components/camel-yammer/src/main/java/org/apache/camel/component/yammer/YammerMessagePollingConsumer.java

/**
 * 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.yammer;

import java.util.concurrent.TimeUnit;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.component.yammer.model.Messages;
import org.apache.camel.impl.ScheduledPollConsumer;
import org.apache.camel.util.ObjectHelper;
import org.codehaus.jackson.map.ObjectMapper;

/**
 * A Yammer consumer that periodically polls messages from Yammer's message API.
 */
public class YammerMessagePollingConsumer extends ScheduledPollConsumer {
    private final YammerEndpoint endpoint;
    private final String apiUrl;
    
    public YammerMessagePollingConsumer(YammerEndpoint endpoint, Processor processor) throws Exception {
        super(endpoint, processor);
        this.endpoint = endpoint;

        long delay = endpoint.getConfig().getDelay();
        setDelay(delay);
        setTimeUnit(TimeUnit.MILLISECONDS);
        apiUrl = getApiUrl();
    }

    private String getApiUrl() throws Exception {    
        StringBuilder url = new StringBuilder();
        
        String function = endpoint.getConfig().getFunction();
        switch (YammerFunctionType.fromUri(function)) {
        case MESSAGES:
            url.append(YammerConstants.YAMMER_BASE_API_URL);
            url.append(function);
            url.append(".json");
            break;
        case ALGO:
        case FOLLOWING:
        case MY_FEED:
        case PRIVATE:
        case SENT:
        case RECEIVED:
            url.append(YammerConstants.YAMMER_BASE_API_URL);
            url.append("messages/");
            url.append(function);
            url.append(".json");
            break;
        default:
            throw new Exception(String.format("%s is not a valid Yammer message function type.", function));
        }        
        
        StringBuilder args = new StringBuilder();
        
        int limit = endpoint.getConfig().getLimit();
        if (limit > 0) {
            args.append("limit=");
            args.append(limit);
        }        

        int olderThan = endpoint.getConfig().getOlderThan();
        if (olderThan > 0) {
            if (args.length() > 0) {
                args.append("&");
            }
            args.append("older_than=");
            args.append(olderThan);
        }        

        int newerThan = endpoint.getConfig().getNewerThan();
        if (newerThan > 0) {
            if (args.length() > 0) {
                args.append("&");
            }            
            args.append("newer_than=");
            args.append(newerThan);
        }        
        
        String threaded = endpoint.getConfig().getThreaded();
        if (ObjectHelper.isNotEmpty(threaded) 
                && ("true".equals(threaded) || "extended".equals(threaded))) {
            if (args.length() > 0) {
                args.append("&");
            }            
            args.append("threaded=");
            args.append(threaded);
        }        
        
        if (args.length() > 0) {
            url.append("?");
            url.append(args);
        }            
        
        return url.toString();
    }

    
    @Override
    protected int poll() throws Exception {
        Exchange exchange = endpoint.createExchange();

        try {
            String jsonBody = endpoint.getConfig().getRequestor(apiUrl).get();   
            
            if (!endpoint.getConfig().isUseJson()) {
                ObjectMapper jsonMapper = new ObjectMapper();
                Messages messages = jsonMapper.readValue(jsonBody, Messages.class);
                exchange.getIn().setBody(messages);
            } else {
                exchange.getIn().setBody(jsonBody);
            }

            // send message to next processor in the route
            getProcessor().process(exchange);
        
            return 1; // number of messages polled
        } finally {
            // log exception if an exception occurred and was not handled
            if (exchange.getException() != null) {
                getExceptionHandler().handleException("Error processing exchange", exchange, exchange.getException());
            }
        }
    }


}