FreshCoffee/src/main/java/com/thebrokenrail/freshcoffee/util/ReLaunchUtil.java

package com.thebrokenrail.freshcoffee.util;

import com.thebrokenrail.freshcoffee.config.HardcodedConfig;
import net.fabricmc.loader.api.FabricLoader;
import org.apache.logging.log4j.LogManager;

import java.io.File;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.lang.management.ManagementFactory;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public final class ReLaunchUtil {
    private static boolean contains(File dir, File targetFile) {
        File[] files = dir.listFiles();
        if (files != null) {
            for (File file : files) {
                try {
                    if (file.toPath().toRealPath().equals(targetFile.toPath().toRealPath()) || contains(file, targetFile)) {
                        return true;
                    }
                } catch (IOException e) {
                    throw new UncheckedIOException(e);
                }
            }
        }
        return false;
    }

    private static List<String> getMainArgs() {
        boolean isMultiMC;
        try {
            Class.forName("org.multimc.EntryPoint");
            isMultiMC = true;
        } catch (ClassNotFoundException e) {
            isMultiMC = false;
        }

        if (isMultiMC) {
            // Replace MultiMC's Entry-Point With Fabric's
            List<String> mainArgs = new ArrayList<>();
            // Set Entry-Point
            mainArgs.add(Util.getMainClass());
            // Get Parameters
            String[] launchArgs = FabricLoader.getInstance().getLaunchArguments(false);
            // Add Parameters
            mainArgs.addAll(Arrays.asList(launchArgs));
            return mainArgs;
        } else {
            return Arrays.asList(System.getProperty("sun.java.command").split(" "));
        }
    }

    private static void reLaunch(String javaBinary) {
        List<String> vmArgs = new ArrayList<>(ManagementFactory.getRuntimeMXBean().getInputArguments());
        // Remove Debugger
        vmArgs.removeIf(arg -> arg.startsWith("-agentlib") || arg.startsWith("-javaagent"));
        // Enable Java Preview Features
        if (PreviewUtil.arePreviewFeaturesRequired()) {
            if (!vmArgs.contains("--enable-preview")) {
                vmArgs.add("--enable-preview");
            }
        } else {
            vmArgs.remove("--enable-preview");
        }

        List<String> mainArgs = getMainArgs();

        String classpathStr = System.getProperty("java.class.path");
        // Remove Built-In Java Libraries From Classpath
        List<String> classpath = new ArrayList<>(Arrays.asList(classpathStr.split(File.pathSeparator)));
        classpath.removeIf(arg -> {
            File file = new File(arg);
            File javaHome = new File(System.getProperty("java.home"));
            return contains(javaHome, file);
        });
        String newClasspathStr = String.join(File.pathSeparator, classpath);

        List<String> args = new ArrayList<>();
        args.add(javaBinary);
        args.addAll(vmArgs);
        args.add("-cp");
        args.add(newClasspathStr);
        args.addAll(mainArgs);

        Util.getLogger().info("ReLaunching Minecraft...");

        Util.getLogger().debug("Launching: " + String.join(" ", args));

        // Release Lock On Log File
        LogManager.shutdown();

        Process process;
        try {
            process = new ProcessBuilder(args).inheritIO().start();
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }

        try {
            int status = process.waitFor();
            System.exit(status);
        } catch (InterruptedException e) {
            process.destroy();
        }
    }

    private static void javaBinaryTestFailed(String reason) {
        Util.getLogger().debug("Java Binary Test Failed: " + reason);
    }

    private static boolean testJavaBinary(String javaBinary) {
        Util.getLogger().debug("Testing Java Binary: " + javaBinary);

        Process process;
        try {
            process = new ProcessBuilder(javaBinary, "-version").start();
        } catch (IOException e) {
            javaBinaryTestFailed(e.toString());
            return false;
        }

        try {
            int status = process.waitFor();
            javaBinaryTestFailed("Exit Code: " + status);
            return status == 0;
        } catch (InterruptedException e) {
            javaBinaryTestFailed(e.toString());
            process.destroy();
            return false;
        }
    }

    public static void reLaunch(boolean testJavaBinary) {
        File[] files = HardcodedConfig.INSTALL_DIR.listFiles();
        if (files != null) {
            List<String> list = new ArrayList<>();
            for (File file : files) {
                if (file.isDirectory()) {
                    list.add(file.getName());
                }
            }

            String newestVersion = JavaVersionUtil.getNewest(list.toArray(new String[0]));

            if (newestVersion != null) {
                File javaDir = Util.getJavaDir(newestVersion);
                File javaBinary = new File(new File(javaDir, "bin"), "java" + PlatformUtil.getExecutableExtension());
                if (!testJavaBinary || testJavaBinary(javaBinary.getAbsolutePath())) {
                    Util.getLogger().info("Using Java Executable: " + javaBinary.getAbsolutePath());
                    reLaunch(javaBinary.getAbsolutePath());
                } else {
                    Util.removeInvalidJDK(javaDir);
                }
            }
        }
    }
}