use crate::*;

/// Defines an enum that transforms its content
/// along either the X axis, the Y axis, or both.
///
/// The `_Unused` variant wraps the `Output` type
/// using `PhantomData` to permit the double generic.
macro_rules! transform_xy {
    ($self:ident : $Enum:ident |$to:ident|$area:expr) => {
        pub enum $Enum<T> { X(T), Y(T), XY(T) }
        impl<T> $Enum<T> {
            pub fn x (item: T)  -> Self { Self::X(item) }
            pub fn y (item: T)  -> Self { Self::Y(item) }
            pub fn xy (item: T) -> Self { Self::XY(item) }
        }
        impl<E: Output, T: Content<E>> Content<E> for $Enum<T> {
            fn content (&self) -> impl Render<E> {
                match self {
                    Self::X(item)  => item,
                    Self::Y(item)  => item,
                    Self::XY(item) => item
                }
            }
            fn layout (&$self, $to: <E as Output>::Area) -> <E as Output>::Area {
                use $Enum::*;
                $area
            }
        }
    }
}

transform_xy!(self: Fill |to|{
    let [x0, y0, wmax, hmax] = to.xywh();
    let [x, y, w, h] = self.content().layout(to).xywh();
    match self {
        X(_)  => [x0, y, wmax, h],
        Y(_)  => [x, y0, w, hmax],
        XY(_) => [x0, y0, wmax, hmax],
    }.into()
});