mod data;
mod handle;
mod like;
mod tag;
mod widgets;

pub use data::*;
pub use handle::*;
pub use like::*;
pub use tag::*;
pub use widgets::*;

use crate::layout::{Len, Painter, SizeCtx, Ui};

pub trait Widget: 'static + Send + Sync {
    fn draw(&mut self, painter: &mut Painter);
    fn desired_width(&mut self, ctx: &mut SizeCtx) -> Len;
    fn desired_height(&mut self, ctx: &mut SizeCtx) -> Len;
}

impl Widget for () {
    fn draw(&mut self, _: &mut Painter) {}
    fn desired_width(&mut self, _: &mut SizeCtx) -> Len {
        Len::ZERO
    }
    fn desired_height(&mut self, _: &mut SizeCtx) -> Len {
        Len::ZERO
    }
}

/// A function that returns a widget given a UI.
/// Useful for defining trait functions on widgets that create a parent widget so that the children
/// don't need to be IDs yet
pub trait WidgetFn<W: Widget + ?Sized>: FnOnce(&mut Ui) -> W {}
impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetFn<W> for F {}

impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetLike<FnTag> for F {
    type Widget = W;
    fn add(self, ui: &mut Ui) -> WidgetHandle<W> {
        self(ui).add(ui)
    }
}

impl<W: Widget> WidgetLike<WidgetTag> for W {
    type Widget = W;
    fn add(self, _: &mut Ui) -> WidgetHandle<W> {
        WIDGETS.insert(self)
    }
}

pub trait WidgetOption {
    fn get(self, ui: &mut Ui) -> Option<WidgetHandle>;
}

impl WidgetOption for () {
    fn get(self, _: &mut Ui) -> Option<WidgetHandle> {
        None
    }
}

impl<F: FnOnce(&mut Ui) -> Option<WidgetHandle>> WidgetOption for F {
    fn get(self, ui: &mut Ui) -> Option<WidgetHandle> {
        self(ui)
    }
}