use crate::{
    ActiveData, Event, EventCtx, EventFn, EventIdCtx, EventLike, HasEvents, IdLike, LayerId,
    Widget, WidgetEventFn, WidgetId, WidgetRef,
    util::{HashMap, HashSet, TypeMap},
};
use std::{any::TypeId, rc::Rc};

pub struct EventManager<Rsc> {
    widget_to_types: HashMap<WidgetId, HashSet<TypeId>>,
    types: TypeMap<dyn EventManagerLike<Rsc>>,
}

impl<Rsc> Default for EventManager<Rsc> {
    fn default() -> Self {
        Self {
            widget_to_types: Default::default(),
            types: Default::default(),
        }
    }
}

impl<Rsc: HasEvents + 'static> EventManager<Rsc> {
    pub fn get_type<E: EventLike>(&mut self) -> &mut TypeEventManager<Rsc, E::Event> {
        self.types.type_or_default()
    }

    pub fn register<W: Widget + ?Sized, E: EventLike>(
        &mut self,
        id: WidgetRef<W>,
        event: E,
        f: impl WidgetEventFn<Rsc, <E::Event as Event>::Data, W>,
    ) {
        self.get_type::<E>().register(id, event, f);
        self.widget_to_types
            .entry(id.id())
            .or_default()
            .insert(Self::type_key::<E>());
    }

    pub fn type_key<E: EventLike>() -> TypeId {
        TypeId::of::<TypeEventManager<Rsc, E::Event>>()
    }
}

pub trait EventsLike {
    fn remove(&mut self, id: WidgetId);
    fn draw(&mut self, active: &ActiveData);
    fn undraw(&mut self, active: &ActiveData);
}

impl<Rsc: HasEvents + 'static> EventsLike for EventManager<Rsc> {
    fn remove(&mut self, id: WidgetId) {
        for t in self.widget_to_types.get(&id).into_flat_iter() {
            self.types.get_mut(t).unwrap().remove(id);
        }
    }

    fn draw(&mut self, active: &ActiveData) {
        for t in self.widget_to_types.get(&active.id).into_flat_iter() {
            self.types.get_mut(t).unwrap().draw(active);
        }
    }

    fn undraw(&mut self, active: &ActiveData) {
        for t in self.widget_to_types.get(&active.id).into_flat_iter() {
            self.types.get_mut(t).unwrap().undraw(active);
        }
    }
}

pub trait EventManagerLike<State> {
    fn remove(&mut self, id: WidgetId);
    fn draw(&mut self, data: &ActiveData);
    fn undraw(&mut self, data: &ActiveData);
}

type EventData<Rsc, E> = (E, Rc<dyn EventFn<Rsc, <E as Event>::Data>>);
pub struct TypeEventManager<Rsc: HasEvents, E: Event> {
    // TODO: reduce visiblity!!
    pub active: HashMap<LayerId, HashMap<WidgetId, E::State>>,
    map: HashMap<WidgetId, Vec<EventData<Rsc, E>>>,
}

impl<Rsc: HasEvents, E: Event> EventManagerLike<Rsc> for TypeEventManager<Rsc, E> {
    fn remove(&mut self, id: WidgetId) {
        self.map.remove(&id);
        for layer in self.active.values_mut() {
            layer.remove(&id);
        }
    }
    fn draw(&mut self, data: &ActiveData) {
        self.active
            .entry(data.layer)
            .or_default()
            .entry(data.id)
            .or_default();
    }
    fn undraw(&mut self, data: &ActiveData) {
        if let Some(layer) = self.active.get_mut(&data.layer) {
            layer.remove(&data.id);
        }
    }
}

impl<Rsc: HasEvents, E: Event> Default for TypeEventManager<Rsc, E> {
    fn default() -> Self {
        Self {
            active: Default::default(),
            map: Default::default(),
        }
    }
}

impl<Rsc: HasEvents + 'static, E: Event> TypeEventManager<Rsc, E> {
    fn register<W: Widget + ?Sized>(
        &mut self,
        widget: WidgetRef<W>,
        event: impl EventLike<Event = E>,
        f: impl WidgetEventFn<Rsc, E::Data, W>,
    ) {
        let event = event.into_event();
        self.map.entry(widget.id()).or_default().push((
            event,
            Rc::new(move |ctx, rsc| {
                f(
                    EventIdCtx {
                        widget,
                        state: ctx.state,
                        data: ctx.data,
                    },
                    rsc,
                );
            }),
        ));
    }

    pub fn run_fn<'a>(
        &mut self,
        id: impl IdLike,
    ) -> impl FnOnce(EventCtx<'_, Rsc, E::Data>, &mut Rsc) + 'a {
        let fs = self.map.get(&id.id()).cloned().unwrap_or_default();
        move |ctx, rsc| {
            for (e, f) in fs {
                if let Some(data) = e.should_run(&ctx.data) {
                    f(
                        EventCtx {
                            state: ctx.state,
                            data,
                        },
                        rsc,
                    )
                }
            }
        }
    }
}