Prepare for adding non-vanilla server types

Agent/Phantom.Agent.Minecraft/Launcher/BaseLauncher.cs

@@ -11,6 +11,8 @@ namespace Phantom.Agent.Minecraft.Launcher;
 
 public abstract class BaseLauncher {
 	private readonly InstanceProperties instanceProperties;
+	
+	protected string MinecraftVersion => instanceProperties.ServerVersion;
 
 	private protected BaseLauncher(InstanceProperties instanceProperties) {
 		this.instanceProperties = instanceProperties;
@@ -25,11 +27,34 @@ public abstract class BaseLauncher {
 			return new LaunchResult.InvalidJvmArguments();
 		}
 
-		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.LaunchProperties.ServerDownloadInfo, instanceProperties.ServerVersion, downloadProgressEventHandler, cancellationToken);
+		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.LaunchProperties.ServerDownloadInfo, MinecraftVersion, downloadProgressEventHandler, cancellationToken);
 		if (vanillaServerJarPath == null) {
 			return new LaunchResult.CouldNotDownloadMinecraftServer();
 		}
 
+		ServerJarInfo? serverJar;
+		try {
+			serverJar = await PrepareServerJar(logger, vanillaServerJarPath, instanceProperties.InstanceFolder, cancellationToken);
+		} catch (OperationCanceledException) {
+			throw;
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while preparing the server jar.");
+			return new LaunchResult.CouldNotPrepareMinecraftServerLauncher();
+		}
+
+		if (!File.Exists(serverJar.FilePath)) {
+			logger.Error("Missing prepared server or launcher jar: {FilePath}", serverJar.FilePath);
+			return new LaunchResult.CouldNotPrepareMinecraftServerLauncher();
+		}
+
+		try {
+			await AcceptEula(instanceProperties);
+			await UpdateServerProperties(instanceProperties);
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while configuring the server.");
+			return new LaunchResult.CouldNotConfigureMinecraftServer();
+		}
+		
 		var startInfo = new ProcessStartInfo {
 			FileName = javaRuntimeExecutable.ExecutablePath,
 			WorkingDirectory = instanceProperties.InstanceFolder,
@@ -43,24 +68,20 @@ public abstract class BaseLauncher {
 		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties, instanceProperties.JvmArguments);
 		CustomizeJvmArguments(jvmArguments);
 
-		var serverJarPath = await PrepareServerJar(vanillaServerJarPath, instanceProperties.InstanceFolder, cancellationToken);
 		var processArguments = startInfo.ArgumentList;
 		jvmArguments.Build(processArguments);
+		
+		foreach (var extraArgument in serverJar.ExtraArgs) {
+			processArguments.Add(extraArgument);
+		}
+		
 		processArguments.Add("-jar");
-		processArguments.Add(serverJarPath);
+		processArguments.Add(serverJar.FilePath);
 		processArguments.Add("nogui");
 
 		var process = new Process { StartInfo = startInfo };
 		var instanceProcess = new InstanceProcess(instanceProperties, process);
 
-		try {
-			await AcceptEula(instanceProperties);
-			await UpdateServerProperties(instanceProperties);
-		} catch (Exception e) {
-			logger.Error(e, "Caught exception while configuring the server.");
-			return new LaunchResult.CouldNotConfigureMinecraftServer();
-		}
-
 		try {
 			process.Start();
 			process.BeginOutputReadLine();
@@ -82,8 +103,8 @@ public abstract class BaseLauncher {
 
 	private protected virtual void CustomizeJvmArguments(JvmArgumentBuilder arguments) {}
 
-	private protected virtual Task<string> PrepareServerJar(string serverJarPath, string instanceFolderPath, CancellationToken cancellationToken) {
+	private protected virtual Task<ServerJarInfo> PrepareServerJar(ILogger logger, string serverJarPath, string instanceFolderPath, CancellationToken cancellationToken) {
-		return Task.FromResult(serverJarPath);
+		return Task.FromResult(new ServerJarInfo(serverJarPath));
 	}
 
 	private static async Task AcceptEula(InstanceProperties instanceProperties) {

Agent/Phantom.Agent.Minecraft/Launcher/LaunchResult.cs

@@ -13,6 +13,8 @@ public abstract record LaunchResult {
 
 	public sealed record CouldNotDownloadMinecraftServer : LaunchResult;
 	
+	public sealed record CouldNotPrepareMinecraftServerLauncher : LaunchResult;
+	
 	public sealed record CouldNotConfigureMinecraftServer : LaunchResult;
 	
 	public sealed record CouldNotStartMinecraftServer : LaunchResult;

Agent/Phantom.Agent.Minecraft/Launcher/ServerJarInfo.cs

@@ -0,0 +1,7 @@
+using System.Collections.Immutable;
+
+namespace Phantom.Agent.Minecraft.Launcher;
+
+sealed record ServerJarInfo(string FilePath, ImmutableArray<string> ExtraArgs) {
+	public ServerJarInfo(string filePath) : this(filePath, ImmutableArray<string>.Empty) {}
+}

Agent/Phantom.Agent.Services/Instances/States/InstanceLaunchingState.cs

@@ -48,6 +48,9 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 		else if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotDownloadMinecraftServer, "Session failed to launch, could not download Minecraft server.");
 		}
+		else if (launchResult is LaunchResult.CouldNotPrepareMinecraftServerLauncher) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotPrepareMinecraftServerLauncher, "Session failed to launch, could not prepare Minecraft server launcher.");
+		}
 		else if (launchResult is LaunchResult.CouldNotConfigureMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotConfigureMinecraftServer, "Session failed to launch, could not configure Minecraft server.");
 		}

Common/Phantom.Common.Data/Instance/InstanceLaunchFailReason.cs

@@ -10,22 +10,24 @@ public enum InstanceLaunchFailReason : byte {
 	InvalidJvmArguments,
 	CouldNotDownloadMinecraftServer,
 	CouldNotConfigureMinecraftServer,
+	CouldNotPrepareMinecraftServerLauncher,
 	CouldNotStartMinecraftServer
 }
 
 public static class InstanceLaunchFailReasonExtensions {
 	public static string ToSentence(this InstanceLaunchFailReason reason) {
 		return reason switch {
-			InstanceLaunchFailReason.ServerPortNotAllowed             => "Server port not allowed.",
+			InstanceLaunchFailReason.ServerPortNotAllowed                   => "Server port not allowed.",
-			InstanceLaunchFailReason.ServerPortAlreadyInUse           => "Server port already in use.",
+			InstanceLaunchFailReason.ServerPortAlreadyInUse                 => "Server port already in use.",
-			InstanceLaunchFailReason.RconPortNotAllowed               => "Rcon port not allowed.",
+			InstanceLaunchFailReason.RconPortNotAllowed                     => "Rcon port not allowed.",
-			InstanceLaunchFailReason.RconPortAlreadyInUse             => "Rcon port already in use.",
+			InstanceLaunchFailReason.RconPortAlreadyInUse                   => "Rcon port already in use.",
-			InstanceLaunchFailReason.JavaRuntimeNotFound              => "Java runtime not found.",
+			InstanceLaunchFailReason.JavaRuntimeNotFound                    => "Java runtime not found.",
-			InstanceLaunchFailReason.InvalidJvmArguments              => "Invalid JVM arguments.",
+			InstanceLaunchFailReason.InvalidJvmArguments                    => "Invalid JVM arguments.",
-			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer  => "Could not download Minecraft server.",
+			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer        => "Could not download Minecraft server.",
-			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer => "Could not configure Minecraft server.",
+			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer       => "Could not configure Minecraft server.",
-			InstanceLaunchFailReason.CouldNotStartMinecraftServer     => "Could not start Minecraft server.",
+			InstanceLaunchFailReason.CouldNotPrepareMinecraftServerLauncher => "Could not prepare Minecraft server launcher.",
-			_                                                         => "Unknown error."
+			InstanceLaunchFailReason.CouldNotStartMinecraftServer           => "Could not start Minecraft server.",
+			_                                                               => "Unknown error."
 		};
 	}
 }