Inline the css-variables-parser dependency (#29571)

Get rid of the `postcss@7` dependency by inlining this simple function.

Author: silverwind

package-lock.json

@@ -23,7 +23,6 @@
     "chartjs-plugin-zoom": "2.0.1",
     "clippie": "4.0.7",
     "css-loader": "6.10.0",
-    "css-variables-parser": "1.0.1",
     "dayjs": "1.11.10",
     "dropzone": "6.0.0-beta.2",
     "easymde": "2.18.0",

package.json

@@ -1,9 +1,28 @@
 import {readFileSync} from 'node:fs';
 import {env} from 'node:process';
-import {parse} from 'css-variables-parser';
+import {parse} from 'postcss';
 
 const isProduction = env.NODE_ENV !== 'development';
 
+function extractRootVars(css) {
+  const root = parse(css);
+  const vars = new Set();
+  root.walkRules((rule) => {
+    if (rule.selector !== ':root') return;
+    rule.each((decl) => {
+      if (decl.value && decl.prop.startsWith('--')) {
+        vars.add(decl.prop.substring(2));
+      }
+    });
+  });
+  return Array.from(vars);
+}
+
+const vars = extractRootVars([
+  readFileSync(new URL('web_src/css/themes/theme-gitea-light.css', import.meta.url), 'utf8'),
+  readFileSync(new URL('web_src/css/themes/theme-gitea-dark.css', import.meta.url), 'utf8'),
+].join('\n'));
+
 export default {
   prefix: 'tw-',
   important: true, // the frameworks are mixed together, so tailwind needs to override other framework's styles
@@ -23,15 +42,10 @@ export default {
   theme: {
     colors: {
       // make `tw-bg-red` etc work with our CSS variables
-      ...Object.fromEntries(
-        Object.keys(parse([
-          readFileSync(new URL('web_src/css/themes/theme-gitea-light.css', import.meta.url), 'utf8'),
-          readFileSync(new URL('web_src/css/themes/theme-gitea-dark.css', import.meta.url), 'utf8'),
-        ].join('\n'), {})).filter((prop) => prop.startsWith('color-')).map((prop) => {
-          const color = prop.substring(6);
-          return [color, `var(--color-${color})`];
-        })
-      ),
+      ...Object.fromEntries(vars.filter((prop) => prop.startsWith('color-')).map((prop) => {
+        const color = prop.substring(6);
+        return [color, `var(--color-${color})`];
+      })),
       inherit: 'inherit',
       current: 'currentcolor',
       transparent: 'transparent',