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

import '../application/events_notifier.dart';
import '../domain/event.dart';
import '../infrastructure/events_repository.dart';
import 'widgets/countdown_timer.dart';
import 'widgets/registration_button.dart';

class EventDetailScreen extends ConsumerWidget {
  const EventDetailScreen({super.key, required this.eventId});

  final String eventId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final eventsAsync = ref.watch(eventsStreamProvider);

    return Scaffold(
      appBar: AppBar(
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () {
            if (context.canPop()) {
              context.pop();
            } else {
              context.go('/events');
            }
          },
        ),
        title: const Text('Event details'),
      ),
      body: eventsAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (error, _) => _NotFound(
          message: 'Could not load event: $error',
        ),
        data: (_) {
          final event = ref.watch(eventByIdProvider(eventId));
          if (event == null) {
            return const _NotFound(message: 'Event not found.');
          }
          return _EventDetailBody(event: event);
        },
      ),
    );
  }
}

class _EventDetailBody extends StatelessWidget {
  const _EventDetailBody({required this.event});

  final Event event;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final scheme = theme.colorScheme;

    final dateLabel =
        DateFormat('EEEE, MMMM d, y  ·  h:mm a').format(event.date);
    final deadlineLabel =
        DateFormat('EEE, MMM d  ·  h:mm a').format(event.registrationDeadline);

    return LayoutBuilder(
      builder: (context, constraints) {
        final isWide = constraints.maxWidth > 720;
        final horizontalPadding = isWide ? 32.0 : 16.0;

        return SingleChildScrollView(
          padding: EdgeInsets.symmetric(
            horizontal: horizontalPadding,
            vertical: 16,
          ),
          child: Center(
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 760),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  _Header(
                    event: event,
                    dateLabel: dateLabel,
                  ),
                  const SizedBox(height: 20),
                  Align(
                    alignment: Alignment.centerLeft,
                    child: CountdownTimer(
                      target: event.date,
                      compact: false,
                    ),
                  ),
                  const SizedBox(height: 24),
                  Text(
                    'About this event',
                    style: theme.textTheme.titleMedium?.copyWith(
                      fontWeight: FontWeight.w700,
                    ),
                  ),
                  const SizedBox(height: 8),
                  Text(
                    event.description,
                    style: theme.textTheme.bodyLarge?.copyWith(
                      height: 1.45,
                      color: scheme.onSurface,
                    ),
                  ),
                  const SizedBox(height: 24),
                  _RegistrationSection(
                    event: event,
                    deadlineLabel: deadlineLabel,
                  ),
                  const SizedBox(height: 32),
                ],
              ),
            ),
          ),
        );
      },
    );
  }
}

class _Header extends StatelessWidget {
  const _Header({required this.event, required this.dateLabel});

  final Event event;
  final String dateLabel;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final scheme = theme.colorScheme;

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: scheme.primaryContainer,
        borderRadius: BorderRadius.circular(20),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          if (event.isCancelled)
            Padding(
              padding: const EdgeInsets.only(bottom: 8),
              child: Container(
                padding: const EdgeInsets.symmetric(
                  horizontal: 10,
                  vertical: 4,
                ),
                decoration: BoxDecoration(
                  color: scheme.error,
                  borderRadius: BorderRadius.circular(999),
                ),
                child: Text(
                  'Cancelled',
                  style: theme.textTheme.labelMedium?.copyWith(
                    color: scheme.onError,
                    fontWeight: FontWeight.w700,
                  ),
                ),
              ),
            ),
          Text(
            event.title,
            style: theme.textTheme.headlineSmall?.copyWith(
              color: scheme.onPrimaryContainer,
              fontWeight: FontWeight.w800,
            ),
          ),
          const SizedBox(height: 12),
          Row(
            children: [
              Icon(
                Icons.calendar_today_outlined,
                size: 18,
                color: scheme.onPrimaryContainer,
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Text(
                  dateLabel,
                  style: theme.textTheme.bodyLarge?.copyWith(
                    color: scheme.onPrimaryContainer,
                  ),
                ),
              ),
            ],
          ),
          const SizedBox(height: 6),
          Row(
            children: [
              Icon(
                Icons.place_outlined,
                size: 18,
                color: scheme.onPrimaryContainer,
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Text(
                  event.location,
                  style: theme.textTheme.bodyLarge?.copyWith(
                    color: scheme.onPrimaryContainer,
                  ),
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }
}

class _RegistrationSection extends StatelessWidget {
  const _RegistrationSection({
    required this.event,
    required this.deadlineLabel,
  });

  final Event event;
  final String deadlineLabel;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final scheme = theme.colorScheme;
    final ratio = event.maxTeams == 0
        ? 0.0
        : (event.teamsRegistered / event.maxTeams).clamp(0.0, 1.0).toDouble();
    final deadlinePassed =
        DateTime.now().isAfter(event.registrationDeadline);

    return Container(
      padding: const EdgeInsets.all(20),
      decoration: BoxDecoration(
        color: scheme.surfaceContainerHighest,
        borderRadius: BorderRadius.circular(20),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Registration',
            style: theme.textTheme.titleMedium?.copyWith(
              fontWeight: FontWeight.w700,
            ),
          ),
          const SizedBox(height: 12),
          Row(
            children: [
              Icon(Icons.groups_outlined, color: scheme.primary),
              const SizedBox(width: 8),
              Text(
                '${event.teamsRegistered} / ${event.maxTeams} teams',
                style: theme.textTheme.titleLarge?.copyWith(
                  color: scheme.primary,
                  fontWeight: FontWeight.w800,
                ),
              ),
            ],
          ),
          const SizedBox(height: 12),
          ClipRRect(
            borderRadius: BorderRadius.circular(999),
            child: LinearProgressIndicator(
              value: ratio,
              minHeight: 8,
              backgroundColor: scheme.surfaceContainer,
              valueColor: AlwaysStoppedAnimation<Color>(scheme.primary),
            ),
          ),
          const SizedBox(height: 12),
          Row(
            children: [
              Icon(
                Icons.timer_off_outlined,
                size: 16,
                color: scheme.onSurfaceVariant,
              ),
              const SizedBox(width: 6),
              Expanded(
                child: Text(
                  deadlinePassed
                      ? 'Registration closed $deadlineLabel'
                      : 'Registration closes $deadlineLabel',
                  style: theme.textTheme.bodySmall?.copyWith(
                    color: scheme.onSurfaceVariant,
                  ),
                ),
              ),
            ],
          ),
          const SizedBox(height: 16),
          RegistrationButton(
            fullWidth: true,
            enabled: !deadlinePassed && !event.isCancelled,
          ),
          if (event.maxTeams > 0 &&
              event.teamsRegistered >= event.maxTeams) ...[
            const SizedBox(height: 8),
            Text(
              'Preferred headcount reached — extras are still welcome to drop in.',
              style: theme.textTheme.bodySmall?.copyWith(
                color: scheme.onSurfaceVariant,
              ),
            ),
          ],
        ],
      ),
    );
  }
}

class _NotFound extends StatelessWidget {
  const _NotFound({required this.message});

  final String message;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.search_off,
              size: 64,
              color: theme.colorScheme.onSurfaceVariant,
            ),
            const SizedBox(height: 16),
            Text(message, style: theme.textTheme.titleMedium),
            const SizedBox(height: 16),
            FilledButton.tonalIcon(
              onPressed: () => context.go('/events'),
              icon: const Icon(Icons.arrow_back),
              label: const Text('Back to events'),
            ),
          ],
        ),
      ),
    );
  }
}