using System;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Media;
using WPFDark.Internals;


namespace WPFDark
{
    public readonly ref struct LayoutRounder
    {
        public readonly double DpiScale;
        
        private readonly FrameworkElement element;
        private readonly double inverseDpiScale;
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public LayoutRounder(FrameworkElement element)
        {
            this.element = element;
            DpiScale = element.PixelsPerDip();
            inverseDpiScale = 1d / DpiScale;
        }
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Pen GetBorderPen(ByteColor color)
            => Caches.GetPen(color, RoundLayoutValue(FrameworkElementExtensions.BorderWidth));
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public double RoundRenderWidth(bool isWithBorder)
        {
            return isWithBorder
                ? RoundLayoutValue(element.RenderSize.Width - FrameworkElementExtensions.BorderWidth)
                : RoundLayoutValue(element.RenderSize.Width);
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public double RoundRenderHeight(bool isWithBorder)
        {
            return isWithBorder
                ? RoundLayoutValue(element.RenderSize.Height - FrameworkElementExtensions.BorderWidth)
                : RoundLayoutValue(element.RenderSize.Height);
        }
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Rect RoundRenderRectangle(bool isWithBorder)
        {
            // ReSharper disable ConditionIsAlwaysTrueOrFalse
            if (isWithBorder)
            {
                return new Rect(
                    RoundLayoutValue(FrameworkElementExtensions.BorderHalfWidth),
                    RoundLayoutValue(FrameworkElementExtensions.BorderHalfWidth),
                    RoundRenderWidth(isWithBorder),
                    RoundRenderHeight(isWithBorder));
            }
            else
            {
                return new Rect(0, 0, RoundRenderWidth(isWithBorder),
                    RoundRenderHeight(isWithBorder));
            }
            // ReSharper restore ConditionIsAlwaysTrueOrFalse
        } 
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public ImmutableRect_double RoundLayoutRect(in ImmutableRect_double rect)
        {
            return new ImmutableRect_double(
                RoundLayoutValue(rect.X),
                RoundLayoutValue(rect.Y),
                RoundLayoutValue(rect.Width),
                RoundLayoutValue(rect.Height));
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Rect RoundLayoutRect(double x, double y, double w, double h)
        {
            return new Rect(
                RoundLayoutValue(x),
                RoundLayoutValue(y),
                RoundLayoutValue(w),
                RoundLayoutValue(h));
        }
        
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public Rect RoundLayoutRect(Rect rect)
        {
            return new Rect(
                RoundLayoutValue(rect.X),
                RoundLayoutValue(rect.Y),
                RoundLayoutValue(rect.Width),
                RoundLayoutValue(rect.Height));
        }
        
        public double RoundLayoutValue(double value)
        {
            double newValue;

            if (NumberHelper.AreClose(DpiScale, 1d) == false)
            {
                newValue = Math.Round(value * DpiScale) * inverseDpiScale;

                if (double.IsNaN(newValue) ||
                    double.IsInfinity(newValue) ||
                    NumberHelper.AreClose(newValue, double.MaxValue))
                {
                    newValue = value;
                }
            }
            else
            {
                newValue = value;
            }

            return newValue;
        }
    }
}