using WPFluent.Converters;

using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;

// ReSharper disable once CheckNamespace
namespace WPFluent.Controls;

/// <summary>
/// Represents the base class for an icon UI element.
/// </summary>
[TypeConverter(typeof(IconElementConverter))]
public abstract class IconElement : FrameworkElement
{
    /// <summary>
    /// Identifies the <see cref="Foreground"/> dependency property.
    /// </summary>
    public static readonly DependencyProperty ForegroundProperty = TextElement.ForegroundProperty
        .AddOwner(
            typeof(IconElement),
            new FrameworkPropertyMetadata(
                SystemColors.ControlTextBrush,
                FrameworkPropertyMetadataOptions.Inherits,
                static(d, args) => ((IconElement)d).OnForegroundChanged(args)));

    private Grid? _layoutRoot;

    static IconElement()
    {
        FocusableProperty.OverrideMetadata(typeof(IconElement), new FrameworkPropertyMetadata(false));
        KeyboardNavigation.IsTabStopProperty.OverrideMetadata(typeof(IconElement), new FrameworkPropertyMetadata(false));
    }

    private void EnsureLayoutRoot()
    {
        if(_layoutRoot != null)
        {
            return;
        }

        _layoutRoot = new Grid { Background = Brushes.Transparent, SnapsToDevicePixels = true };

        _layoutRoot.Children.Add(InitializeChildren());

        AddVisualChild(_layoutRoot);
    }

    protected override Size ArrangeOverride(Size finalSize)
    {
        EnsureLayoutRoot();

        _layoutRoot!.Arrange(new Rect(default, finalSize));
        return finalSize;
    }

    protected override Visual GetVisualChild(int index)
    {
        if(index != 0)
        {
            throw new ArgumentOutOfRangeException(nameof(index), "IconElement should have only 1 child");
        }

        EnsureLayoutRoot();
        return _layoutRoot!;
    }

    protected abstract UIElement InitializeChildren();

    protected override Size MeasureOverride(Size availableSize)
    {
        EnsureLayoutRoot();

        _layoutRoot!.Measure(availableSize);
        return _layoutRoot.DesiredSize;
    }

    protected virtual void OnForegroundChanged(DependencyPropertyChangedEventArgs args)
    {
    }

    protected override int VisualChildrenCount => 1;

    /// <summary>
    /// Coerces the value of an Icon dependency property, allowing the use of either IconElement or IconSourceElement.
    /// </summary>
    /// <param name="_">The dependency object (unused).</param>
    /// <param name="baseValue">The value to be coerced.</param>
    /// <returns>An IconElement, either directly or derived from an IconSourceElement.</returns>
    public static object? Coerce(DependencyObject _, object? baseValue)
    {
        return baseValue switch
        {
            IconSourceElement iconSourceElement => iconSourceElement.CreateIconElement(),
            IconElement or null => baseValue,
            _ => throw new ArgumentException(
                message: $"Expected either '{typeof(IconSourceElement)}' or '{typeof(IconElement)}' but got '{baseValue.GetType()}'.",
                paramName: nameof(baseValue)),
        };
    }

    /// <inheritdoc cref="Control.Foreground"/>
    [Bindable(true)]
    [Category("Appearance")]
    public Brush Foreground { get => (Brush)GetValue(ForegroundProperty); set => SetValue(ForegroundProperty, value); }
}