package com.facebook.app.server.facebook;



import java.io.IOException;

import java.io.InputStreamReader;

import java.io.Reader;

import java.io.UnsupportedEncodingException;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLEncoder;



import javax.jdo.PersistenceManager;



import com.facebook.app.shared.facebookData.FacebookFriend;

import com.facebook.app.shared.facebookData.FacebookLike;

import com.google.gson.Gson;



public class FacebookImporter {

	

	private static class FriendData {

		

		private FacebookFriend[] data = new FacebookFriend[0];

		// to avoid a NullPointerException if the user has just logged out, but the Facebook cookie is still "alive".

		// TODO has to be fixed

	}

	

	private static class LikeData {

		

		private FacebookLike[] data;

	}

	

	private static final int MAX_NUMBER_OF_CONNECTION_ERRORS = 20;



	private final String baseUrl = "https://graph.facebook.com";

	private final String accessToken;

	private final Gson gson = new Gson();



	private int numberOfConnectionErrors = 0;



	public FacebookImporter(String accessToken) {

		this.accessToken = accessToken;

	}

	

	private Reader downloadData(String url) {

		if(numberOfConnectionErrors > MAX_NUMBER_OF_CONNECTION_ERRORS) {

			System.out.println("Connection errors have exceeded limit of " + MAX_NUMBER_OF_CONNECTION_ERRORS);

			return null;

		}

		

		try {

			URL dataURL = new URL(url);

			return new InputStreamReader(dataURL.openStream());

			

		} catch (MalformedURLException e) {

			e.printStackTrace();

			return null;

			

		} catch (IOException e) {

			System.out.println("Catched IOE : " + e.toString());

			// TODO Check whether IOE is cause by open URL connection.

			numberOfConnectionErrors++;

			return downloadData(url);

		}

	}

	

	private FacebookFriend[] importFriendsForFriend(FacebookFriend friend) {



		StringBuilder req = new StringBuilder(baseUrl);

		req.append("/");

		req.append(friend.getId());

		req.append("/friends");

		try {

			req.append("?access_token="

					+ URLEncoder.encode(accessToken, "UTF-8"));

		} catch (UnsupportedEncodingException e1) {

			e1.printStackTrace();

		}



		FriendData friendData = gson.fromJson(downloadData(req.toString()), FriendData.class);

		return friendData.data;

	}



	FacebookLike[] importLikesForFriend(FacebookFriend friend) {



		StringBuilder req = new StringBuilder(baseUrl);

		req.append("/");

		req.append(friend.getId());

		req.append("/likes");

		try {

			req.append("?access_token="

					+ URLEncoder.encode(accessToken, "UTF-8"));

		} catch (UnsupportedEncodingException e1) {

			e1.printStackTrace();

		}



		LikeData likeData = gson.fromJson(downloadData(req.toString()), LikeData.class);

		return likeData.data;

	}



	public FacebookFriend[] importFriends() {



		StringBuilder req = new StringBuilder(baseUrl);

		req.append("/me?access_token=");

		try {

			req.append(URLEncoder.encode(accessToken, "UTF-8"));

		} catch (UnsupportedEncodingException e) {

			e.printStackTrace();

		}



		FacebookFriend me = gson.fromJson(downloadData(req.toString()), FacebookFriend.class);

		

		FacebookFriend[] myFriends = importFriendsForFriend(me);

		FacebookFriend[] friendsWithMe = new FacebookFriend[myFriends.length + 1];



		for (int i = 0; i < myFriends.length; i++) {

			friendsWithMe[i] = myFriends[i];

		}



		friendsWithMe[friendsWithMe.length - 1] = me;

		return friendsWithMe;

	}



	/**

	 * Imports the FacebookLikes for a certain number of FacebookFriends

	 * and saves those friends on the datastore.

	 * 

	 * @param friends

	 */

	public void importAndSaveFacebookData(FacebookFriend[] friends) {

		

		for (FacebookFriend friend: friends) {

			System.out.print(".");

			friend.setLikesWithArray(importLikesForFriend(friend));

		}



		PersistenceManager pm = PersistenceManagerFactorySingleton

				.getPersistenceManagerFactoryInstance().getPersistenceManager();



		try {

			pm.makePersistentAll(friends);



		} finally {

			pm.close();

		}

	}



}