use crate::*;

/// Defines an enum that parametrically transforms its content
/// along either the X axis, the Y axis, or both.
macro_rules! transform_xy_unit {
    (|$self:ident : $Enum:ident, $to:ident|$layout:expr) => {
        pub enum $Enum<U, T> { X(U, T), Y(U, T), XY(U, U, T), }
        impl<U, T> $Enum<U, T> {
            pub fn x (x: U, item: T) -> Self { Self::X(x, item) }
            pub fn y (y: U, item: T) -> Self { Self::Y(y, item) }
            pub fn xy (x: U, y: U, item: T) -> Self { Self::XY(x, y, item) }
        }
        impl<U: Copy + Coordinate, T> $Enum<U, T> {
            pub fn dx (&self) -> U {
                match self {
                    Self::X(x, _)     => *x,
                    Self::Y(_, _)     => 0.into(),
                    Self::XY(x, _, _) => *x,
                }
            }
            pub fn dy (&self) -> U {
                match self {
                    Self::X(_, _) => 0.into(),
                    Self::Y(y, _) => *y,
                    Self::XY(_, y, _) => *y,
                }
            }
        }
        impl<E: Output, T: Content<E>> Content<E> for $Enum<E::Unit, T> {
            fn content (&self) -> impl Render<E> {
                Some(match self {
                    Self::X(_, content)     => content,
                    Self::Y(_, content)     => content,
                    Self::XY(_, _, content) => content,
                })
            }
            fn layout (&$self, $to: E::Area) -> E::Area {
                $layout.into()
            }
        }
    }
}

transform_xy_unit!(|self: Fixed, area|{
    let [x, y, w, h] = area.xywh();
    let fixed_area = match self {
        Self::X(fw, _) => [x, y, *fw, h],
        Self::Y(fh, _) => [x, y, w, *fh],
        Self::XY(fw, fh, _) => [x, y, *fw, *fh],
    };
    let [x, y, w, h] = Render::layout(&self.content(), fixed_area.into()).xywh();
    let fixed_area = match self {
        Self::X(fw, _) => [x, y, *fw, h],
        Self::Y(fh, _) => [x, y, w, *fh],
        Self::XY(fw, fh, _) => [x, y, *fw, *fh],
    };
    fixed_area
});
transform_xy_unit!(|self: Min, area|{
    let area = Render::layout(&self.content(), area);
    match self {
        Self::X(mw, _)      => [area.x(), area.y(), area.w().max(*mw), area.h()],
        Self::Y(mh, _)      => [area.x(), area.y(), area.w(),          area.h().max(*mh)],
        Self::XY(mw, mh, _) => [area.x(), area.y(), area.w().max(*mw), area.h().max(*mh)]
    }});
transform_xy_unit!(|self: Max, area|{
    let [x, y, w, h] = area.xywh();
    Render::layout(&self.content(), match self {
        Self::X(fw, _) => [x, y, *fw, h],
        Self::Y(fh, _) => [x, y, w, *fh],
        Self::XY(fw, fh, _) => [x, y, *fw, *fh],
    }.into())});

transform_xy_unit!(|self: Shrink, area|Render::layout(&self.content(), [
    area.x(), area.y(), area.w().minus(self.dx()), area.h().minus(self.dy())
].into()));
transform_xy_unit!(|self: Expand, area|Render::layout(&self.content(), [
    area.x(), area.y(), area.w() + self.dx(), area.h() + self.dy()
].into()));
transform_xy_unit!(|self: Push, area|{
    let area = Render::layout(&self.content(), area);
    [area.x() + self.dx(), area.y() + self.dy(), area.w(), area.h()]
});
transform_xy_unit!(|self: Pull, area|{
    let area = Render::layout(&self.content(), area);
    [area.x().minus(self.dx()), area.y().minus(self.dy()), area.w(), area.h()]
});
transform_xy_unit!(|self: Margin, area|{
    let area = Render::layout(&self.content(), area);
    let dx = self.dx();
    let dy = self.dy();
    [area.x().minus(dx), area.y().minus(dy), area.w() + dy + dy, area.h() + dy + dy]
});
transform_xy_unit!(|self: Padding, area|{
    let area = Render::layout(&self.content(), area);
    let dx = self.dx();
    let dy = self.dy();
    [area.x() + dx, area.y() + dy, area.w().minus(dy + dy), area.h().minus(dy + dy), ]
});