropertyDefaultFacetViaMethod(
            final Method method,
            final FacetHolder holder,
            final SpecificationLoader specificationLoader,
            final ObjectAdapterProvider adapterProvider) {
        super(holder);
        this.method = method;
        this.specificationLoader = specificationLoader;
        this.adapterProvider = adapterProvider;
    }

    /**
     * Returns a singleton list of the {@link Method} provided in the
     * constructor.
     */
    @Override
    public List<Method> getMethods() {
        return Collections.singletonList(method);
    }

    @Override
    public Intent getIntent(final Method method) {
        return Intent.DEFAULTS;
    }

    @Override
    public ObjectAdapter getDefault(final ObjectAdapter owningAdapter) {
        final Object result = ObjectAdapter.InvokeUtils.invoke(method, owningAdapter);
        if (result == null) {
            return null;
        }
        return createAdapter(method.getReturnType(), result);
    }

    private ObjectAdapter createAdapter(final Class<?> type, final Object object) {
        final ObjectSpecification specification = getSpecificationLoader().loadSpecification(type);
        if (specification.isNotCollection()) {
            return getObjectAdapterProvider().adapterFor(object);
        } else {
            throw new UnknownTypeException("not an object, is this a collection?");
        }
    }

    @Override
    protected String toStringValues() {
        return "method=" + method;
    }

    // //////////////////////////////////////////////////////////////////
    // Dependencies (from constructor)
    // //////////////////////////////////////////////////////////////////

    private SpecificationLoader getSpecificationLoader() {
        return specificationLoader;
    }

    protected ObjectAdapterProvider getObjectAdapterProvider() {
        return adapterProvider;
    }

    @Override public void appendAttributesTo(final Map<String, Object> attributeMap) {
        super.appendAttributesTo(attributeMap);
        ImperativeFacet.Util.appendAttributesTo(this, attributeMap);
    }

}
