DirectLaunch.java

package net.minecraft.launchwrapper;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

/**
 * Used as the main class for standalone modpack JARs.
 */
public class DirectLaunch {
	public static void main(String[] args) throws Exception {
		File gameDir = new File(".");
		
		File nativesDir = new File(gameDir, "mcforkage-standalone-natives");
		if(!nativesDir.isDirectory()) {
			if(!nativesDir.mkdir())
				throw new RuntimeException("Failed to create directory "+nativesDir.getAbsolutePath());
		}
		
		InputStream nativesZipIn = DirectLaunch.class.getResourceAsStream("/mcforkage-standalone-natives.zip");
		ZipInputStream zin = new ZipInputStream(nativesZipIn);
		byte[] buf = new byte[65536];
		try {
			ZipEntry ze;
			while((ze = zin.getNextEntry()) != null) {
				File outfile = new File(nativesDir, ze.getName());
				FileOutputStream out = new FileOutputStream(outfile);
				try {
					while(true) {
						int read = zin.read(buf);
						if(read <= 0)
							break;
						out.write(buf, 0, read);
					}
				} finally {
					out.close();
				}
				zin.closeEntry();
			}
		} finally {
			zin.close();
		}
		
		System.setProperty("org.lwjgl.librarypath", nativesDir.getAbsolutePath());
		
		File assetsDir = getMinecraftAssetsDir();
		
		Launch.main(new String[] {
			"--login",
			"--gameDir",
			gameDir.toString(),
			"--userProperties",
			"{}",
			"--version",
			"1.7.10",
			"--assetIndex",
			"1.7.10",
			"--assetsDir",
			assetsDir.getAbsolutePath()
		});
	}
	
	private static File getMinecraftAssetsDir() {
		return new File(getDotMinecraftDir(), "assets");
	}

	private static File getDotMinecraftDir() {
		// Same rules as Mojang launcher
		
		String osname = System.getProperty("os.name").toLowerCase();
		String userhome = System.getProperty("user.home");
		if(userhome == null)
			userhome = ".";
		if(osname.contains("win")) {
			String appdata = System.getenv("APPDATA");
			if(appdata == null)
				appdata = userhome;
			return new File(new File(appdata), ".minecraft");
		}
		
		File homeFile = new File(userhome);
		
		if(osname.contains("mac"))
			return new File(homeFile, "Library/Application Support/minecraft");
		
		if(osname.contains("linux") || osname.contains("unix"))
			return new File(homeFile, ".minecraft");
		
		return new File(homeFile, "minecraft");
	}
}