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

import '../../../app/providers.dart';
import '../../../core/config/sync_config.dart';
import '../../../core/constants/app_constants.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/utils/formatters.dart';
import '../../../data/local/order_dao.dart';
import '../../../domain/entities/store_account.dart';
import '../../auth/providers/auth_controller.dart';
import '../providers/printer_settings.dart';
import '../widgets/back_office_dialog.dart';
import '../../sync/providers/sync_controller.dart';
import '../widgets/module_widgets.dart';

/// Terminal and store configuration.
class SettingsView extends ConsumerStatefulWidget {
  const SettingsView({super.key});

  @override
  ConsumerState<SettingsView> createState() => _SettingsViewState();
}

class _SettingsViewState extends ConsumerState<SettingsView> {
  bool _scannerSound = true;
  bool _roundOff = true;
  bool _autoLoyalty = true;

  @override
  Widget build(BuildContext context) {
    final store = ref.watch(currentStoreProvider);
    final user = ref.watch(currentUserProvider);

    return ModulePage(
      children: [
        LayoutBuilder(
          builder: (context, constraints) {
            final wide = constraints.maxWidth >= 1040;

            final left = Column(
              children: [
                _storeCard(store),
                const SizedBox(height: AppSpacing.lg),
                _taxCard(),
                const SizedBox(height: AppSpacing.lg),
                _loyaltyCard(),
              ],
            );
            final right = Column(
              children: [
                _hardwareCard(),
                const SizedBox(height: AppSpacing.lg),
                _connectivityCard(),
                const SizedBox(height: AppSpacing.lg),
                _staffCard(store, user),
                const SizedBox(height: AppSpacing.lg),
                _aboutCard(),
              ],
            );

            if (!wide) {
              return Column(
                children: [left, const SizedBox(height: AppSpacing.lg), right],
              );
            }
            return Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Expanded(child: left),
                const SizedBox(width: AppSpacing.lg),
                Expanded(child: right),
              ],
            );
          },
        ),
      ],
    );
  }

  Widget _storeCard(StoreAccount? store) => PanelCard(
        title: 'Store details',
        subtitle: 'Printed on every invoice',
        action: TextButton(onPressed: () {}, child: const Text('Edit')),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            _row('Store name', store?.name ?? AppConstants.storeName),
            _row('Address', store?.address ?? AppConstants.storeAddress),
            _row('GSTIN', store?.gstin ?? AppConstants.storeGstin, mono: true),
            _row('Phone', store?.phone ?? AppConstants.storePhone, mono: true),
            _row('Plan', store?.plan ?? 'Business'),
          ],
        ),
      );

  Widget _taxCard() => PanelCard(
        title: 'Tax & pricing',
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            _row(
              'Default GST slab',
              Formatters.percent(AppConstants.defaultGstRate),
            ),
            _row('Prices include tax', 'Yes'),
            _toggle(
              'Round bills to nearest rupee',
              'Shows the adjustment as a Round Off line',
              _roundOff,
              (v) => setState(() => _roundOff = v),
            ),
          ],
        ),
      );

  Widget _loyaltyCard() => PanelCard(
        title: 'Loyalty programme',
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            _row(
              'Earn rate',
              '1 point per '
                  '${Formatters.money(AppConstants.loyaltyRupeesPerPoint)}',
            ),
            _row(
              'Point value',
              Formatters.money(AppConstants.loyaltyPointValue),
            ),
            _toggle(
              'Apply tier discount automatically',
              'Silver 2%, Gold 5%, Platinum 8%',
              _autoLoyalty,
              (v) => setState(() => _autoLoyalty = v),
            ),
          ],
        ),
      );

  Widget _hardwareCard() {
    final settings = ref.watch(printerSettingsProvider);
    final controller = ref.read(printerSettingsProvider.notifier);
    final printers = ref.watch(availablePrintersProvider);

    return PanelCard(
      title: 'Printer & peripherals',
      subtitle: 'Install the printer in the operating system first — it then '
          'appears in this list.',
      action: TextButton.icon(
        onPressed: () => ref.invalidate(availablePrintersProvider),
        icon: const Icon(Icons.refresh_rounded, size: 16),
        label: const Text('Rescan'),
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          printers.when(
            loading: () => const Padding(
              padding: EdgeInsets.symmetric(vertical: AppSpacing.lg),
              child: Center(child: CircularProgressIndicator()),
            ),
            error: (e, _) => Text(
              'Could not list printers: $e',
              style: const TextStyle(color: AppColors.danger, fontSize: 12.5),
            ),
            data: (list) {
              if (list.isEmpty) {
                return Container(
                  padding: const EdgeInsets.all(AppSpacing.md),
                  decoration: const BoxDecoration(
                    color: AppColors.warningSurface,
                    borderRadius: AppRadius.brSm,
                  ),
                  child: const Row(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Icon(Icons.print_disabled_rounded,
                          size: 18, color: AppColors.warning,),
                      SizedBox(width: AppSpacing.sm),
                      Expanded(
                        child: Text(
                          'No printers found. Add the thermal printer in your '
                          'operating system settings, then tap Rescan. Bills '
                          'still print to screen in the meantime.',
                          style: TextStyle(
                            fontSize: 12.5,
                            color: AppColors.warning,
                            height: 1.45,
                          ),
                        ),
                      ),
                    ],
                  ),
                );
              }

              return Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  DropdownButtonFormField<String>(
                    initialValue: list.any((p) => p.url == settings.printerUrl)
                        ? settings.printerUrl
                        : null,
                    isExpanded: true,
                    decoration: const InputDecoration(
                      labelText: 'Receipt printer',
                      prefixIcon: Icon(Icons.print_outlined),
                      isDense: true,
                    ),
                    hint: const Text('Print to screen only'),
                    items: [
                      for (final p in list)
                        DropdownMenuItem(
                          value: p.url,
                          child: Text(
                            p.isDefault ? '${p.name}  (system default)' : p.name,
                            overflow: TextOverflow.ellipsis,
                          ),
                        ),
                    ],
                    onChanged: (url) => controller.selectPrinter(
                      url == null
                          ? null
                          : list.firstWhere((p) => p.url == url),
                    ),
                  ),
                  const SizedBox(height: AppSpacing.md),
                  Wrap(
                    spacing: AppSpacing.sm,
                    runSpacing: AppSpacing.sm,
                    children: [
                      OutlinedButton.icon(
                        onPressed: () async {
                          final ok = await ref
                              .read(receiptServiceProvider)
                              .printTestPage(
                                  printerUrl: settings.printerUrl,);
                          if (!mounted) return;
                          ScaffoldMessenger.of(context)
                            ..hideCurrentSnackBar()
                            ..showSnackBar(SnackBar(
                              backgroundColor: ok
                                  ? AppColors.success
                                  : AppColors.danger,
                              content: Text(ok
                                  ? 'Test slip sent to the printer.'
                                  : 'Could not reach the printer.',),
                            ),);
                        },
                        icon: const Icon(Icons.receipt_long_rounded, size: 17),
                        label: const Text('Print test slip'),
                      ),
                      if (settings.hasPrinter)
                        TextButton(
                          onPressed: () => controller.selectPrinter(null),
                          style: TextButton.styleFrom(
                            foregroundColor: AppColors.textSecondary,
                          ),
                          child: const Text('Use screen only'),
                        ),
                    ],
                  ),
                ],
              );
            },
          ),
          const Divider(height: AppSpacing.xxl),
          _toggle(
            'Scanner beep',
            'Audible confirmation on every scan',
            _scannerSound,
            (v) => setState(() => _scannerSound = v),
          ),
          _toggle(
            'Print receipt automatically',
            settings.hasPrinter
                ? 'Sends to the selected printer the moment a sale completes'
                : 'Select a printer above to enable this',
            settings.autoPrint,
            settings.hasPrinter ? controller.setAutoPrint : null,
          ),
          _toggle(
            'Open cash drawer on cash sales',
            'Needs a raw ESC/POS link — see the notes in ReceiptService',
            settings.openDrawer,
            controller.setOpenDrawer,
          ),
        ],
      ),
    );
  }

  Widget _staffCard(StoreAccount? store, StaffUser? current) => PanelCard(
        title: 'Users & roles',
        action: TextButton(onPressed: () {}, child: const Text('Manage')),
        child: ResponsiveTable(
          stackBelow: 360,
          columns: const [
            TableCol('Name', flex: 3),
            TableCol('Role', flex: 3),
            TableCol('', flex: 2, numeric: true),
          ],
          rows: (store?.staff ?? const <StaffUser>[])
              .map((s) => [
                    Cell(s.name, bold: true),
                    Cell(s.role.label, color: AppColors.textSecondary),
                    s.id == current?.id
                        ? const TagChip('Signed in',
                            color: AppColors.success,)
                        : const SizedBox.shrink(),
                  ],)
              .toList(),
        ),
      );

  Widget _connectivityCard() {
    final ready = ref.watch(catalogueReadyProvider);
    final lastImport = ref.watch(lastImportAtProvider);
    final outstanding = ref.watch(unsyncedCountProvider).value ?? 0;
    final config = ref.watch(syncConfigProvider);
    final terminal = ref.watch(terminalIdentityProvider);
    final sync = ref.watch(syncEngineStateProvider).value ??
        ref.watch(syncEngineProvider).state;

    return PanelCard(
      title: 'Connectivity & sync',
      subtitle: 'Bills are written to this terminal first and uploaded in the '
          'background. Nothing is ever held up waiting for the network.',
      action: TextButton(
        onPressed: () => showBackOfficeDialog(context),
        child: const Text('Configure'),
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          _row('Catalogue', ready ? 'Loaded' : 'Not imported'),
          _row(
            'Last import',
            lastImport == null ? 'Never' : Formatters.dateTime(lastImport),
          ),
          _row('Terminal', '${terminal.name} · ${terminal.code}'),
          _row('Route', _transportLabel(config)),
          _row('Waiting to upload', '$outstanding bill(s)'),
          _row(
            'Last upload',
            sync.lastSuccessAt == null
                ? 'Never'
                : Formatters.dateTime(sync.lastSuccessAt!),
          ),
          if (sync.isHalted)
            _row('Status', 'Halted — ${sync.lastError ?? 'refused'}')
          else if (sync.nextAttemptAt != null)
            _row(
              'Next attempt',
              '${Formatters.time(sync.nextAttemptAt!)} '
                  '(attempt ${sync.consecutiveFailures + 1})',
            ),
          _row(
            'Bills kept on device',
            '${OrderDao.retentionWindow.inDays} days after upload',
          ),
          _toggle(
            'Simulate offline',
            'Forces import and sync to fail, so you can confirm nothing is '
                'lost when the network drops',
            // Read straight from the provider — no local copy to drift.
            ref.watch(simulateOfflineProvider),
            (v) {
              ref.read(simulateOfflineProvider.notifier).state = v;
              // The pill and the drain both read connectivity, so they have to
              // be told the switch moved.
              ref.read(connectivityServiceProvider).refresh();
              // Clear any stale failure banner left by the previous setting.
              ref.read(catalogueImportProvider.notifier).reset();
              ref.read(orderSyncProvider.notifier).reset();
            },
          ),
        ],
      ),
    );
  }

  String _transportLabel(SyncConfig config) => switch (config.transport) {
        TransportKind.simulated =>
          'Simulated — no back office configured for this terminal',
        TransportKind.http => 'HTTP · ${config.httpBaseUrl}',
        TransportKind.mqtt =>
          'MQTT · ${config.brokerHost}:${config.brokerPort}'
              '${config.useTls ? ' (TLS)' : ''}',
      };

  Widget _aboutCard() {
    final terminal = ref.watch(terminalIdentityProvider);

    return PanelCard(
        title: 'About',
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            _row('Application',
                '${AppConstants.appName} ${AppConstants.appVersion}',),
            _row('Terminal', '${terminal.name} (${terminal.code})'),
            // The identifier support asks for. Stable for the life of the
            // device, and the only thing that ties this till to its history.
            _row('Device ID', terminal.deviceId, mono: true),
            _row('Store', terminal.storeId),
            _row('Data store', 'SQLite (on device, WAL)'),
            const SizedBox(height: AppSpacing.md),
            SizedBox(
              width: double.infinity,
              child: OutlinedButton.icon(
                onPressed: () => showBackOfficeDialog(context),
                icon: const Icon(Icons.settings_ethernet_rounded, size: 17),
                label: const Text('Back office connection'),
              ),
            ),
          ],
        ),
      );
  }

  Widget _row(String label, String value, {bool mono = false}) => Padding(
        padding: const EdgeInsets.symmetric(vertical: AppSpacing.sm),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Flexible(
              flex: 3,
              child: Text(
                label,
                overflow: TextOverflow.ellipsis,
                style: const TextStyle(
                  fontSize: 13,
                  color: AppColors.textSecondary,
                ),
              ),
            ),
            const SizedBox(width: AppSpacing.md),
            Flexible(
              flex: 4,
              child: Text(
                value,
                textAlign: TextAlign.right,
                overflow: TextOverflow.ellipsis,
                style: TextStyle(
                  fontSize: 13,
                  fontWeight: FontWeight.w600,
                  color: AppColors.textPrimary,
                  fontFamily: mono ? 'monospace' : null,
                ),
              ),
            ),
          ],
        ),
      );

  Widget _toggle(
    String title,
    String subtitle,
    bool value,
    ValueChanged<bool>? onChanged,
  ) =>
      Padding(
        padding: const EdgeInsets.symmetric(vertical: AppSpacing.xs),
        child: Row(
          children: [
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    title,
                    style: const TextStyle(
                      fontSize: 13.5,
                      fontWeight: FontWeight.w500,
                    ),
                  ),
                  Text(
                    subtitle,
                    style: const TextStyle(
                      fontSize: 11.5,
                      color: AppColors.textTertiary,
                      height: 1.4,
                    ),
                  ),
                ],
              ),
            ),
            const SizedBox(width: AppSpacing.md),
            Switch(value: value, onChanged: onChanged),
          ],
        ),
      );
}