/*
 * 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.camel.component.cxf.converter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;

import javax.ws.rs.core.Response;
import javax.xml.namespace.QName;
import javax.xml.soap.SOAPException;
import javax.xml.soap.SOAPMessage;

import org.apache.camel.Converter;
import org.apache.camel.Exchange;
import org.apache.camel.TypeConverter;
import org.apache.camel.component.cxf.DataFormat;
import org.apache.camel.converter.stream.CachedOutputStream;
import org.apache.camel.spi.TypeConverterRegistry;
import org.apache.camel.support.ExchangeHelper;
import org.apache.cxf.message.MessageContentsList;

import static org.apache.camel.TypeConverter.MISS_VALUE;

/**
 * The <a href="http://camel.apache.org/type-converter.html">Type Converters</a>
 * for CXF related types' converting .
 */
@Converter(generateLoader = true)
public final class CxfConverter {

    private CxfConverter() {
        // Helper class
    }

    @Converter
    public static MessageContentsList toMessageContentsList(final Object[] array) {
        if (array != null) {
            return new MessageContentsList(array);
        } else {
            return new MessageContentsList();
        }
    }
    
    @Converter
    public static QName toQName(String qname) {
        return QName.valueOf(qname);
    }
    
    @Converter
    public static Object[] toArray(Object object) {
        if (object instanceof Collection) {
            return ((Collection<?>)object).toArray();
        } else {
            Object answer[];
            if (object == null) {
                answer = new Object[0];
            } else {
                answer = new Object[1];
                answer[0] = object;
            }
            return answer;
        }       
    }

    @Converter
    public static String soapMessageToString(final SOAPMessage soapMessage, Exchange exchange) throws SOAPException, IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        soapMessage.writeTo(baos);
        return baos.toString(ExchangeHelper.getCharsetName(exchange));
    }
    
    @Converter
    public static InputStream soapMessageToInputStream(final SOAPMessage soapMessage, Exchange exchange) throws SOAPException, IOException {
        CachedOutputStream cos = new CachedOutputStream(exchange);
        soapMessage.writeTo(cos);
        InputStream in = cos.getInputStream();
        return in;
    }
    
    @Converter
    public static DataFormat toDataFormat(final String name) {
        return DataFormat.valueOf(name.toUpperCase());
    }
    
    @Converter
    public static InputStream toInputStream(Response response, Exchange exchange) {
        Object obj = response.getEntity();
        
        if (obj == null) {
            return null;
        }
        
        if (obj instanceof InputStream) {
            // short circuit the lookup
            return (InputStream)obj;
        }
        
        TypeConverterRegistry registry = exchange.getContext().getTypeConverterRegistry();
        TypeConverter tc = registry.lookup(InputStream.class, obj.getClass());
        
        if (tc != null) {
            return tc.convertTo(InputStream.class, exchange, obj);
        }
        
        return null;
    }

    /**
     * Use a fallback type converter so we can convert the embedded list element 
     * if the value is MessageContentsList.  The algorithm of this converter
     * finds the first non-null list element from the list and applies conversion
     * to the list element.
     * 
     * @param type the desired type to be converted to
     * @param exchange optional exchange which can be null
     * @param value the object to be converted
     * @param registry type converter registry
     * @return the converted value of the desired type or null if no suitable converter found
     */
    @SuppressWarnings("unchecked")
    @Converter(fallback = true)
    public static <T> T convertTo(Class<T> type, Exchange exchange, Object value, 
            TypeConverterRegistry registry) {

        // CXF-WS MessageContentsList class
        if (MessageContentsList.class.isAssignableFrom(value.getClass())) {
            MessageContentsList list = (MessageContentsList)value;
            
            // try to turn the first array element into the object that we want
            for (Object embedded : list) {
                if (embedded != null) {
                    if (type.isInstance(embedded)) {
                        return type.cast(embedded);
                    } else {
                        TypeConverter tc = registry.lookup(type, embedded.getClass());
                        if (tc != null) {
                            Object result = tc.convertTo(type, exchange, embedded);
                            if (result != null) {
                                return (T)result;
                            }
                            // there is no suitable result will be return
                            break;
                        }
                    }
                }
            }
            // return void to indicate its not possible to convert at this time
            return (T) MISS_VALUE;
        }

        // CXF-RS Response class
        if (Response.class.isAssignableFrom(value.getClass())) {
            Response response = (Response) value;
            Object entity = response.getEntity();

            TypeConverter tc = registry.lookup(type, entity.getClass());
            if (tc != null) {
                return tc.convertTo(type, exchange, entity);
            }

            // return void to indicate its not possible to convert at this time
            return (T) MISS_VALUE;
        }
        
        return null;
    }
}
