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/availability/mitra_availability_notifier.dart';
import '../../core/chat/active_session_notifier.dart';
import '../../core/notifications/notif_permission.dart';
import '../../core/theme/halo_tokens.dart';
import 'providers/bestie_history_provider.dart';
import 'widgets/bestie_choice_sheet.dart';
import 'widgets/halo_tab_bar.dart';

/// Session-only dismiss flag for the "notif denied" banner. Resets on cold
/// restart by design — `StateProvider` lives in memory only.
final homeNotifBannerDismissedProvider = StateProvider<bool>((_) => false);

/// Home screen — Phase 4 redesign.
///
/// Renders one of two variants depending on auth state, mirroring the Figma
/// `SHome1st` / `SHomeReturning` components named in
/// `requirement/flow_customer.mermaid.md` §1:
///   - `AuthInitialData` (no JWT) → SHome1st: top login-recover banner +
///     `aku mau curhat` CTA + empty curhatan card.
///   - `AuthAnonymousData` / `AuthAuthenticatedData` → SHomeReturning:
///     `halo, {name}` greeting + `curhat sama bestie baru` CTA + history list.
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);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      ref.read(mitraAvailabilityProvider.notifier).setActive(true);
      // Re-fetch history every time we re-enter /home. Covers post-chat
      // return via thank_you_screen's `context.go('/home')`, where the
      // home widget is freshly constructed and we want the just-completed
      // session reflected without requiring pull-to-refresh.
      ref.invalidate(bestieHistoryProvider);
    });
  }

  @override
  void deactivate() {
    // setActive(false) lives here, NOT in dispose(): modern Riverpod
    // invalidates `ref` as soon as the State enters dispose(), so calling
    // `ref.read` from there throws `Bad state: Cannot use "ref" after the
    // widget was disposed.` That exception fires inside `finalizeTree` and
    // leaves the widget tree in a half-finalized state — observed symptom
    // is a frozen screen on the next push (e.g. Home → Chat).
    ref.read(mitraAvailabilityProvider.notifier).setActive(false);
    super.deactivate();
  }

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

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final notifier = ref.read(mitraAvailabilityProvider.notifier);
    if (state == AppLifecycleState.resumed) {
      ref.read(activeSessionProvider.notifier).refresh();
      ref.invalidate(bestieHistoryProvider);
      notifier.setActive(true);
    } else if (state == AppLifecycleState.paused || state == AppLifecycleState.inactive) {
      notifier.setActive(false);
    }
  }

  /// CTA path for SHomeReturning. Returning users get the bestie-choice sheet
  /// when they have prior history, otherwise jump to the new-payment shell.
  Future<void> _onCurhatBestieBaruPressed(BuildContext context) async {
    bool hasHistory;
    try {
      hasHistory = await ref.read(bestieHistoryHasItemsProvider.future);
    } catch (_) {
      hasHistory = false;
    }
    if (!context.mounted) return;
    if (hasHistory) {
      await BestieChoiceSheet.show(context);
      return;
    }
    context.push('/payment/entry');
  }

  /// CTA path for SHome1st. Per mermaid §2, fresh users hit S2 Nama first
  /// (the call-sign check); display_name_screen kicks off `loginAnonymous`
  /// and pushes into the verif-choice sheet.
  void _onAkuMauCurhatPressed(BuildContext context) {
    context.push('/auth/display-name');
  }

  @override
  Widget build(BuildContext context) {
    final authState = ref.watch(authProvider);
    final authData = authState.valueOrNull;
    // SHomeReturning needs a real session; everything else (AuthInitialData,
    // AsyncError, transient OTP states) renders SHome1st with the login
    // banner so an unauthenticated user is never shown the returning view.
    final isReturning =
        authData is AuthAuthenticatedData || authData is AuthAnonymousData;
    final isFresh = !isReturning;

    return Scaffold(
      backgroundColor: HaloTokens.bg,
      body: SafeArea(
        bottom: false,
        child: Column(
          children: [
            const _NotifDeniedBanner(),
            Expanded(
              child: RefreshIndicator(
                onRefresh: () async {
                  await Future.wait([
                    ref.read(activeSessionProvider.notifier).refresh(),
                    ref.read(mitraAvailabilityProvider.notifier).refresh(),
                    ref.refresh(bestieHistoryProvider.future),
                  ]);
                },
                child: isFresh
                    ? _SHome1stView(onCTA: () => _onAkuMauCurhatPressed(context))
                    : _SHomeReturningView(
                        onCTA: () => _onCurhatBestieBaruPressed(context),
                      ),
              ),
            ),
            const HaloTabBar(active: 'home'),
          ],
        ),
      ),
    );
  }
}

// ─── SHome1st ──────────────────────────────────────────────────────────────

class _SHome1stView extends ConsumerWidget {
  final VoidCallback onCTA;
  const _SHome1stView({required this.onCTA});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final availabilityAsync = ref.watch(mitraAvailabilityProvider);
    final mitraAvailable = availabilityAsync.valueOrNull ?? false;

    return ListView(
      physics: const AlwaysScrollableScrollPhysics(),
      padding: EdgeInsets.zero,
      children: [
        const _LoginRecoverBanner(),
        Padding(
          padding: const EdgeInsets.fromLTRB(28, 24, 28, 16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const _GreetingHaloOnly(),
              const SizedBox(height: 4),
              const _GreetingSubtitle(),
              const SizedBox(height: 32),
              _PrimaryCTA(
                label: 'aku mau curhat',
                enabled: mitraAvailable,
                onPressed: onCTA,
              ),
              if (!mitraAvailable) ...[
                const SizedBox(height: 12),
                const Text(
                  'belum ada bestie tersedia',
                  style: TextStyle(
                    fontFamily: HaloTokens.fontBody,
                    fontSize: 13,
                    color: HaloTokens.inkMuted,
                  ),
                ),
              ],
              const SizedBox(height: 28),
              const _SectionLabel('curhatan sebelumnya'),
              const SizedBox(height: 10),
              const _HistoryEmptyCard(),
            ],
          ),
        ),
      ],
    );
  }
}

class _LoginRecoverBanner extends StatelessWidget {
  const _LoginRecoverBanner();

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 12, 16, 0),
      child: Material(
        color: HaloTokens.brandSofter,
        borderRadius: HaloRadius.md,
        child: InkWell(
          borderRadius: HaloRadius.md,
          onTap: () => context.push('/auth/register'),
          child: Container(
            padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
            decoration: BoxDecoration(
              borderRadius: HaloRadius.md,
              border: Border.all(color: HaloTokens.brand.withValues(alpha: 0.2)),
            ),
            child: Row(
              children: [
                Container(
                  width: 32,
                  height: 32,
                  decoration: const BoxDecoration(
                    color: HaloTokens.brand,
                    borderRadius: BorderRadius.all(Radius.circular(10)),
                  ),
                  alignment: Alignment.center,
                  child: const Text('👋', style: TextStyle(fontSize: 15)),
                ),
                const SizedBox(width: 10),
                const Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        'udah pernah pakai HaloBestie?',
                        style: TextStyle(
                          fontFamily: HaloTokens.fontBody,
                          fontSize: 12.5,
                          fontWeight: FontWeight.w700,
                          color: HaloTokens.brandDark,
                          height: 1.3,
                        ),
                      ),
                      SizedBox(height: 1),
                      Text(
                        'login buat lanjutin obrolan & history kamu',
                        style: TextStyle(
                          fontFamily: HaloTokens.fontBody,
                          fontSize: 11,
                          color: HaloTokens.inkSoft,
                          height: 1.3,
                        ),
                      ),
                    ],
                  ),
                ),
                const SizedBox(width: 8),
                Container(
                  padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 6),
                  decoration: BoxDecoration(
                    color: HaloTokens.surface,
                    borderRadius: const BorderRadius.all(Radius.circular(8)),
                    border: Border.all(color: HaloTokens.brand.withValues(alpha: 0.33)),
                  ),
                  child: const Text(
                    'masuk →',
                    style: TextStyle(
                      fontFamily: HaloTokens.fontBody,
                      fontSize: 12.5,
                      fontWeight: FontWeight.w700,
                      color: HaloTokens.brand,
                    ),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

class _GreetingHaloOnly extends StatelessWidget {
  const _GreetingHaloOnly();

  @override
  Widget build(BuildContext context) {
    return const Text(
      'halo,',
      style: TextStyle(
        fontFamily: HaloTokens.fontDisplay,
        fontSize: 32,
        fontWeight: FontWeight.w700,
        color: HaloTokens.brandDark,
        height: 1.15,
        letterSpacing: -0.64,
      ),
    );
  }
}

class _GreetingSubtitle extends StatelessWidget {
  const _GreetingSubtitle();

  @override
  Widget build(BuildContext context) {
    return ConstrainedBox(
      constraints: const BoxConstraints(maxWidth: 290),
      child: const Text(
        'lagi ngerasa gimana hari ini? bestie akan nemenin kamu kok 🤍',
        style: TextStyle(
          fontFamily: HaloTokens.fontBody,
          fontSize: 14.5,
          color: HaloTokens.inkSoft,
          height: 1.55,
        ),
      ),
    );
  }
}

class _HistoryEmptyCard extends StatelessWidget {
  const _HistoryEmptyCard();

  @override
  Widget build(BuildContext context) {
    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 32),
      decoration: BoxDecoration(
        color: HaloTokens.surface,
        borderRadius: HaloRadius.lg,
        border: Border.all(
          color: HaloTokens.border,
          width: 1,
          style: BorderStyle.solid, // Flutter has no built-in dashed border;
          // a CustomPainter could draw dashes — visual parity is close enough
          // for v1 (border color + radius match Figma exactly).
        ),
      ),
      alignment: Alignment.center,
      child: const Text(
        'belum ada curhatan. mulai aja, bestie udah siap 🌷',
        textAlign: TextAlign.center,
        style: TextStyle(
          fontFamily: HaloTokens.fontBody,
          fontSize: 13,
          color: HaloTokens.inkMuted,
        ),
      ),
    );
  }
}

// ─── SHomeReturning ────────────────────────────────────────────────────────

class _SHomeReturningView extends ConsumerWidget {
  final VoidCallback onCTA;
  const _SHomeReturningView({required this.onCTA});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final authData = ref.watch(authProvider).valueOrNull;
    final activeSessionAsync = ref.watch(activeSessionProvider);
    final availabilityAsync = ref.watch(mitraAvailabilityProvider);
    final historyAsync = ref.watch(bestieHistoryProvider);
    final mitraAvailable = availabilityAsync.valueOrNull ?? false;

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

    return ListView(
      physics: const AlwaysScrollableScrollPhysics(),
      padding: const EdgeInsets.fromLTRB(24, 32, 24, 16),
      children: [
        _GreetingHaloName(name: displayName),
        const SizedBox(height: 4),
        const _GreetingSubtitle(),
        const SizedBox(height: 24),
        activeSessionAsync.when(
          loading: () => const Center(child: CircularProgressIndicator()),
          error: (_, __) => _PrimaryCTA(
            label: 'curhat sama bestie baru',
            enabled: mitraAvailable,
            onPressed: onCTA,
          ),
          data: (snapshot) {
            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 _PrimaryCTA(
              label: 'curhat sama bestie baru',
              enabled: mitraAvailable,
              onPressed: onCTA,
            );
          },
        ),
        if (!mitraAvailable) ...[
          const SizedBox(height: 12),
          const Text(
            'belum ada bestie tersedia',
            style: TextStyle(
              fontFamily: HaloTokens.fontBody,
              fontSize: 13,
              color: HaloTokens.inkMuted,
            ),
          ),
        ],
        const SizedBox(height: 28),
        const _SectionLabel('curhatan sebelumnya'),
        const SizedBox(height: 10),
        historyAsync.when(
          loading: () => const Padding(
            padding: EdgeInsets.symmetric(vertical: 24),
            child: Center(child: CircularProgressIndicator()),
          ),
          error: (_, __) => const _HistoryEmptyCard(),
          data: (items) {
            if (items.isEmpty) return const _HistoryEmptyCard();
            return Column(
              children: [
                for (var i = 0; i < items.length; i++) ...[
                  _HistoryItemTile(item: items[i], seed: i + 1),
                  if (i < items.length - 1) const SizedBox(height: 10),
                ],
              ],
            );
          },
        ),
      ],
    );
  }
}

class _GreetingHaloName extends StatelessWidget {
  final String name;
  const _GreetingHaloName({required this.name});

  @override
  Widget build(BuildContext context) {
    final shown = name.trim().isEmpty ? 'kamu' : name;
    return Text.rich(
      TextSpan(
        style: const TextStyle(
          fontFamily: HaloTokens.fontDisplay,
          fontSize: 32,
          fontWeight: FontWeight.w700,
          height: 1.15,
          letterSpacing: -0.64,
        ),
        children: [
          const TextSpan(
            text: 'halo, ',
            style: TextStyle(color: HaloTokens.brandDark),
          ),
          TextSpan(
            text: shown,
            style: const TextStyle(color: HaloTokens.brand),
          ),
        ],
      ),
    );
  }
}

class _HistoryItemTile extends StatelessWidget {
  final BestieHistoryItem item;
  final int seed;
  const _HistoryItemTile({required this.item, required this.seed});

  @override
  Widget build(BuildContext context) {
    final relative = _relativeWhen(item.endedAt);
    final topicLine = item.topics.isEmpty ? '' : '"${item.topics.first}"';
    return Material(
      color: HaloTokens.surface,
      borderRadius: HaloRadius.lg,
      child: InkWell(
        borderRadius: HaloRadius.lg,
        onTap: () => context.push('/chat/transcript/${item.sessionId}'),
        child: Container(
          padding: const EdgeInsets.all(14),
          decoration: BoxDecoration(
            borderRadius: HaloRadius.lg,
            border: Border.all(color: HaloTokens.border),
          ),
          child: Row(
            children: [
              _OrbPlaceholder(seed: seed),
              const SizedBox(width: 12),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Row(
                      children: [
                        Expanded(
                          child: Text(
                            item.mitraName,
                            maxLines: 1,
                            overflow: TextOverflow.ellipsis,
                            style: const TextStyle(
                              fontFamily: HaloTokens.fontBody,
                              fontSize: 14,
                              fontWeight: FontWeight.w600,
                              color: HaloTokens.ink,
                            ),
                          ),
                        ),
                        const SizedBox(width: 6),
                        Text(
                          relative,
                          style: const TextStyle(
                            fontFamily: HaloTokens.fontBody,
                            fontSize: 10.5,
                            color: HaloTokens.inkMuted,
                          ),
                        ),
                      ],
                    ),
                    if (topicLine.isNotEmpty) ...[
                      const SizedBox(height: 2),
                      Text(
                        topicLine,
                        maxLines: 1,
                        overflow: TextOverflow.ellipsis,
                        style: const TextStyle(
                          fontFamily: HaloTokens.fontBody,
                          fontSize: 12,
                          color: HaloTokens.inkSoft,
                          height: 1.4,
                        ),
                      ),
                    ],
                    if (item.endedAt != null) ...[
                      const SizedBox(height: 4),
                      const Text(
                        'sesi habis · tap untuk lanjutin curhat',
                        style: TextStyle(
                          fontFamily: HaloTokens.fontBody,
                          fontSize: 10,
                          fontStyle: FontStyle.italic,
                          color: HaloTokens.inkMuted,
                        ),
                      ),
                    ],
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  static String _relativeWhen(DateTime? when) {
    if (when == null) return '';
    final diff = DateTime.now().difference(when);
    if (diff.inDays >= 7) return '${(diff.inDays / 7).floor()} mgg lalu';
    if (diff.inDays >= 1) return '${diff.inDays} hari lalu';
    if (diff.inHours >= 1) return '${diff.inHours} jam lalu';
    if (diff.inMinutes >= 1) return '${diff.inMinutes} mnt lalu';
    return 'baru saja';
  }
}

/// Placeholder for the Figma `HBOrb` gradient component. v1 ships as a
/// solid-color disc keyed off `seed`; a real animated orb is a follow-up.
class _OrbPlaceholder extends StatelessWidget {
  final int seed;
  const _OrbPlaceholder({required this.seed});

  @override
  Widget build(BuildContext context) {
    const palette = [
      HaloTokens.brand,
      HaloTokens.lilac,
      HaloTokens.mint,
      HaloTokens.accent,
    ];
    final color = palette[seed % palette.length];
    return Container(
      width: 42,
      height: 42,
      decoration: BoxDecoration(
        gradient: RadialGradient(
          colors: [color.withValues(alpha: 0.95), color.withValues(alpha: 0.55)],
        ),
        shape: BoxShape.circle,
      ),
    );
  }
}

// ─── Shared ────────────────────────────────────────────────────────────────

class _SectionLabel extends StatelessWidget {
  final String text;
  const _SectionLabel(this.text);

  @override
  Widget build(BuildContext context) {
    return Text(
      text,
      style: const TextStyle(
        fontFamily: HaloTokens.fontBody,
        fontSize: 11.5,
        fontWeight: FontWeight.w600,
        color: HaloTokens.inkMuted,
        letterSpacing: 0.69,
      ),
    );
  }
}

class _PrimaryCTA extends StatelessWidget {
  final String label;
  final bool enabled;
  final VoidCallback onPressed;
  const _PrimaryCTA({
    required this.label,
    required this.enabled,
    required this.onPressed,
  });

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      child: DecoratedBox(
        decoration: BoxDecoration(
          borderRadius: HaloRadius.xl,
          boxShadow: enabled ? HaloShadows.button : const [],
        ),
        child: Material(
          color: enabled ? HaloTokens.brand : HaloTokens.brandSofter,
          borderRadius: HaloRadius.xl,
          child: InkWell(
            borderRadius: HaloRadius.xl,
            onTap: enabled ? onPressed : null,
            child: Padding(
              padding: const EdgeInsets.symmetric(vertical: 16, horizontal: 18),
              child: Center(
                child: Text(
                  label,
                  style: TextStyle(
                    fontFamily: HaloTokens.fontBody,
                    fontSize: 15,
                    fontWeight: FontWeight.w600,
                    color: enabled ? Colors.white : HaloTokens.inkMuted,
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

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 Material(
      color: HaloTokens.surface,
      borderRadius: HaloRadius.lg,
      elevation: 2,
      shadowColor: HaloTokens.brand.withValues(alpha: 0.2),
      child: InkWell(
        onTap: onTap,
        borderRadius: HaloRadius.lg,
        child: Padding(
          padding: const EdgeInsets.all(20),
          child: Row(
            children: [
              Badge(
                isLabelVisible: unreadCount > 0,
                label: Text('$unreadCount'),
                child: const CircleAvatar(
                  backgroundColor: HaloTokens.success,
                  child: Icon(Icons.chat, color: Colors.white),
                ),
              ),
              const SizedBox(width: 16),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text(
                      'sesi aktif',
                      style: TextStyle(
                        fontFamily: HaloTokens.fontBody,
                        fontSize: 16,
                        fontWeight: FontWeight.w700,
                        color: HaloTokens.ink,
                      ),
                    ),
                    const SizedBox(height: 4),
                    Text(
                      'sedang curhat dengan $mitraName',
                      style: const TextStyle(
                        fontFamily: HaloTokens.fontBody,
                        fontSize: 14,
                        color: HaloTokens.inkSoft,
                      ),
                    ),
                  ],
                ),
              ),
              const Icon(Icons.chevron_right, color: HaloTokens.inkMuted),
            ],
          ),
        ),
      ),
    );
  }
}

/// Above-the-fold amber banner shown when notif permission is denied. Tap
/// "nyalain" → opens app settings; tap close → hides for the in-memory
/// session (cold restart re-shows it).
class _NotifDeniedBanner extends ConsumerWidget {
  const _NotifDeniedBanner();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final statusAsync = ref.watch(notifPermissionStatusProvider);
    final dismissed = ref.watch(homeNotifBannerDismissedProvider);
    final isDenied = statusAsync.valueOrNull == NotifPermStatus.denied;
    if (!isDenied || dismissed) {
      return const SizedBox.shrink();
    }
    return Container(
      width: double.infinity,
      color: HaloTokens.accentSoft,
      padding: const EdgeInsets.symmetric(
        horizontal: HaloSpacing.s16,
        vertical: HaloSpacing.s8,
      ),
      child: Row(
        children: [
          const Icon(
            Icons.notifications_off_outlined,
            size: 18,
            color: HaloTokens.brandDark,
          ),
          const SizedBox(width: HaloSpacing.s8),
          const Expanded(
            child: Text(
              'notifikasi off — kamu bisa kelewat chat dari bestie',
              style: TextStyle(
                fontFamily: HaloTokens.fontBody,
                fontSize: 12.5,
                color: HaloTokens.ink,
              ),
            ),
          ),
          TextButton(
            style: TextButton.styleFrom(
              foregroundColor: HaloTokens.brandDark,
              padding: const EdgeInsets.symmetric(
                horizontal: HaloSpacing.s8,
              ),
              minimumSize: const Size(0, 32),
              tapTargetSize: MaterialTapTargetSize.shrinkWrap,
              textStyle: const TextStyle(
                fontFamily: HaloTokens.fontBody,
                fontSize: 13,
                fontWeight: FontWeight.w600,
              ),
            ),
            onPressed: () =>
                ref.read(notifPermissionStatusProvider.notifier).openAppSettings(),
            child: const Text('nyalain'),
          ),
          IconButton(
            iconSize: 18,
            visualDensity: VisualDensity.compact,
            padding: EdgeInsets.zero,
            constraints: const BoxConstraints(),
            color: HaloTokens.inkSoft,
            icon: const Icon(Icons.close),
            onPressed: () =>
                ref.read(homeNotifBannerDismissedProvider.notifier).state = true,
          ),
        ],
      ),
    );
  }
}