import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:matrix/encryption.dart';
import 'package:matrix/matrix.dart';

import 'matrix/calls.dart';
import 'matrix/notifications.dart';
import 'screens/call_screen.dart';
import 'screens/home_screen.dart';
import 'screens/login_screen.dart';
import 'screens/room_screen.dart';
import 'state.dart';
import 'theme.dart';
import 'widgets/uia.dart';
import 'widgets/verification_sheet.dart';

final navigatorKey = GlobalKey<NavigatorState>();
final messengerKey = GlobalKey<ScaffoldMessengerState>();

class WarpApp extends ConsumerWidget {
  const WarpApp({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final loginState = ref.watch(loginStateProvider);
    final signedIn = loginState.value == LoginState.loggedIn;
    // Signing in from the sign-up screen, or out from settings, leaves those
    // screens on top of the new home: close them.
    ref.listen(loginStateProvider, (prev, next) {
      if (prev?.value != next.value) {
        navigatorKey.currentState?.popUntil((route) => route.isFirst);
      }
    });
    return MaterialApp(
      title: 'Warp',
      navigatorKey: navigatorKey,
      scaffoldMessengerKey: messengerKey,
      debugShowCheckedModeBanner: false,
      theme: warpTheme(Brightness.light),
      darkTheme: warpTheme(Brightness.dark),
      themeMode: ref.watch(themeModeProvider),
      home: loginState.isLoading
          ? const Scaffold()
          : signedIn
          ? const _SignedIn(key: ValueKey('signed-in'))
          : const LoginScreen(key: ValueKey('signed-out')),
    );
  }
}

/// Everything that runs only while signed in: the notification listener,
/// prompts the SDK raises (a password for an account change, an incoming
/// verification request) and opening rooms from notifications.
class _SignedIn extends ConsumerStatefulWidget {
  const _SignedIn({super.key});

  @override
  ConsumerState<_SignedIn> createState() => _SignedInState();
}

class _SignedInState extends ConsumerState<_SignedIn>
    with WidgetsBindingObserver {
  final _subs = <StreamSubscription>[];

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    final client = ref.read(clientProvider);
    _subs
      ..add(Notifications.watch(client))
      ..add(Notifications.opened.listen(_openRoom))
      ..add(client.onUiaRequest.stream.listen(_onUia))
      ..add(client.onKeyVerificationRequest.stream.listen(_onVerification));
    final calls = ref.read(callsProvider);
    calls.addListener(_onCalls);
    _subs.add(calls.openRequests.listen((_) => _openCall()));
    _subs.add(
      calls.errors.stream.listen(
        (message) => messengerKey.currentState?.showSnackBar(
          SnackBar(content: Text(message)),
        ),
      ),
    );
    Notifications.launchRoomId().then((roomId) {
      if (roomId != null) _openRoom(roomId);
    });
    Notifications.requestPermission();
  }

  IncomingCall? _shownCall;

  /// Shows the incoming call card when a call starts ringing.
  void _onCalls() {
    final calls = ref.read(callsProvider);
    final call = calls.incoming;
    if (call == null || call == _shownCall) return;
    _shownCall = call;
    final context = navigatorKey.currentContext;
    final navigator = navigatorKey.currentState;
    if (context == null || navigator == null) return;
    if (!Notifications.foreground) {
      Notifications.show(
        roomId: call.roomId,
        title: call.callerName,
        body: call.video ? 'Video call' : 'Voice call',
      );
    }
    showIncomingCall(context, calls, navigator);
  }

  @override
  void dispose() {
    ref.read(callsProvider).removeListener(_onCalls);
    WidgetsBinding.instance.removeObserver(this);
    for (final sub in _subs) {
      sub.cancel();
    }
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    // The sync loop keeps running in the background for as long as Android
    // lets the process live; pushes cover the time after that.
    Notifications.foreground = state == AppLifecycleState.resumed;
  }

  void _openRoom(String roomId) {
    final nav = navigatorKey.currentState;
    if (nav == null) return;
    nav.popUntil((route) => route.isFirst);
    nav.push(RoomScreen.route(roomId));
  }

  /// Shows the call screen, unless it is already on top.
  void _openCall() {
    final nav = navigatorKey.currentState;
    if (nav == null || !ref.read(callsProvider).inCall) return;
    var onTop = false;
    nav.popUntil((route) {
      onTop = route.settings.name == 'call';
      return true;
    });
    if (!onTop) nav.push(CallScreen.route());
  }

  void _onUia(UiaRequest request) {
    final context = navigatorKey.currentContext;
    if (context == null) return request.cancel();
    handleUia(context, ref.read(clientProvider), request);
  }

  void _onVerification(KeyVerification request) {
    final context = navigatorKey.currentContext;
    if (context == null) return;
    showVerificationSheet(context, request);
  }

  @override
  Widget build(BuildContext context) => const HomeScreen();
}