use crate::*;
use std::sync::{Arc, atomic::{AtomicUsize, Ordering::Relaxed}};
//use ratatui::prelude::{Style, Color};

// TODO: 🡘  🡙 ←🡙→ indicator to expand window when too small

pub trait HasSize<E: Engine> {
    fn size (&self) -> &Measure<E>;
}

#[macro_export] macro_rules! has_size {
    (<$E:ty>|$self:ident:$Struct:ident$(<$($L:lifetime),*$($T:ident$(:$U:path)?),*>)?|$cb:expr) => {
        impl $(<$($L),*$($T $(: $U)?),*>)? HasSize<$E> for $Struct $(<$($L),*$($T),*>)? {
            fn size (&$self) -> &Measure<$E> { $cb }
        }
    }
}

/// A widget that tracks its render width and height
#[derive(Default)]
pub struct Measure<E: Engine> {
    _engine: PhantomData<E>,
    pub x: Arc<AtomicUsize>,
    pub y: Arc<AtomicUsize>,
}

impl<E: Engine> Content<E> for Measure<E> {
    fn render (&self, to: &mut E::Output) {
        self.x.store(to.area().w().into(), Relaxed);
        self.y.store(to.area().h().into(), Relaxed);
    }
}

impl<E: Engine> Clone for Measure<E> {
    fn clone (&self) -> Self {
        Self {
            _engine: Default::default(),
            x: self.x.clone(),
            y: self.y.clone(),
        }
    }
}

impl<E: Engine> std::fmt::Debug for Measure<E> {
    fn fmt (&self, f: &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error> {
        f.debug_struct("Measure")
            .field("width",  &self.x)
            .field("height", &self.y)
            .finish()
    }
}

impl<E: Engine> Measure<E> {
    pub fn w (&self) -> usize { self.x.load(Relaxed) }
    pub fn h (&self) -> usize { self.y.load(Relaxed) }
    pub fn wh (&self) -> [usize;2] { [self.w(), self.h()] }
    pub fn set_w (&self, w: impl Into<usize>) { self.x.store(w.into(), Relaxed) }
    pub fn set_h (&self, h: impl Into<usize>) { self.y.store(h.into(), Relaxed) }
    pub fn set_wh (&self, w: impl Into<usize>, h: impl Into<usize>) { self.set_w(w); self.set_h(h); }
    pub fn format (&self) -> String { format!("{}x{}", self.w(), self.h()) }
    pub fn new () -> Self {
        Self {
            _engine: PhantomData::default(),
            x: Arc::new(0.into()),
            y: Arc::new(0.into()),
        }
    }
    pub fn of <T: Content<E>> (&self, item: T) -> Bsp<E, Fill<E, &Self>, T> {
        Bsp::b(Fill::xy(&self), item)
    }
}

///// A scrollable area.
//pub struct Scroll<E, F>(pub F, pub Direction, pub u64, PhantomData<E>)
//where
    //E: Engine,
    //F: Send + Sync + Fn(&mut dyn FnMut(&dyn Content<E>)->Usually<()>)->Usually<()>;

//pub trait ContentDebug<E: Engine> {
    //fn debug <W: Content<E>> (other: W) -> DebugOverlay<E, W> {
        //DebugOverlay(Default::default(), other)
    //}
//}

//impl<E: Engine> ContentDebug<E> for E {}

//impl Render<Tui> for Measure<Tui> {
    //fn min_size (&self, _: [u16;2]) -> Perhaps<[u16;2]> {
        //Ok(Some([0u16.into(), 0u16.into()].into()))
    //}
    //fn render (&self, to: &mut TuiOut) -> Usually<()> {
        //self.set_w(to.area().w());
        //self.set_h(to.area().h());
        //Ok(())
    //}
//}

//impl Measure<Tui> {
    //pub fn debug (&self) -> ShowMeasure {
        //ShowMeasure(&self)
    //}
//}

//render!(<Tui>|self: ShowMeasure<'a>|render(|to: &mut TuiOut|Ok({
    //let w = self.0.w();
    //let h = self.0.h();
    //to.blit(&format!(" {w} x {h} "), to.area.x(), to.area.y(), Some(
        //Style::default().bold().italic().bg(Color::Rgb(255, 0, 255)).fg(Color::Rgb(0,0,0))
    //))
//})));

//pub struct ShowMeasure<'a>(&'a Measure<Tui>);

//pub struct DebugOverlay<E: Engine, W: Render<E>>(PhantomData<E>, pub W);

//impl<T: Render<Tui>> Render<Tui> for DebugOverlay<Tui, T> {
    //fn min_size (&self, to: [u16;2]) -> Perhaps<[u16;2]> {
        //self.1.min_size(to)
    //}
    //fn render (&self, to: &mut TuiOut) -> Usually<()> {
        //let [x, y, w, h] = to.area();
        //self.1.render(to)?;
        //Ok(to.blit(&format!("{w}x{h}+{x}+{y}"), x, y, Some(Style::default().green())))
    //}
//}