use crate::{Axis, LayoutLen, Painter, Size};
use std::any::Any;

mod data;
mod handle;
mod like;
mod size_rule;
mod tag;
mod view;
mod widgets;

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

pub trait Widget: Any {
    /// Draws the widget, and returns what it used of the box it was given.
    fn draw(&mut self, painter: &mut Painter) -> Size;

    /// An exact length the widget can give without a painter or its children.
    /// Optional, and saves a draw rather than changing one: a hint that
    /// disagrees with the eventual draw fails a debug assertion.
    fn size_hint(&self, _axis: Axis) -> Option<LayoutLen> {
        None
    }
}

impl Widget for () {
    /// A gap: nothing drawn, at the default length, so a span gives it a share.
    fn draw(&mut self, _: &mut Painter) -> Size {
        Size::default()
    }

    fn size_hint(&self, _axis: Axis) -> Option<LayoutLen> {
        Some(LayoutLen::default())
    }
}

impl dyn Widget {
    pub fn as_any(&self) -> &dyn Any {
        self
    }

    pub fn as_any_mut(&mut self) -> &mut dyn Any {
        self
    }
}

/// 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<State, W: Widget + ?Sized>: FnOnce(&mut State) -> W {}
impl<State, W: Widget + ?Sized, F: FnOnce(&mut State) -> W> WidgetFn<State, W> for F {}

pub struct WidgetArr<const LEN: usize> {
    pub arr: [StrongWidget; LEN],
}

impl<const LEN: usize> WidgetArr<LEN> {
    pub fn new(arr: [StrongWidget; LEN]) -> Self {
        Self { arr }
    }
}

pub trait WidgetOption<State> {
    fn get(self, state: &mut State) -> Option<StrongWidget>;
}

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

impl<State, F: FnOnce(&mut State) -> Option<StrongWidget>> WidgetOption<State> for F {
    fn get(self, state: &mut State) -> Option<StrongWidget> {
        self(state)
    }
}