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.
///
/// A cashier stepping off the counter for a few minutes and a cashier
/// finishing for the day want different things from the *shift*, not from the
/// terminal. A temporary logout leaves the shift open — bills stay queued and
/// today's totals keep accumulating — and simply locks the screen. Ending the
/// shift means counting the drawer, reconciling it, and handing the till back.
///
/// What both do identically: the products come off this terminal. A cashier
/// session never leaves a catalogue sitting on an unattended screen, so an
/// admin re-imports it before the counter is worked again.
///
/// Admins see the plain sign-out dialog: they have no drawer to settle.
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();

  /// Closes the session without closing the shift.
  ///
  /// Explicitly *not* a shift end: unsynced bills stay queued and today's
  /// totals keep accumulating against the same day, so the drawer is still
  /// settled once, at the end. What it does not leave behind is the
  /// catalogue — every cashier sign-out takes the products with it, this one
  /// included, so an admin imports them again before billing resumes.
  Future<void> _temporaryLogout(BuildContext context, WidgetRef ref) async {
    ref.read(cartControllerProvider.notifier).reset();
    await ref.read(authControllerProvider.notifier).signOut();

    // Bump the version so catalogueReadyProvider re-reads hasCatalogue, and
    // drop the cached lists so the next session's grid does not flash this
    // session's products before it re-checks what is on disk.
    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;

    // Resolved while this context is still mounted — the messenger lives above
    // the router, so the bar survives the route change below.
    final messenger = ScaffoldMessenger.of(context);

    Navigator.of(context).pop();
    context.go(AppRoutes.login);

    messenger
      ..hideCurrentSnackBar()
      ..showSnackBar(const SnackBar(
        content: Text(
          'Logged out. The shift is still open, and the product catalogue has '
          'been removed from this terminal.',
        ),
      ),);
  }

  @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 '
                          'will be cleared either way.',
                          style: const TextStyle(
                            fontSize: 12.5,
                            color: AppColors.warning,
                            height: 1.45,
                          ),
                        ),
                      ),
                    ],
                  ),
                ),

              // The one thing both choices do, said once here rather than
              // repeated in each card and discovered at the next login.
              Container(
                margin: const EdgeInsets.only(bottom: AppSpacing.md),
                padding: const EdgeInsets.all(AppSpacing.md),
                decoration: const BoxDecoration(
                  color: AppColors.infoSurface,
                  borderRadius: AppRadius.brSm,
                ),
                child: const Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Icon(Icons.delete_sweep_outlined,
                        size: 18, color: AppColors.info,),
                    SizedBox(width: AppSpacing.sm),
                    Expanded(
                      child: Text(
                        'Either way, the product catalogue is removed from '
                        'this terminal. An admin imports it again before the '
                        'counter is worked.',
                        style: TextStyle(
                          fontSize: 12.5,
                          color: AppColors.info,
                          height: 1.45,
                        ),
                      ),
                    ),
                  ],
                ),
              ),

              _Choice(
                icon: Icons.lock_clock_outlined,
                tone: AppColors.info,
                title: 'Temporary logout',
                body: 'Locks the terminal without closing the shift. Bills '
                    'stay queued and today’s totals keep running, so the '
                    'drawer is still counted once at the end.',
                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, check it against what was rung, then '
                        'hand the till over.'
                    : 'Count the drawer, check it against what was rung, then '
                        'upload the $pending bill(s) still held here.',
                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,),
            ],
          ),
        ),
      ),
    );
  }
}