Properly resolve relative paths in CSS imports (#527)

• Fix inconsistency in function argument type formatting.
• Resolve relative paths when during import resolves in CSS files.

Co-authored-by: SpacingBat3 <[email protected]>

sources/code/main/modules/extensions.ts

@@ -1,12 +1,12 @@
+import { resolve } from "url";
 import { commonCatches } from "./error";
 
 const safeStoragePromise = (import("electron/main"))
   .then(main => main.safeStorage);
 
-async function fetchOrRead(file:string, signal?:AbortSignal) {
+async function fetchOrRead(url:URL, signal?:AbortSignal) {
   const readFile = import("fs/promises").then(fs => fs.readFile);
 
-  const url = new URL(file);
   if(url.protocol === "file:")
     return { read: (await readFile)(url.pathname, {signal}) };
   else
@@ -19,19 +19,19 @@ async function fetchOrRead(file:string, signal?:AbortSignal) {
  * 
  * **Experimental** – it is unknown if that would work properly for all themes.
  */
-async function parseImports(cssString: string, importCalls:string[], maxTries=5):Promise<string> {
+async function parseImports(cssString: string, importCalls: string[], maxTries=5):Promise<string> {
   const anyImport = /^@import .+?$/gm;
   if(!anyImport.test(cssString)) return cssString;
   const promises:Promise<unknown>[] = [];
   cssString.match(anyImport)?.forEach(singleImport => {
     const matches = /^@import (?:(?:url\()?["']?([^"';)]*)["']?)\)?;?/m.exec(singleImport);
     if(matches?.[0] === undefined || matches[1] === undefined) return;
-    const file = matches[1];
+    const file = resolve(importCalls.at(-1) ?? "", matches[1]);
     if(importCalls.includes(file)) {
-      promises.push(Promise.reject(new Error("Circular reference in CSS imports are disallowed!")));
+      promises.push(Promise.reject(new Error("Circular reference in CSS imports are disallowed: " + file)));
       return;
     }
-    promises.push(fetchOrRead(file)
+    promises.push(fetchOrRead(new URL(file))
       .then(data => {
         if (data.download)
           return data.download.then(data => data.text());
@@ -46,8 +46,8 @@ async function parseImports(cssString: string, importCalls:string[], maxTries=5)
   const rejection = result.findIndex(({status})=> status === "rejected");
   if(rejection >= 0) {
     if(maxTries > 0) {
-      console.warn("Couldn't resolve CSS theme imports, retrying again...");
-      maxTries--;
+      console.warn("Couldn't resolve CSS theme imports, retrying...");
+      return parseImports(cssString, importCalls, maxTries - 1);
     }
     else await promises[rejection];
   }