use crate::*;

/// Draws items from an iterator.
pub struct Map<O, A, B, I, F, G>
where
    I: Iterator<Item = A> + Send + Sync,
    F: Fn() -> I + Send + Sync,
{
    __: PhantomData<(O, B)>,
    /// Function that returns iterator over stacked components
    get_iter: F,
    /// Function that returns each stacked component
    get_item: G,
}

impl<'a, O, A, B, I, F, G> Map<O, A, B, I, F, G> where
    I: Iterator<Item = A> + Send + Sync + 'a,
    F: Fn() -> I + Send + Sync + 'a,
{
    pub const fn new (get_iter: F, get_item: G) -> Self {
        Self {
            __: PhantomData,
            get_iter,
            get_item
        }
    }
}

macro_rules! impl_map_direction (($name:ident, $axis:ident, $align:ident)=>{
    impl<'a, O, A, B, I, F> Map<
        O, A, Push<O::Unit, Align<Fixed<O::Unit, Fill<B>>>>, I, F, fn(A, usize)->B
    > where
        O: Out,
        B: Draw<O> + Layout<O>,
        I: Iterator<Item = A> + Send + Sync + 'a,
        F: Fn() -> I + Send + Sync + 'a
    {
        pub const fn $name (
            size:     O::Unit,
            get_iter: F,
            get_item: impl Fn(A, usize)->B + Send + Sync
        ) -> Map<
            O, A,
            Push<O::Unit, Align<Fixed<O::Unit, B>>>,
            I, F,
            impl Fn(A, usize)->Push<O::Unit, Align<Fixed<O::Unit, B>>> + Send + Sync
        > {
            Map {
                __: PhantomData,
                get_iter,
                get_item: move |item: A, index: usize|{
                    // FIXME: multiply
                    let mut push: O::Unit = O::Unit::from(0u16);
                    for _ in 0..index {
                        push = push + size;
                    }
                    Push::$axis(push, Align::$align(Fixed::$axis(size, get_item(item, index))))
                }
            }
        }
    }
});

impl_map_direction!(east,  x, w);
impl_map_direction!(south, y, n);
impl_map_direction!(west,  x, e);
impl_map_direction!(north, y, s);

impl<'a, O, A, B, I, F, G> Layout<O> for Map<O, A, B, I, F, G> where
    O: Out,
    B: Draw<O> + Layout<O>,
    I: Iterator<Item = A> + Send + Sync + 'a,
    F: Fn() -> I + Send + Sync + 'a,
    G: Fn(A, usize)->B + Send + Sync
{
    fn layout (&self, area: O::Area) -> O::Area {
        let Self { get_iter, get_item, .. } = self;
        let mut index = 0;
        let [mut min_x, mut min_y] = area.center();
        let [mut max_x, mut max_y] = area.center();
        for item in get_iter() {
            let [x,y,w,h] = get_item(item, index).layout(area).xywh();
            min_x = min_x.min(x.into());
            min_y = min_y.min(y.into());
            max_x = max_x.max((x + w).into());
            max_y = max_y.max((y + h).into());
            index += 1;
        }
        let w = max_x - min_x;
        let h = max_y - min_y;
        //[min_x.into(), min_y.into(), w.into(), h.into()].into()
        area.center_xy([w.into(), h.into()].into()).into()
    }
}
impl<'a, O, A, B, I, F, G> Draw<O> for Map<O, A, B, I, F, G> where
    O: Out,
    B: Draw<O> + Layout<O>,
    I: Iterator<Item = A> + Send + Sync + 'a,
    F: Fn() -> I + Send + Sync + 'a,
    G: Fn(A, usize)->B + Send + Sync
{
    fn draw (&self, to: &mut O) {
        let Self { get_iter, get_item, .. } = self;
        let mut index = 0;
        let area = self.layout(to.area());
        for item in get_iter() {
            let item = get_item(item, index);
            //to.place_at(area.into(), &item);
            to.place_at(item.layout(area), &item);
            index += 1;
        }
    }
}

#[inline] pub fn map_south<O: Out>(
    item_offset: O::Unit,
    item_height: O::Unit,
    item: impl Draw<O> + Layout<O>
) -> impl Draw<O> + Layout<O> {
    Push::y(item_offset, Fixed::y(item_height, Fill::x(item)))
}

#[inline] pub fn map_south_west<O: Out>(
    item_offset: O::Unit,
    item_height: O::Unit,
    item: impl Draw<O> + Layout<O>
) -> impl Draw<O> + Layout<O> {
    Push::y(item_offset, Align::nw(Fixed::y(item_height, Fill::x(item))))
}

#[inline] pub fn map_east<O: Out>(
    item_offset: O::Unit,
    item_width:  O::Unit,
    item: impl Draw<O> + Layout<O>
) -> impl Draw<O> + Layout<O> {
    Push::x(item_offset, Align::w(Fixed::x(item_width, Fill::y(item))))
}