import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import '../../../core/notifications/notif_permission.dart';
import '../../../core/theme/halo_tokens.dart';
import '../../../core/theme/widgets/widgets.dart';

/// Phase 4 Stage 4 — post-payment notif gate.
///
/// If the OS notif permission is already granted on entry, the screen
/// auto-advances to the searching shell. Otherwise it offers two CTAs:
/// "izinkan notifikasi" (request) and "nanti aja" (skip). Either resolution
/// path advances to the searching shell — Stage 5 will refine that target if
/// the post-payment pairing entry needs to differ.
// TODO(stage5): if Stage 5 introduces a dedicated post-payment pairing entry,
// retarget the advance from `/chat/searching` to whichever route owns the
// blast trigger after a paid session.
class NotifGateScreen extends ConsumerStatefulWidget {
  const NotifGateScreen({super.key});

  @override
  ConsumerState<NotifGateScreen> createState() => _NotifGateScreenState();
}

class _NotifGateScreenState extends ConsumerState<NotifGateScreen> {
  static const String _advanceRoute = '/chat/searching';

  bool _resolving = false;
  bool _autoAdvanced = false;

  void _advance() {
    if (!mounted) return;
    context.go(_advanceRoute);
  }

  Future<void> _onAllow() async {
    if (_resolving) return;
    setState(() => _resolving = true);
    await ref.read(notifPermissionStatusProvider.notifier).request();
    if (!mounted) return;
    _advance();
  }

  void _onLater() => _advance();

  @override
  Widget build(BuildContext context) {
    final statusAsync = ref.watch(notifPermissionStatusProvider);

    // Already-granted users skip the screen entirely. Schedule the redirect
    // post-frame so we don't `context.go` mid-build.
    if (!_autoAdvanced &&
        statusAsync.valueOrNull == NotifPermStatus.granted) {
      _autoAdvanced = true;
      WidgetsBinding.instance.addPostFrameCallback((_) => _advance());
    }

    return PopScope(
      // The notif gate sits between payment-confirmed and the searching
      // shell. There is nothing meaningful to pop back to (the waiting
      // screen is terminal once paid), so we swallow the back gesture.
      canPop: false,
      child: Scaffold(
        backgroundColor: HaloTokens.bg,
        body: SafeArea(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(
              HaloSpacing.s24,
              HaloSpacing.s32,
              HaloSpacing.s24,
              HaloSpacing.s24,
            ),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                const Spacer(),
                Center(
                  child: Container(
                    width: 96,
                    height: 96,
                    decoration: const BoxDecoration(
                      color: HaloTokens.brandSofter,
                      shape: BoxShape.circle,
                    ),
                    child: const Icon(
                      Icons.notifications_active_outlined,
                      color: HaloTokens.brandDark,
                      size: 44,
                    ),
                  ),
                ),
                const SizedBox(height: HaloSpacing.s24),
                const Text(
                  'biar nggak ketinggalan',
                  textAlign: TextAlign.center,
                  style: TextStyle(
                    fontFamily: HaloTokens.fontDisplay,
                    fontSize: 26,
                    height: 30 / 26,
                    fontWeight: FontWeight.w700,
                    color: HaloTokens.ink,
                  ),
                ),
                const SizedBox(height: HaloSpacing.s12),
                const Text(
                  'kami pingin kabarin kamu pas bestie udah siap dengerin. izinin notifikasi biar nggak ada chat yang kelewat.',
                  textAlign: TextAlign.center,
                  style: TextStyle(
                    fontFamily: HaloTokens.fontBody,
                    fontSize: 14,
                    height: 20 / 14,
                    color: HaloTokens.inkSoft,
                  ),
                ),
                const Spacer(),
                HaloButton(
                  label: 'izinkan notifikasi',
                  fullWidth: true,
                  onPressed: _resolving ? null : _onAllow,
                ),
                const SizedBox(height: HaloSpacing.s12),
                HaloButton(
                  label: 'nanti aja',
                  variant: HaloButtonVariant.ghost,
                  fullWidth: true,
                  onPressed: _resolving ? null : _onLater,
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}