/*
 * Seldon -- open source prediction engine
 * =======================================
 * Copyright 2011-2015 Seldon Technologies Ltd and Rummble Ltd (http://www.seldon.io/)
 *
 **********************************************************************************************
 *
 * Licensed 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 io.seldon.external;

import io.seldon.api.APIException;
import io.seldon.api.state.GlobalConfigHandler;
import io.seldon.api.state.GlobalConfigUpdateListener;
import io.seldon.clustering.recommender.RecommendationContext.OptionsHolder;
import io.seldon.external.ExternalPredictionServer.PredictionServerConfig;
import io.seldon.plugins.PluginService;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.protocol.HttpContext;
import org.apache.log4j.Logger;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.map.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class ExternalPluginServer implements GlobalConfigUpdateListener, PluginService {

	private static Logger logger = Logger.getLogger(ExternalPluginServer.class.getName());
	private static final String name = ExternalPluginServer.class.getName();
    private static final String URL_PROPERTY_NAME="io.seldon.algorithm.external.url";
    private static final String ZK_CONFIG_TEMP = "plugin_server"; 
    private PoolingHttpClientConnectionManager cm;
    private CloseableHttpClient httpClient;
    
    ObjectMapper mapper = new ObjectMapper();
    
    public String getName()
    {
    	return name;
    }
    
    public static class PluginServerConfig {
    	public int maxConnections;
    }
    
    @Autowired
    public ExternalPluginServer(GlobalConfigHandler globalConfigHandler){
        cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(150);
        cm.setDefaultMaxPerRoute(150);
        httpClient = HttpClients.custom()
                .setConnectionManager(cm)
                .build();
        globalConfigHandler.addSubscriber(ZK_CONFIG_TEMP, this);
    }
    
	
	@Override
	public void configUpdated(String configKey, String configValue) {
		if (configValue != null && configValue.length() > 0)
		{
			ObjectMapper mapper = new ObjectMapper();
            try {
            	PredictionServerConfig config = mapper.readValue(configValue, PredictionServerConfig.class);
            	cm = new PoolingHttpClientConnectionManager();
                cm.setMaxTotal(config.maxConnections);
                cm.setDefaultMaxPerRoute(config.maxConnections);
                httpClient = HttpClients.custom()
                        .setConnectionManager(cm)
                        .build();
                logger.info("Updated httpclient to use "+config.maxConnections+" max connections");
            } catch (Exception e) {
                throw new RuntimeException(String.format("* Error * parsing statsd configValue[%s]", configValue),e);
            }
		}
		
	}


	@Override
	public JsonNode execute(JsonNode payload, OptionsHolder options) {
		long timeNow = System.currentTimeMillis();
		URI uri = URI.create(options.getStringOption(URL_PROPERTY_NAME));
		try {
			URIBuilder builder = new URIBuilder().setScheme("http")
					.setHost(uri.getHost())
					.setPort(uri.getPort())
					.setPath(uri.getPath())
					.setParameter("json", payload.toString());

			uri = builder.build();
		} catch (URISyntaxException e) 
		{
			throw new APIException(APIException.GENERIC_ERROR);
		}
		HttpContext context = HttpClientContext.create();
		HttpGet httpGet = new HttpGet(uri);
		try  
		{
			if (logger.isDebugEnabled())
				logger.debug("Requesting " + httpGet.getURI().toString());
			CloseableHttpResponse resp = httpClient.execute(httpGet, context);
			if(resp.getStatusLine().getStatusCode() == 200) 
			{
				
			    JsonFactory factory = mapper.getJsonFactory();
			    JsonParser parser = factory.createJsonParser(resp.getEntity().getContent());
			    JsonNode actualObj = mapper.readTree(parser);
				if (logger.isDebugEnabled())
					logger.debug("External prediction server took "+(System.currentTimeMillis()-timeNow) + "ms");
				return actualObj;
			} 
			else 
			{
				logger.error("Couldn't retrieve prediction from external prediction server -- bad http return code: " + resp.getStatusLine().getStatusCode());
				throw new APIException(APIException.GENERIC_ERROR);
			}
		} 
		catch (IOException e) 
		{
			logger.error("Couldn't retrieve prediction from external prediction server - ", e);
			throw new APIException(APIException.GENERIC_ERROR);
		}

	}
}