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//! Change the message type of an element

use std::marker::PhantomData;

use euclid::Size2D;

use crate::{
    event::Event, unit::Cell, view::element::ViewExt as _, Printer,
    View as ViewTrait,
};

/// The view itself
pub struct View<V, O, F> {
    inner: V,
    inner_m: PhantomData<O>,
    map: F,
}

impl<V, O, F> View<V, O, F> {
    pub fn new<T>(view: V, map: F) -> Self
    where
        V: ViewTrait<T, O>,
    {
        Self {
            inner: view,
            inner_m: PhantomData,
            map,
        }
    }
}

/// Shorthand for [`View::new()`]
///
/// [`View::new()`]: View::new
pub fn new<V, T, O, F>(view: V, map: F) -> View<V, O, F>
where
    V: ViewTrait<T, O>,
{
    View::new(view, map)
}

impl<T, M, O, V, F> ViewTrait<T, M> for View<V, O, F>
where
    V: ViewTrait<T, O>,
    F: Fn(O) -> M,
    F: Clone + 'static,
    M: 'static,
    O: 'static,
{
    fn draw(&self, printer: &Printer, focused: bool) {
        self.inner.draw(printer, focused);
    }

    fn width(&self) -> Size2D<u16, Cell> {
        self.inner.width()
    }

    fn height(&self) -> Size2D<u16, Cell> {
        self.inner.height()
    }

    fn layout(&self, constraint: Size2D<u16, Cell>) -> Size2D<u16, Cell> {
        self.inner.layout(constraint)
    }

    fn event(
        &mut self,
        event: &Event<T>,
        focused: bool,
    ) -> Box<dyn Iterator<Item = M>> {
        let f = self.map.clone();

        let x = Iterator::map(self.inner.event(event, focused), move |m| f(m));

        Box::new(x)
    }

    fn interactive(&self) -> bool {
        self.inner.interactive()
    }
}

pub trait ViewExt<'a, T, O, M, F>
where
    F: Fn(O) -> M,
    F: Clone + 'static,
    M: 'static,
    O: 'static,
{
    fn map(self, f: F) -> super::element::View<'a, T, M>
    where
        Self: ViewTrait<T, O> + Sized + 'a,
    {
        View::new(self, f).into_element()
    }
}

impl<'a, T, O, M, F, V> ViewExt<'a, T, O, M, F> for V
where
    F: Fn(O) -> M,
    F: Clone + 'static,
    M: 'static,
    O: 'static,
{
}