using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace GsConfigTool.Helpers;

public static class PlaceholderHelper
{
    public static readonly DependencyProperty PlaceholderProperty =
        DependencyProperty.RegisterAttached(
            "Placeholder",
            typeof(string),
            typeof(PlaceholderHelper),
            new PropertyMetadata(string.Empty, OnPlaceholderChanged));

    public static string GetPlaceholder(DependencyObject obj) =>
        (string)obj.GetValue(PlaceholderProperty);

    public static void SetPlaceholder(DependencyObject obj, string value) =>
        obj.SetValue(PlaceholderProperty, value);

    private static void OnPlaceholderChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is not TextBox tb) return;
        tb.Loaded -= Tb_Loaded;
        tb.Loaded += Tb_Loaded;
        UpdatePlaceholder(tb);
    }

    private static void Tb_Loaded(object sender, RoutedEventArgs e)
    {
        if (sender is not TextBox tb) return;
        tb.TextChanged -= Tb_TextChanged;
        tb.TextChanged += Tb_TextChanged;
        UpdatePlaceholder(tb);
    }

    private static void Tb_TextChanged(object sender, TextChangedEventArgs e)
    {
        if (sender is TextBox tb) UpdatePlaceholder(tb);
    }

    private static void UpdatePlaceholder(TextBox tb)
    {
        var placeholder = GetPlaceholder(tb);
        if (string.IsNullOrEmpty(tb.Text))
        {
            if (!string.IsNullOrEmpty(placeholder))
                tb.Tag = placeholder;
        }
        else
        {
            tb.Tag = null;
        }
    }
}