Allow user to kill editor process from browser (#135)

* Check for terminal

* Added kill functionality in local server, but it doesn't work.

* Made it work.

* Moved button, made it less prominent.

* whoops

editor/local_server.py

@@ -42,7 +42,6 @@ def handle_post_thread(self, data, path):
         if b"code[]" not in data:
             data[b"code[]"] = [b""]
 
-
         if path == "/cancel":
             self.cancellation_event.set()
             self.send_response(HTTPStatus.OK, 'test')
@@ -166,6 +165,11 @@ def handle_post_thread(self, data, path):
             query = data.get(b"query", [b""])[0].decode("utf-8")
             self.wfile.write(bytes(json.dumps(search(query)), "utf-8"))
 
+        elif path == "/kill":
+            # This is (only) fine because we're in a different thread than the actual server
+            self.server.shutdown()
+            self.server.socket.close()
+
     def do_GET(self):
         self.send_response(HTTPStatus.OK, 'test')
         path = "editor/static/" + urllib.parse.unquote(self.path)[1:]
@@ -284,9 +288,23 @@ def start(file_args, port, open_browser):
     main_files = file_args
     global PORT
     PORT = port
-    print(f"http://localhost:{PORT}")
+    url = f"http://localhost:{PORT}"
     socketserver.TCPServer.allow_reuse_address = True
-    httpd = ThreadedHTTPServer(("localhost", PORT), Handler)
+    try:
+        httpd = ThreadedHTTPServer(("localhost", PORT), Handler)
+    except OSError:
+        if supports_color():
+            print("\033[91m", end="")
+        print(f"Port {PORT} is already in use, likely for another instance of the editor.")
+        print("To open a second instance of the editor, specify a different port using --port.")
+        print(f"To replace the previous editor instance with a new one:\n"
+              f"    1. Go to {url}\n"
+              f"    2. Press \"Stop Editor\" at the top\n"
+              f"    3. Run `python3 editor` again")
+        if supports_color():
+            print("\033[0m", end="")
+        return
+    print(url)
     if open_browser:
         webbrowser.open(f"http://localhost:{PORT}", new=0, autoraise=True)
     try:

editor/static/index.html

@@ -46,6 +46,11 @@
             <a class="nav-link" href="#" id="settings-btn">Settings</a>
         </li>
     </ul>
+    <button type="button" class="btn btn-outline-danger" data-toggle="tooltip" id="stop-editor-btn"
+                title="Stop the current editor process"
+    style="margin-right: 15px">Stop Editor
+    </button>
+    <br>
     <form class="documentation-form form-inline my-2 my-lg-0">
         <input id="documentation-search" class="form-control mr-sm-2" type="search" aria-label="Search"
                placeholder="Search">
@@ -201,7 +206,7 @@ <h5 class="modal-title" id="disconnectedModalLabel">Process Disconnected</h5>
                 <p>
                     Warning! The <code>editor</code> process is no longer responding to queries from the front end. <b>You have likely stopped the process in the terminal.</b>
                 <p>
-                    Run <code>python editor -nb</code> in a terminal, then reconnect.
+                    Run <code>python editor -nb</code> in a terminal, then refresh / reconnect.
                 </p>
                 <p>
                     Remember to run <code>python ok</code> (to unlock or submit tests) in a <b>separate</b> terminal window, so that you don't have to stop the editor process.
@@ -218,7 +223,7 @@ <h5 class="modal-title" id="disconnectedModalLabel">Process Disconnected</h5>
 </div>
 
 <div class="modal fade" id="formatFailModal" tabindex="-1" role="dialog"
-     aria-labelledby="disconnectedModalLabel" aria-hidden="true">
+     aria-labelledby="formatFailModalLabel" aria-hidden="true">
     <div class="modal-dialog" role="document">
         <div class="modal-content">
             <div class="modal-header">

editor/static/scripts/settings.js

@@ -9,6 +9,12 @@ function init() {
     $('#settingsModal').on('hide.bs.modal', function (e) {
         saveState();
     });
+    $("#stop-editor-btn").on("click", () => {
+        $.post("/kill");
+        $("#disconnectedModal").modal("show");
+        $("#reconnect-button").hide();
+    });
+
     $.post("./load_settings").done((data) => {
         setAllSettings($.parseJSON(data));
     });