empires: Construct reliable paths for all game API endpoints

[lmno.games] / empires / game.js

diff --git a/empires/game.js b/empires/game.js
index 746cdfdc943d37d55c6d0f6fb6ce3f8315407a42..3f45e7de730bbd8c35037a25cef5a4f7e802ebb2 100644 (file)
--- a/empires/game.js
+++ b/empires/game.js
@@ -1,3 +1,39 @@
+/* Construction of Game API endpoint paths. Logically all endpoints
+ * are just local resources underneath the current path, but just
+ * referring to them by a local name only works if the current path
+ * has a trailing slash.
+ *
+ * That is, if the current path is:
+ *
+ *     https://lmno.games/empires/WXYZ/
+ *
+ * Then a path of "register" goes to:
+ *
+ *     https://lmno.games/empires/WXYZ/register
+ *
+ * Just as we want. But if the current path happens to be:
+ *
+ *     https://lmno.games/empires/WXYZ
+ *
+ * Then a path of "register" goes to:
+ *
+ *     https://lmno.games/empires/register
+ *
+ * Which cannot work since we have lost the game ID in the path.
+ *
+ * Of course, we would like to have canonical URLs for the game (with
+ * the trailing slash) but since that depends on macehinery outside
+ * the scope of this file, let's construct API paths that will work
+ * either way.
+ */
+function GAME_API(endpoint) {
+  var path = window.location.pathname;
+  if (! path.endsWith('/'));
+      path += '/';
+  path += endpoint;
+  return path;
+}
+
 function undisplay(element) {
   element.style.display="none";
 }
@@ -14,7 +50,7 @@ ${message}
 function register(form) {
   var request = new XMLHttpRequest();
 
-  request.open("POST", "register");
+  request.open("POST", GAME_API("register"));
   request.setRequestHeader("Content-Type", "application/json; charset=UTF-8");
   var data = {
     "character": form.character.value
@@ -38,25 +74,25 @@ function toggle_host_tools() {
 function post_reveal() {
   const request = new XMLHttpRequest();
 
-  request.open("POST", "reveal");
+  request.open("POST", GAME_API("reveal"));
   request.send();
 }
 
 function post_start() {
   const request = new XMLHttpRequest();
 
-  request.open("POST", "start");
+  request.open("POST", GAME_API("start"));
   request.send();
 }
 
 function post_reset() {
   const request = new XMLHttpRequest();
 
-  request.open("POST", "reset");
+  request.open("POST", GAME_API("reset"));
   request.send();
 }
 
-const events = new EventSource(window.location + "events");
+const events = new EventSource(GAME_API("events"));
 
 events.onerror = function(event) {
   if (event.target.readyState === EventSource.CLOSED) {