use crate::{
    subscription::{EventStream, Recipe},
    Event, Hasher,
};
use iced_futures::futures::future;
use iced_futures::futures::StreamExt;
use iced_futures::BoxStream;

pub struct Events<Message> {
    pub(super) f: fn(Event) -> Option<Message>,
}

impl<Message> Recipe<Hasher, Event> for Events<Message>
where
    Message: 'static + Send,
{
    type Output = Message;

    fn hash(&self, state: &mut Hasher) {
        use std::hash::Hash;

        struct Marker;
        std::any::TypeId::of::<Marker>().hash(state);
        self.f.hash(state);
    }

    fn stream(
        self: Box<Self>,
        event_stream: EventStream,
    ) -> BoxStream<Self::Output> {
        event_stream
            .filter_map(move |event| future::ready((self.f)(event)))
            .boxed()
    }
}