packages/devtools_app/lib/src/framework/observer/disconnect_observer.dart

// Copyright 2024 The Flutter Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file or at https://developers.google.com/open-source/licenses/bsd.

import 'dart:async';

import 'package:devtools_app_shared/service.dart';
import 'package:devtools_app_shared/ui.dart';
import 'package:devtools_app_shared/utils.dart';
import 'package:flutter/material.dart';

import '../../service/connected_app/connection_info.dart';
import '../../shared/analytics/analytics.dart' as ga;
import '../../shared/analytics/constants.dart' as gac;
import '../../shared/config_specific/import_export/import_export.dart';
import '../../shared/framework/routing.dart';
import '../../shared/globals.dart';
import '../../shared/primitives/query_parameters.dart';

class DisconnectObserver extends StatefulWidget {
  const DisconnectObserver({
    super.key,
    required this.routerDelegate,
    required this.child,
  });

  final Widget child;
  final DevToolsRouterDelegate routerDelegate;

  @override
  State<DisconnectObserver> createState() => DisconnectObserverState();
}

class DisconnectObserverState extends State<DisconnectObserver>
    with AutoDisposeMixin {
  OverlayEntry? currentDisconnectedOverlay;

  late ConnectedState currentConnectionState;

  @override
  void initState() {
    super.initState();

    currentConnectionState =
        serviceConnection.serviceManager.connectedState.value;

    addAutoDisposeListener(serviceConnection.serviceManager.connectedState, () {
      final previousConnectionState = currentConnectionState;
      currentConnectionState =
          serviceConnection.serviceManager.connectedState.value;

      if (currentConnectionState.connected &&
          currentDisconnectedOverlay != null) {
        setState(() {
          hideDisconnectedOverlay();
        });
      } else if (!currentConnectionState.connected) {
        if (previousConnectionState.connected &&
            !currentConnectionState.connected &&
            !currentConnectionState.userInitiatedConnectionState) {
          // We became disconnected by means other than a manual disconnect
          // action, so show the overlay and ensure the 'uri' query paraemter
          // has been cleared.
          unawaited(widget.routerDelegate.clearUriParameter());
          showDisconnectedOverlay();
        }
      }
    });
  }

  @override
  void dispose() {
    hideDisconnectedOverlay();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return widget.child;
  }

  void showDisconnectedOverlay() {
    if (serviceConnection.serviceManager.connectedState.value.connected ||
        currentDisconnectedOverlay != null) {
      return;
    }
    WidgetsBinding.instance.scheduleFrameCallback((_) {
      ga.select(gac.devToolsMain, gac.appDisconnected);
      Overlay.of(context).insert(_createDisconnectedOverlay());
    });
  }

  void hideDisconnectedOverlay() {
    currentDisconnectedOverlay?.remove();
    currentDisconnectedOverlay = null;
  }

  Future<void> _reviewHistory() async {
    assert(offlineDataController.offlineDataJson.isNotEmpty);

    offlineDataController.startShowingOfflineData(
      offlineApp: offlineDataController.previousConnectedApp!,
    );
    hideDisconnectedOverlay();
    final args = <String, String?>{
      DevToolsQueryParams.vmServiceUriKey: null,
      DevToolsQueryParams.offlineScreenIdKey:
          offlineDataController.offlineDataJson[DevToolsExportKeys
                  .activeScreenId
                  .name]
              as String,
    };
    await widget.routerDelegate.popRoute();
    widget.routerDelegate.navigate(snapshotScreenId, args);
  }

  OverlayEntry _createDisconnectedOverlay() {
    final theme = Theme.of(context);
    currentDisconnectedOverlay = OverlayEntry(
      builder: (context) => Material(
        child: Container(
          color: theme.colorScheme.surface,
          child: Center(
            child: Column(
              children: [
                const Spacer(),
                Text('Disconnected', style: theme.textTheme.headlineMedium),
                const SizedBox(height: defaultSpacing),
                if (!isEmbedded())
                  ConnectToNewAppButton(
                    routerDelegate: widget.routerDelegate,
                    onPressed: hideDisconnectedOverlay,
                    gaScreen: gac.devToolsMain,
                  )
                else
                  const Text('Run a new debug session to reconnect.'),
                const Spacer(),
                if (offlineDataController.offlineDataJson.isNotEmpty) ...[
                  ElevatedButton(
                    onPressed: _reviewHistory,
                    child: const Text('Review recent data (offline)'),
                  ),
                  const Spacer(),
                ],
              ],
            ),
          ),
        ),
      ),
    );
    return currentDisconnectedOverlay!;
  }
}