use crate::{
    point, px, Action, AnyDrag, AnyElement, AnyTooltip, AnyView, AppContext, BorrowAppContext,
    BorrowWindow, Bounds, ClickEvent, DispatchPhase, Element, ElementId, FocusHandle, IntoElement,
    IsZero, KeyContext, KeyDownEvent, KeyUpEvent, LayoutId, MouseButton, MouseDownEvent,
    MouseMoveEvent, MouseUpEvent, ParentElement, Pixels, Point, Render, ScrollWheelEvent,
    SharedString, Size, StackingOrder, Style, StyleRefinement, Styled, Task, View, Visibility,
    WindowContext,
};

use collections::HashMap;
use refineable::Refineable;
use smallvec::SmallVec;
use std::{
    any::{Any, TypeId},
    cell::RefCell,
    cmp::Ordering,
    fmt::Debug,
    marker::PhantomData,
    mem,
    rc::Rc,
    time::Duration,
};
use taffy::style::Overflow;
use util::ResultExt;

const DRAG_THRESHOLD: f64 = 2.;
const TOOLTIP_DELAY: Duration = Duration::from_millis(500);

pub struct GroupStyle {
    pub group: SharedString,
    pub style: Box<StyleRefinement>,
}

pub struct DragMoveEvent<T> {
    pub event: MouseMoveEvent,
    pub bounds: Bounds<Pixels>,
    drag: PhantomData<T>,
}

impl<T: 'static> DragMoveEvent<T> {
    pub fn drag<'b>(&self, cx: &'b AppContext) -> &'b T {
        cx.active_drag
            .as_ref()
            .and_then(|drag| drag.value.downcast_ref::<T>())
            .expect("DragMoveEvent is only valid when the stored active drag is of the same type.")
    }
}

impl Interactivity {
    pub fn on_mouse_down(
        &mut self,
        button: MouseButton,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_down_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble
                    && event.button == button
                    && bounds.visibly_contains(&event.position, cx)
                {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn capture_any_mouse_down(
        &mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_down_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Capture && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn on_any_mouse_down(
        &mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_down_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn on_mouse_up(
        &mut self,
        button: MouseButton,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_up_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble
                    && event.button == button
                    && bounds.visibly_contains(&event.position, cx)
                {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn capture_any_mouse_up(
        &mut self,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_up_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Capture && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn on_any_mouse_up(
        &mut self,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_up_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn on_mouse_down_out(
        &mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_down_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Capture && !bounds.visibly_contains(&event.position, cx)
                {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn on_mouse_up_out(
        &mut self,
        button: MouseButton,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_up_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Capture
                    && event.button == button
                    && !bounds.visibly_contains(&event.position, cx)
                {
                    (listener)(event, cx);
                }
            }));
    }

    pub fn on_mouse_move(
        &mut self,
        listener: impl Fn(&MouseMoveEvent, &mut WindowContext) + 'static,
    ) {
        self.mouse_move_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx);
                }
            }));
    }

    pub fn on_drag_move<T>(
        &mut self,
        listener: impl Fn(&DragMoveEvent<T>, &mut WindowContext) + 'static,
    ) where
        T: 'static,
    {
        self.mouse_move_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Capture
                    && cx
                        .active_drag
                        .as_ref()
                        .is_some_and(|drag| drag.value.as_ref().type_id() == TypeId::of::<T>())
                {
                    (listener)(
                        &DragMoveEvent {
                            event: event.clone(),
                            bounds: bounds.bounds,
                            drag: PhantomData,
                        },
                        cx,
                    );
                }
            }));
    }

    pub fn on_scroll_wheel(
        &mut self,
        listener: impl Fn(&ScrollWheelEvent, &mut WindowContext) + 'static,
    ) {
        self.scroll_wheel_listeners
            .push(Box::new(move |event, bounds, phase, cx| {
                if phase == DispatchPhase::Bubble && bounds.visibly_contains(&event.position, cx) {
                    (listener)(event, cx);
                }
            }));
    }

    pub fn capture_action<A: Action>(
        &mut self,
        listener: impl Fn(&A, &mut WindowContext) + 'static,
    ) {
        self.action_listeners.push((
            TypeId::of::<A>(),
            Box::new(move |action, phase, cx| {
                let action = action.downcast_ref().unwrap();
                if phase == DispatchPhase::Capture {
                    (listener)(action, cx)
                }
            }),
        ));
    }

    pub fn on_action<A: Action>(&mut self, listener: impl Fn(&A, &mut WindowContext) + 'static) {
        self.action_listeners.push((
            TypeId::of::<A>(),
            Box::new(move |action, phase, cx| {
                let action = action.downcast_ref().unwrap();
                if phase == DispatchPhase::Bubble {
                    (listener)(action, cx)
                }
            }),
        ));
    }

    pub fn on_boxed_action(
        &mut self,
        action: &dyn Action,
        listener: impl Fn(&Box<dyn Action>, &mut WindowContext) + 'static,
    ) {
        let action = action.boxed_clone();
        self.action_listeners.push((
            (*action).type_id(),
            Box::new(move |_, phase, cx| {
                if phase == DispatchPhase::Bubble {
                    (listener)(&action, cx)
                }
            }),
        ));
    }

    pub fn on_key_down(&mut self, listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static) {
        self.key_down_listeners
            .push(Box::new(move |event, phase, cx| {
                if phase == DispatchPhase::Bubble {
                    (listener)(event, cx)
                }
            }));
    }

    pub fn capture_key_down(
        &mut self,
        listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static,
    ) {
        self.key_down_listeners
            .push(Box::new(move |event, phase, cx| {
                if phase == DispatchPhase::Capture {
                    listener(event, cx)
                }
            }));
    }

    pub fn on_key_up(&mut self, listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static) {
        self.key_up_listeners
            .push(Box::new(move |event, phase, cx| {
                if phase == DispatchPhase::Bubble {
                    listener(event, cx)
                }
            }));
    }

    pub fn capture_key_up(&mut self, listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static) {
        self.key_up_listeners
            .push(Box::new(move |event, phase, cx| {
                if phase == DispatchPhase::Capture {
                    listener(event, cx)
                }
            }));
    }

    pub fn on_drop<T: 'static>(&mut self, listener: impl Fn(&T, &mut WindowContext) + 'static) {
        self.drop_listeners.push((
            TypeId::of::<T>(),
            Box::new(move |dragged_value, cx| {
                listener(dragged_value.downcast_ref().unwrap(), cx);
            }),
        ));
    }

    pub fn can_drop(&mut self, predicate: impl Fn(&dyn Any, &mut WindowContext) -> bool + 'static) {
        self.can_drop_predicate = Some(Box::new(predicate));
    }

    pub fn on_click(&mut self, listener: impl Fn(&ClickEvent, &mut WindowContext) + 'static)
    where
        Self: Sized,
    {
        self.click_listeners
            .push(Box::new(move |event, cx| listener(event, cx)));
    }

    pub fn on_drag<T, W>(
        &mut self,
        value: T,
        constructor: impl Fn(&T, &mut WindowContext) -> View<W> + 'static,
    ) where
        Self: Sized,
        T: 'static,
        W: 'static + Render,
    {
        debug_assert!(
            self.drag_listener.is_none(),
            "calling on_drag more than once on the same element is not supported"
        );
        self.drag_listener = Some((
            Box::new(value),
            Box::new(move |value, cx| constructor(value.downcast_ref().unwrap(), cx).into()),
        ));
    }

    pub fn on_hover(&mut self, listener: impl Fn(&bool, &mut WindowContext) + 'static)
    where
        Self: Sized,
    {
        debug_assert!(
            self.hover_listener.is_none(),
            "calling on_hover more than once on the same element is not supported"
        );
        self.hover_listener = Some(Box::new(listener));
    }

    pub fn tooltip(&mut self, build_tooltip: impl Fn(&mut WindowContext) -> AnyView + 'static)
    where
        Self: Sized,
    {
        debug_assert!(
            self.tooltip_builder.is_none(),
            "calling tooltip more than once on the same element is not supported"
        );
        self.tooltip_builder = Some(Rc::new(build_tooltip));
    }

    pub fn block_mouse(&mut self) {
        self.block_mouse = true;
    }
}

pub trait InteractiveElement: Sized {
    fn interactivity(&mut self) -> &mut Interactivity;

    fn group(mut self, group: impl Into<SharedString>) -> Self {
        self.interactivity().group = Some(group.into());
        self
    }

    fn id(mut self, id: impl Into<ElementId>) -> Stateful<Self> {
        self.interactivity().element_id = Some(id.into());

        Stateful { element: self }
    }

    fn track_focus(mut self, focus_handle: &FocusHandle) -> Focusable<Self> {
        self.interactivity().focusable = true;
        self.interactivity().tracked_focus_handle = Some(focus_handle.clone());
        Focusable { element: self }
    }

    fn key_context<C, E>(mut self, key_context: C) -> Self
    where
        C: TryInto<KeyContext, Error = E>,
        E: Debug,
    {
        if let Some(key_context) = key_context.try_into().log_err() {
            self.interactivity().key_context = Some(key_context);
        }
        self
    }

    fn hover(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self {
        debug_assert!(
            self.interactivity().hover_style.is_none(),
            "hover style already set"
        );
        self.interactivity().hover_style = Some(Box::new(f(StyleRefinement::default())));
        self
    }

    fn group_hover(
        mut self,
        group_name: impl Into<SharedString>,
        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
    ) -> Self {
        self.interactivity().group_hover_style = Some(GroupStyle {
            group: group_name.into(),
            style: Box::new(f(StyleRefinement::default())),
        });
        self
    }

    fn on_mouse_down(
        mut self,
        button: MouseButton,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_mouse_down(button, listener);
        self
    }

    fn capture_any_mouse_down(
        mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().capture_any_mouse_down(listener);
        self
    }

    fn on_any_mouse_down(
        mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_any_mouse_down(listener);
        self
    }

    fn on_mouse_up(
        mut self,
        button: MouseButton,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_mouse_up(button, listener);
        self
    }

    fn capture_any_mouse_up(
        mut self,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().capture_any_mouse_up(listener);
        self
    }

    fn on_mouse_down_out(
        mut self,
        listener: impl Fn(&MouseDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_mouse_down_out(listener);
        self
    }

    fn on_mouse_up_out(
        mut self,
        button: MouseButton,
        listener: impl Fn(&MouseUpEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_mouse_up_out(button, listener);
        self
    }

    fn on_mouse_move(
        mut self,
        listener: impl Fn(&MouseMoveEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_mouse_move(listener);
        self
    }

    fn on_drag_move<T: 'static>(
        mut self,
        listener: impl Fn(&DragMoveEvent<T>, &mut WindowContext) + 'static,
    ) -> Self
    where
        T: 'static,
    {
        self.interactivity().on_drag_move(listener);
        self
    }

    fn on_scroll_wheel(
        mut self,
        listener: impl Fn(&ScrollWheelEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_scroll_wheel(listener);
        self
    }

    /// Capture the given action, before normal action dispatch can fire
    fn capture_action<A: Action>(
        mut self,
        listener: impl Fn(&A, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().capture_action(listener);
        self
    }

    /// Add a listener for the given action, fires during the bubble event phase
    fn on_action<A: Action>(mut self, listener: impl Fn(&A, &mut WindowContext) + 'static) -> Self {
        self.interactivity().on_action(listener);
        self
    }

    fn on_boxed_action(
        mut self,
        action: &dyn Action,
        listener: impl Fn(&Box<dyn Action>, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_boxed_action(action, listener);
        self
    }

    fn on_key_down(
        mut self,
        listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().on_key_down(listener);
        self
    }

    fn capture_key_down(
        mut self,
        listener: impl Fn(&KeyDownEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().capture_key_down(listener);
        self
    }

    fn on_key_up(mut self, listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static) -> Self {
        self.interactivity().on_key_up(listener);
        self
    }

    fn capture_key_up(
        mut self,
        listener: impl Fn(&KeyUpEvent, &mut WindowContext) + 'static,
    ) -> Self {
        self.interactivity().capture_key_up(listener);
        self
    }

    fn drag_over<S: 'static>(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self {
        self.interactivity()
            .drag_over_styles
            .push((TypeId::of::<S>(), f(StyleRefinement::default())));
        self
    }

    fn group_drag_over<S: 'static>(
        mut self,
        group_name: impl Into<SharedString>,
        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
    ) -> Self {
        self.interactivity().group_drag_over_styles.push((
            TypeId::of::<S>(),
            GroupStyle {
                group: group_name.into(),
                style: Box::new(f(StyleRefinement::default())),
            },
        ));
        self
    }

    fn on_drop<T: 'static>(mut self, listener: impl Fn(&T, &mut WindowContext) + 'static) -> Self {
        self.interactivity().on_drop(listener);
        self
    }

    fn can_drop(
        mut self,
        predicate: impl Fn(&dyn Any, &mut WindowContext) -> bool + 'static,
    ) -> Self {
        self.interactivity().can_drop(predicate);
        self
    }

    fn block_mouse(mut self) -> Self {
        self.interactivity().block_mouse();
        self
    }
}

pub trait StatefulInteractiveElement: InteractiveElement {
    fn focusable(mut self) -> Focusable<Self> {
        self.interactivity().focusable = true;
        Focusable { element: self }
    }

    fn overflow_scroll(mut self) -> Self {
        self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
        self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
        self
    }

    fn overflow_x_scroll(mut self) -> Self {
        self.interactivity().base_style.overflow.x = Some(Overflow::Scroll);
        self
    }

    fn overflow_y_scroll(mut self) -> Self {
        self.interactivity().base_style.overflow.y = Some(Overflow::Scroll);
        self
    }

    fn track_scroll(mut self, scroll_handle: &ScrollHandle) -> Self {
        self.interactivity().scroll_handle = Some(scroll_handle.clone());
        self
    }

    fn active(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
    where
        Self: Sized,
    {
        self.interactivity().active_style = Some(Box::new(f(StyleRefinement::default())));
        self
    }

    fn group_active(
        mut self,
        group_name: impl Into<SharedString>,
        f: impl FnOnce(StyleRefinement) -> StyleRefinement,
    ) -> Self
    where
        Self: Sized,
    {
        self.interactivity().group_active_style = Some(GroupStyle {
            group: group_name.into(),
            style: Box::new(f(StyleRefinement::default())),
        });
        self
    }

    fn on_click(mut self, listener: impl Fn(&ClickEvent, &mut WindowContext) + 'static) -> Self
    where
        Self: Sized,
    {
        self.interactivity().on_click(listener);
        self
    }

    fn on_drag<T, W>(
        mut self,
        value: T,
        constructor: impl Fn(&T, &mut WindowContext) -> View<W> + 'static,
    ) -> Self
    where
        Self: Sized,
        T: 'static,
        W: 'static + Render,
    {
        self.interactivity().on_drag(value, constructor);
        self
    }

    fn on_hover(mut self, listener: impl Fn(&bool, &mut WindowContext) + 'static) -> Self
    where
        Self: Sized,
    {
        self.interactivity().on_hover(listener);
        self
    }

    fn tooltip(mut self, build_tooltip: impl Fn(&mut WindowContext) -> AnyView + 'static) -> Self
    where
        Self: Sized,
    {
        self.interactivity().tooltip(build_tooltip);
        self
    }
}

pub trait FocusableElement: InteractiveElement {
    fn focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
    where
        Self: Sized,
    {
        self.interactivity().focus_style = Some(Box::new(f(StyleRefinement::default())));
        self
    }

    fn in_focus(mut self, f: impl FnOnce(StyleRefinement) -> StyleRefinement) -> Self
    where
        Self: Sized,
    {
        self.interactivity().in_focus_style = Some(Box::new(f(StyleRefinement::default())));
        self
    }
}

pub type MouseDownListener =
    Box<dyn Fn(&MouseDownEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;
pub type MouseUpListener =
    Box<dyn Fn(&MouseUpEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;

pub type MouseMoveListener =
    Box<dyn Fn(&MouseMoveEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;

pub type ScrollWheelListener =
    Box<dyn Fn(&ScrollWheelEvent, &InteractiveBounds, DispatchPhase, &mut WindowContext) + 'static>;

pub type ClickListener = Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>;

pub type DragListener = Box<dyn Fn(&dyn Any, &mut WindowContext) -> AnyView + 'static>;

type DropListener = Box<dyn Fn(&dyn Any, &mut WindowContext) + 'static>;

type CanDropPredicate = Box<dyn Fn(&dyn Any, &mut WindowContext) -> bool + 'static>;

pub type TooltipBuilder = Rc<dyn Fn(&mut WindowContext) -> AnyView + 'static>;

pub type KeyDownListener = Box<dyn Fn(&KeyDownEvent, DispatchPhase, &mut WindowContext) + 'static>;

pub type KeyUpListener = Box<dyn Fn(&KeyUpEvent, DispatchPhase, &mut WindowContext) + 'static>;

pub type DragEventListener = Box<dyn Fn(&MouseMoveEvent, &mut WindowContext) + 'static>;

pub type ActionListener = Box<dyn Fn(&dyn Any, DispatchPhase, &mut WindowContext) + 'static>;

#[track_caller]
pub fn div() -> Div {
    #[cfg(debug_assertions)]
    let interactivity = {
        let mut interactivity = Interactivity::default();
        interactivity.location = Some(*core::panic::Location::caller());
        interactivity
    };

    #[cfg(not(debug_assertions))]
    let interactivity = Interactivity::default();

    Div {
        interactivity,
        children: SmallVec::default(),
    }
}

pub struct Div {
    interactivity: Interactivity,
    children: SmallVec<[AnyElement; 2]>,
}

impl Styled for Div {
    fn style(&mut self) -> &mut StyleRefinement {
        &mut self.interactivity.base_style
    }
}

impl InteractiveElement for Div {
    fn interactivity(&mut self) -> &mut Interactivity {
        &mut self.interactivity
    }
}

impl ParentElement for Div {
    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
        &mut self.children
    }
}

impl Element for Div {
    type State = DivState;

    fn request_layout(
        &mut self,
        element_state: Option<Self::State>,
        cx: &mut WindowContext,
    ) -> (LayoutId, Self::State) {
        let mut child_layout_ids = SmallVec::new();
        let (layout_id, interactive_state) = self.interactivity.layout(
            element_state.map(|s| s.interactive_state),
            cx,
            |style, cx| {
                cx.with_text_style(style.text_style().cloned(), |cx| {
                    child_layout_ids = self
                        .children
                        .iter_mut()
                        .map(|child| child.request_layout(cx))
                        .collect::<SmallVec<_>>();
                    cx.request_layout(&style, child_layout_ids.iter().copied())
                })
            },
        );
        (
            layout_id,
            DivState {
                interactive_state,
                child_layout_ids,
            },
        )
    }

    fn paint(
        &mut self,
        bounds: Bounds<Pixels>,
        element_state: &mut Self::State,
        cx: &mut WindowContext,
    ) {
        let mut child_min = point(Pixels::MAX, Pixels::MAX);
        let mut child_max = Point::default();
        let content_size = if element_state.child_layout_ids.is_empty() {
            bounds.size
        } else if let Some(scroll_handle) = self.interactivity.scroll_handle.as_ref() {
            let mut state = scroll_handle.0.borrow_mut();
            state.child_bounds = Vec::with_capacity(element_state.child_layout_ids.len());
            state.bounds = bounds;
            let requested = state.requested_scroll_top.take();

            for (ix, child_layout_id) in element_state.child_layout_ids.iter().enumerate() {
                let child_bounds = cx.layout_bounds(*child_layout_id);
                child_min = child_min.min(&child_bounds.origin);
                child_max = child_max.max(&child_bounds.lower_right());
                state.child_bounds.push(child_bounds);

                if let Some(requested) = requested.as_ref() {
                    if requested.0 == ix {
                        *state.offset.borrow_mut() =
                            bounds.origin - (child_bounds.origin - point(px(0.), requested.1));
                    }
                }
            }
            (child_max - child_min).into()
        } else {
            for child_layout_id in &element_state.child_layout_ids {
                let child_bounds = cx.layout_bounds(*child_layout_id);
                child_min = child_min.min(&child_bounds.origin);
                child_max = child_max.max(&child_bounds.lower_right());
            }
            (child_max - child_min).into()
        };

        self.interactivity.paint(
            bounds,
            content_size,
            &mut element_state.interactive_state,
            cx,
            |_style, scroll_offset, cx| {
                cx.with_element_offset(scroll_offset, |cx| {
                    for child in &mut self.children {
                        child.paint(cx);
                    }
                })
            },
        );
    }
}

impl IntoElement for Div {
    type Element = Self;

    fn element_id(&self) -> Option<ElementId> {
        self.interactivity.element_id.clone()
    }

    fn into_element(self) -> Self::Element {
        self
    }
}

pub struct DivState {
    child_layout_ids: SmallVec<[LayoutId; 2]>,
    interactive_state: InteractiveElementState,
}

impl DivState {
    pub fn is_active(&self) -> bool {
        self.interactive_state
            .pending_mouse_down
            .as_ref()
            .map_or(false, |pending| pending.borrow().is_some())
    }
}

#[derive(Default)]
pub struct Interactivity {
    pub element_id: Option<ElementId>,
    pub key_context: Option<KeyContext>,
    pub focusable: bool,
    pub tracked_focus_handle: Option<FocusHandle>,
    pub scroll_handle: Option<ScrollHandle>,
    pub group: Option<SharedString>,
    pub base_style: Box<StyleRefinement>,
    pub focus_style: Option<Box<StyleRefinement>>,
    pub in_focus_style: Option<Box<StyleRefinement>>,
    pub hover_style: Option<Box<StyleRefinement>>,
    pub group_hover_style: Option<GroupStyle>,
    pub active_style: Option<Box<StyleRefinement>>,
    pub group_active_style: Option<GroupStyle>,
    pub drag_over_styles: Vec<(TypeId, StyleRefinement)>,
    pub group_drag_over_styles: Vec<(TypeId, GroupStyle)>,
    pub mouse_down_listeners: Vec<MouseDownListener>,
    pub mouse_up_listeners: Vec<MouseUpListener>,
    pub mouse_move_listeners: Vec<MouseMoveListener>,
    pub scroll_wheel_listeners: Vec<ScrollWheelListener>,
    pub key_down_listeners: Vec<KeyDownListener>,
    pub key_up_listeners: Vec<KeyUpListener>,
    pub action_listeners: Vec<(TypeId, ActionListener)>,
    pub drop_listeners: Vec<(TypeId, DropListener)>,
    pub can_drop_predicate: Option<CanDropPredicate>,
    pub click_listeners: Vec<ClickListener>,
    pub drag_listener: Option<(Box<dyn Any>, DragListener)>,
    pub hover_listener: Option<Box<dyn Fn(&bool, &mut WindowContext)>>,
    pub tooltip_builder: Option<TooltipBuilder>,
    pub block_mouse: bool,

    #[cfg(debug_assertions)]
    pub location: Option<core::panic::Location<'static>>,
}

#[derive(Clone, Debug)]
pub struct InteractiveBounds {
    pub bounds: Bounds<Pixels>,
    pub stacking_order: StackingOrder,
}

impl InteractiveBounds {
    pub fn visibly_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
        self.bounds.contains(point) && cx.was_top_layer(point, &self.stacking_order)
    }

    pub fn drag_target_contains(&self, point: &Point<Pixels>, cx: &WindowContext) -> bool {
        self.bounds.contains(point)
            && cx.was_top_layer_under_active_drag(point, &self.stacking_order)
    }
}

impl Interactivity {
    pub fn layout(
        &mut self,
        element_state: Option<InteractiveElementState>,
        cx: &mut WindowContext,
        f: impl FnOnce(Style, &mut WindowContext) -> LayoutId,
    ) -> (LayoutId, InteractiveElementState) {
        let mut element_state = element_state.unwrap_or_default();

        if cx.has_active_drag() {
            if let Some(pending_mouse_down) = element_state.pending_mouse_down.as_ref() {
                *pending_mouse_down.borrow_mut() = None;
            }
            if let Some(clicked_state) = element_state.clicked_state.as_ref() {
                *clicked_state.borrow_mut() = ElementClickedState::default();
            }
        }

        // Ensure we store a focus handle in our element state if we're focusable.
        // If there's an explicit focus handle we're tracking, use that. Otherwise
        // create a new handle and store it in the element state, which lives for as
        // as frames contain an element with this id.
        if self.focusable {
            element_state.focus_handle.get_or_insert_with(|| {
                self.tracked_focus_handle
                    .clone()
                    .unwrap_or_else(|| cx.focus_handle())
            });
        }

        if let Some(scroll_handle) = self.scroll_handle.as_ref() {
            element_state.scroll_offset = Some(scroll_handle.0.borrow().offset.clone());
        }

        let style = self.compute_style(None, &mut element_state, cx);
        let layout_id = f(style, cx);
        (layout_id, element_state)
    }

    pub fn paint(
        &mut self,
        bounds: Bounds<Pixels>,
        content_size: Size<Pixels>,
        element_state: &mut InteractiveElementState,
        cx: &mut WindowContext,
        f: impl FnOnce(&Style, Point<Pixels>, &mut WindowContext),
    ) {
        let style = self.compute_style(Some(bounds), element_state, cx);
        let z_index = style.z_index.unwrap_or(0);

        let paint_hover_group_handler = |cx: &mut WindowContext| {
            let hover_group_bounds = self
                .group_hover_style
                .as_ref()
                .and_then(|group_hover| GroupBounds::get(&group_hover.group, cx));

            if let Some(group_bounds) = hover_group_bounds {
                let hovered = group_bounds.contains(&cx.mouse_position());
                cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
                    if phase == DispatchPhase::Capture
                        && group_bounds.contains(&event.position) != hovered
                    {
                        cx.refresh();
                    }
                });
            }
        };

        if style.visibility == Visibility::Hidden {
            cx.with_z_index(z_index, |cx| paint_hover_group_handler(cx));
            return;
        }

        cx.with_z_index(z_index, |cx| {
            style.paint(bounds, cx, |cx| {
                cx.with_text_style(style.text_style().cloned(), |cx| {
                    cx.with_content_mask(style.overflow_mask(bounds, cx.rem_size()), |cx| {
                        #[cfg(debug_assertions)]
                        if self.element_id.is_some()
                            && (style.debug
                                || style.debug_below
                                || cx.has_global::<crate::DebugBelow>())
                            && bounds.contains(&cx.mouse_position())
                        {
                            const FONT_SIZE: crate::Pixels = crate::Pixels(10.);
                            let element_id = format!("{:?}", self.element_id.as_ref().unwrap());
                            let str_len = element_id.len();

                            let render_debug_text = |cx: &mut WindowContext| {
                                if let Some(text) = cx
                                    .text_system()
                                    .shape_text(
                                        element_id.into(),
                                        FONT_SIZE,
                                        &[cx.text_style().to_run(str_len)],
                                        None,
                                    )
                                    .ok()
                                    .and_then(|mut text| text.pop())
                                {
                                    text.paint(bounds.origin, FONT_SIZE, cx).ok();

                                    let text_bounds = crate::Bounds {
                                        origin: bounds.origin,
                                        size: text.size(FONT_SIZE),
                                    };
                                    if self.location.is_some()
                                        && text_bounds.contains(&cx.mouse_position())
                                        && cx.modifiers().command
                                    {
                                        let command_held = cx.modifiers().command;
                                        cx.on_key_event({
                                            move |e: &crate::ModifiersChangedEvent, _phase, cx| {
                                                if e.modifiers.command != command_held
                                                    && text_bounds.contains(&cx.mouse_position())
                                                {
                                                    cx.refresh();
                                                }
                                            }
                                        });

                                        let hovered = bounds.contains(&cx.mouse_position());
                                        cx.on_mouse_event(
                                            move |event: &MouseMoveEvent, phase, cx| {
                                                if phase == DispatchPhase::Capture
                                                    && bounds.contains(&event.position) != hovered
                                                {
                                                    cx.refresh();
                                                }
                                            },
                                        );

                                        cx.on_mouse_event({
                                            let location = self.location.unwrap();
                                            move |e: &crate::MouseDownEvent, phase, cx| {
                                                if text_bounds.contains(&e.position)
                                                    && phase.capture()
                                                {
                                                    cx.stop_propagation();
                                                    let Ok(dir) = std::env::current_dir() else {
                                                        return;
                                                    };

                                                    eprintln!(
                                                        "This element was created at:\n{}:{}:{}",
                                                        dir.join(location.file()).to_string_lossy(),
                                                        location.line(),
                                                        location.column()
                                                    );
                                                }
                                            }
                                        });
                                        cx.paint_quad(crate::outline(
                                            crate::Bounds {
                                                origin: bounds.origin
                                                    + crate::point(
                                                        crate::px(0.),
                                                        FONT_SIZE - px(2.),
                                                    ),
                                                size: crate::Size {
                                                    width: text_bounds.size.width,
                                                    height: crate::px(1.),
                                                },
                                            },
                                            crate::red(),
                                        ))
                                    }
                                }
                            };

                            cx.with_z_index(1, |cx| {
                                cx.with_text_style(
                                    Some(crate::TextStyleRefinement {
                                        color: Some(crate::red()),
                                        line_height: Some(FONT_SIZE.into()),
                                        background_color: Some(crate::white()),
                                        ..Default::default()
                                    }),
                                    render_debug_text,
                                )
                            });
                        }

                        let interactive_bounds = InteractiveBounds {
                            bounds: bounds.intersect(&cx.content_mask().bounds),
                            stacking_order: cx.stacking_order().clone(),
                        };

                        if self.block_mouse
                            || style.background.as_ref().is_some_and(|fill| {
                                fill.color().is_some_and(|color| !color.is_transparent())
                            })
                        {
                            cx.add_opaque_layer(interactive_bounds.bounds);
                        }

                        if !cx.has_active_drag() {
                            if let Some(mouse_cursor) = style.mouse_cursor {
                                let mouse_position = &cx.mouse_position();
                                let hovered =
                                    interactive_bounds.visibly_contains(mouse_position, cx);
                                if hovered {
                                    cx.set_cursor_style(mouse_cursor);
                                }
                            }
                        }

                        // If this element can be focused, register a mouse down listener
                        // that will automatically transfer focus when hitting the element.
                        // This behavior can be suppressed by using `cx.prevent_default()`.
                        if let Some(focus_handle) = element_state.focus_handle.clone() {
                            cx.on_mouse_event({
                                let interactive_bounds = interactive_bounds.clone();
                                move |event: &MouseDownEvent, phase, cx| {
                                    if phase == DispatchPhase::Bubble
                                        && !cx.default_prevented()
                                        && interactive_bounds.visibly_contains(&event.position, cx)
                                    {
                                        cx.focus(&focus_handle);
                                        // If there is a parent that is also focusable, prevent it
                                        // from transferring focus because we already did so.
                                        cx.prevent_default();
                                    }
                                }
                            });
                        }

                        for listener in self.mouse_down_listeners.drain(..) {
                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |event: &MouseDownEvent, phase, cx| {
                                listener(event, &interactive_bounds, phase, cx);
                            })
                        }

                        for listener in self.mouse_up_listeners.drain(..) {
                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |event: &MouseUpEvent, phase, cx| {
                                listener(event, &interactive_bounds, phase, cx);
                            })
                        }

                        for listener in self.mouse_move_listeners.drain(..) {
                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
                                listener(event, &interactive_bounds, phase, cx);
                            })
                        }

                        for listener in self.scroll_wheel_listeners.drain(..) {
                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
                                listener(event, &interactive_bounds, phase, cx);
                            })
                        }

                        paint_hover_group_handler(cx);

                        if self.hover_style.is_some()
                            || self.base_style.mouse_cursor.is_some()
                            || cx.active_drag.is_some() && !self.drag_over_styles.is_empty()
                        {
                            let bounds = bounds.intersect(&cx.content_mask().bounds);
                            let hovered = bounds.contains(&cx.mouse_position());
                            cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
                                if phase == DispatchPhase::Capture
                                    && bounds.contains(&event.position) != hovered
                                {
                                    cx.refresh();
                                }
                            });
                        }

                        let mut drag_listener = mem::take(&mut self.drag_listener);
                        let drop_listeners = mem::take(&mut self.drop_listeners);
                        let click_listeners = mem::take(&mut self.click_listeners);
                        let can_drop_predicate = mem::take(&mut self.can_drop_predicate);

                        if !drop_listeners.is_empty() {
                            cx.on_mouse_event({
                                let interactive_bounds = interactive_bounds.clone();
                                move |event: &MouseUpEvent, phase, cx| {
                                    if let Some(drag) = &cx.active_drag {
                                        if phase == DispatchPhase::Bubble
                                            && interactive_bounds
                                                .drag_target_contains(&event.position, cx)
                                        {
                                            let drag_state_type = drag.value.as_ref().type_id();
                                            for (drop_state_type, listener) in &drop_listeners {
                                                if *drop_state_type == drag_state_type {
                                                    let drag = cx.active_drag.take().expect(
                                                        "checked for type drag state type above",
                                                    );

                                                    let mut can_drop = true;
                                                    if let Some(predicate) = &can_drop_predicate {
                                                        can_drop =
                                                            predicate(drag.value.as_ref(), cx);
                                                    }

                                                    if can_drop {
                                                        listener(drag.value.as_ref(), cx);
                                                        cx.refresh();
                                                        cx.stop_propagation();
                                                    }
                                                }
                                            }
                                        }
                                    }
                                }
                            });
                        }

                        if !click_listeners.is_empty() || drag_listener.is_some() {
                            let pending_mouse_down = element_state
                                .pending_mouse_down
                                .get_or_insert_with(Default::default)
                                .clone();

                            let clicked_state = element_state
                                .clicked_state
                                .get_or_insert_with(Default::default)
                                .clone();

                            cx.on_mouse_event({
                                let interactive_bounds = interactive_bounds.clone();
                                let pending_mouse_down = pending_mouse_down.clone();
                                move |event: &MouseDownEvent, phase, cx| {
                                    if phase == DispatchPhase::Bubble
                                        && event.button == MouseButton::Left
                                        && interactive_bounds.visibly_contains(&event.position, cx)
                                    {
                                        *pending_mouse_down.borrow_mut() = Some(event.clone());
                                        cx.refresh();
                                    }
                                }
                            });

                            cx.on_mouse_event({
                                let pending_mouse_down = pending_mouse_down.clone();
                                move |event: &MouseMoveEvent, phase, cx| {
                                    if phase == DispatchPhase::Capture {
                                        return;
                                    }

                                    let mut pending_mouse_down = pending_mouse_down.borrow_mut();
                                    if let Some(mouse_down) = pending_mouse_down.clone() {
                                        if !cx.has_active_drag()
                                            && (event.position - mouse_down.position).magnitude()
                                                > DRAG_THRESHOLD
                                        {
                                            if let Some((drag_value, drag_listener)) =
                                                drag_listener.take()
                                            {
                                                *clicked_state.borrow_mut() =
                                                    ElementClickedState::default();
                                                let cursor_offset = event.position - bounds.origin;
                                                let drag = (drag_listener)(drag_value.as_ref(), cx);
                                                cx.active_drag = Some(AnyDrag {
                                                    view: drag,
                                                    value: drag_value,
                                                    cursor_offset,
                                                });
                                                pending_mouse_down.take();
                                                cx.refresh();
                                                cx.stop_propagation();
                                            }
                                        }
                                    }
                                }
                            });

                            cx.on_mouse_event({
                                let interactive_bounds = interactive_bounds.clone();
                                let mut captured_mouse_down = None;
                                move |event: &MouseUpEvent, phase, cx| match phase {
                                    // Clear the pending mouse down during the capture phase,
                                    // so that it happens even if another event handler stops
                                    // propagation.
                                    DispatchPhase::Capture => {
                                        let mut pending_mouse_down =
                                            pending_mouse_down.borrow_mut();
                                        if pending_mouse_down.is_some() {
                                            captured_mouse_down = pending_mouse_down.take();
                                            cx.refresh();
                                        }
                                    }
                                    // Fire click handlers during the bubble phase.
                                    DispatchPhase::Bubble => {
                                        if let Some(mouse_down) = captured_mouse_down.take() {
                                            if interactive_bounds
                                                .visibly_contains(&event.position, cx)
                                            {
                                                let mouse_click = ClickEvent {
                                                    down: mouse_down,
                                                    up: event.clone(),
                                                };
                                                for listener in &click_listeners {
                                                    listener(&mouse_click, cx);
                                                }
                                            }
                                        }
                                    }
                                }
                            });
                        }

                        if let Some(hover_listener) = self.hover_listener.take() {
                            let was_hovered = element_state
                                .hover_state
                                .get_or_insert_with(Default::default)
                                .clone();
                            let has_mouse_down = element_state
                                .pending_mouse_down
                                .get_or_insert_with(Default::default)
                                .clone();
                            let interactive_bounds = interactive_bounds.clone();

                            cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
                                if phase != DispatchPhase::Bubble {
                                    return;
                                }
                                let is_hovered = interactive_bounds
                                    .visibly_contains(&event.position, cx)
                                    && has_mouse_down.borrow().is_none()
                                    && !cx.has_active_drag();
                                let mut was_hovered = was_hovered.borrow_mut();

                                if is_hovered != *was_hovered {
                                    *was_hovered = is_hovered;
                                    drop(was_hovered);

                                    hover_listener(&is_hovered, cx);
                                }
                            });
                        }

                        if let Some(tooltip_builder) = self.tooltip_builder.take() {
                            let active_tooltip = element_state
                                .active_tooltip
                                .get_or_insert_with(Default::default)
                                .clone();
                            let pending_mouse_down = element_state
                                .pending_mouse_down
                                .get_or_insert_with(Default::default)
                                .clone();
                            let interactive_bounds = interactive_bounds.clone();

                            cx.on_mouse_event(move |event: &MouseMoveEvent, phase, cx| {
                                let is_hovered = interactive_bounds
                                    .visibly_contains(&event.position, cx)
                                    && pending_mouse_down.borrow().is_none();
                                if !is_hovered {
                                    active_tooltip.borrow_mut().take();
                                    return;
                                }

                                if phase != DispatchPhase::Bubble {
                                    return;
                                }

                                if active_tooltip.borrow().is_none() {
                                    let task = cx.spawn({
                                        let active_tooltip = active_tooltip.clone();
                                        let tooltip_builder = tooltip_builder.clone();

                                        move |mut cx| async move {
                                            cx.background_executor().timer(TOOLTIP_DELAY).await;
                                            cx.update(|_, cx| {
                                                active_tooltip.borrow_mut().replace(
                                                    ActiveTooltip {
                                                        tooltip: Some(AnyTooltip {
                                                            view: tooltip_builder(cx),
                                                            cursor_offset: cx.mouse_position(),
                                                        }),
                                                        _task: None,
                                                    },
                                                );
                                                cx.refresh();
                                            })
                                            .ok();
                                        }
                                    });
                                    active_tooltip.borrow_mut().replace(ActiveTooltip {
                                        tooltip: None,
                                        _task: Some(task),
                                    });
                                }
                            });

                            let active_tooltip = element_state
                                .active_tooltip
                                .get_or_insert_with(Default::default)
                                .clone();
                            cx.on_mouse_event(move |_: &MouseDownEvent, _, _| {
                                active_tooltip.borrow_mut().take();
                            });

                            if let Some(active_tooltip) = element_state
                                .active_tooltip
                                .get_or_insert_with(Default::default)
                                .borrow()
                                .as_ref()
                            {
                                if let Some(tooltip) = active_tooltip.tooltip.clone() {
                                    cx.set_tooltip(tooltip);
                                }
                            }
                        }

                        let active_state = element_state
                            .clicked_state
                            .get_or_insert_with(Default::default)
                            .clone();
                        if active_state.borrow().is_clicked() {
                            cx.on_mouse_event(move |_: &MouseUpEvent, phase, cx| {
                                if phase == DispatchPhase::Capture {
                                    *active_state.borrow_mut() = ElementClickedState::default();
                                    cx.refresh();
                                }
                            });
                        } else {
                            let active_group_bounds = self
                                .group_active_style
                                .as_ref()
                                .and_then(|group_active| GroupBounds::get(&group_active.group, cx));
                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |down: &MouseDownEvent, phase, cx| {
                                if phase == DispatchPhase::Bubble && !cx.default_prevented() {
                                    let group = active_group_bounds
                                        .map_or(false, |bounds| bounds.contains(&down.position));
                                    let element =
                                        interactive_bounds.visibly_contains(&down.position, cx);
                                    if group || element {
                                        *active_state.borrow_mut() =
                                            ElementClickedState { group, element };
                                        cx.refresh();
                                    }
                                }
                            });
                        }

                        let overflow = style.overflow;
                        if overflow.x == Overflow::Scroll || overflow.y == Overflow::Scroll {
                            if let Some(scroll_handle) = &self.scroll_handle {
                                scroll_handle.0.borrow_mut().overflow = overflow;
                            }

                            let scroll_offset = element_state
                                .scroll_offset
                                .get_or_insert_with(Rc::default)
                                .clone();
                            let line_height = cx.line_height();
                            let scroll_max = (content_size - bounds.size).max(&Size::default());
                            // Clamp scroll offset in case scroll max is smaller now (e.g., if children
                            // were removed or the bounds became larger).
                            {
                                let mut scroll_offset = scroll_offset.borrow_mut();
                                scroll_offset.x = scroll_offset.x.clamp(-scroll_max.width, px(0.));
                                scroll_offset.y = scroll_offset.y.clamp(-scroll_max.height, px(0.));
                            }

                            let interactive_bounds = interactive_bounds.clone();
                            cx.on_mouse_event(move |event: &ScrollWheelEvent, phase, cx| {
                                if phase == DispatchPhase::Bubble
                                    && interactive_bounds.visibly_contains(&event.position, cx)
                                {
                                    let mut scroll_offset = scroll_offset.borrow_mut();
                                    let old_scroll_offset = *scroll_offset;
                                    let delta = event.delta.pixel_delta(line_height);

                                    if overflow.x == Overflow::Scroll {
                                        let mut delta_x = Pixels::ZERO;
                                        if !delta.x.is_zero() {
                                            delta_x = delta.x;
                                        } else if overflow.y != Overflow::Scroll {
                                            delta_x = delta.y;
                                        }

                                        scroll_offset.x = (scroll_offset.x + delta_x)
                                            .clamp(-scroll_max.width, px(0.));
                                    }

                                    if overflow.y == Overflow::Scroll {
                                        let mut delta_y = Pixels::ZERO;
                                        if !delta.y.is_zero() {
                                            delta_y = delta.y;
                                        } else if overflow.x != Overflow::Scroll {
                                            delta_y = delta.x;
                                        }

                                        scroll_offset.y = (scroll_offset.y + delta_y)
                                            .clamp(-scroll_max.height, px(0.));
                                    }

                                    if *scroll_offset != old_scroll_offset {
                                        cx.refresh();
                                        cx.stop_propagation();
                                    }
                                }
                            });
                        }

                        if let Some(group) = self.group.clone() {
                            GroupBounds::push(group, bounds, cx);
                        }

                        let scroll_offset = element_state
                            .scroll_offset
                            .as_ref()
                            .map(|scroll_offset| *scroll_offset.borrow());

                        let key_down_listeners = mem::take(&mut self.key_down_listeners);
                        let key_up_listeners = mem::take(&mut self.key_up_listeners);
                        let action_listeners = mem::take(&mut self.action_listeners);
                        cx.with_key_dispatch(
                            self.key_context.clone(),
                            element_state.focus_handle.clone(),
                            |_, cx| {
                                for listener in key_down_listeners {
                                    cx.on_key_event(move |event: &KeyDownEvent, phase, cx| {
                                        listener(event, phase, cx);
                                    })
                                }

                                for listener in key_up_listeners {
                                    cx.on_key_event(move |event: &KeyUpEvent, phase, cx| {
                                        listener(event, phase, cx);
                                    })
                                }

                                for (action_type, listener) in action_listeners {
                                    cx.on_action(action_type, listener)
                                }

                                f(&style, scroll_offset.unwrap_or_default(), cx)
                            },
                        );

                        if let Some(group) = self.group.as_ref() {
                            GroupBounds::pop(group, cx);
                        }
                    });
                });
            });
        });
    }

    pub fn compute_style(
        &self,
        bounds: Option<Bounds<Pixels>>,
        element_state: &mut InteractiveElementState,
        cx: &mut WindowContext,
    ) -> Style {
        let mut style = Style::default();
        style.refine(&self.base_style);

        cx.with_z_index(style.z_index.unwrap_or(0), |cx| {
            if let Some(focus_handle) = self.tracked_focus_handle.as_ref() {
                if let Some(in_focus_style) = self.in_focus_style.as_ref() {
                    if focus_handle.within_focused(cx) {
                        style.refine(in_focus_style);
                    }
                }

                if let Some(focus_style) = self.focus_style.as_ref() {
                    if focus_handle.is_focused(cx) {
                        style.refine(focus_style);
                    }
                }
            }

            if let Some(bounds) = bounds {
                let mouse_position = cx.mouse_position();
                if !cx.has_active_drag() {
                    if let Some(group_hover) = self.group_hover_style.as_ref() {
                        if let Some(group_bounds) = GroupBounds::get(&group_hover.group, cx) {
                            if group_bounds.contains(&mouse_position)
                                && cx.was_top_layer(&mouse_position, cx.stacking_order())
                            {
                                style.refine(&group_hover.style);
                            }
                        }
                    }

                    if let Some(hover_style) = self.hover_style.as_ref() {
                        if bounds
                            .intersect(&cx.content_mask().bounds)
                            .contains(&mouse_position)
                            && cx.was_top_layer(&mouse_position, cx.stacking_order())
                        {
                            style.refine(hover_style);
                        }
                    }
                }

                if let Some(drag) = cx.active_drag.take() {
                    let mut can_drop = true;
                    if let Some(can_drop_predicate) = &self.can_drop_predicate {
                        can_drop = can_drop_predicate(drag.value.as_ref(), cx);
                    }

                    if can_drop {
                        for (state_type, group_drag_style) in &self.group_drag_over_styles {
                            if let Some(group_bounds) =
                                GroupBounds::get(&group_drag_style.group, cx)
                            {
                                if *state_type == drag.value.as_ref().type_id()
                                    && group_bounds.contains(&mouse_position)
                                {
                                    style.refine(&group_drag_style.style);
                                }
                            }
                        }

                        for (state_type, drag_over_style) in &self.drag_over_styles {
                            if *state_type == drag.value.as_ref().type_id()
                                && bounds
                                    .intersect(&cx.content_mask().bounds)
                                    .contains(&mouse_position)
                                && cx.was_top_layer_under_active_drag(
                                    &mouse_position,
                                    cx.stacking_order(),
                                )
                            {
                                style.refine(drag_over_style);
                            }
                        }
                    }

                    cx.active_drag = Some(drag);
                }
            }

            let clicked_state = element_state
                .clicked_state
                .get_or_insert_with(Default::default)
                .borrow();
            if clicked_state.group {
                if let Some(group) = self.group_active_style.as_ref() {
                    style.refine(&group.style)
                }
            }

            if let Some(active_style) = self.active_style.as_ref() {
                if clicked_state.element {
                    style.refine(active_style)
                }
            }
        });

        style
    }
}

#[derive(Default)]
pub struct InteractiveElementState {
    pub focus_handle: Option<FocusHandle>,
    pub clicked_state: Option<Rc<RefCell<ElementClickedState>>>,
    pub hover_state: Option<Rc<RefCell<bool>>>,
    pub pending_mouse_down: Option<Rc<RefCell<Option<MouseDownEvent>>>>,
    pub scroll_offset: Option<Rc<RefCell<Point<Pixels>>>>,
    pub active_tooltip: Option<Rc<RefCell<Option<ActiveTooltip>>>>,
}

pub struct ActiveTooltip {
    tooltip: Option<AnyTooltip>,
    _task: Option<Task<()>>,
}

/// Whether or not the element or a group that contains it is clicked by the mouse.
#[derive(Copy, Clone, Default, Eq, PartialEq)]
pub struct ElementClickedState {
    pub group: bool,
    pub element: bool,
}

impl ElementClickedState {
    fn is_clicked(&self) -> bool {
        self.group || self.element
    }
}

#[derive(Default)]
pub struct GroupBounds(HashMap<SharedString, SmallVec<[Bounds<Pixels>; 1]>>);

impl GroupBounds {
    pub fn get(name: &SharedString, cx: &mut AppContext) -> Option<Bounds<Pixels>> {
        cx.default_global::<Self>()
            .0
            .get(name)
            .and_then(|bounds_stack| bounds_stack.last())
            .cloned()
    }

    pub fn push(name: SharedString, bounds: Bounds<Pixels>, cx: &mut AppContext) {
        cx.default_global::<Self>()
            .0
            .entry(name)
            .or_default()
            .push(bounds);
    }

    pub fn pop(name: &SharedString, cx: &mut AppContext) {
        cx.default_global::<Self>().0.get_mut(name).unwrap().pop();
    }
}

pub struct Focusable<E> {
    pub element: E,
}

impl<E: InteractiveElement> FocusableElement for Focusable<E> {}

impl<E> InteractiveElement for Focusable<E>
where
    E: InteractiveElement,
{
    fn interactivity(&mut self) -> &mut Interactivity {
        self.element.interactivity()
    }
}

impl<E: StatefulInteractiveElement> StatefulInteractiveElement for Focusable<E> {}

impl<E> Styled for Focusable<E>
where
    E: Styled,
{
    fn style(&mut self) -> &mut StyleRefinement {
        self.element.style()
    }
}

impl<E> Element for Focusable<E>
where
    E: Element,
{
    type State = E::State;

    fn request_layout(
        &mut self,
        state: Option<Self::State>,
        cx: &mut WindowContext,
    ) -> (LayoutId, Self::State) {
        self.element.request_layout(state, cx)
    }

    fn paint(&mut self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
        self.element.paint(bounds, state, cx)
    }
}

impl<E> IntoElement for Focusable<E>
where
    E: IntoElement,
{
    type Element = E::Element;

    fn element_id(&self) -> Option<ElementId> {
        self.element.element_id()
    }

    fn into_element(self) -> Self::Element {
        self.element.into_element()
    }
}

impl<E> ParentElement for Focusable<E>
where
    E: ParentElement,
{
    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
        self.element.children_mut()
    }
}

pub struct Stateful<E> {
    element: E,
}

impl<E> Styled for Stateful<E>
where
    E: Styled,
{
    fn style(&mut self) -> &mut StyleRefinement {
        self.element.style()
    }
}

impl<E> StatefulInteractiveElement for Stateful<E>
where
    E: Element,
    Self: InteractiveElement,
{
}

impl<E> InteractiveElement for Stateful<E>
where
    E: InteractiveElement,
{
    fn interactivity(&mut self) -> &mut Interactivity {
        self.element.interactivity()
    }
}

impl<E: FocusableElement> FocusableElement for Stateful<E> {}

impl<E> Element for Stateful<E>
where
    E: Element,
{
    type State = E::State;

    fn request_layout(
        &mut self,
        state: Option<Self::State>,
        cx: &mut WindowContext,
    ) -> (LayoutId, Self::State) {
        self.element.request_layout(state, cx)
    }

    fn paint(&mut self, bounds: Bounds<Pixels>, state: &mut Self::State, cx: &mut WindowContext) {
        self.element.paint(bounds, state, cx)
    }
}

impl<E> IntoElement for Stateful<E>
where
    E: Element,
{
    type Element = Self;

    fn element_id(&self) -> Option<ElementId> {
        self.element.element_id()
    }

    fn into_element(self) -> Self::Element {
        self
    }
}

impl<E> ParentElement for Stateful<E>
where
    E: ParentElement,
{
    fn children_mut(&mut self) -> &mut SmallVec<[AnyElement; 2]> {
        self.element.children_mut()
    }
}

#[derive(Default)]
struct ScrollHandleState {
    // not great to have the nested rc's...
    offset: Rc<RefCell<Point<Pixels>>>,
    bounds: Bounds<Pixels>,
    child_bounds: Vec<Bounds<Pixels>>,
    requested_scroll_top: Option<(usize, Pixels)>,
    overflow: Point<Overflow>,
}

#[derive(Clone)]
pub struct ScrollHandle(Rc<RefCell<ScrollHandleState>>);

impl Default for ScrollHandle {
    fn default() -> Self {
        Self::new()
    }
}

impl ScrollHandle {
    pub fn new() -> Self {
        Self(Rc::default())
    }

    pub fn offset(&self) -> Point<Pixels> {
        *self.0.borrow().offset.borrow()
    }

    pub fn top_item(&self) -> usize {
        let state = self.0.borrow();
        let top = state.bounds.top() - state.offset.borrow().y;

        match state.child_bounds.binary_search_by(|bounds| {
            if top < bounds.top() {
                Ordering::Greater
            } else if top > bounds.bottom() {
                Ordering::Less
            } else {
                Ordering::Equal
            }
        }) {
            Ok(ix) => ix,
            Err(ix) => ix.min(state.child_bounds.len().saturating_sub(1)),
        }
    }

    pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>> {
        self.0.borrow().child_bounds.get(ix).cloned()
    }

    /// scroll_to_item scrolls the minimal amount to ensure that the item is
    /// fully visible
    pub fn scroll_to_item(&self, ix: usize) {
        let state = self.0.borrow();

        let Some(bounds) = state.child_bounds.get(ix) else {
            return;
        };

        let mut scroll_offset = state.offset.borrow_mut();

        if state.overflow.y == Overflow::Scroll {
            if bounds.top() + scroll_offset.y < state.bounds.top() {
                scroll_offset.y = state.bounds.top() - bounds.top();
            } else if bounds.bottom() + scroll_offset.y > state.bounds.bottom() {
                scroll_offset.y = state.bounds.bottom() - bounds.bottom();
            }
        }

        if state.overflow.x == Overflow::Scroll {
            if bounds.left() + scroll_offset.x < state.bounds.left() {
                scroll_offset.x = state.bounds.left() - bounds.left();
            } else if bounds.right() + scroll_offset.x > state.bounds.right() {
                scroll_offset.x = state.bounds.right() - bounds.right();
            }
        }
    }

    pub fn logical_scroll_top(&self) -> (usize, Pixels) {
        let ix = self.top_item();
        let state = self.0.borrow();

        if let Some(child_bounds) = state.child_bounds.get(ix) {
            (
                ix,
                child_bounds.top() + state.offset.borrow().y - state.bounds.top(),
            )
        } else {
            (ix, px(0.))
        }
    }

    pub fn set_logical_scroll_top(&self, ix: usize, px: Pixels) {
        self.0.borrow_mut().requested_scroll_top = Some((ix, px));
    }
}