import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../../core/auth/auth_notifier.dart';
import '../../core/chat/active_session_notifier.dart';
import '../../core/pairing/pairing_notifier.dart';
import '../chat/widgets/pricing_bottom_sheet.dart';
import '../chat/widgets/topic_selection_bottom_sheet.dart';

class HomeScreen extends ConsumerStatefulWidget {
  const HomeScreen({super.key});

  @override
  ConsumerState<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.resumed) {
      // Re-fetch in case a session ended/started while backgrounded.
      ref.read(activeSessionProvider.notifier).refresh();
    }
  }

  Future<void> _onStartChatPressed(BuildContext context) async {
    final topic = await TopicSelectionBottomSheet.show(context);
    if (topic == null || !context.mounted) return;
    await PricingBottomSheet.show(context, topicSensitivity: topic);
  }

  @override
  Widget build(BuildContext context) {
    final authState = ref.watch(authProvider);
    final authData = authState.valueOrNull;
    final activeSessionAsync = ref.watch(activeSessionProvider);

    final displayName = switch (authData) {
      AuthAuthenticatedData d => d.profile['display_name'] as String? ?? '',
      AuthAnonymousData d => d.displayName,
      _ => '',
    };

    ref.listen(pairingProvider, (prev, next) {
      if (next is PairingSearchingData) {
        context.go('/chat/searching');
      } else if (next is PairingNoBestieData) {
        context.go('/chat/no-bestie');
      } else if (next is PairingErrorData) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(next.message)),
        );
      }
    });

    return Scaffold(
        appBar: AppBar(
          title: const Text('Halo Bestie'),
          actions: [
            IconButton(
              icon: const Icon(Icons.history),
              onPressed: () => context.push('/chat/history'),
            ),
            IconButton(
              icon: const Icon(Icons.logout),
              onPressed: () => ref.read(authProvider.notifier).logout(),
            ),
          ],
        ),
        body: Center(
          child: Padding(
            padding: const EdgeInsets.all(32),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Text('Halo, $displayName!', style: const TextStyle(fontSize: 24)),
                const SizedBox(height: 32),
                activeSessionAsync.when(
                  loading: () => const CircularProgressIndicator(),
                  error: (_, __) => _StartChatButton(onPressed: () => _onStartChatPressed(context)),
                  data: (snapshot) {
                    // Hide the "Sesi Aktif" CTA when the session is in `closing`
                    // — the conversation is over, only the goodbye composer
                    // remains. Backend auto-completes such sessions after a
                    // grace period; until then the user shouldn't be invited
                    // back into them from home.
                    final status = snapshot.session?['status'] as String?;
                    final isCurhatable = snapshot.hasSession && status != 'closing';
                    if (isCurhatable) {
                      return _ActiveSessionCard(
                        mitraName: snapshot.mitraName,
                        unreadCount: snapshot.unreadCount,
                        onTap: () {
                          final sessionId = snapshot.sessionId;
                          if (sessionId == null) return;
                          context.push('/chat/session/$sessionId', extra: snapshot.mitraName);
                        },
                      );
                    }
                    return _StartChatButton(onPressed: () => _onStartChatPressed(context));
                  },
                ),
              ],
            ),
          ),
        ),
    );
  }
}

class _StartChatButton extends StatelessWidget {
  final VoidCallback onPressed;
  const _StartChatButton({required this.onPressed});

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const SizedBox(height: 16),
        ElevatedButton(
          style: ElevatedButton.styleFrom(
            padding: const EdgeInsets.symmetric(horizontal: 48, vertical: 16),
          ),
          onPressed: onPressed,
          child: const Text('Mulai Curhat', style: TextStyle(fontSize: 18)),
        ),
      ],
    );
  }
}

class _ActiveSessionCard extends StatelessWidget {
  final String mitraName;
  final int unreadCount;
  final VoidCallback onTap;

  const _ActiveSessionCard({
    required this.mitraName,
    required this.unreadCount,
    required this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    return Card(
      elevation: 2,
      child: InkWell(
        onTap: onTap,
        borderRadius: BorderRadius.circular(12),
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Row(
            children: [
              Badge(
                isLabelVisible: unreadCount > 0,
                label: Text('$unreadCount'),
                child: const CircleAvatar(
                  backgroundColor: Colors.green,
                  child: Icon(Icons.chat, color: Colors.white),
                ),
              ),
              const SizedBox(width: 16),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text(
                      'Sesi Aktif',
                      style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold),
                    ),
                    const SizedBox(height: 4),
                    Text(
                      'Sedang curhat dengan $mitraName',
                      style: const TextStyle(fontSize: 14, color: Colors.grey),
                    ),
                  ],
                ),
              ),
              const Icon(Icons.chevron_right),
            ],
          ),
        ),
      ),
    );
  }
}