/*
 *  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
 *
 *    https://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.grails.web.converters.marshaller.json;

import groovy.lang.GroovySystem;
import groovy.lang.MetaClass;
import groovy.lang.MetaMethod;

import grails.converters.JSON;
import org.grails.web.converters.exceptions.ConverterException;
import org.grails.web.converters.marshaller.ObjectMarshaller;
import org.grails.web.json.JSONWriter;

/**
 * @author Siegfried Puchbauer
 * @since 1.1
 */
public class InstanceMethodBasedMarshaller implements ObjectMarshaller<JSON> {

    public boolean supports(Object object) {
        return getToJSONMethod(object) != null;
    }

    public void marshalObject(Object object, JSON converter) throws ConverterException {
        MetaMethod method = getToJSONMethod(object);
        try {
            Object result = method.invoke(object, new Object[]{ converter });
            if (result != null && !(result instanceof JSON) && !(result instanceof JSONWriter)) {
                converter.convertAnother(result);
            }
        }
        catch (Throwable e) {
            throw e instanceof ConverterException ? (ConverterException) e :
                new ConverterException("Error invoking toJSON method of object with class " + object.getClass().getName(), e);
        }
    }

    protected MetaMethod getToJSONMethod(Object object) {
        MetaClass mc = GroovySystem.getMetaClassRegistry().getMetaClass(object.getClass());
        if (mc != null) {
            return mc.getMetaMethod("toJSON", new Object[] { JSON.class });
        }
        return null;
    }
}
