import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class GameUpdater {
	/*
	 * Simple Game Updater.
	 * TODO: getVersionFromURL needs to delete the .TMP after use!
	 * UPLOAD_DIRECTORY is where the .JAR and .TXT (Version file) are located.
	 * 
	 * The version.txt file should only contain "0.0.0.1" (your version id)
	 * 
	 * Notes: .JAR file name (uploaded to the server) should be in the layout provided:
	 * example: http://www.yourwebsite.co.nf/releases/my_game_0.0.0.1.JAR
	 */

	// The current version of the game.
	private static final String GAME_VERSION = "0.0.0.1";

	// The games name
	private static final String GAME_NAME = "Block_Tamer_Client_";

	// The upload directory
	private static final String UPLOAD_DIRECTORY = "http://www.javatools.co.nf/releases/";

	// A ByteBuffer for reading bytes.
	private static byte[] BYTE_BUFFER = new byte[1024];

	/**
	 * Main entry point into the application.
	 * @param args The arguments (NONE) passed via the user.
	 */
	public static void main(String[] args) {
		try {
			new GameUpdater();
		} catch (MalformedURLException e) {
			e.printStackTrace(); // malformed url (missing headers?)
		} catch (FileNotFoundException e) {
			e.printStackTrace(); // the version file or .jar file cannot be located.
		} catch (IOException e) {
			e.printStackTrace(); // there was a error while reading/writing.
		}
	}

	public GameUpdater() throws MalformedURLException, IOException, FileNotFoundException {
		System.out.println("Current client version is: " + GAME_VERSION);
		
		// obtain the current version from the file.
		String version = getVersionFromUrl(UPLOAD_DIRECTORY + "version.txt");
		
		System.out.println("Most recent uploaded game jar is version: " + version);

		// is the client version out dated?
		boolean outdatedClient = !(new String("" + GAME_VERSION).equals(new String("" + version)));

		if (!outdatedClient) {
			System.out.println("Your client does not need to be updated ^_^");
			return;
		}
		/*
		 * At this point it's safe to assume the client is out dated.
		 */

		// The updated .JAR
		final String jarLocation = UPLOAD_DIRECTORY + GAME_NAME + version + ".jar";

		// The downloaded .JAR save location (Updated)
		final String downloadedJarLocation = GAME_NAME + version + ".jar";

		System.out.println("Your client is out dated, downloading version " + version+ " updates... (" + getURLSizeInKB(jarLocation) + " kb)");

		// download the new .jar
		File newlyDownloadedJar = saveJarFromURL(jarLocation, downloadedJarLocation);
		System.out.println("New Jar has been downloaded to: "+ newlyDownloadedJar.getAbsolutePath());
	}

	private File saveJarFromURL(String urlLocation, String saveLocation)
			throws MalformedURLException, IOException, FileNotFoundException {
		/*
		 * Initialize the Input Stream. (Downloading from remote system / server)
		 */
		BufferedInputStream in = new BufferedInputStream(new URL(urlLocation).openStream());

		/*
		 * Initialize the Output Stream. (Downloading on local system / pc)
		 */
		File savedFile = new File(saveLocation);
		BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(savedFile));

		/*
		 * Begin the download.
		 */
		int inCount;
		while ((inCount = in.read(BYTE_BUFFER, 0, BYTE_BUFFER.length)) != -1) {
			out.write(BYTE_BUFFER, 0, inCount);
		}

		/*
		 * Close the Input/Output streams.
		 */
		out.flush();
		out.close();
		in.close();
		return savedFile;
	}

	@SuppressWarnings("resource")
	private String getVersionFromUrl(String string) throws MalformedURLException, IOException {
		/*
		 * Initialize the Input Stream. (Downloading from remote system / server)
		 */
		BufferedInputStream in = new BufferedInputStream(new URL(string).openStream());

		/*
		 * Initialize the Output Stream. (Downloading on local system / pc)
		 */
		File savedFile = new File("version.txt.tmp");
		BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(savedFile));

		/*
		 * Begin the download.
		 */
		int inCount;
		while ((inCount = in.read(BYTE_BUFFER, 0, BYTE_BUFFER.length)) != -1) {
			out.write(BYTE_BUFFER, 0, inCount);
		}

		/*
		 * Close the Input/Output streams.
		 */
		out.flush();
		out.close();
		in.close();

		// after the version data has been saved, read it and delete the file.
		String version = "";
		if (savedFile.exists()) {
			System.out.println("Checking version data....");
			version = new BufferedReader(new FileReader(savedFile)).readLine();
			// TODO: delete the .TMP file
		}
		return version;
	}

	/* Obtaining the files size in kilobytes */
	public static Double getURLSizeInKB(String urlStr) {
		double contentLength = 0;
		try {
			URL url = new URL(urlStr);
			HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
			contentLength = httpConn.getContentLength();
			httpConn.disconnect();
		} catch (Exception ex) {
			ex.printStackTrace();
		}
		return contentLength;
	}
}