use crate::*;
use super::*;

pub enum Collect<'a, E: Engine, const N: usize> {
    Callback(CallbackCollection<'a, E>),
    //Iterator(IteratorCollection<'a, E>),
    Array(ArrayCollection<'a, E, N>),
    Slice(SliceCollection<'a, E>),
}

impl<'a, E: Engine, const N: usize> Collect<'a, E, N> {
    pub fn iter (&'a self) -> CollectIterator<'a, E, N> {
        CollectIterator(0, &self)
    }
}

impl<'a, E: Engine, const N: usize> From<CallbackCollection<'a, E>> for Collect<'a, E, N> {
    fn from (callback: CallbackCollection<'a, E>) -> Self {
        Self::Callback(callback)
    }
}

impl<'a, E: Engine, const N: usize> From<SliceCollection<'a, E>> for Collect<'a, E, N> {
    fn from (slice: SliceCollection<'a, E>) -> Self {
        Self::Slice(slice)
    }
}

impl<'a, E: Engine, const N: usize> From<ArrayCollection<'a, E, N>> for Collect<'a, E, N>{
    fn from (array: ArrayCollection<'a, E, N>) -> Self {
        Self::Array(array)
    }
}

type CallbackCollection<'a, E> =
    &'a dyn Fn(&'a mut dyn FnMut(&dyn Render<E>)->Usually<()>);

//type IteratorCollection<'a, E> =
    //&'a mut dyn Iterator<Item = dyn Render<E>>;

type SliceCollection<'a, E> =
    &'a [&'a dyn Render<E>];

type ArrayCollection<'a, E, const N: usize> =
    [&'a dyn Render<E>; N];

pub struct CollectIterator<'a, E: Engine, const N: usize>(usize, &'a Collect<'a, E, N>);

impl<'a, E: Engine, const N: usize> Iterator for CollectIterator<'a, E, N> {
    type Item = &'a dyn Render<E>;
    fn next (&mut self) -> Option<Self::Item> {
        match self.1 {
            Collect::Callback(callback) => {
                todo!()
            },
            //Collection::Iterator(iterator) => {
                //iterator.next()
            //},
            Collect::Array(array) => {
                if let Some(item) = array.get(self.0) {
                    self.0 += 1;
                    //Some(item)
                    None
                } else {
                    None
                }
            }
            Collect::Slice(slice) => {
                if let Some(item) = slice.get(self.0) {
                    self.0 += 1;
                    //Some(item)
                    None
                } else {
                    None
                }
            }
        }
    }
}