//! Aligns things to the container. Comes with caveats.
//! ```
//! let four = ||Fixed::<TuiOut, _, _>::xy(4, 4, unit);
//! test(area, &Align::nw(four()), [10, 10, 4, 4]);
//! test(area, &Align::n(four()),  [18, 10, 4, 4]);
//! test(area, &Align::ne(four()), [26, 10, 4, 4]);
//! test(area, &Align::e(four()),  [26, 18, 4, 4]);
//! test(area, &Align::se(four()), [26, 26, 4, 4]);
//! test(area, &Align::s(four()),  [18, 26, 4, 4]);
//! test(area, &Align::sw(four()), [10, 26, 4, 4]);
//! test(area, &Align::w(four()),  [10, 18, 4, 4]);
//! let two_by_four = ||Fixed::<TuiOut, _, _>::xy(4, 2, unit);
//! test(area, &Align::nw(two_by_four()), [10, 10, 4, 2]);
//! test(area, &Align::n(two_by_four()),  [18, 10, 4, 2]);
//! test(area, &Align::ne(two_by_four()), [26, 10, 4, 2]);
//! test(area, &Align::e(two_by_four()),  [26, 19, 4, 2]);
//! test(area, &Align::se(two_by_four()), [26, 28, 4, 2]);
//! test(area, &Align::s(two_by_four()),  [18, 28, 4, 2]);
//! test(area, &Align::sw(two_by_four()), [10, 28, 4, 2]);
//! test(area, &Align::w(two_by_four()),  [10, 19, 4, 2]);
//! ```
use crate::*;
#[derive(Debug, Copy, Clone, Default)] pub enum Alignment { #[default] Center, X, Y, NW, N, NE, E, SE, S, SW, W }
pub struct Align<A>(Alignment, A);
try_from_expr!(<'a, E>: Align<RenderBox<'a, E>>: |state, iter|
    if let Some(Token { value: Value::Key(key), .. }) = iter.peek() {
        match key {
            "align/c"|"align/x"|"align/y"|
            "align/n"|"align/s"|"align/e"|"align/w"|
            "align/nw"|"align/sw"|"align/ne"|"align/se" => {
                let _ = iter.next().unwrap();
                let c = iter.next().expect("no content specified");
                let c = state.get_content(&c.value).expect("no content provided");
                return Some(match key {
                    "align/c"  => Self::c(c),
                    "align/x"  => Self::x(c),
                    "align/y"  => Self::y(c),
                    "align/n"  => Self::n(c),
                    "align/s"  => Self::s(c),
                    "align/e"  => Self::e(c),
                    "align/w"  => Self::w(c),
                    "align/nw" => Self::nw(c),
                    "align/ne" => Self::ne(c),
                    "align/sw" => Self::sw(c),
                    "align/se" => Self::se(c),
                    _ => unreachable!()
                })
            },
            _ => return None
        }
    });
impl<A> Align<A> {
    pub fn c  (a: A) -> Self { Self(Alignment::Center, a) }
    pub fn x  (a: A) -> Self { Self(Alignment::X,      a) }
    pub fn y  (a: A) -> Self { Self(Alignment::Y,      a) }
    pub fn n  (a: A) -> Self { Self(Alignment::N,      a) }
    pub fn s  (a: A) -> Self { Self(Alignment::S,      a) }
    pub fn e  (a: A) -> Self { Self(Alignment::E,      a) }
    pub fn w  (a: A) -> Self { Self(Alignment::W,      a) }
    pub fn nw (a: A) -> Self { Self(Alignment::NW,     a) }
    pub fn sw (a: A) -> Self { Self(Alignment::SW,     a) }
    pub fn ne (a: A) -> Self { Self(Alignment::NE,     a) }
    pub fn se (a: A) -> Self { Self(Alignment::SE,     a) }
}
impl<E: Output, A: Content<E>> Content<E> for Align<A> {
    fn content (&self) -> impl Render<E> {
        &self.1
    }
    fn layout (&self, on: E::Area) -> E::Area {
        use Alignment::*;
        let it = Render::layout(&self.content(), on).xywh();
        let cx = on.x()+(on.w().minus(it.w())/2.into());
        let cy = on.y()+(on.h().minus(it.h())/2.into());
        let fx = (on.x()+on.w()).minus(it.w());
        let fy = (on.y()+on.h()).minus(it.h());
        let [x, y] = match self.0 {
            Center => [cx, cy],
            X =>  [cx, it.y()],
            Y =>  [it.x(), cy],
            NW => [on.x(), on.y()],
            N  => [cx,     on.y()],
            NE => [fx,     on.y()],
            W  => [on.x(), cy],
            E  => [fx,     cy],
            SW => [on.x(), fy],
            S  => [cx,     fy],
            SE => [fx,     fy],
        }.into();
        [x, y, it.w(), it.h()].into()
    }
    fn render (&self, to: &mut E) {
        to.place(Content::layout(self, to.area()), &self.content())
    }
}