From 65f0909ba08c938473ab45f7b54aa31cc9d49a3a Mon Sep 17 00:00:00 2001
From: Manish Jethani <code@manishjethani.io>
Date: Sun, 8 Aug 2021 16:52:02 +0530
Subject: [PATCH] Implement class StaticNetFilteringEngine (#3805)

---
 platform/nodejs/index.js | 46 +++++++++++++++++++++++++++++++++++++
 platform/nodejs/test.js  | 49 ++++++++++++++++++++++------------------
 2 files changed, 73 insertions(+), 22 deletions(-)

diff --git a/platform/nodejs/index.js b/platform/nodejs/index.js
index 4cb0011c2..ac87b1653 100644
--- a/platform/nodejs/index.js
+++ b/platform/nodejs/index.js
@@ -201,6 +201,51 @@ function reset() {
     snfe.reset();
 }
 
+/******************************************************************************/
+
+let pslInitialized = false;
+let staticNetFilteringEngineInstance = null;
+
+class StaticNetFilteringEngine {
+    constructor() {
+        if ( staticNetFilteringEngineInstance !== null ) {
+            throw new Error('Only a single instance is supported.');
+        }
+
+        staticNetFilteringEngineInstance = this;
+
+        this._context = new FilteringContext();
+    }
+
+    async useLists(lists) {
+        await useRawLists(lists);
+    }
+
+    matchRequest({ url, originURL, type }) {
+        this._context.setDocOriginFromURL(originURL);
+        this._context.setURL(url);
+        this._context.setType(type);
+
+        return snfe.matchRequest(this._context);
+    }
+
+    toLogData() {
+        return snfe.toLogData();
+    }
+}
+
+StaticNetFilteringEngine.initialize = async function initialize() {
+    if ( !pslInitialized ) {
+        if ( !pslInit() ) {
+            throw new Error('Failed to initialize public suffix list.');
+        }
+
+        pslInitialized = true;
+    }
+};
+
+/******************************************************************************/
+
 // rollup.js needs module.exports to be set back to the local exports object.
 // This is because some of the code (e.g. publicsuffixlist.js) sets
 // module.exports. Once all included files are written like ES modules, using
@@ -211,6 +256,7 @@ if ( typeof module !== 'undefined' && typeof exports !== 'undefined' ) {
 
 export {
     FilteringContext,
+    StaticNetFilteringEngine,
     enableWASM,
     pslInit,
     createCompiler,
diff --git a/platform/nodejs/test.js b/platform/nodejs/test.js
index 0c8466102..f4691edac 100644
--- a/platform/nodejs/test.js
+++ b/platform/nodejs/test.js
@@ -30,9 +30,7 @@ import { createRequire } from 'module';
 
 import {
     enableWASM,
-    FilteringContext,
-    pslInit,
-    useRawLists,
+    StaticNetFilteringEngine,
 } from './index.js';
 
 /******************************************************************************/
@@ -54,39 +52,46 @@ async function main() {
         console.log(ex);
     }
 
-    await pslInit();
+    await StaticNetFilteringEngine.initialize();
 
-    const snfe = await useRawLists([
+    const engine = new StaticNetFilteringEngine();
+
+    await engine.useLists([
         fetch('easylist').then(raw => ({ name: 'easylist', raw })),
         fetch('easyprivacy').then(raw => ({ name: 'easyprivacy', raw })),
     ]);
 
-    // Reuse filtering context: it's what uBO does
-    const fctxt = new FilteringContext();
+    let result = null;
 
     // Tests
     // Not blocked
-    fctxt.setDocOriginFromURL('https://www.bloomberg.com/');
-    fctxt.setURL('https://www.bloomberg.com/tophat/assets/v2.6.1/that.css');
-    fctxt.setType('stylesheet');
-    if ( snfe.matchRequest(fctxt) !== 0 ) {
-        console.log(snfe.toLogData());
+    result = engine.matchRequest({
+      originURL: 'https://www.bloomberg.com/',
+      url: 'https://www.bloomberg.com/tophat/assets/v2.6.1/that.css',
+      type: 'stylesheet'
+    });
+    if ( result !== 0 ) {
+        console.log(engine.toLogData());
     }
 
     // Blocked
-    fctxt.setDocOriginFromURL('https://www.bloomberg.com/');
-    fctxt.setURL('https://securepubads.g.doubleclick.net/tag/js/gpt.js');
-    fctxt.setType('script');
-    if ( snfe.matchRequest(fctxt) !== 0 ) {
-        console.log(snfe.toLogData());
+    result = engine.matchRequest({
+      originURL: 'https://www.bloomberg.com/',
+      url: 'https://securepubads.g.doubleclick.net/tag/js/gpt.js',
+      type: 'script'
+    });
+    if ( result !== 0 ) {
+        console.log(engine.toLogData());
     }
 
     // Unblocked
-    fctxt.setDocOriginFromURL('https://www.bloomberg.com/');
-    fctxt.setURL('https://sourcepointcmp.bloomberg.com/ccpa.js');
-    fctxt.setType('script');
-    if ( snfe.matchRequest(fctxt) !== 0 ) {
-        console.log(snfe.toLogData());
+    result = engine.matchRequest({
+      originURL: 'https://www.bloomberg.com/',
+      url: 'https://sourcepointcmp.bloomberg.com/ccpa.js',
+      type: 'script'
+    });
+    if ( result !== 0 ) {
+        console.log(engine.toLogData());
     }
 
     process.exit();