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 '../../../core/utils/formatters.dart';
import '../../../core/widgets/primary_button.dart';
import '../../auth/providers/auth_controller.dart';
import '../../pos/providers/cart_controller.dart';
import '../../pos/providers/catalog_providers.dart';
import '../../../domain/repositories/sync_repository.dart';
import '../providers/sync_controller.dart';

/// End-of-shift flow.
///
/// The day's takings are pushed here — the second and last moment this
/// terminal needs a connection. Signing out without pushing is allowed, but
/// the report stays queued locally rather than being discarded.
Future<void> showSignOutDialog(BuildContext context, WidgetRef ref) {
  return showDialog<void>(
    context: context,
    barrierDismissible: false,
    builder: (_) => const _SignOutDialog(),
  );
}

class _SignOutDialog extends ConsumerStatefulWidget {
  const _SignOutDialog();

  @override
  ConsumerState<_SignOutDialog> createState() => _SignOutDialogState();
}

class _SignOutDialogState extends ConsumerState<_SignOutDialog> {
  SyncOutcome? _result;

  Future<void> _finish() async {
    ref.read(cartControllerProvider.notifier).reset();
    await ref.read(authControllerProvider.notifier).signOut();

    // Mirrors what a successful import does on the way in: bump the version
    // so catalogueReadyProvider re-reads hasCatalogue as false, and drop the
    // cached product lists so the next session's grid doesn't flash this
    // session's now-cleared data before it re-fetches.
    ref.read(catalogueVersionProvider.notifier).state++;
    ref.invalidate(allProductsProvider);
    ref.invalidate(visibleProductsProvider);
    ref.invalidate(categoryCountsProvider);
    ref.invalidate(lowStockProductsProvider);

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

  Future<void> _pushThenFinish() async {
    final outcome = await ref.read(orderSyncProvider.notifier).run();
    if (!mounted) return;

    setState(() => _result = outcome);

    if (outcome.isSuccess) {
      await Future<void>.delayed(const Duration(milliseconds: 700));
      if (mounted) _finish();
    }
  }

  @override
  Widget build(BuildContext context) {
    // The operator is settling their own till, so this covers only their bills.
    final report = ref.watch(myShiftReportProvider).value;
    final pending = ref.watch(unsyncedCountProvider).value ?? 0;
    final cart = ref.watch(cartControllerProvider);
    final pushing = ref.watch(orderSyncProvider) is SyncRunning;
    final failed = _result != null && !_result!.isSuccess;

    return AlertDialog(
      title: const Text('End shift'),
      contentPadding: const EdgeInsets.fromLTRB(
        AppSpacing.xxl,
        AppSpacing.lg,
        AppSpacing.xxl,
        AppSpacing.sm,
      ),
      content: SizedBox(
        // Never wider than the viewport allows.
        width: (MediaQuery.sizeOf(context).width - 96).clamp(280.0, 420.0),
        child: SingleChildScrollView(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              if (cart.isNotEmpty)
                _Banner(
                  icon: Icons.warning_amber_rounded,
                  color: AppColors.warning,
                  background: AppColors.warningSurface,
                  message: 'The current bill has ${cart.lineCount} item(s) '
                      'and will be cleared. Park it first if you need it.',
                ),

              if (pending == 0)
                const _Banner(
                  icon: Icons.check_circle_outline_rounded,
                  color: AppColors.success,
                  background: AppColors.successSurface,
                  message: 'Every bill has already been uploaded. Nothing is '
                      'waiting on this terminal.',
                )
              else ...[
                const Text(
                  'Waiting to upload',
                  style: TextStyle(
                    fontSize: 13,
                    fontWeight: FontWeight.w600,
                    color: AppColors.textSecondary,
                  ),
                ),
                const SizedBox(height: AppSpacing.sm),
                _row('Bills pending sync', '$pending'),
                if (report != null) ...[
                  _row('Bills today', '${report.billCount}'),
                  _row('Items sold', report.itemCount.toStringAsFixed(0)),
                  _row('Gross sales', Formatters.money(report.grossSales)),
                  _row('GST collected',
                      Formatters.money(report.taxCollected),),
                ],
              ],

              if (failed) ...[
                const SizedBox(height: AppSpacing.md),
                _Banner(
                  icon: Icons.wifi_off_rounded,
                  color: AppColors.danger,
                  background: AppColors.dangerSurface,
                  message: _result?.error ??
                      'Upload failed. Every bill is still stored on this '
                          'terminal and can be retried from Events.',
                ),
              ],
            ],
          ),
        ),
      ),
      actionsPadding: const EdgeInsets.fromLTRB(
        AppSpacing.xxl,
        0,
        AppSpacing.xxl,
        AppSpacing.lg,
      ),
      actions: [
        // Wrap keeps three actions from overflowing a narrow dialog.
        Wrap(
          alignment: WrapAlignment.end,
          spacing: AppSpacing.sm,
          runSpacing: AppSpacing.sm,
          children: [
            TextButton(
              onPressed: pushing ? null : () => Navigator.of(context).pop(),
              child: const Text('Cancel'),
            ),
            TextButton(
              onPressed: pushing ? null : _finish,
              style: TextButton.styleFrom(
                foregroundColor: AppColors.textSecondary,
              ),
              child: Text(
                pending == 0 ? 'Sign out' : 'Sign out without syncing',
              ),
            ),
            if (pending > 0)
              SizedBox(
                width: 190,
                child: PrimaryButton(
                  label: failed ? 'Retry sync' : 'Sync & sign out',
                  icon: Icons.cloud_upload_rounded,
                  busy: pushing,
                  onPressed: _pushThenFinish,
                ),
              ),
          ],
        ),
      ],
    );
  }

  Widget _row(String label, String value) => Padding(
        padding: const EdgeInsets.symmetric(vertical: 3),
        child: Row(
          children: [
            Expanded(
              child: Text(
                label,
                style: const TextStyle(
                  fontSize: 13.5,
                  color: AppColors.textSecondary,
                ),
              ),
            ),
            Text(
              value,
              style: const TextStyle(
                fontSize: 13.5,
                fontWeight: FontWeight.w700,
              ),
            ),
          ],
        ),
      );
}

class _Banner extends StatelessWidget {
  const _Banner({
    required this.icon,
    required this.color,
    required this.background,
    required this.message,
  });

  final IconData icon;
  final Color color;
  final Color background;
  final String message;

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: const EdgeInsets.only(bottom: AppSpacing.md),
      padding: const EdgeInsets.all(AppSpacing.md),
      decoration: BoxDecoration(
        color: background,
        borderRadius: AppRadius.brSm,
      ),
      child: Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Icon(icon, size: 18, color: color),
          const SizedBox(width: AppSpacing.sm),
          Expanded(
            child: Text(
              message,
              style: TextStyle(fontSize: 12.5, color: color, height: 1.45),
            ),
          ),
        ],
      ),
    );
  }
}