package sparrow;

import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.client.protocol.ClientContext;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.ExecutionContext;
import org.apache.http.protocol.HttpContext;
import org.apache.log4j.Logger;

import java.io.IOException;


/**
 * This class will attempt to follow a link completely until we get to the final URL
 * after all the 302 redirects. A bitly link may refer to a link that actually 302's to something
 * else so we need to follow the trail all the way.
 * @author Jim Plush
 *
 */
public class FinalUrlGrabber {

  static Logger logger = Logger.getLogger(FinalUrlGrabber.class);

  public static String getURL(DefaultHttpClient httpClient, String startURL)
  {



    int cnt = 0;
    String finalURL = null;
    while(!startURL.equals(finalURL))
    {

      if(cnt > 1) {
        SparrowRunner.multiple302.incrementAndGet();
      }

      try {
        finalURL = followURL(httpClient, startURL);
        startURL = followURL(httpClient, finalURL);
      } catch(IOException e) {
        logger.info(e.toString());
        return null;
      }
      if(cnt > 20) {
        return null;
      }
      cnt++;
      //logger.info("START: "+startURL + " FINAL: "+finalURL);

    }

    return finalURL;



  }


  private static String followURL(DefaultHttpClient httpClient, String startURL) throws IOException
  {
    String finalURL = null;
    HttpGet httpget = null;
    HttpHost target = null;
    HttpUriRequest req = null;
    try {

      HttpContext localContext = new BasicHttpContext();
      localContext.setAttribute(ClientContext.COOKIE_STORE,HttpClientFetcher.emptyCookieStore);
      httpget = new HttpGet(startURL);


      httpget.setHeader("Range", "bytes=0-5000");
      HttpResponse response = httpClient.execute(httpget, localContext);

      HttpHost host =  (HttpHost)localContext.getAttribute(ExecutionContext.HTTP_TARGET_HOST);
      HttpUriRequest finalRequest =   (HttpUriRequest)localContext.getAttribute(ExecutionContext.HTTP_REQUEST);

      target = (HttpHost) localContext.getAttribute( ExecutionContext.HTTP_TARGET_HOST );
      req = (HttpUriRequest) localContext.getAttribute( ExecutionContext.HTTP_REQUEST );

      finalURL = target+""+req.getURI();

      return finalURL;

    } catch(Exception e) {

      throw new IOException("UNABLE TO GET LINK: "+startURL+ " "+e.toString());

    } finally {
      if(httpget != null) { try { httpget.abort(); } catch(Exception e) {}}
    }

  }

}