001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.camel.builder;
019
020import java.util.function.BiFunction;
021
022import org.apache.camel.Exchange;
023import org.apache.camel.Message;
024import org.apache.camel.processor.aggregate.AggregationStrategy;
025import org.apache.camel.util.ObjectHelper;
026
027public class AggregationStrategyClause<T> implements AggregationStrategy {
028    private final T parent;
029    private AggregationStrategy strategy;
030
031    public AggregationStrategyClause(T parent) {
032        this.parent = parent;
033        this.strategy = null;
034    }
035
036    @Override
037    public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
038        return ObjectHelper.notNull(strategy, "AggregationStrategy").aggregate(oldExchange, newExchange);
039    }
040
041    // *******************************
042    // Exchange
043    // *******************************
044
045    /**
046     * Define an aggregation strategy which targets the exchnage.
047     */
048    public T exchange(final BiFunction<Exchange, Exchange, Exchange> function) {
049        strategy = function::apply;
050        return parent;
051    }
052
053    // *******************************
054    // Message
055    // *******************************
056
057    /**
058     * Define an aggregation strategy which targets Exchanges In Message.
059     *
060     * <blockquote><pre>{@code
061     * from("direct:aggregate")
062     *     .aggregate()
063     *         .message((old, new) -> {
064     *             if (old == null) {
065     *                 return new;
066     *             }
067     *
068     *             String oldBody = old.getBody(String.class);
069     *             String newBody = new.getBody(String.class);
070     *
071     *             old.setBody(oldBody + "+" + newBody);
072     *
073     *             return old;
074     *         });
075     * }</pre></blockquote>
076     */
077    public T message(final BiFunction<Message, Message, Message> function) {
078        return exchange((Exchange oldExchange, Exchange newExchange) -> {
079            Message oldMessage = oldExchange != null ? oldExchange.getIn() : null;
080            Message newMessage = ObjectHelper.notNull(newExchange, "NewExchange").getIn();
081            Message result = function.apply(oldMessage, newMessage);
082
083            if (oldExchange != null) {
084                oldExchange.setIn(result);
085                return oldExchange;
086            } else {
087                newExchange.setIn(result);
088                return newExchange;
089            }
090        });
091    }
092
093    // *******************************
094    // Body
095    // *******************************
096
097    /**
098     * Define an aggregation strategy which targets Exchanges In Body.
099     *
100     * <blockquote><pre>{@code
101     * from("direct:aggregate")
102     *     .aggregate()
103     *         .body((old, new) -> {
104     *             if (old == null) {
105     *                 return new;
106     *             }
107     *
108     *             return old.toString() + new.toString();
109     *         });
110     * }</pre></blockquote>
111     */
112    public T body(final BiFunction<Object, Object, Object> function) {
113        return body(Object.class, function);
114    }
115
116    /**
117     * Define an aggregation strategy which targets Exchanges In Body.
118     *
119     * <blockquote><pre>{@code
120     * from("direct:aggregate")
121     *     .aggregate()
122     *         .body(String.class, (old, new) -> {
123     *             if (old == null) {
124     *                 return new;
125     *             }
126     *
127     *             return old + new;
128     *         });
129     * }</pre></blockquote>
130     */
131    public <B> T body(final Class<B> type, final BiFunction<B, B, Object> function) {
132        return body(type, type, function);
133    }
134
135    /**
136     * Define an aggregation strategy which targets Exchanges In Body.
137     */
138    public <O, N> T body(final Class<O> oldType, final Class<N> newType, final BiFunction<O, N, Object> function) {
139        return exchange((Exchange oldExchange, Exchange newExchange) -> {
140            Message oldMessage = oldExchange != null ? oldExchange.getIn() : null;
141            Message newMessage = ObjectHelper.notNull(newExchange, "NewExchange").getIn();
142
143            Object result = function.apply(
144                oldMessage != null ? oldMessage.getBody(oldType) : null,
145                newMessage != null ? newMessage.getBody(newType) : null);
146
147            if (oldExchange != null) {
148                oldExchange.getIn().setBody(result);
149                return oldExchange;
150            } else {
151                newExchange.getIn().setBody(result);
152                return newExchange;
153            }
154        });
155    }
156}