use crate::*;
use std::sync::{Arc, atomic::{AtomicUsize, Ordering::Relaxed}};

pub trait HasSize<E: Output> {
    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: Output> {
    _engine: PhantomData<E>,
    pub x: Arc<AtomicUsize>,
    pub y: Arc<AtomicUsize>,
}

// TODO: 🡘  🡙 ←🡙→ indicator to expand window when too small
impl<E: Output> Content<E> for Measure<E> {
    fn render (&self, to: &mut E) {
        self.x.store(to.area().w().into(), Relaxed);
        self.y.store(to.area().h().into(), Relaxed);
    }
}

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

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