From 65fbeb0287226933189b8e162a8c218f8689abb4 Mon Sep 17 00:00:00 2001
From: songbirdzz <165868972+songbirdzz@users.noreply.github.com>
Date: Fri, 24 May 2024 10:01:07 -0700
Subject: [PATCH] Update: Optimize webview video resource obtaining

---
 lib/utils/webview.dart | 81 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 67 insertions(+), 14 deletions(-)

diff --git a/lib/utils/webview.dart b/lib/utils/webview.dart
index dcf6c34..ff25aa9 100644
--- a/lib/utils/webview.dart
+++ b/lib/utils/webview.dart
@@ -1,4 +1,6 @@
 import 'dart:async';
+import 'dart:collection';
+import 'dart:convert';
 
 import 'package:flutter_inappwebview/flutter_inappwebview.dart';
 import 'package:flutter_modular/flutter_modular.dart';
@@ -6,15 +8,59 @@ import 'package:logger/logger.dart';
 
 class Webview {
   static Future<String?> getVideoResourceUrl(String pageUrl) async {
+/*
+ * So, in this method, we basically get video resources in 2 ways:
+ * 1. Use user script to check whether there's a video element in the html,
+ * and get its src attribute. However, this method cannot obtain video resource
+ * when the src is in the blob form.
+ * 2. Listen to network requests. However, due to iframe cross-domain restraints,
+ * we cannot intercept requests made in iframes, and that's how a lot of websites
+ * do to their players. Therefore we see the whole document as a tree and traverse
+ * it by setting href (directly fetch the urls may cause authentication issues, such
+ * as referers or cookies).
+ */
     String? videoResourceUrl;
     final completer = Completer();
-    _Node currentNode = _Node(pageUrl);
+    _Node currentNode = _Node(WebUri(pageUrl));
     List<String> history = [];
+    Future.delayed(
+        const Duration(seconds: 60), () => completer.complete(false));
     final webview = HeadlessInAppWebView(
       initialUrlRequest: URLRequest(url: WebUri(pageUrl)),
+      initialUserScripts: UnmodifiableListView<UserScript>([
+        UserScript(source: """
+                setInterval(() => {
+                  if (document.querySelector('video') !== null && document.querySelector('video').attributes.src.textContent.startsWith('http')) {
+                    console.log(`VIDEO:\${document.querySelector('video').attributes.src.textContent}`);
+                    // window.flutter_inappwebview.callHandler('foundVideoSrc', document.querySelector('video').attributes.src.textContent);
+                  }
+                }, 100);
+                """, injectionTime: UserScriptInjectionTime.AT_DOCUMENT_START)
+      ]),
       onLoadStart: (controller, url) {
         Modular.get<Logger>().i('Loading $url');
-        history.add(url.toString());
+        history.add(_removeQuery(url));
+      },
+      onConsoleMessage: (controller, consoleMessage) {
+        // Receive message from iframes
+        // We cannot use controller.addJavaScriptHandler here because
+        // window.flutter_inappwebview doesn't exist in cross-domain iframes
+        // Therefore we use onConsoleMessage to pass information,
+        // which is based on devtools API.
+        String message = jsonDecode(consoleMessage.message);
+        if (message.startsWith('VIDEO:')) {
+          Modular.get<Logger>().i('Received console message: $consoleMessage');
+          videoResourceUrl = message.substring('VIDEO:'.length);
+          completer.complete(true);
+        }
+      },
+      onWebViewCreated: (controller) {
+        controller.addDevToolsProtocolEventListener(
+            eventName: 'responseReceived',
+            callback: (resp) {
+              Modular.get<Logger>().i('Received resp: $resp');
+              return resp;
+            });
       },
       onLoadResource: (controller, resource) {
         if (resource.url.toString().contains('.m3u8') ||
@@ -26,32 +72,35 @@ class Webview {
           // For Windows webviews (and maybe macOS as well), onLoadResource
           // can't capture requests sent within iframes. Therefore we store
           // and them for later use.
-          currentNode.children
-              .add(_Node(resource.url.toString(), parent: currentNode));
+          currentNode.children.add(_Node(resource.url!, parent: currentNode));
         }
       },
       onLoadStop: (controller, url) async {
         if (completer.isCompleted) return;
-        // This timer seems redundant, however I do have seen some onLoadResource
-        // calls after onLoadStop. So we use a timer here to ensure maxium compatibility
-
+        // Sometimes resource loading requests are still being made after
+        // onLoadStop. Therefore we delay a little bit here to make sure
+        // we won't miss any (or at least won't miss a lot) requests
+        await Future.delayed(const Duration(seconds: 2));
         while (!currentNode.isRoot &&
-            currentNode.children
-                .where((node) => !history.contains(node.url))
+            currentNode.children.reversed
+                .where((node) => !history.contains(_removeQuery(node.url)))
                 .isEmpty) {
           await controller.evaluateJavascript(
               source: "window.location.href='${currentNode.parent!.url}';");
           currentNode = currentNode.parent!;
         }
-        if (currentNode.children
-            .where((node) => !history.contains(node.url))
+        if (currentNode.children.reversed
+            .where((node) => !history.contains(_removeQuery(node.url)))
             .isNotEmpty) {
-          final node = currentNode.children
-              .where((node) => !history.contains(node.url))
+          final node = currentNode.children.reversed
+              .where((node) => !history.contains(_removeQuery(node.url)))
               .first;
           currentNode = node;
           await controller.evaluateJavascript(
               source: "window.location.href='${node.url}';");
+        } else {
+          // Root & no other subframes to go
+          completer.complete(false);
         }
       },
       shouldAllowDeprecatedTLS: (controller, challenge) async =>
@@ -67,10 +116,14 @@ class Webview {
     Modular.get<Logger>().i('Cannot find any video in $pageUrl');
     return null;
   }
+
+  static String _removeQuery(WebUri? url) {
+    return url!.origin + url.path;
+  }
 }
 
 class _Node {
-  final String url;
+  final WebUri url;
   final _Node? parent;
   final List<_Node> children = [];
   bool get isRoot => parent == null;