import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:provider/provider.dart';

import '../../l10n/app_localizations.dart';
import '../../l10n/app_localizations_helpers.dart';
import '../../models/product.dart';
import '../../models/remote_command.dart';
import '../../utils/app_updater.dart';
import '../../viewmodels/admin_pin_view_model.dart';
import '../../viewmodels/bar_screen_view_model.dart';
import '../../viewmodels/pin_lock_view_model.dart';
import '../../viewmodels/product_list_view_model.dart';
import '../../viewmodels/remote_sync_view_model.dart';
import '../../viewmodels/settings_view_model.dart';
import '../dialogs/close_tab_dialog.dart';
import '../dialogs/edit_tab_dialog.dart';
import 'product_grid.dart';
import 'tab_panel.dart';

class BarScreenView extends StatefulWidget {
  const BarScreenView({super.key});

  @override
  State<BarScreenView> createState() => _BarScreenViewState();
}

class _BarScreenViewState extends State<BarScreenView> {
  bool _showSearch = false;
  late final StreamSubscription<RemoteSyncEvent> _remoteCloseSubscription;

  @override
  void initState() {
    super.initState();

    _remoteCloseSubscription = context
        .read<RemoteSyncViewModel>()
        .tabsClosedRemotely
        .listen(_showRemoteClose);

    WidgetsBinding.instance.addPostFrameCallback((_) {
      UpdateChecker.check(context);
    });
  }

  @override
  void dispose() {
    _remoteCloseSubscription.cancel();
    super.dispose();
  }

  void _showRemoteClose(RemoteSyncEvent event) {
    if (!mounted) return;

    final l10n = AppLocalizations.of(context);
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(
          l10n.tabClosedRemotely(
            event.tabCustomerName ?? '',
            event.requestedBy ?? '',
          ),
        ),
        behavior: SnackBarBehavior.floating,
      ),
    );
  }

  Future<void> _addProduct(Product product) async {
    final l10n = AppLocalizations.of(context);
    final viewModel = context.read<BarScreenViewModel>();

    if (viewModel.selectedTab == null) {
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text(l10n.openOrSelectTab)));
      return;
    }

    try {
      await viewModel.addProductToSelectedTab(product);
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text(l10n.couldNotAddProductToTab)));
    }
  }

  void _showSyncProblem({required String title, required String description}) {
    final l10n = AppLocalizations.of(context);
    showDialog<void>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: Text(title),
        content: SelectableText(description),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(dialogContext).pop(),
            child: Text(l10n.close),
          ),
        ],
      ),
    );
  }

  void _logout() {
    context.read<PinLockViewModel>().lock();
    context.read<AdminPinViewModel>().lock();
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final viewModel = context.watch<BarScreenViewModel>();
    final productsViewModel = context.watch<ProductListViewModel>();
    final settings = context.watch<SettingsViewModel>().settings;

    return Scaffold(
      appBar: AppBar(
        title: Text(l10n.barTabs),
        actions: [
          IconButton(
            tooltip: _showSearch ? l10n.closeSearch : l10n.searchTabs,
            isSelected: _showSearch,
            onPressed: () => setState(() => _showSearch = !_showSearch),
            icon: const Icon(Icons.search_rounded),
            selectedIcon: const Icon(Icons.search_off_rounded),
          ),
          const SizedBox(width: 6),
          IconButton(
            tooltip: l10n.admin,
            onPressed: () => context.push('/admin'),
            icon: const Icon(Icons.admin_panel_settings_outlined),
          ),
          if (kDebugMode) ...[
            const SizedBox(width: 6),
            _DebugShortcut(
              tooltip: l10n.manageProducts,
              icon: Icons.inventory_2_outlined,
              location: '/products',
            ),
            const SizedBox(width: 6),
            _DebugShortcut(
              tooltip: l10n.tabHistory,
              icon: Icons.history_rounded,
              location: '/history',
            ),
          ],
          if (context.watch<RemoteSyncViewModel>().wasRevoked) ...[
            const SizedBox(width: 6),
            IconButton(
              tooltip: l10n.deviceAccessRevoked,
              color: Theme.of(context).colorScheme.error,
              onPressed: () => context.push('/admin'),
              icon: const Icon(Icons.cloud_off_rounded),
            ),
          ],
          // A failing sync is otherwise invisible: the bar keeps working
          // offline while nothing from the website arrives
          if (context.watch<RemoteSyncViewModel>().lastError
              case final error?) ...[
            const SizedBox(width: 6),
            // Offline is normal for a bar; anything else needs attention
            if (context.watch<RemoteSyncViewModel>().isOffline)
              IconButton(
                tooltip: l10n.offline,
                onPressed: () => _showSyncProblem(
                  title: l10n.offline,
                  description: l10n.offlineDescription,
                ),
                icon: const Icon(Icons.wifi_off_rounded),
              )
            else
              IconButton(
                tooltip: '${l10n.syncProblem}: $error',
                color: Theme.of(context).colorScheme.error,
                onPressed: () => _showSyncProblem(
                  title: l10n.syncProblem,
                  description: '${l10n.syncProblemDescription}\n\n$error',
                ),
                icon: const Icon(Icons.sync_problem_rounded),
              ),
          ],
          const SizedBox(width: 6),
          IconButton(
            tooltip: l10n.refresh,
            onPressed: () => context.read<RemoteSyncViewModel>().syncNow(),
            icon: const Icon(Icons.refresh_rounded),
          ),
          const SizedBox(width: 6),
          IconButton(
            tooltip: l10n.settings,
            onPressed: () => context.push('/settings'),
            icon: const Icon(Icons.settings),
          ),
          if (context.watch<PinLockViewModel>().isPinSet) ...[
            const SizedBox(width: 6),
            IconButton(
              tooltip: l10n.logout,
              onPressed: _logout,
              icon: const Icon(Icons.logout),
            ),
          ],
        ],
        actionsPadding: const EdgeInsets.symmetric(horizontal: 8),
      ),
      resizeToAvoidBottomInset: false,
      body: Builder(
        builder: (context) {
          if (viewModel.isLoading) {
            return const Center(
              child: CircularProgressIndicator(strokeWidth: 2.5),
            );
          }

          if (viewModel.loadError != null) {
            return _LoadError(message: l10n.errorText(viewModel.loadError));
          }

          return Row(
            children: [
              Expanded(
                flex: 2,
                child: ProductGrid(
                  products: productsViewModel.products,
                  rows: settings.barGridRows,
                  hasSelectedTab: viewModel.selectedTab != null,
                  onProductTap: _addProduct,
                ),
              ),
              Container(width: 1, color: Theme.of(context).dividerColor),
              Expanded(
                child: TabPanel(
                  tabs: viewModel.tabs,
                  selectedTab: viewModel.selectedTab,
                  selectedTabId: viewModel.selectedTabId,
                  showSearch: _showSearch,
                  onTabSelected: viewModel.selectTab,
                  onItemQuantityChanged: viewModel.changeItemQuantity,
                  onCloseTabPressed: () => confirmCloseTab(context),
                  onTabEdited: (tab) => showEditTabDialog(context, tab),
                  onTabDeleted: (tab) => confirmDeleteTab(context, tab),
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}

class _DebugShortcut extends StatelessWidget {
  final String tooltip;
  final IconData icon;
  final String location;

  const _DebugShortcut({
    required this.tooltip,
    required this.icon,
    required this.location,
  });

  @override
  Widget build(BuildContext context) {
    return IconButton(
      tooltip: tooltip,
      style: IconButton.styleFrom(
        backgroundColor: Colors.yellow,
        foregroundColor: Colors.black,
      ),
      onPressed: () => context.push(location),
      icon: Icon(icon),
    );
  }
}

class _LoadError extends StatelessWidget {
  final String message;

  const _LoadError({required this.message});

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.error_outline_rounded,
              size: 40,
              color: Theme.of(context).colorScheme.error,
            ),
            const SizedBox(height: 12),
            Text(
              message,
              textAlign: TextAlign.center,
              style: Theme.of(context).textTheme.bodyLarge,
            ),
          ],
        ),
      ),
    );
  }
}