async transform()

in packages/rollup-css-plugin/css-plugin.js [41:132]
47 lines of code
3 McCabe index (conditional complexity)

    async transform(code, id) {
      if (!filter(id)) {
        return null;
      }
      let plugins = [];

      const cssModulesCache = new Map();
      sourcesList.push(id);
      const postcssConfig = await postcssConfigPromise;

      async function compileIfNeeded(resolvedPath) {
        if (compiledCodeMap.has(resolvedPath)) {
          return;
        }
        const fileContent = await fs.readFile(resolvedPath, 'utf-8');
        const result = await postcss(plugins).process(fileContent, {
          from: resolvedPath,
          to: resolvedPath,
          map: false,
        });
        log('compileIfNeeded.compiled', resolvedPath);

        compiledCodeMap.set(resolvedPath, result.css);
      }

      plugins = [
        postcssImport({
          resolve: (fileId, basedir) => {
            const resolvedPath = path.resolve(basedir, fileId);
            log('postcssImport.resolve', fileId, basedir, resolvedPath);
            depGraph.addDependency(id, resolvedPath);
            return resolvedPath;
          },
          load: async filename => {
            await compileIfNeeded(filename);

            return `/* "@import" of "${path.basename(filename)}" extracted */\n`;
          },
        }),
        ...(postcssConfig.plugins || []),
        postcssUrl({
          includeUriFragment: true,
          url: 'inline',
        }),
        cssModules({
          generateScopedName(name, filename) {
            return `ring-${path.basename(filename, '.css')}-${name}`;
          },
          getJSON: (filepath, json) => {
            cssModulesCache.set(filepath, json);
          },
          // Override Loader to prevent css-modules from inlining content of imported files for @value bar form '../foo.css' syntax
          // See https://github.com/madyankin/postcss-modules/blob/bd64c71ddfd81b615104b0727ce9a623da0eaef6/src/FileSystemLoader.js#L68
          Loader: class CustomLoader extends FileSystemLoader {
            async fetch(file, relativeTo, _trace) {
              const res = await super.fetch(file, relativeTo, _trace);
              const normalizedFile = file.replace(/^["']|["']$/g, '');
              const resolvedPath = path.join(path.dirname(relativeTo), normalizedFile);

              await compileIfNeeded(resolvedPath);
              depGraph.addDependency(id, resolvedPath);

              this.sources[resolvedPath] = `/* "@value" import of "${path.basename(resolvedPath)}" extracted */\n`;

              return res;
            }
          },
          resolve: async (file, importer) => {
            const resolvedPath = path.resolve(path.dirname(importer), file);
            log('cssModules.resolve', file, importer, resolvedPath);
            await compileIfNeeded(resolvedPath);
            depGraph.addDependency(id, resolvedPath);
            return resolvedPath;
          },
        }),
      ];

      const result = await postcss(plugins).process(code, {
        from: id,
        to: id,
        map: false,
      });
      log('source.compiled', id);

      compiledCodeMap.set(id, result.css);

      return {
        code: `export default ${JSON.stringify(cssModulesCache.get(id))};`,
        map: result.map,
        moduleSideEffects: 'no-treeshake',
      };
    },