// From iced_aw, license MIT

//! Menu tree overlay
use std::{borrow::Cow, sync::Arc};

use super::{menu_bar::MenuBarState, menu_tree::MenuTree};
use crate::style::menu_bar::StyleSheet;

use iced::window;
use iced_core::{Border, Renderer as IcedRenderer, Shadow, Widget};
use iced_widget::core::{
    Clipboard, Layout, Length, Padding, Point, Rectangle, Shell, Size, Vector, event,
    layout::{Limits, Node},
    mouse::{self, Cursor},
    overlay, renderer, touch,
    widget::Tree,
};

/// The condition of when to close a menu
#[derive(Debug, Clone, Copy)]
pub struct CloseCondition {
    /// Close menus when the cursor moves outside the check bounds
    pub leave: bool,

    /// Close menus when the cursor clicks outside the check bounds
    pub click_outside: bool,

    /// Close menus when the cursor clicks inside the check bounds
    pub click_inside: bool,
}

/// The width of an item
#[derive(Debug, Clone, Copy)]
pub enum ItemWidth {
    /// Use uniform width
    Uniform(u16),
    /// Static tries to use the width value of each menu(menu tree with children),
    /// the widths of items(menu tree with empty children) will be the same as the menu they're in,
    /// if that value is None,
    /// the default value will be used instead,
    /// which is the value of the Static variant
    Static(u16),
}

/// The height of an item
#[derive(Debug, Clone, Copy)]
pub enum ItemHeight {
    /// Use uniform height.
    Uniform(u16),
    /// Static tries to use `MenuTree.height` as item height,
    /// when it's `None` it'll fallback to the value of the `Static` variant.
    Static(u16),
    /// Dynamic tries to automatically choose the proper item height for you,
    /// but it only works in certain cases:
    ///
    /// - Fixed height
    /// - Shrink height
    /// - Menu tree height
    ///
    /// If none of these is the case, it'll fallback to the value of the `Dynamic` variant.
    Dynamic(u16),
}

/// Methods for drawing path highlight
#[derive(Debug, Clone, Copy)]
pub enum PathHighlight {
    /// Draw the full path,
    Full,
    /// Omit the active item(the last item in the path)
    OmitActive,
    /// Omit the active item if it's not a menu
    MenuActive,
}

/// X+ goes right and Y+ goes down
#[derive(Debug, Clone, Copy)]
pub(crate) enum Direction {
    Positive,
    Negative,
}

/// Adaptive open direction
#[derive(Debug)]
#[allow(clippy::struct_excessive_bools)]
struct Aod {
    // whether or not to use aod
    horizontal: bool,
    vertical: bool,

    // whether or not to use overlap
    horizontal_overlap: bool,
    vertical_overlap: bool,

    // default direction
    horizontal_direction: Direction,
    vertical_direction: Direction,

    // Offset of the child in the default direction
    horizontal_offset: f32,
    vertical_offset: f32,
}
impl Aod {
    /// Returns child position and offset position
    #[allow(clippy::too_many_arguments)]
    fn adaptive(
        parent_pos: f32,
        parent_size: f32,
        child_size: f32,
        max_size: f32,
        offset: f32,
        on: bool,
        overlap: bool,
        direction: Direction,
    ) -> (f32, f32) {
        /*
        Imagine there're two sticks, parent and child
        parent: o-----o
        child:  o----------o

        Now we align the child to the parent in one dimension
        There are 4 possibilities:

        1. to the right
                    o-----oo----------o

        2. to the right but allow overlaping
                    o-----o
                    o----------o

        3. to the left
        o----------oo-----o

        4. to the left but allow overlaping
                    o-----o
               o----------o

        The child goes to the default direction by default,
        if the space on the default direction runs out it goes to the the other,
        whether to use overlap is the caller's decision

        This can be applied to any direction
        */

        match direction {
            Direction::Positive => {
                let space_negative = parent_pos;
                let space_positive = max_size - parent_pos - parent_size;

                if overlap {
                    let overshoot = child_size - parent_size;
                    if on && space_negative > space_positive && overshoot > space_positive {
                        (parent_pos - overshoot, parent_pos - overshoot)
                    } else {
                        (parent_pos, parent_pos)
                    }
                } else {
                    let overshoot = child_size + offset;
                    if on && space_negative > space_positive && overshoot > space_positive {
                        (parent_pos - overshoot, parent_pos - offset)
                    } else {
                        (parent_pos + parent_size + offset, parent_pos + parent_size)
                    }
                }
            }
            Direction::Negative => {
                let space_positive = parent_pos;
                let space_negative = max_size - parent_pos - parent_size;

                if overlap {
                    let overshoot = child_size - parent_size;
                    if on && space_negative > space_positive && overshoot > space_positive {
                        (parent_pos, parent_pos)
                    } else {
                        (parent_pos - overshoot, parent_pos - overshoot)
                    }
                } else {
                    let overshoot = child_size + offset;
                    if on && space_negative > space_positive && overshoot > space_positive {
                        (parent_pos + parent_size + offset, parent_pos + parent_size)
                    } else {
                        (parent_pos - overshoot, parent_pos - offset)
                    }
                }
            }
        }
    }

    /// Returns child position and offset position
    fn resolve(
        &self,
        parent_bounds: Rectangle,
        children_size: Size,
        viewport_size: Size,
    ) -> (Point, Point) {
        let (x, ox) = Self::adaptive(
            parent_bounds.x,
            parent_bounds.width,
            children_size.width,
            viewport_size.width,
            self.horizontal_offset,
            self.horizontal,
            self.horizontal_overlap,
            self.horizontal_direction,
        );
        let (y, oy) = Self::adaptive(
            parent_bounds.y,
            parent_bounds.height,
            children_size.height,
            viewport_size.height,
            self.vertical_offset,
            self.vertical,
            self.vertical_overlap,
            self.vertical_direction,
        );

        ([x, y].into(), [ox, oy].into())
    }
}

/// A part of a menu where items are displayed.
///
/// When the bounds of a menu exceed the viewport,
/// only items inside the viewport will be displayed,
/// when scrolling happens, this should be updated
#[derive(Debug, Clone, Copy)]
pub(super) struct MenuSlice {
    pub(super) start_index: usize,
    pub(super) end_index: usize,
    pub(super) lower_bound_rel: f32,
    pub(super) upper_bound_rel: f32,
}

#[derive(Debug, Clone)]
/// Menu bounds in overlay space
pub struct MenuBounds {
    child_positions: Vec<f32>,
    child_sizes: Vec<Size>,
    children_bounds: Rectangle,
    pub parent_bounds: Rectangle,
    check_bounds: Rectangle,
    offset_bounds: Rectangle,
}
impl MenuBounds {
    #[allow(clippy::too_many_arguments)]
    fn new<Message>(
        menu_tree: &MenuTree<Message>,
        renderer: &crate::Renderer,
        item_width: ItemWidth,
        item_height: ItemHeight,
        viewport_size: Size,
        overlay_offset: Vector,
        aod: &Aod,
        bounds_expand: u16,
        parent_bounds: Rectangle,
        tree: &mut [Tree],
        is_overlay: bool,
    ) -> Self {
        let (children_size, child_positions, child_sizes) =
            get_children_layout(menu_tree, renderer, item_width, item_height, tree);

        // viewport space parent bounds
        let view_parent_bounds = parent_bounds + overlay_offset;

        // overlay space children position
        let (children_position, offset_position) = {
            let (cp, op) = aod.resolve(view_parent_bounds, children_size, viewport_size);
            if is_overlay {
                (cp - overlay_offset, op - overlay_offset)
            } else {
                (Point::ORIGIN, op - overlay_offset)
            }
        };

        // calc offset bounds
        let delta = children_position - offset_position;
        let offset_size = if delta.x.abs() > delta.y.abs() {
            Size::new(delta.x, children_size.height)
        } else {
            Size::new(children_size.width, delta.y)
        };
        let offset_bounds = Rectangle::new(offset_position, offset_size);

        let children_bounds = Rectangle::new(children_position, children_size);
        let check_bounds = pad_rectangle(children_bounds, bounds_expand.into());

        Self {
            child_positions,
            child_sizes,
            children_bounds,
            parent_bounds,
            check_bounds,
            offset_bounds,
        }
    }
}

#[derive(Clone)]
pub(crate) struct MenuState {
    /// The index of the active menu item
    pub(crate) index: Option<usize>,
    scroll_offset: f32,
    pub menu_bounds: MenuBounds,
}
impl MenuState {
    pub(super) fn layout<Message>(
        &self,
        overlay_offset: Vector,
        slice: MenuSlice,
        renderer: &crate::Renderer,
        menu_tree: &[MenuTree<Message>],
        tree: &mut [Tree],
    ) -> Node {
        let MenuSlice {
            start_index,
            end_index,
            lower_bound_rel,
            upper_bound_rel,
        } = slice;

        debug_assert_eq!(menu_tree.len(), self.menu_bounds.child_positions.len());

        // viewport space children bounds
        let children_bounds = self.menu_bounds.children_bounds + overlay_offset;
        let child_nodes = self.menu_bounds.child_positions[start_index..=end_index]
            .iter()
            .zip(self.menu_bounds.child_sizes[start_index..=end_index].iter())
            .zip(menu_tree[start_index..=end_index].iter())
            .map(|((cp, size), mt)| {
                let mut position = *cp;
                let mut size = *size;

                if position < lower_bound_rel && (position + size.height) > lower_bound_rel {
                    size.height = position + size.height - lower_bound_rel;
                    position = lower_bound_rel;
                } else if position <= upper_bound_rel && (position + size.height) > upper_bound_rel
                {
                    size.height = upper_bound_rel - position;
                }

                let limits = Limits::new(size, size);

                mt.item
                    .layout(&mut tree[mt.index], renderer, &limits)
                    .move_to(Point::new(0.0, position + self.scroll_offset))
            })
            .collect::<Vec<_>>();

        Node::with_children(children_bounds.size(), child_nodes).move_to(children_bounds.position())
    }

    fn layout_single<Message>(
        &self,
        overlay_offset: Vector,
        index: usize,
        renderer: &crate::Renderer,
        menu_tree: &MenuTree<Message>,
        tree: &mut Tree,
    ) -> Node {
        // viewport space children bounds
        let children_bounds = self.menu_bounds.children_bounds + overlay_offset;

        let position = self.menu_bounds.child_positions[index];
        let limits = Limits::new(Size::ZERO, self.menu_bounds.child_sizes[index]);
        let parent_offset = children_bounds.position() - Point::ORIGIN;
        let node = menu_tree.item.layout(tree, renderer, &limits);
        node.clone().move_to(Point::new(
            parent_offset.x,
            parent_offset.y + position + self.scroll_offset,
        ))
    }

    /// returns a slice of the menu items that are inside the viewport
    pub(super) fn slice(
        &self,
        viewport_size: Size,
        overlay_offset: Vector,
        item_height: ItemHeight,
    ) -> MenuSlice {
        // viewport space children bounds
        let children_bounds = self.menu_bounds.children_bounds + overlay_offset;

        let max_index = self.menu_bounds.child_positions.len().saturating_sub(1);

        // viewport space absolute bounds
        let lower_bound = children_bounds.y.max(0.0);
        let upper_bound = (children_bounds.y + children_bounds.height).min(viewport_size.height);

        // menu space relative bounds
        let lower_bound_rel = lower_bound - (children_bounds.y + self.scroll_offset);
        let upper_bound_rel = upper_bound - (children_bounds.y + self.scroll_offset);

        // index range
        let (start_index, end_index) = match item_height {
            ItemHeight::Uniform(u) => {
                let start_index = (lower_bound_rel / f32::from(u)).floor() as usize;
                let end_index = ((upper_bound_rel / f32::from(u)).floor() as usize).min(max_index);
                (start_index, end_index)
            }
            ItemHeight::Static(_) | ItemHeight::Dynamic(_) => {
                let positions = &self.menu_bounds.child_positions;
                let sizes = &self.menu_bounds.child_sizes;

                let start_index = search_bound(0, 0, max_index, lower_bound_rel, positions, sizes);
                let end_index = search_bound(
                    max_index,
                    start_index,
                    max_index,
                    upper_bound_rel,
                    positions,
                    sizes,
                )
                .min(max_index);

                (start_index, end_index)
            }
        };

        MenuSlice {
            start_index,
            end_index,
            lower_bound_rel,
            upper_bound_rel,
        }
    }
}

#[derive(Clone)]
pub(crate) struct Menu<'b, Message: std::clone::Clone> {
    pub(crate) tree: MenuBarState,
    // Flattened menu tree
    pub(crate) menu_roots: Cow<'b, Vec<MenuTree<Message>>>,
    pub(crate) bounds_expand: u16,
    /// Allows menu overlay items to overlap the parent
    pub(crate) menu_overlays_parent: bool,
    pub(crate) close_condition: CloseCondition,
    pub(crate) item_width: ItemWidth,
    pub(crate) item_height: ItemHeight,
    pub(crate) bar_bounds: Rectangle,
    pub(crate) main_offset: i32,
    pub(crate) cross_offset: i32,
    pub(crate) root_bounds_list: Vec<Rectangle>,
    pub(crate) path_highlight: Option<PathHighlight>,
    pub(crate) style: Cow<'b, <crate::Theme as StyleSheet>::Style>,
    pub(crate) position: Point,
    pub(crate) is_overlay: bool,
    /// window id for this popup
    pub(crate) window_id: window::Id,
    pub(crate) depth: usize,
    pub(crate) on_surface_action:
        Option<Arc<dyn Fn(crate::surface::Action) -> Message + Send + Sync + 'static>>,
}
impl<'b, Message: Clone + 'static> Menu<'b, Message> {
    pub(crate) fn overlay(self) -> overlay::Element<'b, Message, crate::Theme, crate::Renderer> {
        overlay::Element::new(Box::new(self))
    }

    pub(crate) fn layout(&self, renderer: &crate::Renderer, limits: Limits) -> Node {
        // layout children;
        let position = self.position;
        let mut intrinsic_size = Size::ZERO;

        let empty = Vec::new();
        self.tree.inner.with_data_mut(|data| {
            if data.active_root.len() < self.depth + 1 || data.menu_states.len() < self.depth + 1 {
                return Node::new(limits.min());
            }

            let overlay_offset = Point::ORIGIN - position;
            let tree_children: &mut Vec<Tree> = &mut data.tree.children;

            let children = (if self.is_overlay { 0 } else { self.depth }..=if self.is_overlay {
                data.active_root.len() - 1
            } else {
                self.depth
            })
                .map(|active_root| {
                    if self.menu_roots.is_empty() {
                        return (&empty, vec![]);
                    }
                    let (active_tree, roots) =
                        data.active_root[..=active_root].iter().skip(1).fold(
                            (
                                &mut tree_children[data.active_root[0]].children,
                                &self.menu_roots[data.active_root[0]].children,
                            ),
                            |(tree, mt), next_active_root| (tree, &mt[*next_active_root].children),
                        );

                    data.menu_states[if self.is_overlay { 0 } else { self.depth }
                        ..=if self.is_overlay {
                            data.active_root.len() - 1
                        } else {
                            self.depth
                        }]
                        .iter()
                        .enumerate()
                        .filter(|ms| self.is_overlay || ms.0 < 1)
                        .fold(
                            (roots, Vec::new()),
                            |(menu_root, mut nodes), (_i, ms)| {
                                let slice =
                                    ms.slice(limits.max(), overlay_offset, self.item_height);
                                let _start_index = slice.start_index;
                                let _end_index = slice.end_index;
                                let children_node = ms.layout(
                                    overlay_offset,
                                    slice,
                                    renderer,
                                    menu_root,
                                    active_tree,
                                );
                                let node_size = children_node.size();
                                intrinsic_size.height += node_size.height;
                                intrinsic_size.width = intrinsic_size.width.max(node_size.width);

                                nodes.push(children_node);
                                // if popup just use len 1?
                                // only the last menu can have a None active index
                                (
                                    ms.index
                                        .map_or(menu_root, |active| &menu_root[active].children),
                                    nodes,
                                )
                            },
                        )
                })
                .map(|(_, l)| l)
                .next()
                .unwrap_or_default();

            // overlay space viewport rectangle
            Node::with_children(
                limits.resolve(Length::Shrink, Length::Shrink, intrinsic_size),
                children,
            )
            .translate(Point::ORIGIN - position)
        })
    }

    #[allow(clippy::too_many_lines)]
    fn on_event(
        &mut self,
        event: event::Event,
        layout: Layout<'_>,
        view_cursor: Cursor,
        renderer: &crate::Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
    ) -> (Option<(usize, MenuState)>, event::Status) {
        use event::{
            Event::{Mouse, Touch},
            Status::{Captured, Ignored},
        };
        use mouse::{
            Button::Left,
            Event::{ButtonPressed, ButtonReleased, CursorMoved, WheelScrolled},
        };
        use touch::Event::{FingerLifted, FingerMoved, FingerPressed};

        if !self
            .tree
            .inner
            .with_data(|data| data.open || data.active_root.len() <= self.depth)
        {
            return (None, Ignored);
        }

        let viewport = layout.bounds();

        let viewport_size = viewport.size();
        let overlay_offset = Point::ORIGIN - viewport.position();
        let overlay_cursor = view_cursor.position().unwrap_or_default() - overlay_offset;
        let menu_roots = match &mut self.menu_roots {
            Cow::Borrowed(_) => panic!(),
            Cow::Owned(o) => o.as_mut_slice(),
        };
        let menu_status = process_menu_events(
            self,
            event.clone(),
            view_cursor,
            renderer,
            clipboard,
            shell,
            overlay_offset,
        );

        init_root_menu(
            self,
            renderer,
            shell,
            overlay_cursor,
            viewport_size,
            overlay_offset,
            self.bar_bounds,
            self.main_offset as f32,
        );

        let ret = match event {
            Mouse(WheelScrolled { delta }) => {
                process_scroll_events(self, delta, overlay_cursor, viewport_size, overlay_offset)
                    .merge(menu_status)
            }

            Mouse(ButtonPressed(Left)) | Touch(FingerPressed { .. }) => {
                self.tree.inner.with_data_mut(|data| {
                    data.pressed = true;
                    data.view_cursor = view_cursor;
                });
                Captured
            }

            Mouse(CursorMoved { position }) | Touch(FingerMoved { position, .. }) => {
                let view_cursor = Cursor::Available(position);
                let overlay_cursor = view_cursor.position().unwrap_or_default() - overlay_offset;
                if !self.is_overlay && !view_cursor.is_over(viewport) {
                    return (None, menu_status);
                }

                let (new_root, status) = process_overlay_events(
                    self,
                    renderer,
                    viewport_size,
                    overlay_offset,
                    view_cursor,
                    overlay_cursor,
                    self.cross_offset as f32,
                    shell,
                );

                return (new_root, status.merge(menu_status));
            }

            Mouse(ButtonReleased(_)) | Touch(FingerLifted { .. }) => {
                self.tree.inner.with_data_mut(|state| {
                    state.pressed = false;

                    // process close condition
                    if state
                        .view_cursor
                        .position()
                        .unwrap_or_default()
                        .distance(view_cursor.position().unwrap_or_default())
                        < 2.0
                    {
                        let is_inside = state.menu_states[..=if self.is_overlay {
                            state.active_root.len().saturating_sub(1)
                        } else {
                            self.depth
                        }]
                            .iter()
                            .any(|ms| ms.menu_bounds.check_bounds.contains(overlay_cursor));
                        let mut needs_reset = false;
                        needs_reset |= self.close_condition.click_inside
                            && is_inside
                            && matches!(
                                event,
                                Mouse(ButtonReleased(Left)) | Touch(FingerLifted { .. })
                            );

                        needs_reset |= self.close_condition.click_outside && !is_inside;

                        if needs_reset {
                            #[cfg(all(
                                feature = "wayland",
                                feature = "winit",
                                feature = "surface-message"
                            ))]
                            if let Some(handler) = self.on_surface_action.as_ref() {
                                let mut root = self.window_id;
                                let mut depth = self.depth;
                                while let Some(parent) =
                                    state.popup_id.iter().find(|(_, v)| **v == root)
                                {
                                    // parent of root popup is the window, so we stop.
                                    if depth == 0 {
                                        break;
                                    }
                                    root = *parent.0;
                                    depth = depth.saturating_sub(1);
                                }
                                shell
                                    .publish((handler)(crate::surface::Action::DestroyPopup(root)));
                            }

                            state.reset();
                            return Captured;
                        }
                    }

                    // close all menus when clicking inside the menu bar
                    if self.bar_bounds.contains(overlay_cursor) {
                        state.reset();
                        Captured
                    } else {
                        menu_status
                    }
                })
            }

            _ => menu_status,
        };
        (None, ret)
    }

    #[allow(unused_results, clippy::too_many_lines)]
    fn draw(
        &self,
        renderer: &mut crate::Renderer,
        theme: &crate::Theme,
        style: &renderer::Style,
        layout: Layout<'_>,
        view_cursor: Cursor,
    ) {
        self.tree.inner.with_data(|state| {
            if !state.open || state.active_root.len() <= self.depth {
                return;
            }
            let active_root = &state.active_root[..=if self.is_overlay { 0 } else { self.depth }];
            let viewport = layout.bounds();
            let viewport_size = viewport.size();
            let overlay_offset = Point::ORIGIN - viewport.position();

            let render_bounds = if self.is_overlay {
                Rectangle::new(Point::ORIGIN, viewport.size())
            } else {
                Rectangle::new(Point::ORIGIN, Size::INFINITY)
            };

            let styling = theme.appearance(&self.style);
            let roots = active_root.iter().skip(1).fold(
                &self.menu_roots[active_root[0]].children,
                |mt, next_active_root| (&mt[*next_active_root].children),
            );
            let indices = state.get_trimmed_indices(self.depth).collect::<Vec<_>>();
            state.menu_states[if self.is_overlay { 0 } else { self.depth }..=if self.is_overlay {
                state.menu_states.len() - 1
            } else {
                self.depth
            }]
                .iter()
                .zip(layout.children())
                .enumerate()
                .filter(|ms: &(usize, (&MenuState, Layout<'_>))| self.is_overlay || ms.0 < 1)
                .fold(
                    roots,
                    |menu_roots: &Vec<MenuTree<Message>>, (i, (ms, children_layout))| {
                        let draw_path = self.path_highlight.as_ref().is_some_and(|ph| match ph {
                            PathHighlight::Full => true,
                            PathHighlight::OmitActive => {
                                !indices.is_empty() && i < indices.len() - 1
                            }
                            PathHighlight::MenuActive => self.depth == state.active_root.len() - 1,
                        });

                        // react only to the last menu
                        let view_cursor = if self.depth == state.active_root.len() - 1
                            || i == state.menu_states.len() - 1
                        {
                            view_cursor
                        } else {
                            Cursor::Available([-1.0; 2].into())
                        };

                        let draw_menu = |r: &mut crate::Renderer| {
                            // calc slice
                            let slice = ms.slice(viewport_size, overlay_offset, self.item_height);
                            let start_index = slice.start_index;
                            let end_index = slice.end_index;

                            let children_bounds = children_layout.bounds();

                            // draw menu background
                            // let bounds = pad_rectangle(children_bounds, styling.background_expand.into());
                            // println!("cursor: {:?}", view_cursor);
                            // println!("bg_bounds: {:?}", bounds);
                            // println!("color: {:?}\n", styling.background);
                            let menu_quad = renderer::Quad {
                                bounds: pad_rectangle(
                                    children_bounds,
                                    styling.background_expand.into(),
                                ),
                                border: Border {
                                    radius: styling.menu_border_radius.into(),
                                    width: styling.border_width,
                                    color: styling.border_color,
                                },
                                shadow: Shadow::default(),
                            };
                            let menu_color = styling.background;
                            r.fill_quad(menu_quad, menu_color);
                            // draw path hightlight
                            if let (true, Some(active)) = (draw_path, ms.index) {
                                if let Some(active_layout) = children_layout
                                    .children()
                                    .nth(active.saturating_sub(start_index))
                                {
                                    let path_quad = renderer::Quad {
                                        bounds: active_layout.bounds(),
                                        border: Border {
                                            radius: styling.menu_border_radius.into(),
                                            ..Default::default()
                                        },
                                        shadow: Shadow::default(),
                                    };

                                    r.fill_quad(path_quad, styling.path);
                                }
                            }
                            if start_index < menu_roots.len() {
                                // draw item
                                menu_roots[start_index..=end_index]
                                    .iter()
                                    .zip(children_layout.children())
                                    .for_each(|(mt, clo)| {
                                        mt.item.draw(
                                            &state.tree.children[active_root[0]].children[mt.index],
                                            r,
                                            theme,
                                            style,
                                            clo,
                                            view_cursor,
                                            &children_layout.bounds(),
                                        );
                                    });
                            }
                        };

                        renderer.with_layer(render_bounds, draw_menu);

                        // only the last menu can have a None active index
                        ms.index
                            .map_or(menu_roots, |active| &menu_roots[active].children)
                    },
                );
        });
    }
}
impl<Message: Clone + 'static> overlay::Overlay<Message, crate::Theme, crate::Renderer>
    for Menu<'_, Message>
{
    fn layout(&mut self, renderer: &crate::Renderer, bounds: Size) -> iced_core::layout::Node {
        Menu::layout(
            self,
            renderer,
            Limits::NONE
                .min_width(bounds.width)
                .max_width(bounds.width)
                .min_height(bounds.height)
                .max_height(bounds.height),
        )
    }

    fn on_event(
        &mut self,
        event: iced::Event,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        renderer: &crate::Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
    ) -> event::Status {
        self.on_event(event, layout, cursor, renderer, clipboard, shell)
            .1
    }

    fn draw(
        &self,
        renderer: &mut crate::Renderer,
        theme: &crate::Theme,
        style: &renderer::Style,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
    ) {
        self.draw(renderer, theme, style, layout, cursor);
    }
}

impl<Message: std::clone::Clone + 'static> Widget<Message, crate::Theme, crate::Renderer>
    for Menu<'_, Message>
{
    fn size(&self) -> Size<Length> {
        Size {
            width: Length::Shrink,
            height: Length::Shrink,
        }
    }

    fn layout(
        &self,
        _tree: &mut Tree,
        renderer: &crate::Renderer,
        limits: &iced_core::layout::Limits,
    ) -> iced_core::layout::Node {
        Menu::layout(self, renderer, *limits)
    }

    fn draw(
        &self,
        _tree: &Tree,
        renderer: &mut crate::Renderer,
        theme: &crate::Theme,
        style: &renderer::Style,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        _viewport: &Rectangle,
    ) {
        Menu::draw(self, renderer, theme, style, layout, cursor);
    }

    #[allow(clippy::too_many_lines)]
    fn on_event(
        &mut self,
        tree: &mut Tree,
        event: iced::Event,
        layout: Layout<'_>,
        cursor: mouse::Cursor,
        renderer: &crate::Renderer,
        clipboard: &mut dyn Clipboard,
        shell: &mut Shell<'_, Message>,
        viewport: &Rectangle,
    ) -> event::Status {
        let (new_root, status) = self.on_event(event, layout, cursor, renderer, clipboard, shell);

        #[cfg(all(feature = "wayland", feature = "winit", feature = "surface-message"))]
        if let Some((new_root, new_ms)) = new_root {
            use iced_runtime::platform_specific::wayland::popup::{
                SctkPopupSettings, SctkPositioner,
            };
            let overlay_offset = Point::ORIGIN - viewport.position();

            let overlay_cursor = cursor.position().unwrap_or_default() - overlay_offset;

            let Some((mut menu, popup_id)) = self.tree.inner.with_data_mut(|state| {
                let popup_id = *state
                    .popup_id
                    .entry(self.window_id)
                    .or_insert_with(window::Id::unique);
                let active_roots = state
                    .active_root
                    .get(self.depth)
                    .cloned()
                    .unwrap_or_default();

                let root_bounds_list = layout
                    .children()
                    .next()
                    .unwrap()
                    .children()
                    .map(|lo| lo.bounds())
                    .collect();

                let mut popup_menu = Menu {
                    tree: self.tree.clone(),
                    menu_roots: Cow::Owned(Cow::into_owned(self.menu_roots.clone())),
                    bounds_expand: self.bounds_expand,
                    menu_overlays_parent: false,
                    close_condition: self.close_condition,
                    item_width: self.item_width,
                    item_height: self.item_height,
                    bar_bounds: layout.bounds(),
                    main_offset: self.main_offset,
                    cross_offset: self.cross_offset,
                    root_bounds_list,
                    path_highlight: self.path_highlight,
                    style: Cow::Owned(Cow::into_owned(self.style.clone())),
                    position: Point::new(0., 0.),
                    is_overlay: false,
                    window_id: popup_id,
                    depth: self.depth + 1,
                    on_surface_action: self.on_surface_action.clone(),
                };

                state.active_root.push(new_root);

                Some((popup_menu, popup_id))
            }) else {
                return status;
            };
            // XXX we push a new active root manually instead
            init_root_popup_menu(
                &mut menu,
                renderer,
                shell,
                cursor.position().unwrap(),
                layout.bounds().size(),
                Vector::new(0., 0.),
                layout.bounds(),
                self.main_offset as f32,
            );
            let (anchor_rect, gravity) = self.tree.inner.with_data_mut(|state| {
                (state
                    .menu_states
                    .get(self.depth + 1)
                    .map(|s| s.menu_bounds.parent_bounds)
                    .map_or_else(
                        || {
                            let bounds = layout.bounds();
                            Rectangle {
                                x: bounds.x as i32,
                                y: bounds.y as i32,
                                width: bounds.width as i32,
                                height: bounds.height as i32,
                            }
                        },
                        |r| Rectangle {
                            x: r.x as i32,
                            y: r.y as i32,
                            width: r.width as i32,
                            height: r.height as i32,
                        },
                    ), match (state.horizontal_direction, state.vertical_direction) {
                        (Direction::Positive, Direction::Positive) => cctk::wayland_protocols::xdg::shell::client::xdg_positioner::Gravity::BottomRight,
                        (Direction::Positive, Direction::Negative) => cctk::wayland_protocols::xdg::shell::client::xdg_positioner::Gravity::TopRight,
                        (Direction::Negative, Direction::Positive) => cctk::wayland_protocols::xdg::shell::client::xdg_positioner::Gravity::BottomLeft,
                        (Direction::Negative, Direction::Negative) => cctk::wayland_protocols::xdg::shell::client::xdg_positioner::Gravity::TopLeft,
                    })
            });

            let menu_node = Widget::layout(
                &menu,
                &mut Tree::empty(),
                renderer,
                &Limits::NONE.min_width(1.).min_height(1.),
            );

            let popup_size = menu_node.size();
            let positioner = SctkPositioner {
                size: Some((
                    popup_size.width.ceil() as u32 + 2,
                    popup_size.height.ceil() as u32 + 2,
                )),
                anchor_rect,
                anchor:
                    cctk::wayland_protocols::xdg::shell::client::xdg_positioner::Anchor::TopRight,
                gravity,
                reactive: true,
                ..Default::default()
            };
            let parent = self.window_id;
            shell.publish((self.on_surface_action.as_ref().unwrap())(
                crate::surface::action::simple_popup(
                    move || SctkPopupSettings {
                        parent,
                        id: popup_id,
                        positioner: positioner.clone(),
                        parent_size: None,
                        grab: true,
                        close_with_children: false,
                        input_zone: None,
                    },
                    Some(move || {
                        crate::Element::from(
                            crate::widget::container(menu.clone()).center(Length::Fill),
                        )
                        .map(crate::action::app)
                    }),
                ),
            ));

            return status;
        }
        status
    }
}

impl<'a, Message> From<Menu<'a, Message>>
    for iced::Element<'a, Message, crate::Theme, crate::Renderer>
where
    Message: std::clone::Clone + 'static,
{
    fn from(value: Menu<'a, Message>) -> Self {
        Self::new(value)
    }
}

fn pad_rectangle(rect: Rectangle, padding: Padding) -> Rectangle {
    Rectangle {
        x: rect.x - padding.left,
        y: rect.y - padding.top,
        width: rect.width + padding.horizontal(),
        height: rect.height + padding.vertical(),
    }
}

#[allow(clippy::too_many_arguments)]
pub(crate) fn init_root_menu<Message: Clone>(
    menu: &mut Menu<'_, Message>,
    renderer: &crate::Renderer,
    shell: &mut Shell<'_, Message>,
    overlay_cursor: Point,
    viewport_size: Size,
    overlay_offset: Vector,
    bar_bounds: Rectangle,
    main_offset: f32,
) {
    menu.tree.inner.with_data_mut(|state| {
        if !(state.menu_states.get(menu.depth).is_none()
            && (!menu.is_overlay || bar_bounds.contains(overlay_cursor)))
            || menu.depth > 0
            || !state.open
        {
            return;
        }

        for (i, (&root_bounds, mt)) in menu
            .root_bounds_list
            .iter()
            .zip(menu.menu_roots.iter())
            .enumerate()
        {
            if mt.children.is_empty() {
                continue;
            }

            if root_bounds.contains(overlay_cursor) {
                let view_center = viewport_size.width * 0.5;
                let rb_center = root_bounds.center_x();

                state.horizontal_direction = if menu.is_overlay && rb_center > view_center {
                    Direction::Negative
                } else {
                    Direction::Positive
                };

                let aod = Aod {
                    horizontal: true,
                    vertical: true,
                    horizontal_overlap: true,
                    vertical_overlap: false,
                    horizontal_direction: state.horizontal_direction,
                    vertical_direction: state.vertical_direction,
                    horizontal_offset: 0.0,
                    vertical_offset: main_offset,
                };
                let menu_bounds = MenuBounds::new(
                    mt,
                    renderer,
                    menu.item_width,
                    menu.item_height,
                    viewport_size,
                    overlay_offset,
                    &aod,
                    menu.bounds_expand,
                    root_bounds,
                    &mut state.tree.children[0].children,
                    menu.is_overlay,
                );
                state.active_root.push(i);
                let ms = MenuState {
                    index: None,
                    scroll_offset: 0.0,
                    menu_bounds,
                };
                state.menu_states.push(ms);

                // Hack to ensure menu opens properly
                shell.invalidate_layout();

                break;
            }
        }
    });
}

#[cfg(all(feature = "wayland", feature = "winit", feature = "surface-message"))]
pub(super) fn init_root_popup_menu<Message>(
    menu: &mut Menu<'_, Message>,
    renderer: &crate::Renderer,
    shell: &mut Shell<'_, Message>,
    overlay_cursor: Point,
    viewport_size: Size,
    overlay_offset: Vector,
    bar_bounds: Rectangle,
    main_offset: f32,
) where
    Message: std::clone::Clone,
{
    menu.tree.inner.with_data_mut(|state| {
        if !(state.menu_states.get(menu.depth).is_none()
            && (!menu.is_overlay || bar_bounds.contains(overlay_cursor)))
        {
            return;
        }

        let active_roots = &state.active_root[..=menu.depth];

        let mt = active_roots
            .iter()
            .skip(1)
            .fold(&menu.menu_roots[active_roots[0]], |mt, next_active_root| {
                &mt.children[*next_active_root]
            });
        let i = active_roots.last().unwrap();
        let root_bounds = menu.root_bounds_list[*i];

        assert!(!mt.children.is_empty(), "skipping menu with no children");
        let aod = Aod {
            horizontal: true,
            vertical: true,
            horizontal_overlap: true,
            vertical_overlap: false,
            horizontal_direction: state.horizontal_direction,
            vertical_direction: state.vertical_direction,
            horizontal_offset: 0.0,
            vertical_offset: main_offset,
        };
        let menu_bounds = MenuBounds::new(
            mt,
            renderer,
            menu.item_width,
            menu.item_height,
            viewport_size,
            overlay_offset,
            &aod,
            menu.bounds_expand,
            root_bounds,
            // TODO how to select the tree for the popup
            &mut state.tree.children[0].children,
            menu.is_overlay,
        );

        let view_center = viewport_size.width * 0.5;
        let rb_center = root_bounds.center_x();

        state.horizontal_direction = if rb_center > view_center {
            Direction::Negative
        } else {
            Direction::Positive
        };

        let ms = MenuState {
            index: None,
            scroll_offset: 0.0,
            menu_bounds,
        };
        state.menu_states.push(ms);

        // Hack to ensure menu opens properly
        shell.invalidate_layout();
    });
}

#[allow(clippy::too_many_arguments)]
fn process_menu_events<Message: std::clone::Clone>(
    menu: &mut Menu<Message>,
    event: event::Event,
    view_cursor: Cursor,
    renderer: &crate::Renderer,
    clipboard: &mut dyn Clipboard,
    shell: &mut Shell<'_, Message>,
    overlay_offset: Vector,
) -> event::Status {
    use event::Status;

    let my_state = &mut menu.tree;
    let menu_roots = match &mut menu.menu_roots {
        Cow::Borrowed(_) => panic!(),
        Cow::Owned(o) => o.as_mut_slice(),
    };
    my_state.inner.with_data_mut(|state| {
        if state.active_root.len() <= menu.depth {
            return event::Status::Ignored;
        }

        let Some(hover) = state.menu_states.last_mut() else {
            return Status::Ignored;
        };

        let Some(hover_index) = hover.index else {
            return Status::Ignored;
        };

        let mt = state.active_root.iter().skip(1).fold(
            // then use menu states for each open menu
            &mut menu_roots[state.active_root[0]],
            |mt, next_active_root| &mut mt.children[*next_active_root],
        );

        let mt = &mut mt.children[hover_index];
        let tree = &mut state.tree.children[state.active_root[0]].children[mt.index];

        // get layout
        let child_node = hover.layout_single(
            overlay_offset,
            hover.index.expect("missing index within menu state."),
            renderer,
            mt,
            tree,
        );
        let child_layout = Layout::new(&child_node);

        // process only the last widget
        mt.item.on_event(
            tree,
            event,
            child_layout,
            view_cursor,
            renderer,
            clipboard,
            shell,
            &Rectangle::default(),
        )
    })
}

#[allow(unused_results, clippy::too_many_lines, clippy::too_many_arguments)]
fn process_overlay_events<Message>(
    menu: &mut Menu<Message>,
    renderer: &crate::Renderer,
    viewport_size: Size,
    overlay_offset: Vector,
    view_cursor: Cursor,
    overlay_cursor: Point,
    cross_offset: f32,
    _shell: &mut Shell<'_, Message>,
) -> (Option<(usize, MenuState)>, event::Status)
where
    Message: std::clone::Clone,
{
    use event::Status::{Captured, Ignored};
    /*
    if no active root || pressed:
        return
    else:
        remove invalid menus // overlay space
        update active item
        if active item is a menu:
            add menu // viewport space
    */
    let mut new_menu_root = None;

    menu.tree.inner.with_data_mut(|state| {

        /* When overlay is running, cursor_position in any widget method will go negative
        but I still want Widget::draw() to react to cursor movement */
        state.view_cursor = view_cursor;

        // * remove invalid menus

        let mut prev_bounds = std::iter::once(menu.bar_bounds)
            .chain(
                if menu.is_overlay {
                    state.menu_states[..state.menu_states.len().saturating_sub(1)].iter()
                } else {
                    state.menu_states[..menu.depth].iter()
                }
                .map(|s| s.menu_bounds.children_bounds),
            )
            .collect::<Vec<_>>();

        if menu.is_overlay && menu.close_condition.leave {
            for i in (0..state.menu_states.len()).rev() {
                let mb = &state.menu_states[i].menu_bounds;

                if mb.parent_bounds.contains(overlay_cursor)
                    || menu.is_overlay && mb.children_bounds.contains(overlay_cursor)
                    || mb.offset_bounds.contains(overlay_cursor)
                    || (mb.check_bounds.contains(overlay_cursor)
                        && prev_bounds.iter().all(|pvb| !pvb.contains(overlay_cursor)))
                {
                    break;
                }
                prev_bounds.pop();
                state.active_root.pop();
                state.menu_states.pop();
            }
        } else if menu.is_overlay {
            for i in (0..state.menu_states.len()).rev() {
                let mb = &state.menu_states[i].menu_bounds;

                if mb.parent_bounds.contains(overlay_cursor)
                    || mb.children_bounds.contains(overlay_cursor)
                    || prev_bounds.iter().all(|pvb| !pvb.contains(overlay_cursor))
                {
                    break;
                }
                prev_bounds.pop();
                state.active_root.pop();
                state.menu_states.pop();
            }
        }

        // * update active item
        let menu_states_len = state.menu_states.len();

        let Some(last_menu_state) = state.menu_states.get_mut(if menu.is_overlay {
            menu_states_len.saturating_sub(1)
        } else {
            menu.depth
        }) else {
            if menu.is_overlay {
                // no menus left
                // TODO do we want to avoid this for popups?
                // state.active_root.remove(menu.depth);

                // keep state.open when the cursor is still inside the menu bar
                // this allows the overlay to keep drawing when the cursor is
                // moving aroung the menu bar
                if !menu.bar_bounds.contains(overlay_cursor) {
                    state.open = false;
                }
            }

            return (new_menu_root, Captured);
        };

        let last_menu_bounds = &last_menu_state.menu_bounds;
        let last_parent_bounds = last_menu_bounds.parent_bounds;
        let last_children_bounds = last_menu_bounds.children_bounds;

        if (menu.is_overlay && !menu.menu_overlays_parent && last_parent_bounds.contains(overlay_cursor))
        // cursor is in the parent part
        || menu.is_overlay && !last_children_bounds.contains(overlay_cursor)
        // cursor is outside
        {

            last_menu_state.index = None;
            return (new_menu_root, Captured);
        }

        // calc new index
        let height_diff = (overlay_cursor.y
            - (last_children_bounds.y + last_menu_state.scroll_offset))
            .clamp(0.0, last_children_bounds.height - 0.001);

        let active_root = if menu.is_overlay {
            &state.active_root
        } else {
            &state.active_root[..=menu.depth]
        };

        if state.pressed {
            return (new_menu_root, Ignored);
        }
        let roots = active_root.iter().skip(1).fold(
            &menu.menu_roots[active_root[0]].children,
            |mt, next_active_root| &mt[*next_active_root].children,
        );
        let tree = &mut state.tree.children[active_root[0]].children;

        let active_menu: &Vec<MenuTree<Message>> = roots;
        let new_index = match menu.item_height {
            ItemHeight::Uniform(u) => (height_diff / f32::from(u)).floor() as usize,
            ItemHeight::Static(_) | ItemHeight::Dynamic(_) => {
                let max_index = active_menu.len() - 1;
                search_bound(
                    0,
                    0,
                    max_index,
                    height_diff,
                    &last_menu_bounds.child_positions,
                    &last_menu_bounds.child_sizes,
                )
            }
        };

        let remove = last_menu_state
            .index
            .as_ref()
            .is_some_and(|i| *i != new_index && !active_menu[*i].children.is_empty());

        #[cfg(all(feature = "wayland", feature = "winit", feature = "surface-message"))]
        {
            if remove {
                if let Some(id) = state.popup_id.remove(&menu.window_id) {
                    state.active_root.truncate(menu.depth + 1);
                    _shell.publish((menu.on_surface_action.as_ref().unwrap())({
                        crate::surface::action::destroy_popup(id)
                    }));
                }
            }
        }
        let item = &active_menu[new_index];
        // set new index
        let old_index = last_menu_state.index.replace(new_index);

        // get new active item
        // * add new menu if the new item is a menu
        if !item.children.is_empty() && old_index.is_none_or(|i| i != new_index) {
            let item_position = Point::new(
                0.0,
                last_menu_bounds.child_positions[new_index] + last_menu_state.scroll_offset,
            );
            let item_size = last_menu_bounds.child_sizes[new_index];

            // overlay space item bounds
            let item_bounds = Rectangle::new(item_position, item_size)
                + (last_menu_bounds.children_bounds.position() - Point::ORIGIN);

            let aod = Aod {
                horizontal: true,
                vertical: true,
                horizontal_overlap: false,
                vertical_overlap: true,
                horizontal_direction: state.horizontal_direction,
                vertical_direction: state.vertical_direction,
                horizontal_offset: cross_offset,
                vertical_offset: 0.0,
            };
            let ms = MenuState {
                index: None,
                scroll_offset: 0.0,
                menu_bounds: MenuBounds::new(
                    item,
                    renderer,
                    menu.item_width,
                    menu.item_height,
                    viewport_size,
                    overlay_offset,
                    &aod,
                    menu.bounds_expand,
                    item_bounds,
                    tree,
                    menu.is_overlay,
                ),
            };

            new_menu_root = Some((new_index, ms.clone()));
            if menu.is_overlay {
                state.active_root.push(new_index);
            } else {
                state.menu_states.truncate(menu.depth + 1);
            }
            state.menu_states.push(ms);
        } else if !menu.is_overlay && remove {
            state.menu_states.truncate(menu.depth + 1);
        }

        (new_menu_root, Captured)
    })
}

fn process_scroll_events<Message>(
    menu: &mut Menu<'_, Message>,
    delta: mouse::ScrollDelta,
    overlay_cursor: Point,
    viewport_size: Size,
    overlay_offset: Vector,
) -> event::Status
where
    Message: Clone,
{
    use event::Status::{Captured, Ignored};
    use mouse::ScrollDelta;

    menu.tree.inner.with_data_mut(|state| {
        let delta_y = match delta {
            ScrollDelta::Lines { y, .. } => y * 60.0,
            ScrollDelta::Pixels { y, .. } => y,
        };

        let calc_offset_bounds = |menu_state: &MenuState, viewport_size: Size| -> (f32, f32) {
            // viewport space children bounds
            let children_bounds = menu_state.menu_bounds.children_bounds + overlay_offset;

            let max_offset = (0.0 - children_bounds.y).max(0.0);
            let min_offset =
                (viewport_size.height - (children_bounds.y + children_bounds.height)).min(0.0);
            (max_offset, min_offset)
        };

        // update
        if state.menu_states.is_empty() {
            return Ignored;
        } else if state.menu_states.len() == 1 {
            let last_ms = &mut state.menu_states[0];

            if last_ms.index.is_none() {
                return Captured;
            }

            let (max_offset, min_offset) = calc_offset_bounds(last_ms, viewport_size);
            last_ms.scroll_offset = (last_ms.scroll_offset + delta_y).clamp(min_offset, max_offset);
        } else {
            // >= 2
            let max_index = state.menu_states.len() - 1;
            let last_two = &mut state.menu_states[max_index - 1..=max_index];

            if last_two[1].index.is_some() {
                // scroll the last one
                let (max_offset, min_offset) = calc_offset_bounds(&last_two[1], viewport_size);
                last_two[1].scroll_offset =
                    (last_two[1].scroll_offset + delta_y).clamp(min_offset, max_offset);
            } else {
                if !last_two[0]
                    .menu_bounds
                    .children_bounds
                    .contains(overlay_cursor)
                {
                    return Captured;
                }

                // scroll the second last one
                let (max_offset, min_offset) = calc_offset_bounds(&last_two[0], viewport_size);
                let scroll_offset =
                    (last_two[0].scroll_offset + delta_y).clamp(min_offset, max_offset);
                let clamped_delta_y = scroll_offset - last_two[0].scroll_offset;
                last_two[0].scroll_offset = scroll_offset;

                // update the bounds of the last one
                last_two[1].menu_bounds.parent_bounds.y += clamped_delta_y;
                last_two[1].menu_bounds.children_bounds.y += clamped_delta_y;
                last_two[1].menu_bounds.check_bounds.y += clamped_delta_y;
            }
        }
        Captured
    })
}

#[allow(clippy::pedantic)]
/// Returns (children_size, child_positions, child_sizes)
fn get_children_layout<Message>(
    menu_tree: &MenuTree<Message>,
    renderer: &crate::Renderer,
    item_width: ItemWidth,
    item_height: ItemHeight,
    tree: &mut [Tree],
) -> (Size, Vec<f32>, Vec<Size>) {
    let width = match item_width {
        ItemWidth::Uniform(u) => f32::from(u),
        ItemWidth::Static(s) => f32::from(menu_tree.width.unwrap_or(s)),
    };

    let child_sizes: Vec<Size> = match item_height {
        ItemHeight::Uniform(u) => {
            let count = menu_tree.children.len();
            (0..count).map(|_| Size::new(width, f32::from(u))).collect()
        }
        ItemHeight::Static(s) => menu_tree
            .children
            .iter()
            .map(|mt| Size::new(width, f32::from(mt.height.unwrap_or(s))))
            .collect(),
        ItemHeight::Dynamic(d) => menu_tree
            .children
            .iter()
            .map(|mt| {
                mt.item
                    .element
                    .with_data(|w| match w.as_widget().size().height {
                        Length::Fixed(f) => Size::new(width, f),
                        Length::Shrink => {
                            let l_height = w
                                .as_widget()
                                .layout(
                                    &mut tree[mt.index],
                                    renderer,
                                    &Limits::new(Size::ZERO, Size::new(width, f32::MAX)),
                                )
                                .size()
                                .height;

                            let height = if (f32::MAX - l_height) < 0.001 {
                                f32::from(d)
                            } else {
                                l_height
                            };

                            Size::new(width, height)
                        }
                        _ => mt.height.map_or_else(
                            || Size::new(width, f32::from(d)),
                            |h| Size::new(width, f32::from(h)),
                        ),
                    })
            })
            .collect(),
    };

    let max_index = menu_tree.children.len().saturating_sub(1);
    let child_positions: Vec<f32> = std::iter::once(0.0)
        .chain(child_sizes[0..max_index].iter().scan(0.0, |acc, x| {
            *acc += x.height;
            Some(*acc)
        }))
        .collect();

    let height = child_sizes.iter().fold(0.0, |acc, x| acc + x.height);

    (Size::new(width, height), child_positions, child_sizes)
}

fn search_bound(
    default: usize,
    default_left: usize,
    default_right: usize,
    bound: f32,
    positions: &[f32],
    sizes: &[Size],
) -> usize {
    // binary search
    let mut left = default_left;
    let mut right = default_right;

    let mut index = default;
    while left != right {
        let m = ((left + right) / 2) + 1;
        if positions[m] > bound {
            right = m - 1;
        } else {
            left = m;
        }
    }
    // let height = f32::from(menu_tree.children[left].height.unwrap_or(default_height));
    let height = sizes[left].height;
    if positions[left] + height > bound {
        index = left;
    }
    index
}