use crate::{Painter, Ui, WidgetId, WidgetIdFnRet};
use std::{any::Any, marker::PhantomData};

pub trait Widget<Ctx>: Any {
    fn draw(&self, painter: Painter<Ctx>);
}

pub struct WidgetTag;
pub struct FnTag;

pub trait WidgetLike<Ctx, Tag> {
    type Widget: 'static;
    fn add(self, ui: &mut Ui<Ctx>) -> WidgetId<Self::Widget>;
    fn with_id<W2>(
        self,
        f: impl FnOnce(&mut Ui<Ctx>, WidgetId<Self::Widget>) -> WidgetId<W2>,
    ) -> WidgetIdFnRet!(W2, Ctx)
    where
        Self: Sized,
    {
        move |ui| {
            let id = self.add(ui);
            f(ui, id)
        }
    }
}

// pub trait WidgetFn<W: Widget<Ctx>, Ctx> = FnOnce(&mut Ui<Ctx>) -> W;

/// 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
/// currently a macro for rust analyzer (doesn't support trait aliases atm)
macro_rules! WidgetFnRet {
    ($W:ty, $Ctx:ty) => {
        impl FnOnce(&mut $crate::Ui<$Ctx>) -> $W
    };
}
pub(crate) use WidgetFnRet;

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

impl<W: Widget<Ctx>, Ctx> WidgetLike<Ctx, WidgetTag> for W {
    type Widget = W;
    fn add(self, ui: &mut Ui<Ctx>) -> WidgetId<W> {
        ui.add_widget(self)
    }
}

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 struct ArrTag;
pub trait WidgetArrLike<const LEN: usize, Ctx, Tags> {
    type Ws;
    fn ui(self, ui: &mut Ui<Ctx>) -> WidgetArr<LEN, Self::Ws>;
}

impl<const LEN: usize, Ws, Ctx> WidgetArrLike<LEN, Ctx, ArrTag> for WidgetArr<LEN, Ws> {
    type Ws = Ws;
    fn ui(self, _: &mut Ui<Ctx>) -> WidgetArr<LEN, Ws> {
        self
    }
}

impl<W: WidgetLike<Ctx, WidgetTag>, Ctx> WidgetArrLike<1, Ctx, WidgetTag> for W {
    type Ws = (W::Widget,);
    fn ui(self, ui: &mut Ui<Ctx>) -> WidgetArr<1, (W::Widget,)> {
        WidgetArr::new([self.add(ui).erase_type()])
    }
}

// I hate this language it's so bad why do I even use it
macro_rules! impl_widget_arr {
    ($n:expr;$($W:ident)*) => {
        impl_widget_arr!($n;$($W)*;$(${concat($W,Tag)})*);
    };
    ($n:expr;$($W:ident)*;$($Tag:ident)*) => {
        impl<$($W: WidgetLike<Ctx, $Tag>,$Tag,)* Ctx> WidgetArrLike<$n, Ctx, ($($Tag,)*)> for ($($W,)*) {
            type Ws = ($($W::Widget,)*);
            fn ui(self, ui: &mut Ui<Ctx>) -> WidgetArr<$n, ($($W::Widget,)*)> {
                #[allow(non_snake_case)]
                let ($($W,)*) = self;
                WidgetArr::new(
                    [$($W.add(ui).cast_type(),)*],
                )
            }
        }
    };
}

impl_widget_arr!(1;A);
impl_widget_arr!(2;A B);
impl_widget_arr!(3;A B C);
impl_widget_arr!(4;A B C D);
impl_widget_arr!(5;A B C D E);
impl_widget_arr!(6;A B C D E F);
impl_widget_arr!(7;A B C D E F G);
impl_widget_arr!(8;A B C D E F G H);
impl_widget_arr!(9;A B C D E F G H I);
impl_widget_arr!(10;A B C D E F G H I J);
impl_widget_arr!(11;A B C D E F G H I J K);
impl_widget_arr!(12;A B C D E F G H I J K L);