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

import '../../../core/router/app_router.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../auth/providers/auth_controller.dart';
import '../../pos/providers/cart_controller.dart';
import '../../pos/providers/catalog_providers.dart';
import '../../pos/providers/navigation_provider.dart';
import '../../sync/providers/sync_controller.dart';
import '../../sync/widgets/sign_out_dialog.dart';

/// Asks what "signing out" means before doing it.
///
/// Both cashier paths clear the products — the till never keeps a catalogue
/// across a sign-out, whatever the reason. What they differ on is the drawer:
/// a temporary logout locks the screen and leaves the money alone, while
/// ending the shift counts it and reconciles it against what was rung.
/// Treating both as one button meant either the drawer was never settled, or a
/// cashier stepping away for ten minutes had to count it first.
///
/// Admins see the plain sign-out dialog: they have no drawer to settle, and
/// their sign-out deliberately leaves the catalogue in place for whoever picks
/// the terminal up.
Future<void> showSessionEndSheet(BuildContext context, WidgetRef ref) async {
  if (!ref.read(isCashierModeProvider)) {
    return showSignOutDialog(context, ref);
  }

  return showDialog<void>(
    context: context,
    barrierDismissible: true,
    builder: (_) => const _SessionEndDialog(),
  );
}

class _SessionEndDialog extends ConsumerWidget {
  const _SessionEndDialog();

  /// Locks the screen and returns to the login screen.
  ///
  /// Explicitly *not* a shift end — the drawer is left alone, unsynced bills
  /// stay queued, and today's totals keep accumulating against the same day.
  /// The catalogue still goes: a terminal sitting unattended at a login screen
  /// must not be holding a shop's prices and stock, and an admin re-imports in
  /// seconds.
  Future<void> _temporaryLogout(BuildContext context, WidgetRef ref) async {
    ref.read(cartControllerProvider.notifier).reset();
    await ref.read(authControllerProvider.notifier).signOut();

    ref.read(catalogueVersionProvider.notifier).state++;
    ref.invalidate(allProductsProvider);
    ref.invalidate(visibleProductsProvider);
    ref.invalidate(categoryCountsProvider);
    ref.invalidate(lowStockProductsProvider);

    ref.read(activeModuleProvider.notifier).state = PosModule.pos;
    ref.read(searchQueryProvider.notifier).state = '';
    ref.read(selectedCategoryProvider.notifier).state = null;

    if (!context.mounted) return;
    Navigator.of(context).pop();
    context.go(AppRoutes.login);
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final pending = ref.watch(unsyncedCountProvider).value ?? 0;
    final cart = ref.watch(cartControllerProvider);

    return AlertDialog(
      title: const Text('Leaving the till'),
      contentPadding: const EdgeInsets.fromLTRB(
        AppSpacing.xxl,
        AppSpacing.lg,
        AppSpacing.xxl,
        AppSpacing.sm,
      ),
      content: SizedBox(
        width: (MediaQuery.sizeOf(context).width - 96).clamp(280.0, 460.0),
        child: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              if (cart.isNotEmpty)
                Container(
                  margin: const EdgeInsets.only(bottom: AppSpacing.md),
                  padding: const EdgeInsets.all(AppSpacing.md),
                  decoration: const BoxDecoration(
                    color: AppColors.warningSurface,
                    borderRadius: AppRadius.brSm,
                  ),
                  child: Row(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      const Icon(Icons.warning_amber_rounded,
                          size: 18, color: AppColors.warning,),
                      const SizedBox(width: AppSpacing.sm),
                      Expanded(
                        child: Text(
                          'The current bill has ${cart.lineCount} item(s), and '
                          'the imported products are cleared either way.',
                          style: const TextStyle(
                            fontSize: 12.5,
                            color: AppColors.warning,
                            height: 1.45,
                          ),
                        ),
                      ),
                    ],
                  ),
                ),

              _Choice(
                icon: Icons.lock_outline_rounded,
                tone: AppColors.info,
                title: 'Temporary logout',
                body: 'Locks the screen. The drawer is left as it is and the '
                    'day keeps running — an admin re-imports the products when '
                    'you come back.',
                onTap: () => _temporaryLogout(context, ref),
              ),
              const SizedBox(height: AppSpacing.md),
              _Choice(
                icon: Icons.point_of_sale_rounded,
                tone: AppColors.primary,
                title: 'End shift',
                body: pending == 0
                    ? 'Count the drawer. It has to match what was rung before '
                        'the till can be handed over.'
                    : 'Count the drawer and upload the $pending bill(s) still '
                        'held here. The count has to match before you can sign '
                        'out.',
                onTap: () {
                  Navigator.of(context).pop();
                  context.push(AppRoutes.endShift);
                },
                emphasised: true,
              ),
            ],
          ),
        ),
      ),
      actionsPadding: const EdgeInsets.fromLTRB(
        AppSpacing.xxl,
        0,
        AppSpacing.xxl,
        AppSpacing.lg,
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: const Text('Stay signed in'),
        ),
      ],
    );
  }
}

class _Choice extends StatelessWidget {
  const _Choice({
    required this.icon,
    required this.tone,
    required this.title,
    required this.body,
    required this.onTap,
    this.emphasised = false,
  });

  final IconData icon;
  final Color tone;
  final String title;
  final String body;
  final VoidCallback onTap;
  final bool emphasised;

  @override
  Widget build(BuildContext context) {
    return Material(
      color: emphasised ? AppColors.primarySurface : AppColors.surfaceAlt,
      borderRadius: AppRadius.brLg,
      child: InkWell(
        onTap: onTap,
        borderRadius: AppRadius.brLg,
        child: Container(
          padding: const EdgeInsets.all(AppSpacing.lg),
          decoration: BoxDecoration(
            borderRadius: AppRadius.brLg,
            border: Border.all(
              color: emphasised ? AppColors.primaryBorder : AppColors.border,
            ),
          ),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Icon(icon, size: 22, color: tone),
              const SizedBox(width: AppSpacing.md),
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Text(
                      title,
                      style: const TextStyle(
                        fontSize: 15,
                        fontWeight: FontWeight.w700,
                        color: AppColors.textPrimary,
                      ),
                    ),
                    const SizedBox(height: 2),
                    Text(
                      body,
                      style: const TextStyle(
                        fontSize: 12.5,
                        color: AppColors.textSecondary,
                        height: 1.5,
                      ),
                    ),
                  ],
                ),
              ),
              const SizedBox(width: AppSpacing.sm),
              const Icon(Icons.chevron_right_rounded,
                  size: 20, color: AppColors.textTertiary,),
            ],
          ),
        ),
      ),
    );
  }
}