add repl to executable

fuck.js

@@ -1,12 +1,38 @@
 #!/usr/bin/env node
 
+var stream = require('stream');
+var util = require('util');
 var lib = require("./jsfuck.js");
+var repl = require('repl');
 
 if(process.argv.length !== 3) {
-	console.error("Usage: jsfuck <js file>");
-	return;
-}
 
-var data = require("fs").readFileSync(process.argv[2], "utf8");
-var output = lib.JSFuck.encode(data, false);
-console.log(output);
+  function Stream() {
+    stream.Transform.call(this);
+  }
+  util.inherits(Stream, stream.Transform);
+
+  Stream.prototype._transform = function (chunk, encoding, callback) {
+    var script = lib.JSFuck.encode(chunk.toString());
+    var lines = script.split(/\n+/);
+    for (var i = 0; i < lines.length; i++) {
+      // ignore empty lines
+      if (lines[i] !== '') this.push(lines[i] + '\n');
+    }
+    callback();
+  };
+
+  var fuckScript = new Stream();
+  repl.start({
+    prompt: "FUCK> ",
+    input: fuckScript,
+    useColors: true,
+    output: process.stdout
+  });
+
+  process.stdin.pipe(fuckScript);
+} else {
+  var data = require("fs").readFileSync(process.argv[2], "utf8");
+  var output = lib.JSFuck.encode(data, false);
+  console.log(output);
+}