use crate::layout::{Len, Painter, SizeCtx, Ui};
use std::{any::Any, marker::PhantomData};

mod id;
mod like;
mod tag;
mod widgets;

pub use id::*;
pub use like::*;
pub use tag::*;
pub use widgets::*;

pub trait Widget: Any {
    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>: FnOnce(&mut Ui) -> W {}
impl<W: Widget, F: FnOnce(&mut Ui) -> W> WidgetFn<W> for F {}

pub struct WidgetArr<const LEN: usize, Ws> {
    pub arr: [WidgetId; LEN],
    _pd: PhantomData<Ws>,
}

impl<const LEN: usize, Ws> WidgetArr<LEN, Ws> {
    pub fn new(arr: [WidgetId; LEN]) -> Self {
        Self {
            arr,
            _pd: PhantomData,
        }
    }
}

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

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

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