/**
 * @author Hyacinthe MENIET
 * Created on 26 août 07
 */
package net.dotmyself.restclient.flickrphotos;

import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.text.MessageFormat;
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 Flickr Photos Web Services.
 */
public class PhotoMapper {
	
	private static final String baseUrl = "http://www.flickr.com/services/rest/";
	private static final String appId = "your_own_code"; //replace with your own code
	private static final String method = "flickr.photos.search";
	private static final String urlEncoding = "ISO-8859-1";
	/**
	 * Retrieves photographs by tags.
	 * @param tags
	 * 	Small blocks of text attached to a photograph to identify its content.
	 * @return list of {@link Photo} or <code>null</code> if
	 * 	no {@link Photo} could be found.
	 * @throws UnsupportedEncodingException 
	 * @throws MalformedURLException 
	 * @throws JAXBException 
	 */
	public static List<Photo> getPhotos(String tags) 
		throws UnsupportedEncodingException, MalformedURLException, JAXBException {
		
		StringBuilder sb = new StringBuilder(baseUrl);
		sb.append("?api_key=");
		sb.append(URLEncoder.encode(appId, urlEncoding));
		sb.append("&method=");
		sb.append(URLEncoder.encode(method, urlEncoding));
		if(tags != null && tags.length() > 1) {
			sb.append("&tags=");
			sb.append(URLEncoder.encode(tags, urlEncoding));
		}
		Photos ps = extractPhotos(new URL(sb.toString()));
		return (ps != null) ? ps.getPhoto() : null;
	}
	/**
	 * Uses the JAXB classes to process the returned XML
	 * and returns the corresponding {@link Photos}
	 * @param url
	 * 	The URL for the query.
	 * @return
	 * 	{@link Photos} or <code>null</code> if
	 * 	no {@link Photos} could be found.
	 * @throws JAXBException 
	 */
	private static Photos extractPhotos(URL url) throws JAXBException {
		JAXBContext context = JAXBContext.newInstance(Rsp.class);
		Unmarshaller unmarshaller = context.createUnmarshaller();
		Rsp rsp = (Rsp) unmarshaller.unmarshal(url);
		return (rsp != null) ? rsp.getPhotos() : null;
	}
	/**
	 * Creates the photographs thumbnail URL.
	 * @param photo
	 * 	The {@link Photo}
	 * @return
	 * 	The thumbnail URL.
	 * @throws UnsupportedEncodingException
	 */
	public static String buildThumbnailUrl(Photo photo) throws UnsupportedEncodingException {
		if(photo == null) {
			throw new NullPointerException("You should provide a valid Photo in order to ask to thumbnail URL");
		}
		String url = MessageFormat.format("http://farm{0}.static.flickr.com/{1}/{2}_{3}_t.jpg",
				new Object[] {
					URLEncoder.encode(photo.getFarm().toString(), urlEncoding),
					URLEncoder.encode(photo.getServer().toString(), urlEncoding),
					URLEncoder.encode(photo.getId().toString(), urlEncoding),
					URLEncoder.encode(photo.getSecret().toString(), urlEncoding)
				});
		return url;
	}

}