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

import '../core/formatters.dart';
import '../core/theme.dart';
import '../models/shift.dart';
import '../state/shifts_controller.dart';
import '../widgets/common.dart';
import '../widgets/glass_segments.dart';
import '../widgets/krow_wordmark.dart';
import '../widgets/shift_card.dart';
import '../widgets/week_strip.dart';

enum _Tab { booked, open, history }

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

  @override
  ConsumerState<ShiftsScreen> createState() => _ShiftsScreenState();
}

class _ShiftsScreenState extends ConsumerState<ShiftsScreen> {
  _Tab _tab = _Tab.booked;

  /// Where we came from, so the new list can slide in from the right side.
  _Tab _previousTab = _Tab.booked;
  DateTime _selectedDay = DateTime.now();
  String _query = '';
  String _filter = 'All';

  void _selectTab(_Tab tab) {
    if (tab == _tab) return;
    setState(() {
      _previousTab = _tab;
      _tab = tab;
    });
  }

  List<DateTime> get _week {
    final now = DateTime.now();
    return [for (var i = 0; i < 7; i++) now.add(Duration(days: i))];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          BrandHeader(
            padding: const EdgeInsets.fromLTRB(20, 8, 20, 20),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                HeaderBrandLine(
                  trailing: HeaderEyebrow(Fmt.monthYear(DateTime.now())),
                ),
                const SizedBox(height: 8),
                const Text(
                  'Shifts',
                  style: TextStyle(
                    fontSize: 27,
                    fontWeight: FontWeight.w700,
                    letterSpacing: -0.9,
                    color: Colors.white,
                  ),
                ),
                const SizedBox(height: 18),
                _HeaderSegments(value: _tab, onChanged: _selectTab),
              ],
            ),
          ),
          Expanded(
            // The list slides in from the side the new tab sits on, so the
            // content moves the same way your eye just did.
            child: AnimatedSwitcher(
              duration: const Duration(milliseconds: 280),
              switchInCurve: Curves.easeOutCubic,
              switchOutCurve: Curves.easeIn,
              layoutBuilder: (current, previous) => Stack(
                alignment: Alignment.topCenter,
                children: [...previous, ?current],
              ),
              transitionBuilder: (child, animation) {
                final incoming = child.key == ValueKey(_tab);
                final direction = _tab.index >= _previousTab.index ? 1.0 : -1.0;
                return FadeTransition(
                  opacity: animation,
                  child: SlideTransition(
                    position: Tween(
                      begin: Offset(incoming ? 0.08 * direction : 0, 0),
                      end: Offset.zero,
                    ).animate(animation),
                    child: child,
                  ),
                );
              },
              child: KeyedSubtree(
                key: ValueKey(_tab),
                child: switch (_tab) {
                  _Tab.booked => _BookedTab(
                    week: _week,
                    selected: _selectedDay,
                    onSelect: (d) => setState(() => _selectedDay = d),
                  ),
                  _Tab.open => _OpenTab(
                    query: _query,
                    filter: _filter,
                    onQuery: (q) => setState(() => _query = q),
                    onFilter: (f) => setState(() => _filter = f),
                  ),
                  _Tab.history => const _HistoryTab(),
                },
              ),
            ),
          ),
        ],
      ),
    );
  }
}

class _HeaderSegments extends StatelessWidget {
  const _HeaderSegments({required this.value, required this.onChanged});

  final _Tab value;
  final ValueChanged<_Tab> onChanged;

  @override
  Widget build(BuildContext context) {
    return GlassSegments<_Tab>(
      segments: const [
        (_Tab.booked, 'Booked'),
        (_Tab.open, 'Open'),
        (_Tab.history, 'History'),
      ],
      value: value,
      onChanged: onChanged,
    );
  }
}

class _BookedTab extends ConsumerWidget {
  const _BookedTab({
    required this.week,
    required this.selected,
    required this.onSelect,
  });

  final List<DateTime> week;
  final DateTime selected;
  final ValueChanged<DateTime> onSelect;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final booked = ref.watch(bookedShiftsProvider);
    final forDay = booked.where((s) => Fmt.sameDay(s.start, selected)).toList();
    final marked = <int>{
      for (var i = 0; i < week.length; i++)
        if (booked.any((s) => Fmt.sameDay(s.start, week[i]))) i,
    };

    return ListView(
      padding: const EdgeInsets.fromLTRB(20, 18, 20, 24),
      children: [
        WeekStrip(
          days: week,
          selected: selected,
          onSelect: onSelect,
          marked: marked,
        ),
        SectionLabel(
          '${Fmt.dayFull(selected)} · ${forDay.length} '
          '${forDay.length == 1 ? 'shift' : 'shifts'}',
        ),
        if (forDay.isEmpty)
          const EmptyState(
            icon: LucideIcons.ticket,
            title: 'Nothing booked this day',
            message: 'Switch to Open above to claim a shift near you.',
          )
        else
          for (final shift in forDay)
            Padding(
              padding: const EdgeInsets.only(bottom: 11),
              child: ShiftCard(
                shift: shift,
                onTap: () => context.push('/shift/${shift.id}'),
              ),
            ),
        const SizedBox(height: 6),
        const InfoBanner(
          'Auto-Match only offers you shifts inside the availability blocks you '
          'have switched on.',
        ),
      ],
    );
  }
}

class _OpenTab extends ConsumerWidget {
  const _OpenTab({
    required this.query,
    required this.filter,
    required this.onQuery,
    required this.onFilter,
  });

  final String query;
  final String filter;
  final ValueChanged<String> onQuery;
  final ValueChanged<String> onFilter;

  static const _filters = ['All', 'Today', 'This week', 'Top pay'];

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    var shifts = ref.watch(openShiftsProvider);
    final now = DateTime.now();

    if (query.isNotEmpty) {
      final q = query.toLowerCase();
      shifts = shifts
          .where(
            (s) =>
                s.role.toLowerCase().contains(q) ||
                s.business.toLowerCase().contains(q) ||
                s.venue.toLowerCase().contains(q),
          )
          .toList();
    }
    shifts = switch (filter) {
      'Today' => shifts.where((s) => Fmt.sameDay(s.start, now)).toList(),
      'This week' =>
        shifts.where((s) => s.start.difference(now).inDays < 7).toList(),
      'Top pay' => shifts.where((s) => s.rate >= 22).toList(),
      _ => shifts,
    };

    return ListView(
      padding: const EdgeInsets.fromLTRB(20, 18, 20, 24),
      children: [
        TextField(
          onChanged: onQuery,
          decoration: const InputDecoration(
            hintText: 'Role, business or area',
            prefixIcon: Icon(LucideIcons.search, size: 18),
          ),
        ),
        const SizedBox(height: 14),
        SingleChildScrollView(
          scrollDirection: Axis.horizontal,
          child: Row(
            children: [
              for (final f in _filters)
                Padding(
                  padding: const EdgeInsets.only(right: 8),
                  child: ChoiceChip(
                    label: Text(f),
                    selected: f == filter,
                    showCheckmark: false,
                    selectedColor: KrowPalette.blue,
                    labelStyle: TextStyle(
                      fontSize: 12.5,
                      fontWeight: FontWeight.w500,
                      color: f == filter ? Colors.white : KrowPalette.mute,
                    ),
                    onSelected: (_) => onFilter(f),
                  ),
                ),
            ],
          ),
        ),
        SectionLabel('${shifts.length} shifts · highest paying first'),
        if (shifts.isEmpty)
          const EmptyState(
            icon: LucideIcons.search,
            title: 'Nothing matches',
            message: 'Try a different filter or clear your search.',
          )
        else
          for (final shift in shifts)
            Padding(
              padding: const EdgeInsets.only(bottom: 11),
              child: ShiftCard(
                shift: shift,
                showDate: true,
                onTap: () => context.push('/shift/${shift.id}'),
                trailingAction: _ApplyButton(shift: shift),
              ),
            ),
      ],
    );
  }
}

class _ApplyButton extends ConsumerWidget {
  const _ApplyButton({required this.shift});

  final Shift shift;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        Text(
          Fmt.money(shift.scheduledPay),
          style: const TextStyle(
            fontSize: 16,
            fontWeight: FontWeight.w700,
            letterSpacing: -0.6,
          ),
        ),
        const SizedBox(width: 10),
        FilledButton(
          onPressed: () {
            HapticFeedback.selectionClick();
            ref.read(shiftsProvider.notifier).apply(shift.id);
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                content: Text(
                  '${shift.role} at ${shift.business} booked for '
                  '${Fmt.dayShort(shift.start)}',
                ),
              ),
            );
          },
          style: FilledButton.styleFrom(
            minimumSize: const Size(0, 34),
            padding: const EdgeInsets.symmetric(horizontal: 16),
            textStyle: const TextStyle(
              fontSize: 12.5,
              fontWeight: FontWeight.w700,
            ),
          ),
          child: const Text('Apply'),
        ),
      ],
    );
  }
}

class _HistoryTab extends ConsumerWidget {
  const _HistoryTab();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final history = ref.watch(historyShiftsProvider);
    final completed = history
        .where((s) => s.status == ShiftStatus.completed)
        .length;
    final cancelled = history
        .where((s) => s.status == ShiftStatus.cancelled)
        .length;
    final logged = ref.watch(hoursLoggedProvider);

    return ListView(
      padding: const EdgeInsets.fromLTRB(20, 18, 20, 24),
      children: [
        StatRail(
          stats: [
            ('Completed', '$completed'),
            ('Cancelled', '$cancelled'),
            ('Logged', Fmt.duration(logged)),
          ],
        ),
        const SectionLabel('Everything you have worked'),
        if (history.isEmpty)
          const EmptyState(
            icon: LucideIcons.history,
            title: 'No history yet',
            message: 'Shifts you finish or cancel will show up here.',
          )
        else
          for (final shift in history)
            Padding(
              padding: const EdgeInsets.only(bottom: 11),
              child: ShiftCard(
                shift: shift,
                showDate: true,
                onTap: () => context.push('/shift/${shift.id}'),
              ),
            ),
      ],
    );
  }
}