/common/buildcraft/core/Version.java

package buildcraft.core;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

import net.minecraftforge.common.Property;
import buildcraft.BuildCraftCore;
import buildcraft.core.proxy.CoreProxy;

public class Version implements Runnable {
    
    private static Version instance = new Version();

	public enum EnumUpdateState {
		CURRENT, OUTDATED, CONNECTION_ERROR
	}

	public static final String VERSION = "@VERSION@";
	public static final String BUILD_NUMBER = "@BUILD_NUMBER@";
	private static final String REMOTE_VERSION_FILE = "http://bit.ly/buildcraftver";
	private static final String REMOTE_CHANGELOG_ROOT = "https://dl.dropbox.com/u/44760587/buildcraft/changelog/";

	public static EnumUpdateState currentVersion = EnumUpdateState.CURRENT;

	public static final int FORGE_VERSION_MAJOR = 4;
	public static final int FORGE_VERSION_MINOR = 0;
	public static final int FORGE_VERSION_PATCH = 0;

	private static String recommendedVersion;
	private static String[] cachedChangelog;

	public static String getVersion() {
		return VERSION + " (:" + BUILD_NUMBER + ")";
	}

	public static boolean isOutdated() {
		return currentVersion == EnumUpdateState.OUTDATED;
	}

	public static boolean needsUpdateNoticeAndMarkAsSeen() {
		if (!isOutdated())
			return false;

		Property property = BuildCraftCore.mainConfiguration.get("vars", "version.seen", VERSION);
		property.comment = "indicates the last version the user has been informed about and will suppress further notices on it.";
		String seenVersion = property.value;

		if (recommendedVersion == null || recommendedVersion.equals(seenVersion))
			return false;

		property.value = recommendedVersion;
		BuildCraftCore.mainConfiguration.save();
		return true;
	}

	public static String getRecommendedVersion() {
		return recommendedVersion;
	}

	public static void versionCheck() {
		try {

			String location = REMOTE_VERSION_FILE;
			HttpURLConnection conn = null;
			while (location != null && !location.isEmpty()) {
				URL url = new URL(location);
				conn = (HttpURLConnection) url.openConnection();
				conn.setRequestProperty("User-Agent",
						"Mozilla/5.0 (Windows; U; Windows NT 6.0; ru; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.11 (.NET CLR 3.5.30729)");
				conn.connect();
				location = conn.getHeaderField("Location");
			}

			BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

			String line = null;
			String mcVersion = CoreProxy.proxy.getMinecraftVersion();
			while ((line = reader.readLine()) != null) {
				if (line.startsWith(mcVersion)) {
					if (line.contains(DefaultProps.MOD)) {

						String[] tokens = line.split(":");
						recommendedVersion = tokens[2];

						if (line.endsWith(VERSION)) {
						    BuildCraftCore.bcLog.finer("Using the latest version [" + getVersion() + "] for Minecraft " + mcVersion);
							currentVersion = EnumUpdateState.CURRENT;
							return;
						}
					}
				}
			}

			BuildCraftCore.bcLog.warning("Using outdated version [" + VERSION + " (build:" + BUILD_NUMBER + ")] for Minecraft " + mcVersion
					+ ". Consider updating.");
			currentVersion = EnumUpdateState.OUTDATED;

		} catch (Exception e) {
			BuildCraftCore.bcLog.warning("Unable to read from remote version authority.");
			BuildCraftCore.bcLog.warning(e.toString());
			currentVersion = EnumUpdateState.CONNECTION_ERROR;
		}
	}

	public static String[] getChangelog() {
		if (cachedChangelog == null) {
			cachedChangelog = grabChangelog(recommendedVersion);
		}

		return cachedChangelog;
	}

	public static String[] grabChangelog(String version) {

		try {

			String location = REMOTE_CHANGELOG_ROOT + version;
			HttpURLConnection conn = null;
			while (location != null && !location.isEmpty()) {
				URL url = new URL(location);
				conn = (HttpURLConnection) url.openConnection();
				conn.setRequestProperty("User-Agent",
						"Mozilla/5.0 (Windows; U; Windows NT 6.0; ru; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.11 (.NET CLR 3.5.30729)");
				conn.connect();
				location = conn.getHeaderField("Location");
			}

			BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

			String line = null;
			ArrayList<String> changelog = new ArrayList<String>();
			while ((line = reader.readLine()) != null) {
				if (line.startsWith("#")) {
					continue;
				}
				if (line.isEmpty()) {
					continue;
				}

				changelog.add(line);
			}

			return changelog.toArray(new String[0]);

		} catch (Exception ex) {
			ex.printStackTrace();
			BuildCraftCore.bcLog.warning("Unable to read changelog from remote site.");
		}

		return new String[] { String.format("Unable to retrieve changelog for %s %s", DefaultProps.MOD, version) };
	}

    @Override
    public void run() {

        int count = 0;
        currentVersion = null;
        
        BuildCraftCore.bcLog.info("Beginning version check");
        
        try {
            while ((count < 3) && ((currentVersion == null) || (currentVersion == EnumUpdateState.CONNECTION_ERROR))) {
                versionCheck();
                count++;
                
                if (currentVersion == EnumUpdateState.CONNECTION_ERROR) {
                    BuildCraftCore.bcLog.info("Version check attempt " + count + " failed, trying again in 10 seconds");
                    Thread.sleep(10000);
                }
            }
        }
        catch (InterruptedException e) {
            e.printStackTrace();
        }
        
        if (currentVersion == EnumUpdateState.CONNECTION_ERROR) {
            BuildCraftCore.bcLog.info("Version check failed");
        }
        
    }
    
    public static void check() {
        
        new Thread(instance).start();
    }

}