/**
 * @author Hyacinthe MENIET
 * Created on 25 août 07
 */
package net.dotmyself.restclient.yahoosearch;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.List;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;

/**
 * A class designed to wrap the Yahoo! Term Extraction service.
 */
public class TermExtractionMapper {
	
	private static final String baseUrl = "http://api.search.yahoo.com/ContentAnalysisService/V1/termExtraction";
	private static final String appId = "YahooDemo"; //replace with your own code
	private static final String urlEncoding = "ISO-8859-1";
	
	/**
	 * Retrieves the important words and phrases in a block of text.
	 * @param context
	 * 	The block of text that the terms will be extracted from.
	 * @param query
	 * 	A query to help identify the topic of the context.
	 * @return
	 * 	List of extracted String or <code>null</code> if
     * 	no String could be found.
	 * @throws JAXBException
	 * @throws IOException 
	 */
	public static List<String> getTerms (String context, String query) 
		throws JAXBException, IOException {
		
		// builds de query string
		StringBuilder sb = new StringBuilder("appid=");
		sb.append(URLEncoder.encode(appId, urlEncoding));
		if(context != null && context.length() > 1) {
			sb.append("&context=");
			sb.append(URLEncoder.encode(context, urlEncoding));
		}
		if(query != null && query.length() > 1) {
			sb.append("&query=");
			sb.append(URLEncoder.encode(query, urlEncoding));
		}
		// perform a POST connection
		URL url = new URL(baseUrl);
		URLConnection conn = url.openConnection();
		conn.setDoOutput(true);
		OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
		writer.write(sb.toString());
		writer.flush();
		// reads the response
		JAXBContext jbctx = JAXBContext.newInstance("net.dotmyself.restclient.yahoosearch");
		Unmarshaller unmarshaller = jbctx.createUnmarshaller();
		ResultSet rs = (ResultSet) unmarshaller.unmarshal(conn.getInputStream());
		return (rs != null) ? rs.getResult() : null; 
	}
}