1 files changed, 70 insertions, 1 deletions

diff --git a/src/main/java/org/glavo/javah/Main.java b/src/main/java/org/glavo/javah/Main.java
index 26facc6..60bc0b1 100644
--- a/src/main/java/org/glavo/javah/Main.java
+++ b/src/main/java/org/glavo/javah/Main.java
@@ -1,6 +1,75 @@
 package org.glavo.javah;
 
+import java.io.InputStream;
+import java.nio.file.Paths;
+import java.util.jar.Manifest;
+
 public class Main {
-    public static void main(String[] args) {
+    private static final String HELP_MESSAGE =
+            "usage:\n" +
+                    "  gjavah [options] <classes>\n" +
+                    "where [options] include:\n" +
+                    "    -o <file>                       Output file (only one of -d or -o may be used)\n" +
+                    "    -d <dir>                        Output directory\n" +
+                    "    --module-path <path>            Path from which to search  modules\n" +
+                    "    --class-path <path> | " +
+                    "-classpath <path> | -cp <path>\n" +
+                    "                                    " +
+                    "                                Path from which to search classes\n" +
+                    "    --version                       Print version information\n" +
+                    "    -h  --help  -?                  Print this message";
+
+    public static void main(String[] args) throws Exception {
+        if (args.length == 0) {
+            System.err.println(HELP_MESSAGE);
+            System.exit(-1);
+        }
+        JavahTask task = new JavahTask();
+        task.addRuntimeClasspath();
+        loop:
+        for (int i = 0; i < args.length; i++) {
+            String arg = args[i];
+            switch (arg) {
+                case "--version":
+                case "-version":
+                    try (InputStream in = Main.class.getResourceAsStream("/META-INF/MANIFEST.MF")) {
+                        Manifest manifest = new Manifest(in);
+                        System.out.println("gjavah version: " + manifest.getMainAttributes().getValue("GJavah-Version"));
+                    }
+                    return;
+                case "-h":
+                case "--help":
+                case "-help":
+                case "-?":
+                    System.out.println(HELP_MESSAGE);
+                    return;
+                case "-o":
+                    task.setOutputToSignalFile(true);
+                    task.setOutputPath(Paths.get(args[++i]));
+                    break;
+                case "-d":
+                    task.setOutputToSignalFile(false);
+                    task.setOutputPath(Paths.get(args[++i]));
+                    break;
+                case "--module-path":
+                    task.addModulePaths(args[++i]);
+                    break;
+                case "--class-path":
+                case "--classpath":
+                case "-classpath":
+                case "-cp":
+                    task.addClasspaths(args[++i]);
+                    break;
+                default:
+                    for (int j = i; j < args.length; j++) {
+                        task.addClass(args[i]);
+                    }
+                    break loop;
+            }
+            if (task.getClassList().isEmpty()) {
+                System.err.println("error: no classes specified");
+            }
+            task.run();
+        }
     }
 }