Introduce subcommands to build script

Build.java

@@ -1,8 +1,8 @@
 import static nobuild.NoBuild.*;
 
-import java.nio.file.Paths;
+import java.util.ArrayDeque;
 import java.util.Arrays;
-import java.util.stream.Collectors;
+import java.util.Optional;
 
 public class Build {
   static final String program = "jtags";
@@ -10,32 +10,69 @@ public class Build {
   public static void main(String[] args) {
     rebuildSelf(Build.class, args);
 
+    var arguments = new ArrayDeque<>(Arrays.asList(args));
+
+    if (arguments.size() == 0) {
+      printUsage();
+      System.exit(1);
+    }
+
     String mainClass = "xyz.naofal.jtags.Jtags";
     String[] sourcePaths = glob("src/main/java/**.java");
-    String[] classPaths = glob("third-party/jars/*.jar");
+    String[] classPaths = {};
 
+    var subcommand = arguments.pop();
+    switch (subcommand) {
+      case "build":
+        buildJtags(mainClass, sourcePaths, classPaths);
+        break;
+
+      case "run":
+        buildJtags(mainClass, sourcePaths, classPaths);
+        runJava(classPaths, mainClass, arguments.toArray(String[]::new));
+        break;
+
+      case "package":
+        buildJtags(mainClass, sourcePaths, classPaths);
+        packageJar(Optional.ofNullable(arguments.poll()));
+        break;
+
+      default:
+        logger.severe("Unknown subcommand: " + subcommand);
+        printUsage();
+        System.exit(1);
+        break;
+    }
+  }
+
+  static void buildJtags(String mainClass, String[] sourcePaths, String[] classPaths) {
     if (classNeedsRebuild(mainClass, sourcePaths)) {
-      ensureDependencies();
       logger.info("Compiling %s...".formatted(program));
       compileJava(classPaths, sourcePaths);
     }
-
-    var argumentPartitions =
-        Arrays.stream(args).collect(Collectors.partitioningBy(it -> it.startsWith("-D")));
-    String[] javaArguments = argumentPartitions.get(true).toArray(String[]::new);
-    String[] programArguments = argumentPartitions.get(false).toArray(String[]::new);
-
-    runJava(classPaths, javaArguments, mainClass, programArguments);
   }
 
-  private static void ensureDependencies() {
-    Dependency[] dependencies = {
-      new Dependency("com.h2database", "h2", "2.3.232"),
-    };
+  static void packageJar(Optional<String> jarfile) {
+    command(
+        "jar",
+        "cfe",
+        jarfile.orElse("Jtags.jar"),
+        "xyz.naofal.jtags.Jtags",
+        "-C",
+        buildClassPath,
+        ".");
+  }
 
-    if (!downloadDependencies(mavenCentral, Paths.get("third-party", "jars"), dependencies)) {
-      logger.severe("Could not download all dependencies");
-      System.exit(1);
-    }
+  static void printUsage() {
+    System.err.println(
+        """
+        Usage: java Build <subcommand> [args...]
+        Subcommands:
+          build          Build %1$s
+          run [args...]  Run %1$s with arguments
+          package        Package %1$s to a JAR file
+            [file]         Output JAR filename [Default: Jtags.jar]
+        """
+            .formatted(program));
   }
 }