Override theme with url theme query param

webapp/titanembeds/static/js/embed.js

@@ -6,6 +6,8 @@
 /* global moment */
 
 (function () {
+    const theme_options = ["DiscordDark"]; // All the avaliable theming names
+    
     var has_already_been_focused = false; // keep track of if the embed has initially been focused.
     var logintimer; // timer to keep track of user inactivity after hitting login
     var fetchtimeout; // fetch routine timer
@@ -121,8 +123,19 @@
         });
         
         $( "#theme-selector" ).change(function() {
-            const theme_options = ["DiscordDark"];
             var theme = $("#theme-selector option:selected").val();
+            changeTheme(theme);
+        });
+        
+        var themeparam = getParameterByName('theme');
+        if (themeparam && $.inArray(themeparam, theme_options) != -1) {
+            changeTheme(themeparam);
+            $("#theme-selector option").removeAttr('selected');
+            $("#theme-selector option[value=" + themeparam + "]").attr('selected', 'selected');
+        }
+    });
+    
+    function changeTheme(theme) {
         if (theme == "") {
           $("#css-theme").attr("href", "");
           disable_userdef_css(false);
@@ -130,8 +143,18 @@
             disable_userdef_css(true);
             $("#css-theme").attr("href", "/static/themes/" + theme + "/css/style.css");
         }
-        });
+    }
-    });
+    
+    /* https://stackoverflow.com/questions/901115/how-can-i-get-query-string-values-in-javascript */
+    function getParameterByName(name, url) {
+        if (!url) url = window.location.href;
+        name = name.replace(/[\[\]]/g, "\\$&");
+        var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
+            results = regex.exec(url);
+        if (!results) return null;
+        if (!results[2]) return '';
+        return decodeURIComponent(results[2].replace(/\+/g, " "));
+    }
     
     function disable_userdef_css(boolean) {
         var usrcss = $("#user-defined-css").text();