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

import '../../../app/providers.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/utils/formatters.dart';
import '../../../domain/entities/promo.dart';
import '../../../domain/entities/store_account.dart';
import '../../auth/providers/auth_controller.dart';
import '../../../core/widgets/empty_state.dart';
import '../widgets/module_widgets.dart';
import '../widgets/promo_editor_dialog.dart';

/// Discount rules and campaigns.
///
/// This was a mockup: three hardcoded rows with a toggle that changed nothing,
/// and no promo code anywhere in the domain or data layers. A cashier looking
/// at it would reasonably conclude promotions were running. They were not.
class PromosView extends ConsumerWidget {
  const PromosView({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final promosAsync = ref.watch(promosProvider);
    final isAdmin = ref.watch(currentUserProvider)?.role == StaffRole.admin;

    return ModulePage(
      children: [
        promosAsync.when(
          loading: () => const Padding(
            padding: EdgeInsets.all(AppSpacing.xxl),
            child: Center(child: CircularProgressIndicator()),
          ),
          error: (e, _) => Text('Could not load campaigns: $e'),
          data: (promos) => Column(
            children: [
              _summary(promos),
              const SizedBox(height: AppSpacing.lg),
              _campaignList(context, ref, promos, isAdmin: isAdmin),
            ],
          ),
        ),
      ],
    );
  }

  Widget _summary(List<Promo> promos) {
    final live = promos.where((p) => p.isLiveAt(DateTime.now())).length;
    final scheduled = promos
        .where((p) =>
            p.isActive &&
            p.validFrom != null &&
            p.validFrom!.isAfter(DateTime.now()),)
        .length;

    return Row(
      children: [
        Expanded(
          child: StatTile(
            label: 'Running now',
            value: '$live',
            icon: Icons.play_circle_outline_rounded,
            color: AppColors.success,
          ),
        ),
        const SizedBox(width: AppSpacing.md),
        Expanded(
          child: StatTile(
            label: 'Scheduled',
            value: '$scheduled',
            icon: Icons.schedule_rounded,
            color: AppColors.info,
          ),
        ),
        const SizedBox(width: AppSpacing.md),
        Expanded(
          child: StatTile(
            label: 'Paused',
            value: '${promos.where((p) => !p.isActive).length}',
            icon: Icons.pause_circle_outline_rounded,
            color: AppColors.textTertiary,
          ),
        ),
      ],
    );
  }

  Widget _campaignList(
    BuildContext context,
    WidgetRef ref,
    List<Promo> promos, {
    required bool isAdmin,
  }) {
    return PanelCard(
      title: 'Campaigns',
      subtitle: promos.isEmpty
          ? 'Nothing running. Add a campaign and the till applies it '
              'automatically.'
          : 'Applied automatically at the till, in priority order',
      action: isAdmin
          ? FilledButton.icon(
              onPressed: () => showPromoEditor(context),
              icon: const Icon(Icons.add_rounded, size: 18),
              label: const Text('New campaign'),
              style: FilledButton.styleFrom(
                backgroundColor: AppColors.primary,
                minimumSize: const Size(0, 40),
              ),
            )
          : null,
      child: promos.isEmpty
          ? const EmptyState(
              title: 'No campaigns yet',
              message: 'A campaign here is applied to every bill that '
                  'qualifies, without the cashier doing anything.',
              emoji: '🏷️',
              compact: true,
            )
          : Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                for (final promo in promos)
                  _PromoRow(promo: promo, isAdmin: isAdmin),
              ],
            ),
    );
  }
}

class _PromoRow extends ConsumerWidget {
  const _PromoRow({required this.promo, required this.isAdmin});

  final Promo promo;
  final bool isAdmin;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final live = promo.isLiveAt(DateTime.now());

    return Container(
      margin: const EdgeInsets.only(bottom: AppSpacing.sm),
      padding: const EdgeInsets.all(AppSpacing.md),
      decoration: BoxDecoration(
        color: AppColors.surfaceAlt,
        borderRadius: AppRadius.brMd,
        border: Border.all(color: AppColors.border),
      ),
      // Wrap prevents collision when the panel is narrow.
      child: Wrap(
        alignment: WrapAlignment.spaceBetween,
        crossAxisAlignment: WrapCrossAlignment.center,
        spacing: AppSpacing.md,
        runSpacing: AppSpacing.sm,
        children: [
          SizedBox(
            width: 360,
            child: Row(
              children: [
                Container(
                  width: 38,
                  height: 38,
                  decoration: BoxDecoration(
                    color: (live ? AppColors.success : AppColors.textTertiary)
                        .withValues(alpha: 0.12),
                    borderRadius: AppRadius.brSm,
                  ),
                  child: Icon(
                    Icons.sell_rounded,
                    size: 18,
                    color: live ? AppColors.success : AppColors.textTertiary,
                  ),
                ),
                const SizedBox(width: AppSpacing.md),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      Text(
                        promo.name,
                        overflow: TextOverflow.ellipsis,
                        style: const TextStyle(fontWeight: FontWeight.w700),
                      ),
                      Text(
                        promo.summary,
                        overflow: TextOverflow.ellipsis,
                        style: const TextStyle(
                          fontSize: 12.5,
                          color: AppColors.textSecondary,
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),

          Wrap(
            crossAxisAlignment: WrapCrossAlignment.center,
            spacing: AppSpacing.sm,
            children: [
              if (promo.stackable)
                const TagChip('Stacks', color: AppColors.info),
              // The distinction a shop actually needs: switched on, but out of
              // its date range or wrong day, is not the same as switched off.
              if (promo.isActive && !live)
                const TagChip('Not today', color: AppColors.warning),
              Text(
                _window(promo),
                style: const TextStyle(
                  fontSize: 12,
                  color: AppColors.textTertiary,
                ),
              ),
              if (isAdmin) ...[
                Switch(
                  value: promo.isActive,
                  onChanged: (v) async {
                    await ref
                        .read(localStoreProvider)
                        .promos
                        .setActive(promo.id, active: v);
                    ref
                      ..invalidate(promosProvider)
                      ..invalidate(activePromosProvider);
                  },
                ),
                IconButton(
                  tooltip: 'Edit',
                  icon: const Icon(Icons.edit_outlined, size: 17),
                  onPressed: () => showPromoEditor(context, existing: promo),
                ),
                IconButton(
                  tooltip: 'Delete',
                  icon: const Icon(Icons.delete_outline_rounded, size: 17),
                  color: AppColors.danger,
                  onPressed: () => _confirmDelete(context, ref),
                ),
              ],
            ],
          ),
        ],
      ),
    );
  }

  String _window(Promo promo) {
    final from = promo.validFrom;
    final to = promo.validTo;

    if (from == null && to == null) {
      return promo.daysOfWeek.isEmpty ? 'Always' : _days(promo.daysOfWeek);
    }

    final range = [
      if (from != null) 'from ${Formatters.date(from)}',
      if (to != null) 'to ${Formatters.date(to)}',
    ].join(' ');

    return promo.daysOfWeek.isEmpty
        ? range
        : '$range · ${_days(promo.daysOfWeek)}';
  }

  static String _days(Set<int> days) {
    const names = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
    final sorted = days.toList()..sort();
    return sorted.map((d) => names[d - 1]).join(', ');
  }

  Future<void> _confirmDelete(BuildContext context, WidgetRef ref) async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: Text('Delete "${promo.name}"?'),
        content: const Text(
          'Bills already rung keep the discount they were given — a bill '
          'stores the amount, not a link to the campaign. Only future sales '
          'are affected.',
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(dialogContext).pop(false),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.of(dialogContext).pop(true),
            style: TextButton.styleFrom(foregroundColor: AppColors.danger),
            child: const Text('Delete'),
          ),
        ],
      ),
    );

    if (confirmed != true) return;

    await ref.read(localStoreProvider).promos.delete(promo.id);
    ref
      ..invalidate(promosProvider)
      ..invalidate(activePromosProvider);
  }
}