using System.Text.RegularExpressions;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;
using UtopiaCanteenSystem.ViewModels;

namespace UtopiaCanteenSystem.Views;

/// <summary>
/// Minimal code-behind for focus management and Enter-key submission.
/// </summary>
public partial class ScannerDashboardView : UserControl
{
    private bool _isUnloaded;
    private bool _suppressScannerFocus;
    private DispatcherTimer? _focusSuppressionTimer;

    public ScannerDashboardView()
    {
        InitializeComponent();
        Loaded += OnLoaded;
        Unloaded += OnUnloaded;
    }

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        _isUnloaded = false;
        FocusRfidInput(selectAll: true, DispatcherPriority.Input);
    }

    private void OnUnloaded(object sender, RoutedEventArgs e)
    {
        _isUnloaded = true;
        
        // Clean up timer
        _focusSuppressionTimer?.Stop();
        _focusSuppressionTimer = null;
    }

    private void FocusRfidInput(bool selectAll, DispatcherPriority priority)
    {
        if (_isUnloaded)
            return;

        Dispatcher.BeginInvoke(() =>
        {
            if (_isUnloaded || !IsVisible || !IsEnabled)
                return;

            // Don't auto-focus scanner input if focus suppression is active
            if (_suppressScannerFocus)
                return;

            // Don't auto-focus scanner input if the Order History modal is open
            if (DataContext is ScannerDashboardViewModel vm && vm.IsOrderHistoryModalOpen)
                return;

            RfidInputTextBox.Focus();
            Keyboard.Focus(RfidInputTextBox);

            if (selectAll)
                RfidInputTextBox.SelectAll();
        }, priority);
    }

    private void RfidInputTextBox_OnLostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
    {
        // Don't auto-focus scanner input if focus suppression is active
        if (_suppressScannerFocus)
            return;

        // Don't auto-focus scanner input if the Order History modal is open
        if (DataContext is ScannerDashboardViewModel vm && vm.IsOrderHistoryModalOpen)
            return;

        // If focus moved into the menu panel (e.g. Site number field), don't steal it back.
        if (IsDescendantOf(MenuPanel, e.NewFocus as DependencyObject))
            return;

        // SIMPLE FIX: Just add a small delay before refocusing
        // This gives buttons time to process their click events
        DispatcherTimer focusTimer = new DispatcherTimer
        {
            Interval = TimeSpan.FromMilliseconds(150) // 150ms is enough for click to process
        };

        focusTimer.Tick += (s, args) =>
        {
            focusTimer.Stop();

            // Check conditions again after delay
            if (_suppressScannerFocus)
                return;

            if (DataContext is ScannerDashboardViewModel viewModel && viewModel.IsOrderHistoryModalOpen)
                return;

            // Only refocus if we're not already focused somewhere else
            // If modal opened, it will have focus now
            if (Keyboard.FocusedElement != RfidInputTextBox)
            {
                FocusRfidInput(selectAll: false, DispatcherPriority.ApplicationIdle);
            }
        };

        focusTimer.Start();
    }

    private static bool IsDescendantOf(DependencyObject? ancestor, DependencyObject? element)
    {
        if (ancestor == null || element == null) return false;
        while (element != null)
        {
            if (element == ancestor) return true;
            element = VisualTreeHelper.GetParent(element);
        }
        return false;
    }

    private void RfidInputTextBox_OnKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key != Key.Enter)
            return;

        if (DataContext is ScannerDashboardViewModel vm && vm.ScanCommand.CanExecute(null))
        {
            vm.ScanCommand.Execute(null);
            e.Handled = true;
        }
    }

    private void SiteNumberTextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
    {
        e.Handled = !Regex.IsMatch(e.Text, @"^\d+$");
    }

    private void MenuToggleButton_Unchecked(object sender, RoutedEventArgs e)
    {
        // When user closes the menu, focus scanner input so they can scan without clicking it.
        FocusRfidInput(selectAll: false, DispatcherPriority.ApplicationIdle);
    }

    private void OrderHistoryModalOverlay_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        // Only close if the user actually clicked the dark overlay background,
        // not when the event is bubbling from inside the dialog content.
        if (!ReferenceEquals(e.OriginalSource, sender))
            return;

        CloseOrderHistoryModal();
        e.Handled = true;
    }

    private void OrderHistoryModalContent_Loaded(object sender, RoutedEventArgs e)
    {
        // No special behavior required here for now; this hook exists to satisfy XAML and
        // is a good place to move focus inside the dialog if needed later.
    }

    private void OrderHistoryModalClose_Click(object sender, RoutedEventArgs e)
    {
        CloseOrderHistoryModal();
    }

    private void CloseOrderHistoryModal()
    {
        if (DataContext is ScannerDashboardViewModel vm)
        {
            vm.IsOrderHistoryModalOpen = false;
            // Suppress scanner focus temporarily after closing modal
            SuppressScannerFocusTemporarily();
        }
    }

    private void SuppressScannerFocusTemporarily()
    {
        _suppressScannerFocus = true;
        
        // Clear any existing timer
        _focusSuppressionTimer?.Stop();
        
        // Create a timer to clear suppression after UI settles
        _focusSuppressionTimer = new DispatcherTimer
        {
            Interval = TimeSpan.FromMilliseconds(300) // Short delay to let UI settle
        };
        _focusSuppressionTimer.Tick += (s, e) =>
        {
            _suppressScannerFocus = false;
            _focusSuppressionTimer.Stop();
            _focusSuppressionTimer = null;
            
            // Now restore scanner focus after suppression period
            FocusRfidInput(selectAll: false, DispatcherPriority.ApplicationIdle);
        };
        _focusSuppressionTimer.Start();
    }
}