Ask for a valid mc version instead of crashing

Author: JustRed23

src/main/java/org/kettingpowered/launcher/KettingLauncher.java

@@ -85,6 +85,9 @@ public class KettingLauncher {
     private final ParsedArgs args;
     private final BetterUI ui;
     private final Libraries libs = new Libraries();
+
+    private final List<String> serverVersions = new ArrayList<>();
+    private final List<String> availableMcVersions = new ArrayList<>();
 
     KettingLauncher(String[] str_args) throws Exception {
         ui = new BetterUI(KettingConstants.NAME);
@@ -98,7 +101,21 @@ public class KettingLauncher {
     public void init() throws Exception {
         final String mc_version;
         if (Main.DEBUG && Bundled) System.out.println("We are in a bundled jar. Read Version information from manifest.");
-        if (!Bundled) mc_version = MCVersion.getMc(args);
+
+        //Cache ketting versions
+        final List<String> depVersions = new MavenManifest(KettingConstants.KETTINGSERVER_GROUP, Main.FORGE_SERVER_ARTIFACT_ID).getDepVersions();
+        serverVersions.addAll(depVersions);
+
+        //Strip the minecraft version from the ketting version, by splitting by - and getting the first entry
+        availableMcVersions.addAll(depVersions.stream().map(version -> {
+            try {
+                return version.split("-")[0];
+            } catch (Exception e) { //Make sure that we don't crash, if the version is invalid
+                return null;
+            }
+        }).filter(Objects::nonNull).distinct().sorted().toList());
+
+        if (!Bundled) mc_version = MCVersion.getMc(args, availableMcVersions);
         else mc_version = Bundled_McVersion;
         //This cannot get moved past the ensureOneServerAndUpdate call. 
         //It will cause the just downloaded server to be removed, which causes issues.
@@ -259,7 +276,6 @@ else if(versions.size() > 1) {
         if (needsDownload) System.out.println("Downloading Server, since there is none currently present. Using determined Minecraft version: "+ mc_version);
         // get the newest version
         if (args.enableServerUpdator() || needsDownload) {
-            final List<String> serverVersions = new MavenManifest(KettingConstants.KETTINGSERVER_GROUP, Main.FORGE_SERVER_ARTIFACT_ID).getDepVersions();
             final List<Tuple<MajorMinorPatchVersion<Integer>, MajorMinorPatchVersion<Integer>>> parsedServerVersions = MajorMinorPatchVersion.parseKettingServerVersionList(serverVersions.stream()).getOrDefault(mc_mmp, new ArrayList<>());
             if (Main.DEBUG) {
                 System.out.println("Available Ketting versions");

src/main/java/org/kettingpowered/launcher/info/MCVersion.java

@@ -8,19 +8,14 @@
 import org.kettingpowered.launcher.utils.FileUtils;
 
 import java.io.*;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Comparator;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Objects;
+import java.util.*;
 
 /**
  * @author C0D3 M4513R
  */
 public class MCVersion {
     private static String mc;
-    public static String getMc(ParsedArgs args){
+    public static String getMc(ParsedArgs args, List<String> supportedMcVersions){
         if (mc != null) return mc;
 
         //Check for a mcversion.txt file, this has priority
@@ -88,16 +83,35 @@ public static String getMc(ParsedArgs args){
                 System.out.println("There are multiple mapping configurations for multiple minecraft versions present in the libraries folder.");
             }
         }
-        //and now we are out of options.
-        System.err.println("""
-                Could not determine the active server minecraft version. Please specify it, by specifying one of the following:
-                 - creating a file named 'mcversion.txt' with the desired minecraft version (e.g. 1.20.4).
-                 - the '--minecraftVersion' argument. E.g.: add ' --minecraftVersion 1.20.4 ' after the '-jar' argument
-                 - the java property 'kettinglauncher.minecraftVersion' E.g.: ' -Dkettinglauncher.minecraftVersion=1.20.4 ' before the '-jar' argument
-                 - the environment variable 'kettinglauncher_minecraftVersion' E.g. ' kettinglauncher_minecraftVersion=1.20.4 ' before the java executable.
-                 """);
-        System.exit(1);
-        throw new RuntimeException();//bogus, but has to be there to stop the compiler from complaining, that there is no return value here.
+        //Ask for a version
+        {
+            System.out.println("Could not automatically determine the minecraft version.");
+            System.out.println("Please enter the minecraft version you want to use");
+            System.out.println("The following versions are supported: " + String.join(", ", supportedMcVersions));
+            System.out.print("Minecraft version: ");
+
+            int wrong = 0;
+
+            Scanner console = new Scanner(System.in);
+            while (true) {
+                String answer = console.nextLine();
+                if (answer == null || answer.isBlank()) {
+                    if (wrong++ >= 2) {
+                        System.err.println("You have typed the wrong answer too many times. Exiting.");
+                        System.exit(1);
+                    }
+                    System.err.println("Please enter a valid version.");
+                    System.out.print("Minecraft version: ");
+                    continue;
+                }
+                if (supportedMcVersions.contains(answer.trim())) {
+                    mc = answer;
+                    return mc;
+                }
+                System.out.println("The version you entered is not supported.");
+                System.out.print("Minecraft version: ");
+            }
+        }
     }
 
     private static String readFromIS(@Nullable InputStream versionStream) {