egui-treeize 0.1.1

//! This module provides functionality for showing [`Treeize`] graph in [`Ui`].

use std::{collections::HashMap, hash::Hash};

use egui::{
  Align, Color32, CornerRadius, Frame, Id, LayerId, Layout, Margin, Modifiers, PointerButton, Pos2,
  Rect, Scene, Sense, Shape, Stroke, StrokeKind, Style, Ui, UiBuilder, UiKind, UiStackInfo, Vec2,
  collapsing_header::paint_default_icon,
  emath::{GuiRounding, TSTransform},
  epaint::Shadow,
  pos2,
  response::Flags,
  vec2,
};
use egui_scale::EguiScale;

use crate::{
  InPin, InPinId, Node, NodeId, OutPin, OutPinId, Treeize,
  layout::{LayoutConfig, layout_with_viewer},
  ui::wire::WireId,
};

mod background_pattern;
mod pin;
mod scale;
pub(crate) mod state;
mod viewer;
mod wire;

use self::{
  pin::AnyPin,
  state::{NewWires, NodeState, TreeizeState},
  wire::{draw_wire, hit_wire, pick_wire_style},
};

pub use self::{
  background_pattern::{BackgroundPattern, Grid},
  pin::{AnyPins, PinInfo, PinShape, PinWireInfo, TreeizePin},
  state::get_selected_nodes,
  viewer::TreeizeViewer,
  wire::{WireLayer, WireStyle},
};

/// Controls how header, pins, body are placed in the node.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "egui-probe", derive(egui_probe::EguiProbe))]
pub enum NodeLayoutKind {
  /// Input pins, body and output pins are placed horizontally.
  ///
  /// +---------In----------+
  /// |       Header        |
  /// +----+-----------+----+
  /// |                     |
  /// |        Body         |
  /// |                     |
  /// +--------Out----------+
  ///
  #[default]
  Compact,
}

/// Controls how node elements are laid out.
///
///
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "egui-probe", derive(egui_probe::EguiProbe))]
pub struct NodeLayout {
  /// Controls method of laying out node elements.
  pub kind: NodeLayoutKind,

  /// Controls minimal height of pin rows.
  pub min_pin_row_height: f32,

  /// Controls how pin rows heights are set.
  /// If true, all pin rows will have the same height, matching the largest content.
  /// False by default.
  pub equal_pin_row_heights: bool,
}

impl NodeLayout {
  /// Creates new [`NodeLayout`] with `compact` kind and flexible pin heights.
  #[must_use]
  #[inline]
  pub const fn compact() -> Self {
    NodeLayout {
      kind: NodeLayoutKind::Compact,
      min_pin_row_height: 0.0,
      equal_pin_row_heights: false,
    }
  }
}

impl From<NodeLayoutKind> for NodeLayout {
  #[inline]
  fn from(kind: NodeLayoutKind) -> Self {
    NodeLayout { kind, min_pin_row_height: 0.0, equal_pin_row_heights: false }
  }
}

impl Default for NodeLayout {
  #[inline]
  fn default() -> Self {
    Self::compact()
  }
}

#[derive(Clone, Copy, Debug)]
enum OuterHeights<'a> {
  Flexible { rows: &'a [f32] },
}

#[derive(Clone, Copy, Debug)]
struct Heights<'a> {
  rows: &'a [f32],
  outer: OuterHeights<'a>,
  min_outer: f32,
}

impl Heights<'_> {
  fn get(&self, idx: usize) -> (f32, f32) {
    let inner = match self.rows.get(idx) {
      Some(&value) => value,
      None => 0.0,
    };

    let outer = match &self.outer {
      OuterHeights::Flexible { rows } => match rows.get(idx) {
        Some(&outer) => outer.max(inner),
        None => inner,
      },
    };

    (inner, outer.max(self.min_outer))
  }
}

impl NodeLayout {
  fn input_heights(self, state: &NodeState) -> Heights<'_> {
    let rows = state.input_heights().as_slice();

    let outer = OuterHeights::Flexible { rows: state.output_heights().as_slice() };

    Heights { rows, outer, min_outer: self.min_pin_row_height }
  }

  fn output_heights(self, state: &'_ NodeState) -> Heights<'_> {
    let rows = state.output_heights().as_slice();
    let outer = OuterHeights::Flexible { rows: state.input_heights().as_slice() };

    Heights { rows, outer, min_outer: self.min_pin_row_height }
  }
}

/// Controls style of node selection rect.
#[derive(Clone, Copy, Debug, Default, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "egui-probe", derive(egui_probe::EguiProbe))]
pub struct SelectionStyle {
  /// Margin between selection rect and node frame.
  pub margin: Margin,

  /// Rounding of selection rect.
  pub rounding: CornerRadius,

  /// Fill color of selection rect.
  pub fill: Color32,

  /// Stroke of selection rect.
  pub stroke: Stroke,
}

/// Controls how pins are placed in the node.
#[derive(Clone, Copy, Debug, Default, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "egui-probe", derive(egui_probe::EguiProbe))]
pub enum PinPlacement {
  /// Pins are placed inside the node frame.
  #[default]
  Inside,

  /// Pins are placed on the edge of the node frame.
  Edge,

  /// Pins are placed outside the node frame.
  Outside {
    /// Margin between node frame and pins.
    margin: f32,
  },
}

/// Style for rendering Treeize.
#[derive(Clone, Copy, Debug, PartialEq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "egui-probe", derive(egui_probe::EguiProbe))]
pub struct TreeizeStyle {
  /// Controls how nodes are laid out.
  /// Defaults to [`NodeLayoutKind::Coil`].
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub node_layout: Option<NodeLayout>,

  /// Frame used to draw nodes.
  /// Defaults to [`Frame::window`] constructed from current ui's style.
  #[cfg_attr(
    feature = "serde",
    serde(skip_serializing_if = "Option::is_none", default, with = "serde_frame_option")
  )]
  pub node_frame: Option<Frame>,

  /// Frame used to draw node headers.
  /// Defaults to [`node_frame`] without shadow and transparent fill.
  ///
  /// If set, it should not have shadow and fill should be either opaque of fully transparent
  /// unless layering of header fill color with node fill color is desired.
  #[cfg_attr(
    feature = "serde",
    serde(skip_serializing_if = "Option::is_none", default, with = "serde_frame_option")
  )]
  pub header_frame: Option<Frame>,

  /// Blank space for dragging node by its header.
  /// Elements in the header are placed after this space.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub header_drag_space: Option<Vec2>,

  /// Whether nodes can be collapsed.
  /// If true, headers will have collapsing button.
  /// When collapsed, node will not show its pins and body.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub collapsible: Option<bool>,

  /// Size of pins.
  #[cfg_attr(feature = "egui-probe", egui_probe(range = 0.0..))]
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub pin_size: Option<f32>,

  /// Default fill color for pins.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub pin_fill: Option<Color32>,

  /// Default stroke for pins.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub pin_stroke: Option<Stroke>,

  /// Shape of pins.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub pin_shape: Option<PinShape>,

  /// Placement of pins.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub pin_placement: Option<PinPlacement>,

  /// Width of wires.
  #[cfg_attr(feature = "egui-probe", egui_probe(range = 0.0..))]
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub wire_width: Option<f32>,

  /// Size of wire frame which controls curvature of wires.
  #[cfg_attr(feature = "egui-probe", egui_probe(range = 0.0..))]
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub wire_frame_size: Option<f32>,

  /// Whether to downscale wire frame when nodes are close.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub downscale_wire_frame: Option<bool>,

  /// Weather to upscale wire frame when nodes are far.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub upscale_wire_frame: Option<bool>,

  /// Controls default style of wires.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub wire_style: Option<WireStyle>,

  /// Layer where wires are rendered.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub wire_layer: Option<WireLayer>,

  /// Frame used to draw background
  #[cfg_attr(
    feature = "serde",
    serde(skip_serializing_if = "Option::is_none", default, with = "serde_frame_option")
  )]
  pub bg_frame: Option<Frame>,

  /// Background pattern.
  /// Defaults to [`BackgroundPattern::Grid`].
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub bg_pattern: Option<BackgroundPattern>,

  /// Stroke for background pattern.
  /// Defaults to `ui.visuals().widgets.noninteractive.bg_stroke`.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub bg_pattern_stroke: Option<Stroke>,

  /// Minimum viewport scale that can be set.
  #[cfg_attr(feature = "egui-probe", egui_probe(range = 0.0..=1.0))]
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub min_scale: Option<f32>,

  /// Maximum viewport scale that can be set.
  #[cfg_attr(feature = "egui-probe", egui_probe(range = 1.0..))]
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub max_scale: Option<f32>,

  /// Stroke for selection.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub select_stoke: Option<Stroke>,

  /// Fill for selection.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub select_fill: Option<Color32>,

  /// Flag to control how rect selection works.
  /// If set to true, only nodes fully contained in selection rect will be selected.
  /// If set to false, nodes intersecting with selection rect will be selected.
  pub select_rect_contained: Option<bool>,

  /// Style for node selection.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub select_style: Option<SelectionStyle>,

  /// Controls whether to show magnified text in crisp mode.
  /// This zooms UI style to max scale and scales down the scene.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  pub crisp_magnified_text: Option<bool>,

  /// Controls smoothness of wire curves.
  #[cfg_attr(feature = "serde", serde(skip_serializing_if = "Option::is_none", default))]
  #[cfg_attr(
        feature = "egui-probe",
        egui_probe(range = 0.0f32..=10.0f32 by 0.05f32)
    )]
  pub wire_smoothness: Option<f32>,

  #[doc(hidden)]
  #[cfg_attr(feature = "egui-probe", egui_probe(skip))]
  #[cfg_attr(feature = "serde", serde(skip_serializing, default))]
  /// Do not access other than with .., here to emulate `#[non_exhaustive(pub)]`
  pub _non_exhaustive: (),
}

impl TreeizeStyle {
  fn get_node_layout(&self) -> NodeLayout {
    self.node_layout.unwrap_or_default()
  }

  fn get_pin_size(&self, style: &Style) -> f32 {
    self.pin_size.unwrap_or(style.spacing.interact_size.y * 0.6)
  }

  fn get_pin_fill(&self, style: &Style) -> Color32 {
    self.pin_fill.unwrap_or(style.visuals.widgets.active.bg_fill)
  }

  fn get_pin_stroke(&self, style: &Style) -> Stroke {
    self.pin_stroke.unwrap_or_else(|| {
      Stroke::new(
        style.visuals.widgets.active.bg_stroke.width,
        style.visuals.widgets.active.bg_stroke.color,
      )
    })
  }

  fn get_pin_shape(&self) -> PinShape {
    self.pin_shape.unwrap_or(PinShape::Circle)
  }

  fn get_pin_placement(&self) -> PinPlacement {
    self.pin_placement.unwrap_or_default()
  }

  fn get_wire_width(&self, style: &Style) -> f32 {
    self.wire_width.unwrap_or_else(|| self.get_pin_size(style) * 0.1)
  }

  fn get_wire_frame_size(&self, style: &Style) -> f32 {
    self.wire_frame_size.unwrap_or_else(|| self.get_pin_size(style) * 3.0)
  }

  fn get_downscale_wire_frame(&self) -> bool {
    self.downscale_wire_frame.unwrap_or(true)
  }

  fn get_upscale_wire_frame(&self) -> bool {
    self.upscale_wire_frame.unwrap_or(false)
  }

  fn get_wire_style(&self) -> WireStyle {
    self.wire_style.unwrap_or(WireStyle::Bezier5)
  }

  fn get_wire_layer(&self) -> WireLayer {
    self.wire_layer.unwrap_or(WireLayer::BehindNodes)
  }

  fn get_header_drag_space(&self, style: &Style) -> Vec2 {
    self
      .header_drag_space
      .unwrap_or_else(|| vec2(style.spacing.icon_width, style.spacing.icon_width))
  }

  fn get_collapsible(&self) -> bool {
    self.collapsible.unwrap_or(true)
  }

  fn get_bg_frame(&self, style: &Style) -> Frame {
    self.bg_frame.unwrap_or_else(|| Frame::canvas(style))
  }

  fn get_bg_pattern_stroke(&self, style: &Style) -> Stroke {
    self.bg_pattern_stroke.unwrap_or(style.visuals.widgets.noninteractive.bg_stroke)
  }

  fn get_min_scale(&self) -> f32 {
    self.min_scale.unwrap_or(0.2)
  }

  fn get_max_scale(&self) -> f32 {
    self.max_scale.unwrap_or(2.0)
  }

  fn get_node_frame(&self, style: &Style) -> Frame {
    self.node_frame.unwrap_or_else(|| Frame::window(style))
  }

  fn get_header_frame(&self, style: &Style) -> Frame {
    self.header_frame.unwrap_or_else(|| self.get_node_frame(style).shadow(Shadow::NONE))
  }

  fn get_select_stroke(&self, style: &Style) -> Stroke {
    self.select_stoke.unwrap_or_else(|| {
      Stroke::new(
        style.visuals.selection.stroke.width,
        style.visuals.selection.stroke.color.gamma_multiply(0.5),
      )
    })
  }

  fn get_select_fill(&self, style: &Style) -> Color32 {
    self.select_fill.unwrap_or_else(|| style.visuals.selection.bg_fill.gamma_multiply(0.3))
  }

  fn get_select_rect_contained(&self) -> bool {
    self.select_rect_contained.unwrap_or(false)
  }

  fn get_select_style(&self, style: &Style) -> SelectionStyle {
    self.select_style.unwrap_or_else(|| SelectionStyle {
      margin: style.spacing.window_margin,
      rounding: style.visuals.window_corner_radius,
      fill: self.get_select_fill(style),
      stroke: self.get_select_stroke(style),
    })
  }

  fn get_crisp_magnified_text(&self) -> bool {
    self.crisp_magnified_text.unwrap_or(false)
  }

  fn get_wire_smoothness(&self) -> f32 {
    self.wire_smoothness.unwrap_or(1.0)
  }
}

#[cfg(feature = "serde")]
mod serde_frame_option {
  use serde::{Deserialize, Deserializer, Serialize, Serializer};

  #[derive(Serialize, Deserialize)]
  pub struct Frame {
    pub inner_margin: egui::Margin,
    pub outer_margin: egui::Margin,
    pub rounding: egui::CornerRadius,
    pub shadow: egui::epaint::Shadow,
    pub fill: egui::Color32,
    pub stroke: egui::Stroke,
  }

  #[allow(clippy::ref_option)]
  pub fn serialize<S>(frame: &Option<egui::Frame>, serializer: S) -> Result<S::Ok, S::Error>
  where
    S: Serializer,
  {
    match frame {
      Some(frame) => Frame {
        inner_margin: frame.inner_margin,
        outer_margin: frame.outer_margin,
        rounding: frame.corner_radius,
        shadow: frame.shadow,
        fill: frame.fill,
        stroke: frame.stroke,
      }
      .serialize(serializer),
      None => serializer.serialize_none(),
    }
  }

  pub fn deserialize<'de, D>(deserializer: D) -> Result<Option<egui::Frame>, D::Error>
  where
    D: Deserializer<'de>,
  {
    let frame_opt = Option::<Frame>::deserialize(deserializer)?;
    Ok(frame_opt.map(|frame| egui::Frame {
      inner_margin: frame.inner_margin,
      outer_margin: frame.outer_margin,
      corner_radius: frame.rounding,
      shadow: frame.shadow,
      fill: frame.fill,
      stroke: frame.stroke,
    }))
  }
}

impl TreeizeStyle {
  /// Creates new [`TreeizeStyle`] filled with default values.
  #[must_use]
  pub const fn new() -> Self {
    TreeizeStyle {
      node_layout: None,
      pin_size: None,
      pin_fill: None,
      pin_stroke: None,
      pin_shape: None,
      pin_placement: None,
      wire_width: None,
      wire_frame_size: None,
      downscale_wire_frame: None,
      upscale_wire_frame: None,
      wire_style: None,
      wire_layer: None,
      header_drag_space: None,
      collapsible: None,

      bg_frame: None,
      bg_pattern: None,
      bg_pattern_stroke: None,

      min_scale: None,
      max_scale: None,
      node_frame: None,
      header_frame: None,
      select_stoke: None,
      select_fill: None,
      select_rect_contained: None,
      select_style: None,
      crisp_magnified_text: None,
      wire_smoothness: None,

      _non_exhaustive: (),
    }
  }
}

impl Default for TreeizeStyle {
  #[inline]
  fn default() -> Self {
    Self::new()
  }
}

struct DrawNodeResponse {
  node_moved: Option<(NodeId, Vec2)>,
  node_to_top: Option<NodeId>,
  drag_released: bool,
  pin_hovered: Option<AnyPin>,
  final_rect: Rect,
}

struct DrawPinsResponse {
  drag_released: bool,
  pin_hovered: Option<AnyPin>,
}

struct DrawBodyResponse {
  final_rect: Rect,
}

struct PinResponse {
  pos: Pos2,
  wire_color: Color32,
  wire_style: WireStyle,
}

/// Widget to display [`Treeize`] graph in [`Ui`].
#[derive(Clone, Copy, Debug)]
pub struct TreeizeWidget {
  id_salt: Id,
  id: Option<Id>,
  style: TreeizeStyle,
  min_size: Vec2,
  max_size: Vec2,
}

/// Signal to layout the treeize.
pub struct TreeizeLayoutSignal {
  /// Signal to layout the treeize.
  pub layout_signal: bool,
  /// Configuration for the layout.
  pub layout_config: LayoutConfig,
}

impl Default for TreeizeWidget {
  #[inline]
  fn default() -> Self {
    Self::new()
  }
}

impl TreeizeWidget {
  /// Returns new [`TreeizeWidget`] with default parameters.
  #[inline]
  #[must_use]
  pub fn new() -> Self {
    TreeizeWidget {
      id_salt: Id::new(":treeize:"),
      id: None,
      style: TreeizeStyle::new(),
      min_size: Vec2::ZERO,
      max_size: Vec2::INFINITY,
    }
  }

  /// Assign an explicit and globally unique [`Id`].
  ///
  /// Use this if you want to persist the state of the widget
  /// when it changes position in the widget hierarchy.
  ///
  /// Prefer using [`TreeizeWidget::id_salt`] otherwise.
  #[inline]
  #[must_use]
  pub const fn id(mut self, id: Id) -> Self {
    self.id = Some(id);
    self
  }

  /// Assign a source for the unique [`Id`]
  ///
  /// It must be locally unique for the current [`Ui`] hierarchy position.
  ///
  /// Ignored if [`TreeizeWidget::id`] was set.
  #[inline]
  #[must_use]
  pub fn id_salt(mut self, id_salt: impl Hash) -> Self {
    self.id_salt = Id::new(id_salt);
    self
  }

  /// Set style parameters for the [`Treeize`] widget.
  #[inline]
  #[must_use]
  pub const fn style(mut self, style: TreeizeStyle) -> Self {
    self.style = style;
    self
  }

  /// Set minimum size of the [`Treeize`] widget.
  #[inline]
  #[must_use]
  pub const fn min_size(mut self, min_size: Vec2) -> Self {
    self.min_size = min_size;
    self
  }

  /// Set maximum size of the [`Treeize`] widget.
  #[inline]
  #[must_use]
  pub const fn max_size(mut self, max_size: Vec2) -> Self {
    self.max_size = max_size;
    self
  }

  #[inline]
  fn get_id(&self, ui_id: Id) -> Id {
    self.id.unwrap_or_else(|| ui_id.with(self.id_salt))
  }

  /// Render [`Treeize`] using given viewer and style into the [`Ui`].
  #[inline]
  pub fn show<T, V>(
    &self,
    treeize: &mut Treeize<T>,
    viewer: &mut V,
    ui: &mut Ui,
    center_signal: Option<bool>,
    layout_signal: Option<&TreeizeLayoutSignal>,
  ) -> egui::Response
  where
    V: TreeizeViewer<T>,
  {
    let treeize_id = self.get_id(ui.id());

    show_treeize(
      treeize_id,
      self.style,
      self.min_size,
      self.max_size,
      treeize,
      viewer,
      ui,
      center_signal,
      layout_signal,
    )
  }
}

#[inline(never)]
#[allow(clippy::too_many_arguments, clippy::too_many_lines)]
fn show_treeize<T, V>(
  treeize_id: Id,
  mut style: TreeizeStyle,
  min_size: Vec2,
  max_size: Vec2,
  treeize: &mut Treeize<T>,
  viewer: &mut V,
  ui: &mut Ui,
  center_signal: Option<bool>,
  layout_signal: Option<&TreeizeLayoutSignal>,
) -> egui::Response
where
  V: TreeizeViewer<T>,
{
  let (mut latest_pos, modifiers) = ui.ctx().input(|i| (i.pointer.latest_pos(), i.modifiers));

  let bg_frame = style.get_bg_frame(ui.style());

  let outer_size_bounds = ui.available_size_before_wrap().max(min_size).min(max_size);

  let outer_resp = ui.allocate_response(outer_size_bounds, Sense::hover());

  ui.painter().add(bg_frame.paint(outer_resp.rect));

  let mut content_rect = outer_resp.rect - bg_frame.total_margin();

  // Make sure we don't shrink to the negative:
  content_rect.max.x = content_rect.max.x.max(content_rect.min.x);
  content_rect.max.y = content_rect.max.y.max(content_rect.min.y);

  let treeize_layer_id = LayerId::new(ui.layer_id().order, treeize_id);

  ui.ctx().set_sublayer(ui.layer_id(), treeize_layer_id);

  let mut min_scale = style.get_min_scale();
  let mut max_scale = style.get_max_scale();

  let ui_rect = content_rect;

  let mut treeize_state =
    TreeizeState::load(ui.ctx(), treeize_id, treeize, ui_rect, min_scale, max_scale);
  let mut to_global = treeize_state.to_global();

  let clip_rect = ui.clip_rect();

  let mut ui = ui.new_child(
    UiBuilder::new()
      .ui_stack_info(UiStackInfo::new(UiKind::Frame).with_frame(bg_frame))
      .layer_id(treeize_layer_id)
      .max_rect(Rect::EVERYTHING)
      .sense(Sense::click_and_drag()),
  );

  if style.get_crisp_magnified_text() {
    style.scale(max_scale);
    ui.style_mut().scale(max_scale);

    min_scale /= max_scale;
    max_scale = 1.0;
  }

  clamp_scale(&mut to_global, min_scale, max_scale, ui_rect);

  let mut treeize_resp = ui.response();
  Scene::new().zoom_range(min_scale..=max_scale).register_pan_and_zoom(
    &ui,
    &mut treeize_resp,
    &mut to_global,
  );

  if treeize_resp.changed() {
    ui.ctx().request_repaint();
  }

  // Inform viewer about current transform.
  viewer.current_transform(&mut to_global, treeize);

  treeize_state.set_to_global(to_global);

  let to_global = to_global;
  let from_global = to_global.inverse();

  // Graph viewport
  let viewport = (from_global * ui_rect).round_ui();
  let viewport_clip = from_global * clip_rect;

  ui.set_clip_rect(viewport.intersect(viewport_clip));
  ui.expand_to_include_rect(viewport);

  // Set transform for treeize layer.
  ui.ctx().set_transform_layer(treeize_layer_id, to_global);

  // Map latest pointer position to graph space.
  latest_pos = latest_pos.map(|pos| from_global * pos);

  viewer.draw_background(
    style.bg_pattern.as_ref(),
    &viewport,
    &style,
    ui.style(),
    ui.painter(),
    treeize,
  );

  let mut node_moved = None;
  let mut node_to_top = None;

  // Process selection rect.
  let mut rect_selection_ended = None;
  if modifiers.shift || treeize_state.is_rect_selection() {
    let select_resp = ui.interact(treeize_resp.rect, treeize_id.with("select"), Sense::drag());

    if select_resp.dragged_by(PointerButton::Primary)
      && let Some(pos) = select_resp.interact_pointer_pos()
    {
      if treeize_state.is_rect_selection() {
        treeize_state.update_rect_selection(pos);
      } else {
        treeize_state.start_rect_selection(pos);
      }
    }

    if select_resp.drag_stopped_by(PointerButton::Primary) {
      if let Some(select_rect) = treeize_state.rect_selection() {
        rect_selection_ended = Some(select_rect);
      }
      treeize_state.stop_rect_selection();
    }
  }

  let wire_frame_size = style.get_wire_frame_size(ui.style());
  let wire_width = style.get_wire_width(ui.style());
  let wire_threshold = style.get_wire_smoothness();

  let wire_shape_idx = match style.get_wire_layer() {
    WireLayer::BehindNodes => Some(ui.painter().add(Shape::Noop)),
    WireLayer::AboveNodes => None,
  };

  let mut input_info = HashMap::new();
  let mut output_info = HashMap::new();

  let mut pin_hovered = None;

  let draw_order = treeize_state.update_draw_order(treeize);
  let mut drag_released = false;

  let mut node_rects = Vec::new();

  for node_idx in draw_order {
    if !treeize.nodes.contains(node_idx.0) {
      continue;
    }

    // show_node(node_idx);
    let response = draw_node(
      treeize,
      &mut ui,
      node_idx,
      viewer,
      &mut treeize_state,
      &style,
      treeize_id,
      &mut input_info,
      modifiers,
      &mut output_info,
    );

    if let Some(response) = response {
      if let Some(v) = response.node_to_top {
        node_to_top = Some(v);
      }
      if let Some(v) = response.node_moved {
        node_moved = Some(v);
      }
      if let Some(v) = response.pin_hovered {
        pin_hovered = Some(v);
      }
      drag_released |= response.drag_released;

      if rect_selection_ended.is_some() {
        node_rects.push((node_idx, response.final_rect));
      }
    }
  }

  let mut hovered_wire = None;
  let mut wire_shapes = Vec::new();

  // Draw and interact with wires
  for wire in treeize.wires.iter() {
    let Some(from_r) = output_info.get(&wire.out_pin) else {
      continue;
    };
    let Some(to_r) = input_info.get(&wire.in_pin) else {
      continue;
    };

    if !treeize_state.has_new_wires() && treeize_resp.contains_pointer() && hovered_wire.is_none() {
      // Try to find hovered wire
      // If not dragging new wire
      // And not hovering over item above.

      if let Some(latest_pos) = latest_pos {
        let wire_hit = hit_wire(
          ui.ctx(),
          WireId::Connected { treeize_id, out_pin: wire.out_pin, in_pin: wire.in_pin },
          wire_frame_size,
          style.get_upscale_wire_frame(),
          style.get_downscale_wire_frame(),
          from_r.pos,
          to_r.pos,
          latest_pos,
          wire_width.max(2.0),
          pick_wire_style(from_r.wire_style, to_r.wire_style),
        );

        if wire_hit {
          hovered_wire = Some(wire);
        }
      }
    }

    let color = mix_colors(from_r.wire_color, to_r.wire_color);

    let mut draw_width = wire_width;
    if hovered_wire == Some(wire) {
      draw_width *= 1.5;
    }

    draw_wire(
      &ui,
      WireId::Connected { treeize_id, out_pin: wire.out_pin, in_pin: wire.in_pin },
      &mut wire_shapes,
      wire_frame_size,
      style.get_upscale_wire_frame(),
      style.get_downscale_wire_frame(),
      from_r.pos,
      to_r.pos,
      Stroke::new(draw_width, color),
      wire_threshold,
      pick_wire_style(from_r.wire_style, to_r.wire_style),
    );
  }

  if let Some(select_rect) = rect_selection_ended {
    let select_nodes = node_rects.into_iter().filter_map(|(id, rect)| {
      let select = if style.get_select_rect_contained() {
        select_rect.contains_rect(rect)
      } else {
        select_rect.intersects(rect)
      };

      if select { Some(id) } else { None }
    });

    if modifiers.command {
      treeize_state.deselect_many_nodes(select_nodes);
    } else {
      treeize_state.select_many_nodes(!modifiers.shift, select_nodes);
    }
  }

  if let Some(select_rect) = treeize_state.rect_selection() {
    ui.painter().rect(
      select_rect,
      0.0,
      style.get_select_fill(ui.style()),
      style.get_select_stroke(ui.style()),
      StrokeKind::Inside,
    );
  }

  // If right button is clicked while new wire is being dragged, cancel it.
  // This is to provide way to 'not open' the link graph node menu, but just
  // releasing the new wire to empty space.
  //
  // This uses `button_down` directly, instead of `clicked_by` to improve
  // responsiveness of the cancel action.
  if treeize_state.has_new_wires() && ui.input(|x| x.pointer.button_down(PointerButton::Secondary))
  {
    let _ = treeize_state.take_new_wires();
    treeize_resp.flags.remove(Flags::CLICKED);
  }

  // Wire end position will be overridden when link graph menu is opened.
  let mut wire_end_pos = latest_pos.unwrap_or_else(|| treeize_resp.rect.center());

  if drag_released {
    let new_wires = treeize_state.take_new_wires();
    if new_wires.is_some() {
      ui.ctx().request_repaint();
    }
    match (new_wires, pin_hovered) {
      (Some(NewWires::In(in_pins)), Some(AnyPin::Out(out_pin))) => {
        for in_pin in in_pins {
          viewer.connect(&OutPin::new(treeize, out_pin), &InPin::new(treeize, in_pin), treeize);
        }
      }
      (Some(NewWires::Out(out_pins)), Some(AnyPin::In(in_pin))) => {
        for out_pin in out_pins {
          viewer.connect(&OutPin::new(treeize, out_pin), &InPin::new(treeize, in_pin), treeize);
        }
      }
      (Some(new_wires), None) if treeize_resp.hovered() => {
        let pins = match &new_wires {
          NewWires::In(x) => AnyPins::In(x),
          NewWires::Out(x) => AnyPins::Out(x),
        };

        if viewer.has_dropped_wire_menu(pins, treeize) {
          // A wire is dropped without connecting to a pin.
          // Show context menu for the wire drop.
          treeize_state.set_new_wires_menu(new_wires);

          // Force open context menu.
          treeize_resp.flags.insert(Flags::LONG_TOUCHED);
        }
      }
      _ => {}
    }
  }

  if let Some(interact_pos) = ui.ctx().input(|i| i.pointer.interact_pos()) {
    if let Some(new_wires) = treeize_state.take_new_wires_menu() {
      let pins = match &new_wires {
        NewWires::In(x) => AnyPins::In(x),
        NewWires::Out(x) => AnyPins::Out(x),
      };

      if viewer.has_dropped_wire_menu(pins, treeize) {
        treeize_resp.context_menu(|ui| {
          let pins = match &new_wires {
            NewWires::In(x) => AnyPins::In(x),
            NewWires::Out(x) => AnyPins::Out(x),
          };

          let menu_pos = from_global * ui.cursor().min;

          // Override wire end position when the wire-drop context menu is opened.
          wire_end_pos = menu_pos;

          // The context menu is opened as *link* graph menu.
          viewer.show_dropped_wire_menu(menu_pos, ui, pins, treeize);

          // Even though menu could be closed in `show_dropped_wire_menu`,
          // we need to revert the new wires here, because menu state is inaccessible.
          // Next frame context menu won't be shown and wires will be removed.
          treeize_state.set_new_wires_menu(new_wires);
        });
      }
    } else if viewer.has_graph_menu(interact_pos, treeize) {
      treeize_resp.context_menu(|ui| {
        let menu_pos = from_global * ui.cursor().min;

        viewer.show_graph_menu(menu_pos, ui, treeize);
      });
    }
  }

  match treeize_state.new_wires() {
    None => {}
    Some(NewWires::In(in_pins)) => {
      for &in_pin in in_pins {
        let from_pos = wire_end_pos;
        let to_r = &input_info[&in_pin];

        draw_wire(
          &ui,
          WireId::NewInput { treeize_id, in_pin },
          &mut wire_shapes,
          wire_frame_size,
          style.get_upscale_wire_frame(),
          style.get_downscale_wire_frame(),
          from_pos,
          to_r.pos,
          Stroke::new(wire_width, to_r.wire_color),
          wire_threshold,
          to_r.wire_style,
        );
      }
    }
    Some(NewWires::Out(out_pins)) => {
      for &out_pin in out_pins {
        let from_r = &output_info[&out_pin];
        let to_pos = wire_end_pos;

        draw_wire(
          &ui,
          WireId::NewOutput { treeize_id, out_pin },
          &mut wire_shapes,
          wire_frame_size,
          style.get_upscale_wire_frame(),
          style.get_downscale_wire_frame(),
          from_r.pos,
          to_pos,
          Stroke::new(wire_width, from_r.wire_color),
          wire_threshold,
          from_r.wire_style,
        );
      }
    }
  }

  match wire_shape_idx {
    None => {
      ui.painter().add(Shape::Vec(wire_shapes));
    }
    Some(idx) => {
      ui.painter().set(idx, Shape::Vec(wire_shapes));
    }
  }

  ui.advance_cursor_after_rect(Rect::from_min_size(treeize_resp.rect.min, Vec2::ZERO));

  if let Some(node) = node_to_top
    && treeize.nodes.contains(node.0)
  {
    treeize_state.node_to_top(node);
  }

  if let Some((node, delta)) = node_moved
    && treeize.nodes.contains(node.0)
  {
    ui.ctx().request_repaint();
    if treeize_state.selected_nodes().contains(&node) {
      for node in treeize_state.selected_nodes() {
        let node = &mut treeize.nodes[node.0];
        node.pos += delta;
      }
    } else {
      let node = &mut treeize.nodes[node.0];
      node.pos += delta;
    }
  }

  if let Some(layout_signal) = layout_signal
    && layout_signal.layout_signal
  {
    layout_with_viewer(treeize, viewer, layout_signal.layout_config, ui.ctx(), treeize_id);
  }

  // Do centering unless no nodes are present.
  if let Some(center_signal) = center_signal
    && center_signal
  {
    let mut nodes_bb = Rect::NOTHING;

    for (node_id, _) in treeize.node_ids() {
      let node_state_id = treeize_id.with(("treeize-node", node_id));
      if let Some(node_data) = NodeState::pick_data(ui.ctx(), node_state_id) {
        nodes_bb =
          nodes_bb.union(Rect::from_min_size(treeize.nodes[node_id.0].pos, node_data.size));
      }
    }

    if nodes_bb.is_finite() {
      let nodes_bb = nodes_bb.expand(100.0);
      treeize_state.look_at(nodes_bb, ui_rect, min_scale, max_scale);
    }
  }

  if modifiers.command && treeize_resp.clicked_by(PointerButton::Primary) {
    treeize_state.deselect_all_nodes();
  }

  treeize_state.store(treeize, ui.ctx());

  treeize_resp
}

#[allow(clippy::too_many_arguments)]
#[allow(clippy::too_many_lines)]
fn draw_inputs<T, V>(
  treeize: &mut Treeize<T>,
  viewer: &mut V,
  node: NodeId,
  inputs: &[InPin],
  pin_size: f32,
  style: &TreeizeStyle,
  node_ui: &mut Ui,
  inputs_rect: Rect,
  payload_clip_rect: Rect,
  input_y: f32,
  min_pin_x_left: f32,
  min_pin_x_right: f32,
  treeize_state: &mut TreeizeState,
  modifiers: Modifiers,
  input_positions: &mut HashMap<InPinId, PinResponse>,
  heights: Heights,
) -> DrawPinsResponse
where
  V: TreeizeViewer<T>,
{
  let mut drag_released = false;
  let mut pin_hovered = None;

  // Input pins on the left.
  let mut inputs_ui = node_ui.new_child(
    UiBuilder::new()
      .max_rect(inputs_rect.round_ui())
      .layout(Layout::top_down(Align::Min))
      .id_salt("inputs"),
  );

  let treeize_clip_rect = node_ui.clip_rect();
  inputs_ui.shrink_clip_rect(payload_clip_rect);

  let pin_layout = Layout::left_to_right(Align::Min);

  for in_pin in inputs {
    // Show input pin.
    let cursor = inputs_ui.cursor();
    let (height, height_outer) = heights.get(in_pin.id.input);

    let margin = (height_outer - height) / 2.0;
    let outer_rect = cursor.with_max_y(cursor.top() + height_outer);
    let inner_rect = outer_rect.shrink2(vec2(0.0, margin));

    let builder = UiBuilder::new().layout(pin_layout).max_rect(inner_rect);

    inputs_ui.scope_builder(builder, |pin_ui| {
      let x0 = pin_ui.max_rect().min.x;
      let x1 = pin_ui.max_rect().max.x;

      // Show input content
      let treeize_pin = viewer.show_input(in_pin, pin_ui, treeize);
      if !treeize.nodes.contains(node.0) {
        // If removed
        return;
      }

      let pin_rect =
        treeize_pin.pin_rect(min_pin_x_left.max(x0), min_pin_x_right.max(x1), input_y, pin_size);

      // Interact with pin shape.
      pin_ui.set_clip_rect(treeize_clip_rect);

      let r = pin_ui.interact(pin_rect, pin_ui.next_auto_id(), Sense::click_and_drag());

      pin_ui.skip_ahead_auto_ids(1);

      if r.clicked_by(PointerButton::Secondary) {
        if treeize_state.has_new_wires() {
          treeize_state.remove_new_wire_in(in_pin.id);
        } else {
          viewer.drop_inputs(in_pin, treeize);
          if !treeize.nodes.contains(node.0) {
            // If removed
            return;
          }
        }
      }
      if r.drag_started_by(PointerButton::Primary) {
        if modifiers.command {
          treeize_state.start_new_wires_out(&in_pin.remotes);
          if !modifiers.shift {
            treeize.drop_inputs(in_pin.id);
            if !treeize.nodes.contains(node.0) {
              // If removed
              return;
            }
          }
        } else {
          treeize_state.start_new_wire_in(in_pin.id);
        }
      }

      if r.drag_stopped() {
        drag_released = true;
      }

      let mut visual_pin_rect = r.rect;

      if r.contains_pointer() {
        if treeize_state.has_new_wires_in() {
          if modifiers.shift && !modifiers.command {
            treeize_state.add_new_wire_in(in_pin.id);
          }
          if !modifiers.shift && modifiers.command {
            treeize_state.remove_new_wire_in(in_pin.id);
          }
        }
        pin_hovered = Some(AnyPin::In(in_pin.id));
        visual_pin_rect = visual_pin_rect.scale_from_center(1.2);
      }

      let wire_info = treeize_pin.draw(style, pin_ui.style(), visual_pin_rect, pin_ui.painter());

      input_positions.insert(
        in_pin.id,
        PinResponse {
          pos: r.rect.center(),
          wire_color: wire_info.color,
          wire_style: wire_info.style,
        },
      );

      pin_ui.expand_to_include_y(outer_rect.bottom());
    });
  }

  let final_rect = inputs_ui.min_rect();
  node_ui.expand_to_include_rect(final_rect.intersect(payload_clip_rect));

  DrawPinsResponse { drag_released, pin_hovered }
}

#[allow(clippy::too_many_arguments)]
#[allow(clippy::too_many_lines)]
fn draw_outputs<T, V>(
  treeize: &mut Treeize<T>,
  viewer: &mut V,
  node: NodeId,
  outputs: &[OutPin],
  pin_size: f32,
  style: &TreeizeStyle,
  node_ui: &mut Ui,
  outputs_rect: Rect,
  payload_clip_rect: Rect,
  output_y: f32,
  min_pin_y_left: f32,
  min_pin_y_right: f32,
  treeize_state: &mut TreeizeState,
  modifiers: Modifiers,
  output_positions: &mut HashMap<OutPinId, PinResponse>,
  heights: Heights,
) -> DrawPinsResponse
where
  V: TreeizeViewer<T>,
{
  let mut drag_released = false;
  let mut pin_hovered = None;

  let mut outputs_ui = node_ui.new_child(
    UiBuilder::new()
      .max_rect(outputs_rect.round_ui())
      .layout(Layout::top_down(Align::Max))
      .id_salt("outputs"),
  );

  let treeize_clip_rect = node_ui.clip_rect();
  outputs_ui.shrink_clip_rect(payload_clip_rect);

  let pin_layout = Layout::right_to_left(Align::Min);

  // Output pins on the right.
  for out_pin in outputs {
    // Show output pin.
    let cursor = outputs_ui.cursor();
    let (height, height_outer) = heights.get(out_pin.id.output);

    let margin = (height_outer - height) / 2.0;
    let outer_rect = cursor.with_max_y(cursor.top() + height_outer);
    let inner_rect = outer_rect.shrink2(vec2(0.0, margin));

    let builder = UiBuilder::new().layout(pin_layout).max_rect(inner_rect);

    outputs_ui.scope_builder(builder, |pin_ui| {
      let x0 = pin_ui.max_rect().min.x;
      let x1 = pin_ui.max_rect().max.x;

      // Show output content
      let treeize_pin = viewer.show_output(out_pin, pin_ui, treeize);
      if !treeize.nodes.contains(node.0) {
        // If removed
        return;
      }

      let pin_rect =
        treeize_pin.pin_rect(min_pin_y_left.max(x0), min_pin_y_right.max(x1), output_y, pin_size);

      pin_ui.set_clip_rect(treeize_clip_rect);

      let r = pin_ui.interact(pin_rect, pin_ui.next_auto_id(), Sense::click_and_drag());

      pin_ui.skip_ahead_auto_ids(1);

      if r.clicked_by(PointerButton::Secondary) {
        if treeize_state.has_new_wires() {
          treeize_state.remove_new_wire_out(out_pin.id);
        } else {
          viewer.drop_outputs(out_pin, treeize);
          if !treeize.nodes.contains(node.0) {
            // If removed
            return;
          }
        }
      }
      if r.drag_started_by(PointerButton::Primary) {
        if modifiers.command {
          treeize_state.start_new_wires_in(&out_pin.remotes);

          if !modifiers.shift {
            treeize.drop_outputs(out_pin.id);
            if !treeize.nodes.contains(node.0) {
              // If removed
              return;
            }
          }
        } else {
          treeize_state.start_new_wire_out(out_pin.id);
        }
      }

      if r.drag_stopped() {
        drag_released = true;
      }

      let mut visual_pin_rect = r.rect;

      if r.contains_pointer() {
        if treeize_state.has_new_wires_out() {
          if modifiers.shift && !modifiers.command {
            treeize_state.add_new_wire_out(out_pin.id);
          }
          if !modifiers.shift && modifiers.command {
            treeize_state.remove_new_wire_out(out_pin.id);
          }
        }
        pin_hovered = Some(AnyPin::Out(out_pin.id));
        visual_pin_rect = visual_pin_rect.scale_from_center(1.2);
      }

      let wire_info = treeize_pin.draw(style, pin_ui.style(), visual_pin_rect, pin_ui.painter());

      output_positions.insert(
        out_pin.id,
        PinResponse {
          pos: r.rect.center(),
          wire_color: wire_info.color,
          wire_style: wire_info.style,
        },
      );

      pin_ui.expand_to_include_y(outer_rect.bottom());
    });
  }
  let final_rect = outputs_ui.min_rect();
  node_ui.expand_to_include_rect(final_rect.intersect(payload_clip_rect));

  DrawPinsResponse { drag_released, pin_hovered }
}

#[allow(clippy::too_many_arguments)]
fn draw_body<T, V>(
  treeize: &mut Treeize<T>,
  viewer: &mut V,
  node: NodeId,
  ui: &mut Ui,
  body_rect: Rect,
  payload_clip_rect: Rect,
  _treeize_state: &TreeizeState,
) -> DrawBodyResponse
where
  V: TreeizeViewer<T>,
{
  let mut body_ui = ui.new_child(
    UiBuilder::new()
      .max_rect(body_rect.round_ui())
      .layout(Layout::left_to_right(Align::Min))
      .id_salt("body"),
  );

  body_ui.shrink_clip_rect(payload_clip_rect);

  viewer.show_body(node, &mut body_ui, treeize);

  let final_rect = body_ui.min_rect();
  ui.expand_to_include_rect(final_rect.intersect(payload_clip_rect));
  // node_state.set_body_width(body_size.x);

  DrawBodyResponse { final_rect }
}

//First step for split big function to parts
/// Draw one node. Return Pins info
#[inline]
#[allow(clippy::too_many_lines)]
#[allow(clippy::too_many_arguments)]
fn draw_node<T, V>(
  treeize: &mut Treeize<T>,
  ui: &mut Ui,
  node: NodeId,
  viewer: &mut V,
  treeize_state: &mut TreeizeState,
  style: &TreeizeStyle,
  treeize_id: Id,
  input_positions: &mut HashMap<InPinId, PinResponse>,
  modifiers: Modifiers,
  output_positions: &mut HashMap<OutPinId, PinResponse>,
) -> Option<DrawNodeResponse>
where
  V: TreeizeViewer<T>,
{
  let Node { pos, open, ref value } = treeize.nodes[node.0];

  let inputs_count = usize::from(viewer.has_input(value));
  let outputs_count = usize::from(viewer.has_output(value));

  let inputs = (0..inputs_count)
    .map(|idx| InPin::new(treeize, InPinId { node, input: idx }))
    .collect::<Vec<_>>();

  let outputs = (0..outputs_count)
    .map(|idx| OutPin::new(treeize, OutPinId { node, output: idx }))
    .collect::<Vec<_>>();

  let node_pos = pos.round_ui();

  // Generate persistent id for the node.
  let node_id = treeize_id.with(("treeize-node", node));

  let openness = ui.ctx().animate_bool(node_id, open);

  let mut node_state = NodeState::load(ui.ctx(), node_id, ui.spacing());

  let node_rect = node_state.node_rect(node_pos, openness);

  let mut node_to_top = None;
  let mut node_moved = None;
  let mut drag_released = false;
  let mut pin_hovered = None;

  let node_frame =
    viewer.node_frame(style.get_node_frame(ui.style()), node, &inputs, &outputs, treeize);

  let header_frame =
    viewer.header_frame(style.get_header_frame(ui.style()), node, &inputs, &outputs, treeize);

  // Rect for node + frame margin.
  let node_frame_rect = node_rect + node_frame.total_margin();

  if treeize_state.selected_nodes().contains(&node) {
    let select_style = style.get_select_style(ui.style());

    let select_rect = node_frame_rect + select_style.margin;

    ui.painter().rect(
      select_rect,
      select_style.rounding,
      select_style.fill,
      select_style.stroke,
      StrokeKind::Inside,
    );
  }

  // Size of the pin.
  // Side of the square or diameter of the circle.
  let pin_size = style.get_pin_size(ui.style()).max(0.0);

  let pin_placement = style.get_pin_placement();

  let header_drag_space = style.get_header_drag_space(ui.style()).max(Vec2::ZERO);

  // Interact with node frame.
  let r = ui.interact(node_frame_rect, node_id.with("frame"), Sense::click_and_drag());

  if !modifiers.shift && !modifiers.command && r.dragged_by(PointerButton::Primary) {
    node_moved = Some((node, r.drag_delta()));
  }

  if r.clicked_by(PointerButton::Primary) || r.dragged_by(PointerButton::Primary) {
    if modifiers.shift {
      treeize_state.select_one_node(modifiers.command, node);
    } else if modifiers.command {
      treeize_state.deselect_one_node(node);
    }
  }

  if r.clicked() || r.dragged() {
    node_to_top = Some(node);
  }

  if viewer.has_node_menu(&treeize.nodes[node.0].value) {
    r.context_menu(|ui| {
      viewer.show_node_menu(node, &inputs, &outputs, ui, treeize);
    });
  }

  if !treeize.nodes.contains(node.0) {
    node_state.clear(ui.ctx());
    // If removed
    return None;
  }

  if viewer.has_on_hover_popup(&treeize.nodes[node.0].value) {
    r.on_hover_ui_at_pointer(|ui| {
      viewer.show_on_hover_popup(node, &inputs, &outputs, ui, treeize);
    });
  }

  if !treeize.nodes.contains(node.0) {
    node_state.clear(ui.ctx());
    // If removed
    return None;
  }

  let node_ui = &mut ui.new_child(
    UiBuilder::new()
      .max_rect(node_frame_rect.round_ui())
      .layout(Layout::top_down(Align::Center))
      .id_salt(node_id),
  );

  let r = node_frame.show(node_ui, |ui| {
    if viewer.has_node_style(node, &inputs, &outputs, treeize) {
      viewer.apply_node_style(ui.style_mut(), node, &inputs, &outputs, treeize);
    }

    // Input pins' center side by Y axis.
    let input_y = match pin_placement {
      PinPlacement::Inside => {
        pin_size.mul_add(0.5, node_frame_rect.top() + node_frame.inner_margin.topf())
      }
      PinPlacement::Edge => node_frame_rect.top(),
      PinPlacement::Outside { margin } => pin_size.mul_add(-0.5, node_frame_rect.top() - margin),
    };

    // Output pins' center side by Y axis.
    let output_y = match pin_placement {
      PinPlacement::Inside => {
        pin_size.mul_add(-0.5, node_frame_rect.bottom() - node_frame.inner_margin.bottomf())
      }
      PinPlacement::Edge => node_frame_rect.bottom(),
      PinPlacement::Outside { margin } => pin_size.mul_add(0.5, node_frame_rect.bottom() + margin),
    };

    // Input/output pin block

    if (openness < 1.0 && open) || (openness > 0.0 && !open) {
      ui.ctx().request_repaint();
    }

    let has_body = viewer.has_body(&treeize.nodes.get(node.0).unwrap().value);

    let payload_rect_y = if has_body {
      node_rect.min.y
        + node_state.header_height()
        + header_frame.total_margin().bottom
        + ui.spacing().item_spacing.y
        - node_state.payload_offset(openness)
    } else {
      node_rect.min.y
    };
    // Pins are placed under the header and must not go outside of the header frame.
    let payload_rect = Rect::from_min_max(pos2(node_rect.min.x, payload_rect_y), node_rect.max);

    let node_layout = viewer.node_layout(style.get_node_layout(), node, &inputs, &outputs, treeize);

    let payload_clip_rect = Rect::from_min_max(node_rect.min, pos2(node_rect.max.x, f32::INFINITY));

    let body_rect = if has_body {
      let body_rect = Rect::from_min_max(
        pos2(node_rect.left(), payload_rect.top()),
        pos2(node_rect.right(), payload_rect.bottom()),
      );
      let r = draw_body(treeize, viewer, node, ui, body_rect, payload_clip_rect, treeize_state);

      r.final_rect
    } else {
      Rect::ZERO
    };

    if !treeize.nodes.contains(node.0) {
      // If removed
      return;
    }

    // Render header frame.
    let mut header_rect = Rect::NAN;

    let mut header_frame_rect = Rect::NAN; //node_rect + header_frame.total_margin();

    // Show node's header
    let header_ui: &mut Ui = &mut ui.new_child(
      UiBuilder::new()
        .max_rect(node_rect.round_ui() + header_frame.total_margin())
        .layout(Layout::top_down(Align::Center))
        .id_salt("header"),
    );

    header_frame.show(header_ui, |ui: &mut Ui| {
      ui.with_layout(Layout::left_to_right(Align::Min), |ui| {
        if style.get_collapsible() && has_body {
          let (_, r) = ui.allocate_exact_size(
            vec2(ui.spacing().icon_width, ui.spacing().icon_width),
            Sense::click(),
          );
          paint_default_icon(ui, openness, &r);

          if r.clicked_by(PointerButton::Primary) {
            // Toggle node's openness.
            treeize.open_node(node, !open);
          }
        }

        if has_body {
          ui.allocate_exact_size(header_drag_space, Sense::hover());
          viewer.show_header(node, ui, treeize);
        } else {
          ui.allocate_exact_size(vec2(1.0, 0.0), Sense::hover());
          viewer.show_header(node, ui, treeize);
          ui.allocate_exact_size(vec2(1.0, 0.0), Sense::hover());
        }

        header_rect = ui.min_rect();
      });

      header_frame_rect = header_rect + header_frame.total_margin();

      ui.advance_cursor_after_rect(Rect::from_min_max(
        header_rect.min,
        pos2(f32::max(header_rect.max.x, node_rect.max.x), header_rect.min.y),
      ));
    });

    if !treeize.nodes.contains(node.0) {
      // If removed
      return;
    }

    ui.expand_to_include_rect(header_rect);
    let header_size = header_rect.size();
    node_state.set_header_height(header_size.y);

    match node_layout.kind {
      NodeLayoutKind::Compact => {
        let r = draw_inputs(
          treeize,
          viewer,
          node,
          &inputs,
          pin_size,
          style,
          ui,
          payload_rect,
          payload_clip_rect,
          input_y,
          header_rect.min.x,
          header_rect.max.x,
          treeize_state,
          modifiers,
          input_positions,
          node_layout.input_heights(&node_state),
        );
        drag_released |= r.drag_released;
        if r.pin_hovered.is_some() {
          pin_hovered = r.pin_hovered;
        }

        let r = draw_outputs(
          treeize,
          viewer,
          node,
          &outputs,
          pin_size,
          style,
          ui,
          payload_rect,
          payload_clip_rect,
          output_y,
          header_rect.min.x,
          header_rect.max.x,
          treeize_state,
          modifiers,
          output_positions,
          node_layout.output_heights(&node_state),
        );
        drag_released |= r.drag_released;
        if r.pin_hovered.is_some() {
          pin_hovered = r.pin_hovered;
        }
      }
    }

    let node_size_y = if has_body {
      header_size.y + header_frame.total_margin().bottom + body_rect.height()
    } else {
      header_size.y
    };

    node_state.set_size(vec2(f32::max(header_size.x, body_rect.width()), node_size_y));
  });

  if !treeize.nodes.contains(node.0) {
    ui.ctx().request_repaint();
    node_state.clear(ui.ctx());
    // If removed
    return None;
  }

  viewer.final_node_rect(node, r.response.rect, ui, treeize);

  node_state.store(ui.ctx());
  Some(DrawNodeResponse {
    node_moved,
    node_to_top,
    drag_released,
    pin_hovered,
    final_rect: r.response.rect,
  })
}

const fn mix_colors(a: Color32, b: Color32) -> Color32 {
  #![allow(clippy::cast_possible_truncation)]

  Color32::from_rgba_premultiplied(
    u8::midpoint(a.r(), b.r()),
    u8::midpoint(a.g(), b.g()),
    u8::midpoint(a.b(), b.b()),
    u8::midpoint(a.a(), b.a()),
  )
}

impl<T> Treeize<T> {
  /// Render [`Treeize`] using given viewer and style into the [`Ui`].
  #[inline]
  pub fn show<V>(&mut self, viewer: &mut V, style: &TreeizeStyle, id_salt: impl Hash, ui: &mut Ui)
  where
    V: TreeizeViewer<T>,
  {
    show_treeize(
      ui.make_persistent_id(id_salt),
      *style,
      Vec2::ZERO,
      Vec2::INFINITY,
      self,
      viewer,
      ui,
      None,
      None,
    );
  }
}

#[inline]
fn clamp_scale(to_global: &mut TSTransform, min_scale: f32, max_scale: f32, ui_rect: Rect) {
  if to_global.scaling >= min_scale && to_global.scaling <= max_scale {
    return;
  }

  let new_scaling = to_global.scaling.clamp(min_scale, max_scale);
  *to_global = scale_transform_around(to_global, new_scaling, ui_rect.center());
}

#[inline]
#[must_use]
fn transform_matching_points(from: Pos2, to: Pos2, scaling: f32) -> TSTransform {
  TSTransform { scaling, translation: to.to_vec2() - from.to_vec2() * scaling }
}

#[inline]
#[must_use]
fn scale_transform_around(transform: &TSTransform, scaling: f32, point: Pos2) -> TSTransform {
  let from = (point - transform.translation) / transform.scaling;
  transform_matching_points(from, point, scaling)
}

#[test]
const fn treeize_style_is_send_sync() {
  const fn is_send_sync<T: Send + Sync>() {}
  is_send_sync::<TreeizeStyle>();
}