import java.net.*;
import java.io.*;
import java.util.Map;
import java.util.Set;
import java.util.Iterator;
import java.util.StringTokenizer;

/**
 * The TranscriptReciever class obtains HTTPS access to Dowling College's 
 * Banner Database when given a student's user id and password, subsequently
 * providing streamed access to the transcript HTML.
 */
public class TranscriptReciever
{
	/*
	private static final String LOGIN_ADDR = "https://ban4web.dowling.edu/prod/plsql/twgkwbis.P_WWWLogin";
	private static final String VALDN_ADDR = "https://ban4web.dowling.edu/prod/plsql/twgkwbis.P_ValLogin";
	private static final String TRANS_ADDR = "https://ban4web.dowling.edu/prod/plsql/hwskotrn.P_ViewTran";
	*/
	
	private static final String LOGIN_ADDR = "https://bannerweb.dowling.edu/pls/PPOD/twgkwbis.P_WWWLogin";
	private static final String VALDN_ADDR = "https://bannerweb.dowling.edu/pls/PPOD/twgkwbis.P_ValLogin";
	private static final String TRANS_ADDR = "https://bannerweb.dowling.edu/pls/PPOD/hwskotrn.P_ViewTran";

	private static final String LOGIN_COOK = "SESSID=; TESTID=set";
	private static final String TRANS_POST = "levl=&tprt=STDT";

	private URL url;
	private HttpURLConnection urlConn;
	private String cookie;

	/**
	 * Constructs a TranscriptReciever object.
	 */
	public TranscriptReciever()
	{
	}
	
	// Some methods used in developing this class...
	/*
	private void printHeaderFields()
	{
		Map map = urlConn.getHeaderFields();
		Set keySet = map.keySet();
		Iterator iter = keySet.iterator();
		
		while(iter.hasNext())
		{
			Object key = iter.next();
			System.out.println(key + " = " + map.get(key));
		}
	}

	private void printContent() throws IOException
	{
		BufferedReader in = new BufferedReader(new InputStreamReader(
			urlConn.getInputStream()));

		String str;

		while((str=in.readLine()) != null)
			System.out.println(str);					
	}
	*/
		
	private void parseCookie()
	{
		cookie = urlConn.getHeaderField("Set-Cookie");

		/*
		cookie = "";
		
		String allCookies = urlConn.getHeaderField("Set-Cookie");
		int index = allCookies.indexOf(";");

		System.out.println(allCookies);
		
		if(index >= 0)
			cookie = allCookies.substring(0, index);		
		*/
	}

	private void login(String userId, String password) throws MalformedURLException, IOException
	{
		url = new URL(VALDN_ADDR);
		urlConn = (HttpURLConnection) url.openConnection();

		urlConn.setRequestMethod("POST");
		urlConn.setDoInput(true);
		urlConn.setDoOutput(true);
		urlConn.setUseCaches(true);

		urlConn.setRequestProperty("Cookie", LOGIN_COOK);
		urlConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

		DataOutputStream out = new DataOutputStream(urlConn.getOutputStream());

		String content = "sid=" + URLEncoder.encode(userId, "UTF-8") +
			"&pin=" + URLEncoder.encode(password, "UTF-8");

		out.writeBytes(content);
		out.flush();
		out.close();
		
		parseCookie();
	}
	
	private InputStream getTranscriptHTML() throws MalformedURLException, IOException
	{
		url = new URL(TRANS_ADDR);
		
		urlConn = (HttpURLConnection) url.openConnection();

		urlConn.setRequestMethod("POST");
		urlConn.setDoInput(true);
		urlConn.setDoOutput(true);
		urlConn.setUseCaches(true);

		urlConn.setRequestProperty("Cookie", cookie);
		urlConn.setRequestProperty("Content-Type", "text/html");

		DataOutputStream out = new DataOutputStream(urlConn.getOutputStream());		

		out.writeBytes(TRANS_POST);
		out.flush();
		out.close();

		return urlConn.getInputStream();				
	}
	
	/**
	 * Retrieves an InputStream to the student's transcript. The 
	 * InputStream simply returns the raw HTML without any sort of
	 * preprocessing.
	 * @param userId The student's userId for Banner.
	 * @param password The student's password for Banner.
	 * @return An InputStream to the transcript HTML
	 * @exception IOException If a connection to Banner cannot be obtained.
	 * @exception TranscriptException If the username and password was invalid.
	 * @exception MalformedURLException If the addresses used internally to access Banner are malformed.
	 */
	public InputStream getTranscriptStream(String userId, String password) throws IOException, TranscriptException, 
		MalformedURLException
	{
		login(userId, password);

		if(cookie == null)
			return null;

		InputStream in = getTranscriptHTML();
	
		return in;
	}	
}