package eu.dnetlib.parthenos.virtuoso;

import java.io.IOException;
import java.io.OutputStream;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import eu.dnetlib.parthenos.publisher.ParthenosPublisherException;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpEntity;
import org.apache.http.HttpHeaders;
import org.apache.http.NameValuePair;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.apache.jena.query.ResultSet;
import org.apache.jena.sparql.engine.http.QueryEngineHTTP;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.*;

/**
 * Created by Alessia Bardi on 31/01/2018.
 * Read-only API for virtuoso.
 *
 * //TODO: error handling (http://www.springboottutorial.com/spring-boot-exception-handling-for-rest-services)
 * //TODO: pagination
 * //TODO swagger documentation?
 *
 * @author Alessia Bardi
 */
@RestController
public class VirtuosoReadAPI {

	private static final Log log = LogFactory.getLog(VirtuosoReadAPI.class);

	@Value("${virtuoso.sparqlurl}")
	private String sparqlUrl;
	@Value("${virtuoso.pwd}")
	private String username;
	@Value("${virtuoso.pwd}")
	private String password;
	@Value("${virtuoso.uri.base.default}")
	private String defaultBaseURI;
	@Value("${virtuoso.connectionstring")
	private String virtuosoConnectionString;

	@Autowired
	private Configuration freemarkerConfig;

	@RequestMapping(value = "/virtuoso/apiSubjectsWithType", produces = { "application/json" }, method = RequestMethod.GET)
	public List<String> getSubjectsForApiWithType(@RequestParam final String api, @RequestParam final String typeNamespace, @RequestParam final String typeName, @RequestParam final int limit, @RequestParam final int offset){
		String fullTypeName = typeNamespace + typeName;
		log.debug(String.format("Getting subjects of type %s for API %s limit %d offset %d", fullTypeName, api, limit, offset));
		//if I add the ORDER BY the query is too slow: let's hope we are not getting the same subjects over and over again
		String queryForSubjectsTemplate = "DEFINE input:inference 'parthenos_rules' SELECT DISTINCT ?s WHERE { GRAPH ?g {?s a <%s> .} . GRAPH dnet:graph {?g dnet:collectedFrom <%s> .}} LIMIT %d OFFSET %d";
		String q = String.format(queryForSubjectsTemplate, fullTypeName, defaultBaseURI+api, limit, offset);
		log.debug("SPARQL query: "+q);
		final QueryEngineHTTP serviceRequest = new QueryEngineHTTP(sparqlUrl, q);
		ResultSet subjects = serviceRequest.execSelect();
		List<String> res = Lists.newArrayList(Iterators.filter(Iterators.transform(subjects, qs -> qs.getResource("s").getURI()), input -> input.startsWith("http")));
		serviceRequest.close();
		return res;
	}


	@RequestMapping(value = "/virtuoso/subject", produces = { "application/rdf+xml", "application/xml" }, method = RequestMethod.GET)
	@ResponseStatus(value = HttpStatus.OK)
	public void getSubject(@RequestParam final String subjectURL, @RequestParam final String typeName, @RequestParam(name="timeout") final String timeoutMs, final OutputStream responseStream)
			throws IOException, TemplateException, ParthenosPublisherException {

		sendConstructResponse(generateQuery(subjectURL, typeName), timeoutMs, responseStream);
	}

	public String getRDF(final String subjectURL, final String typeName, final String apiId, final String timeoutMs)
			throws IOException, TemplateException, ParthenosPublisherException {

		return executeSparqlPost(generateQuery(subjectURL, typeName), timeoutMs);
	}

	protected String generateQuery(final String subjectURL, final String typeName) throws IOException, TemplateException {
		String templateName = typeName+".sparql";
		Template temp = freemarkerConfig.getTemplate(templateName);
		Map<String, String> values = new HashMap<>();
		values.put("subjectURL", subjectURL);

		StringWriter sw = new StringWriter();
		temp.process(values, sw);
		String q = sw.toString();
		log.debug("Querying for "+subjectURL+" with query "+templateName);
		return q;
	}


	protected void sendConstructResponse(final String query, final String timeoutMs, final OutputStream responseStream) throws IOException, ParthenosPublisherException {
		String res = executeSparqlPost(query, timeoutMs);
		IOUtils.write(res, responseStream);
	}

	protected String executeSparqlPost(final String query, final String timeoutMs) throws IOException, ParthenosPublisherException {
		try (CloseableHttpClient httpclient = HttpClients.createDefault()) {
			HttpPost httpPost = new HttpPost(sparqlUrl);
			httpPost.setHeader(HttpHeaders.ACCEPT, "application/rdf+xml");
			List<NameValuePair> nvps = Lists.newArrayList();
			nvps.add(new BasicNameValuePair("query", query));
			if (StringUtils.isNotBlank(timeoutMs)) {
				nvps.add(new BasicNameValuePair("timeout", timeoutMs));
			}
			httpPost.setEntity(new UrlEncodedFormEntity(nvps));


			try (CloseableHttpResponse response2 = httpclient.execute(httpPost)) {
				HttpEntity entity2 = response2.getEntity();
				String res = IOUtils.toString(entity2.getContent());
				EntityUtils.consume(entity2);
				int statusCode = response2.getStatusLine().getStatusCode();
				switch(statusCode){
				case 200:
					return res;
				case 504:
					String msg = String.format("ERROR 504 on query %s", query);
					throw new ParthenosPublisherException(msg);
				default:
					String errorMessage = String.format("ERROR HTTP STATUS CODE %d, REASON PHRASE: %s\n ERROR BODY: %s", statusCode, response2.getStatusLine(), res);
					log.error(errorMessage);
					return "";
					//throw new ParthenosPublisherException(errorMessage);
				}
			}
		}


	}
	




}