Chore: process line stream

Build/lib/process-line.ts

@@ -1,3 +1,5 @@
+import { TransformStream } from 'node:stream/web';
+
 export function processLine(line: string): string | null {
   if (!line) {
     return null;
@@ -11,8 +13,7 @@ export function processLine(line: string): string | null {
   const line_0: string = trimmed[0];
 
   if (
-    line_0 === '#'
-    || line_0 === ' '
+    line_0 === ' '
     || line_0 === '\r'
     || line_0 === '\n'
     || line_0 === '!'
@@ -21,16 +22,48 @@ export function processLine(line: string): string | null {
     return null;
   }
 
+  if (line_0 === '#') {
+    if (trimmed[1] !== '#') {
+      // # Comment
+      return null;
+    }
+    if (trimmed[2] === '#' && trimmed[3] === '#') {
+      // ################## EOF ##################
+      return null;
+    }
+    /**
+     * AdGuard Filter can be:
+     *
+     * ##.class
+     * ##tag.class
+     * ###id
+     */
+  }
+
   return trimmed;
 }
 
-export async function processLineFromReadline(rl: AsyncIterable<string>): Promise<string[]> {
-  const res: string[] = [];
-  for await (const line of rl) {
-    const l: string | null = processLine(line);
-    if (l) {
-      res.push(l);
-    }
+export class ProcessLineStream extends TransformStream<string, string> {
+  // private __buf = '';
+  constructor() {
+    super({
+      transform(l, controller) {
+        const line = processLine(l);
+        if (line) {
+          controller.enqueue(line);
+        }
+      }
+    });
   }
-  return res;
 }
+
+// export class ProcessLineNodeStream extends Transform {
+//   _transform(chunk: string, encoding: BufferEncoding, callback: TransformCallback) {
+//     // Convert chunk to string and then to uppercase
+//     const upperCased = chunk.toUpperCase();
+//     // Push transformed data to readable side
+//     this.push(upperCased);
+//     // Call callback when done
+//     callback();
+//   }
+// }