import 'dart:async';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:intl/intl.dart';
import 'package:mileograph_flutter/components/dashboard/latest_loco_changes_panel.dart';
import 'package:mileograph_flutter/components/dashboard/leaderboard_panel.dart';
import 'package:mileograph_flutter/components/dashboard/top_traction_panel.dart';
import 'package:mileograph_flutter/components/widgets/animated_count_text.dart';
import 'package:mileograph_flutter/objects/objects.dart';
import 'package:mileograph_flutter/services/authservice.dart';
import 'package:mileograph_flutter/services/data_service.dart';
import 'package:mileograph_flutter/services/distance_unit_service.dart';
import 'package:provider/provider.dart';

class Dashboard extends StatefulWidget {
  const Dashboard({super.key});

  @override
  State<Dashboard> createState() => _DashboardState();
}

class _DashboardState extends State<Dashboard> {
  bool _showAllOnThisDay = false;
  bool _isCurrent = false;
  Timer? _carouselTimer;
  int _carouselIndex = 0;
  int _carouselItemCount = 0;
  final Random _carouselRandom = Random();
  List<ClassClearanceProgress> _carouselItems = const [];
  String _carouselSignature = '';

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    final data = context.watch<DataService>();
    final auth = context.watch<AuthService>();
    final distanceUnits = context.watch<DistanceUnitService>();
    final stats = data.homepageStats;

    final isInitialLoading = data.isHomepageLoading && stats == null;

    return RefreshIndicator(
      onRefresh: () async {
        await _refreshDashboardData(force: true);
      },
      child: LayoutBuilder(
        builder: (context, constraints) {
          _handleRouteFocus();
          const spacing = 16.0;
          final maxWidth = constraints.maxWidth;
          return Stack(
            children: [
              ListView(
                padding: const EdgeInsets.all(16),
                children: [
                  _buildHero(context, auth, data, stats, distanceUnits),
                  const SizedBox(height: spacing),
                  _buildTiles(
                    context,
                    data,
                    distanceUnits,
                    maxWidth,
                    spacing,
                  ),
                ],
              ),
              if (isInitialLoading)
                Positioned.fill(
                  child: Container(
                    color: Theme.of(
                      context,
                    ).colorScheme.surface.withValues(alpha: 0.7),
                    child: const Center(
                      child: Column(
                        mainAxisSize: MainAxisSize.min,
                        children: [
                          CircularProgressIndicator(),
                          SizedBox(height: 12),
                          Text('Loading dashboard data...'),
                        ],
                      ),
                    ),
                  ),
                ),
            ],
          );
        },
      ),
    );
  }

  Widget _buildHero(
    BuildContext context,
    AuthService auth,
    DataService data,
    HomepageStats? stats,
    DistanceUnitService distanceUnits,
  ) {
    final colorScheme = Theme.of(context).colorScheme;
    final greetingName =
        stats?.user?.fullName ?? auth.fullName ?? auth.username ?? 'there';
    final totalMileage = stats?.totalMileage ?? 0;
    final currentYearMileage = data.getMileageForCurrentYear();
    final legCount = stats?.legCount ?? data.trips.length;

    return Card(
      clipBehavior: Clip.antiAlias,
      elevation: 2,
      child: Container(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            colors: [
              colorScheme.primaryContainer,
              colorScheme.secondaryContainer,
            ],
            begin: Alignment.topLeft,
            end: Alignment.bottomRight,
          ),
        ),
        padding: const EdgeInsets.all(18),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            _heroHeading(context, greetingName, colorScheme),
            const SizedBox(height: 18),
            Wrap(
              spacing: 12,
              runSpacing: 12,
              children: [
                _animatedMetricTile(
                  context,
                  label: 'Total mileage',
                  value: totalMileage.toDouble(),
                  formatter: (val) =>
                      distanceUnits.format(val, decimals: 1),
                  icon: Icons.route,
                  color: colorScheme.onPrimaryContainer,
                ),
                _animatedMetricTile(
                  context,
                  label: 'This year',
                  value: currentYearMileage.toDouble(),
                  formatter: (val) =>
                      distanceUnits.format(val, decimals: 1),
                  icon: Icons.calendar_today,
                  color: colorScheme.onPrimaryContainer,
                ),
                _animatedMetricTile(
                  context,
                  label: 'Entries logged',
                  value: legCount.toDouble(),
                  formatter: (val) => val.round().toString(),
                  icon: Icons.format_list_bulleted,
                  color: colorScheme.onPrimaryContainer,
                ),
              ],
            ),
            const SizedBox(height: 16),
            _buildClassClearanceCarousel(context, data, colorScheme),
          ],
        ),
      ),
    );
  }

  Widget _buildClassClearanceCarousel(
    BuildContext context,
    DataService data,
    ColorScheme colorScheme,
  ) {
    final items = data.classClearanceProgress;
    final loading = data.isClassClearanceProgressLoading;
    _refreshCarouselItems(items);
    _startCarouselIfNeeded(_carouselItems.length);

    if (loading && _carouselItems.isEmpty) {
      return const Padding(
        padding: EdgeInsets.symmetric(vertical: 8.0),
        child: Center(
          child: SizedBox(
            height: 16,
            width: 16,
            child: CircularProgressIndicator(strokeWidth: 2),
          ),
        ),
      );
    }

    if (_carouselItems.isEmpty) {
      return Text(
        'No class clearance progress yet.',
        style: Theme.of(context).textTheme.labelSmall?.copyWith(
              color: colorScheme.onPrimaryContainer.withValues(alpha: 0.8),
            ),
      );
    }

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          'Class clearance (in progress)',
          style: Theme.of(context).textTheme.labelSmall?.copyWith(
                color: colorScheme.onPrimaryContainer.withValues(alpha: 0.8),
              ),
        ),
        const SizedBox(height: 6),
        SizedBox(
          height: 58,
          child: AnimatedSwitcher(
            duration: const Duration(milliseconds: 450),
            switchInCurve: Curves.easeOutCubic,
            switchOutCurve: Curves.easeInCubic,
            transitionBuilder: (child, animation) {
              final tween = Tween<Offset>(
                begin: const Offset(0, 0.4),
                end: Offset.zero,
              );
              return ClipRect(
                child: SlideTransition(
                  position: animation.drive(tween),
                  child: FadeTransition(opacity: animation, child: child),
                ),
              );
            },
            child: _buildClassClearanceSlide(
              context,
              _carouselItems[_carouselIndex % _carouselItems.length],
              colorScheme,
              key: ValueKey(_carouselIndex),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildClassClearanceSlide(
    BuildContext context,
    ClassClearanceProgress progress,
    ColorScheme colorScheme,
    {Key? key}
  ) {
    final pct = progress.percentComplete.clamp(0, 100);
    final textTheme = Theme.of(context).textTheme;
    final ratio = progress.total == 0
        ? 0.0
        : (progress.completed / progress.total).clamp(0.0, 1.0);
    final activeRatio = progress.total == 0
        ? 0.0
        : (progress.activeTotal / progress.total).clamp(0.0, 1.0);
    return TweenAnimationBuilder<double>(
      key: key ?? ValueKey(progress.className),
      tween: Tween(begin: 0, end: ratio),
      duration: const Duration(milliseconds: 1200),
      curve: Curves.easeOutCubic,
      builder: (context, value, child) {
        final ratioValue = ratio == 0 ? 0.0 : (value / ratio).clamp(0.0, 1.0);
        final animatedHad = (progress.completed * ratioValue).round();
        final animatedActive = (progress.activeTotal * ratioValue).round();
        final animatedActiveRatio =
            (activeRatio * ratioValue).clamp(0.0, activeRatio);
        return Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Expanded(
                  child: Text(
                    progress.className,
                    style: textTheme.labelLarge?.copyWith(
                      color: colorScheme.onPrimaryContainer,
                      fontWeight: FontWeight.w700,
                    ),
                    overflow: TextOverflow.ellipsis,
                  ),
                ),
                const SizedBox(width: 8),
                Text(
                  '${pct.toStringAsFixed(0)}% • $animatedHad/$animatedActive/${progress.total}',
                  style: textTheme.labelSmall?.copyWith(
                    color: colorScheme.onPrimaryContainer
                        .withValues(alpha: 0.8),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 6),
            ClipRRect(
              borderRadius: BorderRadius.circular(10),
              child: SizedBox(
                height: 8,
                child: Stack(
                  children: [
                    Container(
                      color: colorScheme.onPrimaryContainer.withValues(
                        alpha: 0.2,
                      ),
                    ),
                    FractionallySizedBox(
                      alignment: Alignment.centerLeft,
                      widthFactor: animatedActiveRatio.isNaN
                          ? 0
                          : animatedActiveRatio,
                      child: Container(
                        color:
                            colorScheme.onPrimaryContainer.withValues(alpha: 0.5),
                      ),
                    ),
                    FractionallySizedBox(
                      alignment: Alignment.centerLeft,
                      widthFactor: value.isNaN ? 0 : value,
                      child: Container(
                        color: colorScheme.onPrimaryContainer,
                      ),
                    ),
                  ],
                ),
              ),
            ),
          ],
        );
      },
    );
  }

  void _startCarouselIfNeeded(int count) {
    if (count <= 1) {
      _stopCarousel();
      return;
    }
    if (_carouselItemCount != count) {
      _carouselItemCount = count;
      _carouselIndex = 0;
    }
    if (_carouselTimer != null) return;
    _carouselTimer = Timer.periodic(const Duration(seconds: 8), (_) {
      if (!mounted || _carouselItemCount == 0) return;
      setState(() {
        _carouselIndex = (_carouselIndex + 1) % _carouselItemCount;
      });
    });
  }

  void _stopCarousel() {
    _carouselTimer?.cancel();
    _carouselTimer = null;
  }

  void _refreshCarouselItems(List<ClassClearanceProgress> items) {
    final signature = items
        .map((item) =>
            '${item.className}:${item.completed}:${item.activeTotal}:${item.total}')
        .join('|');
    if (signature == _carouselSignature) return;
    _carouselSignature = signature;
    _carouselItems = List<ClassClearanceProgress>.from(items)
      ..shuffle(_carouselRandom);
  }

  @override
  void dispose() {
    _stopCarousel();
    super.dispose();
  }

  Widget _animatedMetricTile(
    BuildContext context, {
    required String label,
    required double value,
    required String Function(double) formatter,
    required IconData icon,
    required Color color,
  }) {
    final bg = Colors.white.withValues(alpha: 0.14);
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
      decoration: BoxDecoration(
        color: bg,
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: Colors.white.withValues(alpha: 0.18)),
      ),
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Icon(icon, color: color),
          const SizedBox(width: 10),
          Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                label,
                style: Theme.of(context).textTheme.labelSmall?.copyWith(
                  color: color.withValues(alpha: 0.85),
                  letterSpacing: 0.4,
                ),
              ),
              AnimatedCountText(
                value: value,
                formatter: formatter,
                style: Theme.of(context).textTheme.titleMedium?.copyWith(
                  fontWeight: FontWeight.w800,
                  color: color,
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildTiles(
    BuildContext context,
    DataService data,
    DistanceUnitService distanceUnits,
    double maxWidth,
    double spacing,
  ) {
    final isWide = maxWidth >= 1200;

    if (isWide) {
      return Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Expanded(
            flex: 2,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: [
                _buildOnThisDayCard(context, data, distanceUnits),
                const SizedBox(height: 16),
                _buildTripsCard(context, data, distanceUnits),
                const SizedBox(height: 16),
                const LatestLocoChangesPanel(expanded: true),
              ],
            ),
          ),
          const SizedBox(width: 16),
          Expanded(
            flex: 1,
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              children: const [
                TopTractionPanel(),
                SizedBox(height: 16),
                LeaderboardPanel(),
              ],
            ),
          ),
        ],
      );
    }

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        _buildOnThisDayCard(context, data, distanceUnits),
        const SizedBox(height: 16),
        const TopTractionPanel(),
        const SizedBox(height: 16),
        const LeaderboardPanel(),
        const SizedBox(height: 16),
        _buildTripsCard(context, data, distanceUnits),
        const SizedBox(height: 16),
        const LatestLocoChangesPanel(),
      ],
    );
  }

  Widget _heroHeading(
    BuildContext context,
    String greetingName,
    ColorScheme colorScheme,
  ) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          'Dashboard',
          style: Theme.of(context).textTheme.labelMedium?.copyWith(
            color: colorScheme.onPrimaryContainer,
            letterSpacing: 0.4,
          ),
        ),
        const SizedBox(height: 2),
        Text(
          'Welcome back, $greetingName',
          style: Theme.of(context).textTheme.headlineSmall?.copyWith(
            color: colorScheme.onPrimaryContainer,
            fontWeight: FontWeight.w800,
          ),
        ),
      ],
    );
  }

  Widget _buildOnThisDayCard(
      BuildContext context, DataService data, DistanceUnitService distanceUnits) {
    final filtered = data.onThisDay
        .where((leg) => leg.beginTime.year != DateTime.now().year)
        .toList();
    final textTheme = Theme.of(context).textTheme;
    final showMore = filtered.length > 5;
    final visible = _showAllOnThisDay ? filtered : filtered.take(6).toList();
    return _panel(
      context,
      icon: Icons.history_toggle_off,
      title: 'On this day',
      trailing: data.isOnThisDayLoading
          ? const SizedBox(
              height: 18,
              width: 18,
              child: CircularProgressIndicator(strokeWidth: 2),
            )
          : null,
      action: showMore
          ? TextButton(
              onPressed: () =>
                  setState(() => _showAllOnThisDay = !_showAllOnThisDay),
              child: Text(_showAllOnThisDay ? 'Show less' : 'Show more'),
            )
          : null,
      child: filtered.isEmpty
          ? Text(
              'No historical moves for today yet.',
              style: textTheme.bodyMedium,
            )
          : Column(
              children: [
                for (int idx = 0; idx < visible.length; idx++) ...[
                  _otdRow(context, visible[idx], textTheme, distanceUnits),
                  if (idx != visible.length - 1) const Divider(height: 12),
                ],
              ],
            ),
    );
  }

  Widget _otdRow(BuildContext context, Leg leg, TextTheme textTheme,
      DistanceUnitService distanceUnits) {
    final traction = leg.locos;
    return Row(
      crossAxisAlignment: CrossAxisAlignment.center,
      children: [
        Container(
          width: 64,
          height: 56,
          padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 6),
          decoration: BoxDecoration(
            color: Theme.of(context).colorScheme.surfaceContainerHighest,
            borderRadius: BorderRadius.circular(12),
          ),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                leg.beginTime.year.toString(),
                style: textTheme.titleMedium?.copyWith(
                  fontWeight: FontWeight.w800,
                ),
              ),
              const SizedBox(height: 2),
              Text(_formatTime(leg.beginTime), style: textTheme.labelSmall),
            ],
          ),
        ),
        const SizedBox(width: 12),
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '${leg.start} → ${leg.end}',
                style: textTheme.titleSmall?.copyWith(
                  fontWeight: FontWeight.w700,
                ),
                maxLines: 2,
                overflow: TextOverflow.ellipsis,
              ),
              if (leg.headcode.isNotEmpty) ...[
                const SizedBox(height: 4),
                Row(
                  children: [
                    Text(
                      leg.headcode,
                      style: textTheme.labelSmall?.copyWith(
                        color: textTheme.bodySmall?.color?.withValues(
                          alpha: 0.7,
                        ),
                      ),
                    ),
                  ],
                ),
              ],
              const SizedBox(height: 4),
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const SizedBox(width: 6),
                  Expanded(
                    child: traction.isEmpty
                        ? Text(
                            'No traction recorded',
                            style: textTheme.labelSmall?.copyWith(
                              color: textTheme.bodySmall?.color?.withValues(
                                alpha: 0.7,
                              ),
                            ),
                          )
                        : Wrap(
                            spacing: 8,
                            runSpacing: 4,
                            children: traction.map((loco) {
                              final iconColor = loco.powering
                                  ? Theme.of(context).colorScheme.primary
                                  : Theme.of(context).hintColor;
                              final label = '${loco.locoClass} ${loco.number}';
                              return Row(
                                mainAxisSize: MainAxisSize.min,
                                children: [
                                  Icon(Icons.train, size: 14, color: iconColor),
                                  const SizedBox(width: 4),
                                  Text(
                                    label,
                                    style: textTheme.labelSmall?.copyWith(
                                      color: textTheme.bodySmall?.color
                                          ?.withValues(alpha: 0.85),
                                    ),
                                  ),
                                ],
                              );
                            }).toList(),
                          ),
                  ),
                ],
              ),
            ],
          ),
        ),
        const SizedBox(width: 12),
        Column(
          crossAxisAlignment: CrossAxisAlignment.end,
          children: [
            Text(
              distanceUnits.format(leg.mileage, decimals: 1),
              style: textTheme.labelLarge?.copyWith(
                fontWeight: FontWeight.w800,
              ),
            ),
          ],
        ),
      ],
    );
  }

  Widget _panel(
    BuildContext context, {
    required IconData icon,
    required String title,
    required Widget child,
    Widget? trailing,
    Widget? action,
  }) {
    return Card(
      clipBehavior: Clip.antiAlias,
      child: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Icon(icon, size: 20),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    title,
                    style: Theme.of(context).textTheme.titleMedium?.copyWith(
                      fontWeight: FontWeight.w800,
                    ),
                  ),
                ),
                if (action != null)
                  Padding(
                    padding: const EdgeInsets.only(right: 8.0),
                    child: action,
                  ),
                if (trailing != null) trailing,
              ],
            ),
            const SizedBox(height: 12),
            child,
          ],
        ),
      ),
    );
  }

  Widget _buildTripsCard(
      BuildContext context, DataService data, DistanceUnitService distanceUnits) {
    final tripsUnsorted = data.trips;
    List<TripSummary> trips = [];
    if (tripsUnsorted.isNotEmpty) {
      trips = [...tripsUnsorted]..sort(TripSummary.compareByDateDesc);
    }
    return _panel(
      context,
      icon: Icons.bookmark,
      title: 'Trips',
      action: TextButton(
        onPressed: () => context.push('/logbook/trips'),
        child: const Text('View all'),
      ),
      child: trips.isEmpty
          ? Text(
              'No trips logged yet. Add one from the Trips page.',
              style: Theme.of(context).textTheme.bodyMedium,
            )
          : Column(
              children: trips.take(6).map((trip) {
                return Padding(
                  padding: const EdgeInsets.symmetric(vertical: 6.0),
                  child: Row(
                    children: [
                      Container(
                        width: 42,
                        height: 42,
                        decoration: BoxDecoration(
                          color: Theme.of(context).colorScheme.primaryContainer,
                          borderRadius: BorderRadius.circular(12),
                        ),
                        child: const Icon(Icons.book, size: 18),
                      ),
                      const SizedBox(width: 10),
                      Expanded(
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: [
                            Text(
                              trip.tripName,
                              style: Theme.of(context).textTheme.titleSmall
                                  ?.copyWith(fontWeight: FontWeight.w700),
                            ),
                            AnimatedCountText(
                              value: trip.tripMileage,
                              formatter: (val) =>
                                  distanceUnits.format(val, decimals: 1),
                              style: Theme.of(context).textTheme.labelMedium,
                            ),
                          ],
                        ),
                      ),
                    ],
                  ),
                );
              }).toList(),
            ),
    );
  }

  String _formatTime(DateTime date) {
    return DateFormat('HH:mm').format(date);
  }

  Future<void> _refreshDashboardData({bool force = false}) async {
    final data = context.read<DataService>();
    await data.fetchHomepageStats();
    await Future.wait([
      data.fetchOnThisDay(),
      data.fetchTripDetails(),
      data.fetchHadTraction(),
      data.fetchLatestLocoChanges(),
      data.fetchClassClearanceProgress(limit: 75, onlyIncomplete: true),
    ]);
  }

  void _handleRouteFocus() {
    final isCurrent = ModalRoute.of(context)?.isCurrent ?? true;
    if (isCurrent && !_isCurrent) {
      _isCurrent = true;
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (!mounted) return;
        _refreshDashboardData();
      });
      return;
    }
    if (!isCurrent && _isCurrent) {
      _isCurrent = false;
    }
  }
}