fix(datastore): add networking monitor by regular ping

Author: 5d

AmplifyPlugins/Core/AWSPluginsCore/WebSocket/AmplifyNetworkMonitor.swift

@@ -5,7 +5,7 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-
+import Foundation
 import Network
 import Combine
 
@@ -19,6 +19,7 @@ public final class AmplifyNetworkMonitor {
     }
 
     private let monitor: NWPathMonitor
+    private var pingMonitor: AnyCancellable?
 
     private let subject = PassthroughSubject<State, Never>()
 
@@ -38,6 +39,8 @@ public final class AmplifyNetworkMonitor {
             label: "com.amazonaws.amplify.ios.network.websocket.monitor",
             qos: .userInitiated
         ))
+
+        pingMonitor = startPingMonitor()
     }
 
     public func updateState(_ nextState: State) {
@@ -46,6 +49,35 @@ public final class AmplifyNetworkMonitor {
 
     deinit {
         subject.send(completion: .finished)
+        pingMonitor?.cancel()
         monitor.cancel()
     }
+
+    private func pingCloudflare() -> Future<State, Never> {
+        Future { promise in
+            let oneDNS = URL(string: "https://1.1.1.1")!
+            var request = URLRequest(url: oneDNS)
+            request.httpMethod = "HEAD"
+            request.timeoutInterval = .seconds(2)
+
+            URLSession.shared.dataTask(with: request) { _, response, error in
+                if let error {
+                    promise(.success(State.offline))
+                } else if let httpResponse = response as? HTTPURLResponse {
+                    promise(.success(httpResponse.statusCode < 400 ? State.online : State.offline))
+                }
+            }.resume()
+        }
+    }
+
+    private func startPingMonitor() -> AnyCancellable {
+        return Timer.TimerPublisher(interval: .seconds(2), runLoop: .main, mode: .common)
+            .autoconnect()
+            .receive(on: DispatchQueue.global(qos: .default))
+            .compactMap { [weak self] _ in self?.pingCloudflare() }
+            .flatMap { $0 }
+            .sink { [weak self] state in
+                self?.updateState(state)
+            }
+    }
 }