package zall.util.facebook;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.logging.Logger;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletResponse;

import zutil.Hasher;
import zutil.log.LogUtil;
import zutil.parser.Base64Decoder;
import zutil.parser.DataNode;
import zutil.parser.json.JSONParser;

/**
 * This class connects to Facebook and 
 * retrieves information about the user
 * 
 * @author Ziver
 */
public class FacebookConnect {
	private static Logger logger = LogUtil.getLogger();

	/** The URL to the Facebook OpenGraph service. (must end with a '/') **/
	public static final String SERVICE_URL = "https://graph.facebook.com/";

	/** The application id for this application generated by Facebook **/
	protected static String application_id = null;
	/** The application secret for this application generated by Facebook **/
	protected static String application_secret = null;


	protected String access_token;
	protected FBUser user;

	private FacebookConnect( String access_token, String uid ){
		this.access_token = access_token;
		user = FBUser.get( this, uid );
	}

	/**
	 * @return 		the main user
	 */
	public FBUser getUser(){
		return user;
	}

	/**
	 * Returns the given user by UID
	 * 
	 * @param 	uid		is the user id of the user
	 * @return			a FBUser object or null if there is no such user
	 */
	public FBUser getUser(String uid){
		return FBUser.get( this, uid );
	}

	/**
	 * @return			The access token for this session
	 */
	protected String getAccessToken(){
		return access_token;
	}

	/**
	 * Generates a url for calling the Facebook OpenGraph API
	 * 
	 * @param 		page		is the page ex. a UID
	 * @return					A URL to the service
	 * @throws MalformedURLException 
	 */
	protected URL getServiceURL(String page) throws MalformedURLException{
		return getServiceURL(page, null);
	}

	/**
	 * Generates a url for calling the Facebook OpenGraph API
	 * 
	 * @param 		page		is the page ex. a UID
	 * @param 		params		is URL parameters ex. "?name=lol" or "&name=lol&lol=name" or "name=lol" etc...
	 * @return					A URL to the service
	 * @throws MalformedURLException 
	 */
	protected URL getServiceURL(String page, String params) throws MalformedURLException{
		StringBuilder url = new StringBuilder( SERVICE_URL );
		url.append( page );
		url.append( '?' );
		url.append( "access_token=" );
		url.append( access_token );

		if( params != null && !params.isEmpty() ){
			if( params.charAt(0) == '?' )
				params = params.substring( 1 );
			if( params.charAt(0) != '&' )
				url.append( '&' );

			url.append( params );
		}
		return new URL( url.toString() );
	}

	/**
	 * Sets the static values for this application
	 * @param 	id			is the application id for this application generated by Facebook
	 * @param 	secret		is the application secret for this application generated by Facebook
	 */
	public static void setApplicationID(String id, String secret){
		application_id = id;
		application_secret = secret;
	}

	public static String getAplicationId() {
		return application_id;
	}

	/**
	 * Creates a new instance of the FacebookConnect for the logged in user
	 * or null if the creation was unsuccessful.
	 * 
	 * @param 	cookies		is the cookies from the client
	 * @return				A new FacebookConnect object or null if the creation was unsuccessful
	 */
	public static FacebookConnect getConnection( Cookie[] cookies ){
		if( cookies == null ){
			logger.severe("Cookie is not set!");
			return null;
		}
		
		String cookie_name = "fbsr_" + application_id;
		// Find the cookie
		for(Cookie cookie : cookies) {
			if ( cookie_name.equals(cookie.getName()) ){
				// remove the trailing "
				String value = cookie.getValue();
				return getConnection( value );
			}
		}
		return null;
	}

	/**
	 * Creates a new instance of the FacebookConnect for the logged in user
	 * or null if the creation was unsuccessful.
	 * 
	 * @param 	value		is the string value from facebook
	 * @return				A new FacebookConnect object or null if the creation was unsuccessful
	 */
	public static FacebookConnect getConnection( String value ){
		if( application_id == null ){
			logger.severe("Application_id is not set!");
			return null;
		}
		if( application_secret == null ){
			logger.severe("Application_secret is not set!");
			return null;
		}
		
		value = value.trim();
		if( value.isEmpty() )
			return null;
		value = value.replaceAll("-", "+");
		value = value.replaceAll("_", "/");
		
		// Parse the attributes
		String[] attrib = value.split("\\.", 2);
		String signature = Base64Decoder.decodeToHex( attrib[0] );
		System.out.println( signature );
		//attrib[1] = Base64Decoder.addPadding( attrib[1] );
		String data = Base64Decoder.decode( attrib[1] );
		DataNode map = JSONParser.read( data );
		System.out.println(map);

		if ( !map.getString("algorithm").equalsIgnoreCase("HMAC-SHA256") ) {
			logger.severe("Unknown algorithm: '"+map.getString("algorithm")+"' Expected 'HMAC-SHA256'");
			return null;
		}
		// Check hash signature
		String local_sig = Hasher.HMAC_SHA256( attrib[1], application_secret );
		System.out.println(local_sig);
		if ( !signature.equals( local_sig )) {
			logger.severe("Bad Signed JSON signature: '"+signature+"' Expected '"+local_sig+"'");
			return null;
		}
		
		//if( map.containsKey( "access_token" ) )
		//	return new FacebookConnect( map.get( "access_token" ), map.get( "uid" ) );
		//return null;
		return null;
	}
	
	/**
	 * This method remove the cookie from the user by setting the MaxAge to -1
	 * 
	 * @param 		response		is the response that the cookie will be added to
	 */
	public void logout(HttpServletResponse response) {
		Cookie cookie = new Cookie( "fbsr_" + application_id, null);
		cookie.setMaxAge( 0 );
		cookie.setPath("/");
		response.addCookie( cookie );		
	}

}