figcraft/crates/doc/src/lib.rs

//! The FigCraft document model.
//!
//! A [`Document`] holds pages; each page is the root of a tree of [`Node`]s (frames, groups, shapes,
//! text, components, instances…). Nodes are stored by id in a map of `Arc`s, so cloning a document
//! (an undo snapshot) only copies pointers, and editing one node copies only that node.
//!
//! Everything here is pure data plus queries and structural edits; commands, history and rendering
//! live in higher crates.
#![deny(clippy::unwrap_used, clippy::expect_used, clippy::panic, clippy::unimplemented, clippy::todo, clippy::unreachable)]

pub mod colors;
pub mod comments;
pub mod geometry;
pub mod library;
pub mod node;
pub mod props;
pub mod proto;
pub mod styles;
pub mod text;
pub mod vector;
pub mod vector_faces;

pub use colors::*;
pub use comments::*;
pub use figcraft_color as color;
pub use figcraft_geom as geom;
pub use library::*;
pub use node::*;
pub use props::*;
pub use styles::*;
pub use text::*;
pub use vector::*;
pub use vector_faces::Face;

use figcraft_color::{Color, ColorProfile};
use figcraft_geom::{Affine, Point, Rect};
use serde::{Deserialize, Serialize};
use std::collections::BTreeMap;
use std::sync::Arc;

/// Stable node identifier, unique within a document.
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
#[serde(transparent)]
pub struct NodeId(pub u64);

impl std::fmt::Display for NodeId {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl std::str::FromStr for NodeId {
    type Err = std::num::ParseIntError;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        // Accept "12" and Figma-style "0:12".
        let t = s.trim();
        let t = t.rsplit(':').next().unwrap_or(t);
        t.parse::<u64>().map(NodeId)
    }
}

#[derive(Debug, thiserror::Error, PartialEq)]
pub enum DocError {
    #[error("no such node {0}")]
    NoNode(NodeId),
    #[error("{0} can't contain children")]
    NotContainer(NodeId),
    #[error("moving {0} into {1} would create a cycle")]
    Cycle(NodeId, NodeId),
    #[error("{0}")]
    Invalid(String),
}

pub type DocResult<T> = Result<T, DocError>;

/// The set of touched node ids. Never part of equality or serialisation.
#[derive(Clone, Debug, Default)]
pub struct Dirty(pub std::collections::BTreeSet<NodeId>);

impl PartialEq for Dirty {
    fn eq(&self, _: &Self) -> bool {
        true
    }
}

/// Raw image bytes (encoded PNG/JPEG/…) kept by content hash.
#[derive(Clone, Debug, PartialEq)]
pub struct ImageData {
    pub bytes: Arc<Vec<u8>>,
    pub width: u32,
    pub height: u32,
}

/// A whole design file.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct Document {
    pub name: String,
    /// Page ids in order.
    pub pages: Vec<NodeId>,
    nodes: imbl::OrdMap<NodeId, Arc<Node>>,
    /// Nodes touched since the last [`take_dirty`](Self::take_dirty) (edited, added or removed).
    #[serde(skip)]
    dirty: Dirty,
    next_id: u64,
    #[serde(default)]
    pub styles: Vec<Style>,
    #[serde(default)]
    pub variables: Variables,
    /// Images by content hash; serialized separately by the format crate.
    #[serde(skip)]
    pub images: BTreeMap<String, ImageData>,
    /// The page shown when the file opens.
    #[serde(default)]
    pub current_page: Option<NodeId>,
    /// Colours used recently / saved in "Document colors".
    #[serde(default)]
    pub document_colors: Vec<Color>,
    /// Comment threads on any page.
    #[serde(default)]
    pub comments: Vec<Comment>,
    /// Enabled libraries and the components and styles copied from them.
    #[serde(default, skip_serializing_if = "Libraries::is_unused")]
    pub libraries: Arc<Libraries>,
    /// This file's published library; serialized separately by the format crate.
    #[serde(skip)]
    pub published: Option<Arc<PublishedLibrary>>,
    /// The colour space colour values are in (sRGB unless the file says otherwise).
    #[serde(default, skip_serializing_if = "ColorProfile::is_srgb")]
    pub color_profile: ColorProfile,
    /// Image adjustment presets saved in this file.
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub image_presets: Vec<ImagePreset>,
}

impl Default for Document {
    fn default() -> Self {
        Self::new("Untitled")
    }
}

impl Document {
    /// A new file with one empty page ("Page 1").
    pub fn new(name: impl Into<String>) -> Self {
        let mut doc = Self {
            name: name.into(),
            pages: Vec::new(),
            nodes: imbl::OrdMap::new(),
            dirty: Dirty::default(),
            next_id: 1,
            styles: Vec::new(),
            variables: Variables::default(),
            images: BTreeMap::new(),
            current_page: None,
            document_colors: Vec::new(),
            comments: Vec::new(),
            libraries: Arc::default(),
            published: None,
            color_profile: ColorProfile::Srgb,
            image_presets: Vec::new(),
        };
        let p = doc.add_page("Page 1");
        doc.current_page = Some(p);
        doc
    }

    /// Node ids touched since the last call (edited, added or removed), clearing the record.
    pub fn take_dirty(&mut self) -> std::collections::BTreeSet<NodeId> {
        std::mem::take(&mut self.dirty.0)
    }

    /// Node ids touched so far (without clearing).
    pub fn dirty(&self) -> &std::collections::BTreeSet<NodeId> {
        &self.dirty.0
    }

    /// A fresh unused id.
    pub fn alloc_id(&mut self) -> NodeId {
        let id = NodeId(self.next_id);
        self.next_id = self.next_id.saturating_add(1);
        id
    }

    pub fn node(&self, id: NodeId) -> Option<&Node> {
        self.nodes.get(&id).map(Arc::as_ref)
    }

    pub fn node_arc(&self, id: NodeId) -> Option<&Arc<Node>> {
        self.nodes.get(&id)
    }

    /// Mutable access (copy-on-write when a snapshot shares the node).
    pub fn node_mut(&mut self, id: NodeId) -> Option<&mut Node> {
        let n = self.nodes.get_mut(&id).map(Arc::make_mut);
        if n.is_some() {
            self.dirty.0.insert(id);
        }
        n
    }

    pub fn get(&self, id: NodeId) -> DocResult<&Node> {
        self.node(id).ok_or(DocError::NoNode(id))
    }

    pub fn get_mut(&mut self, id: NodeId) -> DocResult<&mut Node> {
        self.node_mut(id).ok_or(DocError::NoNode(id))
    }

    pub fn contains(&self, id: NodeId) -> bool {
        self.nodes.contains_key(&id)
    }

    pub fn node_count(&self) -> usize {
        self.nodes.len()
    }

    /// Ids of the nodes added, removed or changed (by value) since `before`, ascending, or `None`
    /// when more than `limit` differ. Structure the two versions share is skipped, so comparing an
    /// edit with the version it came from costs about the size of the edit, not of the document.
    pub fn changed_ids(&self, before: &Document, limit: usize) -> Option<Vec<NodeId>> {
        let mut out = Vec::new();
        for d in before.nodes.diff(&self.nodes) {
            if out.len() >= limit {
                return None;
            }
            out.push(match d {
                imbl::ordmap::DiffItem::Add(k, _) | imbl::ordmap::DiffItem::Remove(k, _) => *k,
                imbl::ordmap::DiffItem::Update { new: (k, _), .. } => *k,
            });
        }
        Some(out)
    }

    /// Every node id (pages included), ascending.
    pub fn ids(&self) -> impl Iterator<Item = NodeId> + '_ {
        self.nodes.keys().copied()
    }

    pub fn nodes(&self) -> impl Iterator<Item = &Node> + '_ {
        self.nodes.values().map(Arc::as_ref)
    }

    /// Add a page at the end.
    pub fn add_page(&mut self, name: &str) -> NodeId {
        let id = self.alloc_id();
        let node = Node::new(
            id,
            NodeKind::Page { background: Color::DEFAULT_PAGE, flows: Vec::new(), prototype: Default::default(), guides: Vec::new() },
            name,
            0.0,
            0.0,
        );
        self.nodes.insert(id, Arc::new(node));
        self.dirty.0.insert(id);
        self.pages.push(id);
        id
    }

    /// The page a node is on (a page is on itself).
    pub fn page_of(&self, id: NodeId) -> Option<NodeId> {
        let mut cur = id;
        for _ in 0..10_000 {
            let n = self.node(cur)?;
            if n.is_page() {
                return Some(cur);
            }
            cur = n.parent?;
        }
        None
    }

    pub fn first_page(&self) -> Option<NodeId> {
        self.pages.first().copied()
    }

    /// Insert `node` (its id must come from [`alloc_id`](Self::alloc_id)) as a child of `parent` at
    /// `index` (None = on top).
    pub fn insert(&mut self, mut node: Node, parent: NodeId, index: Option<usize>) -> DocResult<NodeId> {
        let p = self.get(parent)?;
        if !p.kind.is_container() {
            return Err(DocError::NotContainer(parent));
        }
        let id = node.id;
        if self.nodes.contains_key(&id) {
            return Err(DocError::Invalid(format!("node {id} already exists")));
        }
        if id.0 >= self.next_id {
            self.next_id = id.0.saturating_add(1);
        }
        node.parent = Some(parent);
        self.nodes.insert(id, Arc::new(node));
        self.dirty.0.insert(id);
        let p = self.get_mut(parent)?;
        let at = index.unwrap_or(p.children.len()).min(p.children.len());
        p.children.insert(at, id);
        Ok(id)
    }

    /// Create a node of `kind` under `parent`, positioned at `(x, y)` in the parent's space.
    pub fn create(&mut self, parent: NodeId, kind: NodeKind, name: &str, x: f64, y: f64, w: f64, h: f64) -> DocResult<NodeId> {
        let id = self.alloc_id();
        let mut node = Node::new(id, kind, name, w, h);
        node.transform = Affine::translate((x, y));
        self.insert(node, parent, None)
    }

    /// Whether `ancestor` is `id` or one of its ancestors.
    pub fn is_ancestor(&self, ancestor: NodeId, id: NodeId) -> bool {
        let mut cur = Some(id);
        let mut guard = 0;
        while let Some(c) = cur {
            if c == ancestor {
                return true;
            }
            guard += 1;
            if guard > 10_000 {
                return false;
            }
            cur = self.node(c).and_then(|n| n.parent);
        }
        false
    }

    /// Ancestors from the parent up to (and including) the page.
    pub fn ancestors(&self, id: NodeId) -> Vec<NodeId> {
        let mut out = Vec::new();
        let mut cur = self.node(id).and_then(|n| n.parent);
        while let Some(c) = cur {
            if out.len() > 10_000 {
                break;
            }
            out.push(c);
            cur = self.node(c).and_then(|n| n.parent);
        }
        out
    }

    /// `id` and all its descendants, pre-order.
    pub fn subtree(&self, id: NodeId) -> Vec<NodeId> {
        let mut out = Vec::new();
        let mut stack = vec![id];
        while let Some(c) = stack.pop() {
            if out.len() > 5_000_000 {
                break;
            }
            let Some(n) = self.node(c) else { continue };
            out.push(c);
            stack.extend(n.children.iter().rev());
        }
        out
    }

    /// Remove a node and its subtree. Pages can only be removed while another page remains.
    pub fn remove(&mut self, id: NodeId) -> DocResult<()> {
        let node = self.get(id)?;
        let parent = node.parent;
        if node.is_page() {
            if self.pages.len() <= 1 {
                return Err(DocError::Invalid("a file needs at least one page".into()));
            }
            self.pages.retain(|p| *p != id);
            if self.current_page == Some(id) {
                self.current_page = self.pages.first().copied();
            }
        }
        if let Some(parent) = parent
            && let Some(p) = self.node_mut(parent)
        {
            p.children.retain(|c| *c != id);
        }
        for d in self.subtree(id) {
            self.nodes.remove(&d);
            self.dirty.0.insert(d);
        }
        Ok(())
    }

    /// Index of `id` among its siblings.
    pub fn index_in_parent(&self, id: NodeId) -> Option<usize> {
        let parent = self.node(id)?.parent?;
        self.node(parent)?.children.iter().position(|c| *c == id)
    }

    /// Move `id` under `new_parent` at `index` (None = top), keeping its world position.
    pub fn reparent(&mut self, id: NodeId, new_parent: NodeId, index: Option<usize>) -> DocResult<()> {
        if self.is_ancestor(id, new_parent) {
            return Err(DocError::Cycle(id, new_parent));
        }
        let np = self.get(new_parent)?;
        if !np.kind.is_container() {
            return Err(DocError::NotContainer(new_parent));
        }
        let node = self.get(id)?;
        if node.is_page() {
            return Err(DocError::Invalid("pages can't be moved into nodes".into()));
        }
        let world = self.world_transform(id);
        let old_parent = node.parent;
        let old_index = self.index_in_parent(id);
        if let Some(op) = old_parent
            && let Some(p) = self.node_mut(op)
        {
            p.children.retain(|c| *c != id);
        }
        let parent_world = self.world_transform(new_parent);
        let np = self.get_mut(new_parent)?;
        let mut at = index.unwrap_or(np.children.len());
        // Moving within the same parent: the removal shifted later indices.
        if old_parent == Some(new_parent)
            && let (Some(oi), Some(_)) = (old_index, index)
            && oi < at
        {
            at = at.saturating_sub(1);
        }
        let at = at.min(np.children.len());
        np.children.insert(at, id);
        let n = self.get_mut(id)?;
        n.parent = Some(new_parent);
        n.transform = parent_world.inverse() * world;
        Ok(())
    }

    /// Reorder `id` within its parent to `index`.
    pub fn reorder(&mut self, id: NodeId, index: usize) -> DocResult<()> {
        let parent = self.get(id)?.parent.ok_or(DocError::Invalid("page".into()))?;
        let p = self.get_mut(parent)?;
        p.children.retain(|c| *c != id);
        let at = index.min(p.children.len());
        p.children.insert(at, id);
        Ok(())
    }

    /// Transform from `id`'s local space to its page.
    pub fn world_transform(&self, id: NodeId) -> Affine {
        let mut xf = Affine::IDENTITY;
        let mut cur = Some(id);
        let mut guard = 0;
        while let Some(c) = cur {
            let Some(n) = self.node(c) else { break };
            if n.is_page() {
                break;
            }
            xf = n.transform * xf;
            cur = n.parent;
            guard += 1;
            if guard > 10_000 {
                break;
            }
        }
        xf
    }

    /// Set `id`'s transform so that its world transform becomes `world`.
    pub fn set_world_transform(&mut self, id: NodeId, world: Affine) -> DocResult<()> {
        let parent = self.get(id)?.parent;
        let pw = parent.map(|p| self.world_transform(p)).unwrap_or(Affine::IDENTITY);
        self.get_mut(id)?.transform = pw.inverse() * world;
        Ok(())
    }

    /// Axis-aligned bounds of the node's box in page coordinates.
    pub fn world_bounds(&self, id: NodeId) -> Option<Rect> {
        let n = self.node(id)?;
        if n.is_page() {
            return self.page_content_bounds(id);
        }
        Some(figcraft_geom::transform_rect_bbox(self.world_transform(id), n.local_rect()))
    }

    /// Bounds of everything painted by a node, effects and strokes included (page coordinates).
    pub fn world_render_bounds(&self, id: NodeId) -> Option<Rect> {
        let n = self.node(id)?;
        let reach = n.paint_reach();
        let mut r = figcraft_geom::transform_rect_bbox(self.world_transform(id), n.local_rect().inflate(reach, reach));
        if !(n.clip && n.kind.is_frame_like()) || n.kind.bounds_follow_children() {
            for c in &n.children {
                if let Some(cr) = self.world_render_bounds(*c) {
                    r = r.union(cr);
                }
            }
        }
        Some(r)
    }

    /// Union of the top-level nodes' bounds on a page.
    pub fn page_content_bounds(&self, page: NodeId) -> Option<Rect> {
        let p = self.node(page)?;
        p.children.iter().filter_map(|c| self.world_bounds(*c)).reduce(|a, b| a.union(b))
    }

    /// Union of several nodes' world bounds.
    pub fn bounds_of(&self, ids: &[NodeId]) -> Option<Rect> {
        ids.iter().filter_map(|i| self.world_bounds(*i)).reduce(|a, b| a.union(b))
    }

    /// Resize a group/boolean so its box tightly wraps its children (children keep world position).
    pub fn fit_to_children(&mut self, id: NodeId) -> DocResult<()> {
        let n = self.get(id)?;
        if n.children.is_empty() {
            return Ok(());
        }
        let world = self.world_transform(id);
        let inv = world.inverse();
        // Children bounds in the group's current local space.
        let mut local: Option<Rect> = None;
        for c in &n.children {
            let Some(cn) = self.node(*c) else { continue };
            let r = figcraft_geom::transform_rect_bbox(inv * self.world_transform(*c), cn.local_rect());
            local = Some(local.map_or(r, |l| l.union(r)));
        }
        let Some(local) = local else { return Ok(()) };
        let children = n.children.clone();
        let child_worlds: Vec<(NodeId, Affine)> = children.iter().map(|c| (*c, self.world_transform(*c))).collect();
        let shift = Affine::translate((local.x0, local.y0));
        let nw = world * shift;
        {
            let g = self.get_mut(id)?;
            g.transform *= shift;
            g.width = local.width();
            g.height = local.height();
        }
        let ninv = nw.inverse();
        for (c, w) in child_worlds {
            if let Some(cn) = self.node_mut(c) {
                cn.transform = ninv * w;
            }
        }
        Ok(())
    }

    /// Fit every group/boolean ancestor of `id` (innermost first).
    pub fn fit_ancestors(&mut self, id: NodeId) {
        for a in self.ancestors(id) {
            let follows = self.node(a).is_some_and(|n| n.kind.bounds_follow_children());
            if follows {
                let _ = self.fit_to_children(a);
            } else {
                break;
            }
        }
    }

    /// Deep-copy `id`'s subtree under `parent` (at `index`), returning the new root id. The copy
    /// keeps the original's local transform; ids are fresh.
    pub fn duplicate_into(&mut self, id: NodeId, parent: NodeId, index: Option<usize>) -> DocResult<NodeId> {
        let mut map = BTreeMap::new();
        let src_nodes: Vec<Node> = self.subtree(id).into_iter().filter_map(|i| self.node(i).cloned()).collect();
        for n in &src_nodes {
            let nid = self.alloc_id();
            map.insert(n.id, nid);
        }
        self.paste_nodes(&src_nodes, &map, id, parent, index)
    }

    /// Insert copies of `nodes` (a subtree rooted at `root`, from this or another document) with ids
    /// remapped by `map`. Interactions and instance references pointing inside the subtree are
    /// remapped too.
    pub fn paste_nodes(
        &mut self,
        nodes: &[Node],
        map: &BTreeMap<NodeId, NodeId>,
        root: NodeId,
        parent: NodeId,
        index: Option<usize>,
    ) -> DocResult<NodeId> {
        let p = self.get(parent)?;
        if !p.kind.is_container() {
            return Err(DocError::NotContainer(parent));
        }
        let new_root = *map.get(&root).ok_or(DocError::NoNode(root))?;
        for n in nodes {
            let Some(new_id) = map.get(&n.id) else { continue };
            let mut c = n.clone();
            c.id = *new_id;
            c.children = n.children.iter().filter_map(|k| map.get(k).copied()).collect();
            c.parent = if n.id == root { Some(parent) } else { n.parent.and_then(|p| map.get(&p).copied()) };
            for it in &mut c.interactions {
                for a in &mut it.actions {
                    remap_action(a, map);
                }
            }
            if let NodeKind::Instance { component, .. } = &mut c.kind
                && let Some(m) = map.get(component)
            {
                *component = *m;
            }
            if new_id.0 >= self.next_id {
                self.next_id = new_id.0.saturating_add(1);
            }
            self.nodes.insert(*new_id, Arc::new(c));
            self.dirty.0.insert(*new_id);
        }
        let p = self.get_mut(parent)?;
        let at = index.unwrap_or(p.children.len()).min(p.children.len());
        p.children.insert(at, new_root);
        Ok(new_root)
    }

    /// Find nodes on `page` (or all pages) whose name contains `query` (case-insensitive).
    pub fn find_by_name(&self, query: &str, page: Option<NodeId>) -> Vec<NodeId> {
        let q = query.to_lowercase();
        let roots: Vec<NodeId> = page.map(|p| vec![p]).unwrap_or_else(|| self.pages.clone());
        roots
            .into_iter()
            .flat_map(|r| self.subtree(r))
            .filter(|i| self.node(*i).is_some_and(|n| !n.is_page() && n.name.to_lowercase().contains(&q)))
            .collect()
    }

    /// The nearest frame-like ancestor (excluding `id` itself).
    pub fn containing_frame(&self, id: NodeId) -> Option<NodeId> {
        self.ancestors(id).into_iter().find(|a| self.node(*a).is_some_and(|n| n.kind.is_frame_like() || matches!(n.kind, NodeKind::Section { .. })))
    }

    /// The top-level frame containing `id` (or `id` if it is one).
    pub fn top_level_frame(&self, id: NodeId) -> Option<NodeId> {
        let mut chain = vec![id];
        chain.extend(self.ancestors(id));
        // chain ends with the page; the element before it is the top-level node.
        let page_pos = chain.iter().position(|c| self.node(*c).is_some_and(Node::is_page))?;
        let top = *chain.get(page_pos.checked_sub(1)?)?;
        self.node(top).filter(|n| n.kind.is_frame_like()).map(|_| top)
    }

    /// Top-level frames of a page in reading order (rows top to bottom, then left to right).
    pub fn top_frames(&self, page: NodeId) -> Vec<NodeId> {
        let Some(p) = self.node(page) else { return vec![] };
        let mut v: Vec<(NodeId, Rect)> = p
            .children
            .iter()
            .filter(|c| self.node(**c).is_some_and(|n| n.kind.is_frame_like()))
            .filter_map(|c| self.world_bounds(*c).map(|b| (*c, b)))
            .collect();
        v.sort_by(|a, b| a.1.y0.total_cmp(&b.1.y0).then(a.1.x0.total_cmp(&b.1.x0)));
        v.into_iter().map(|(i, _)| i).collect()
    }

    /// A unique name like "Frame 3" for a new node of a kind.
    pub fn next_name(&self, base: &str) -> String {
        let mut max = 0u64;
        for n in self.nodes() {
            if let Some(rest) = n.name.strip_prefix(base)
                && let Some(num) = rest.strip_prefix(' ')
                && let Ok(k) = num.parse::<u64>()
            {
                max = max.max(k);
            }
        }
        format!("{base} {}", max + 1)
    }

    pub fn style(&self, id: &str) -> Option<&Style> {
        self.styles.iter().find(|s| s.id == id || s.name == id)
    }

    /// The effective variable modes for a node (walking up its ancestors).
    pub fn modes_for(&self, id: NodeId) -> BTreeMap<CollectionId, ModeId> {
        let mut out = BTreeMap::new();
        let mut chain = vec![id];
        chain.extend(self.ancestors(id));
        for c in chain.into_iter().rev() {
            if let Some(n) = self.node(c) {
                for (k, v) in &n.var_modes {
                    out.insert(k.clone(), v.clone());
                }
            }
        }
        out
    }

    /// Check structural invariants (used by tests and after loading untrusted files).
    pub fn validate(&self) -> Vec<String> {
        let mut issues = Vec::new();
        for (id, n) in self.nodes.iter() {
            if n.id != *id {
                issues.push(format!("node key {id} has id {}", n.id));
            }
            for c in &n.children {
                match self.node(*c) {
                    Some(cn) if cn.parent == Some(*id) => {}
                    Some(_) => issues.push(format!("child {c} of {id} has another parent")),
                    None => issues.push(format!("child {c} of {id} missing")),
                }
            }
            if let Some(p) = n.parent
                && !self.node(p).is_some_and(|pn| pn.children.contains(id))
            {
                issues.push(format!("{id} not listed in parent {p}"));
            }
            // The library store's root is a page that is never listed.
            let listed = self.pages.contains(id) || (n.is_page() && self.libraries.store == Some(*id));
            if n.is_page() != listed {
                issues.push(format!("page list mismatch for {id}"));
            }
        }
        issues
    }

    /// Repair what [`validate`](Self::validate) reports (lenient loading of untrusted files).
    pub fn repair(&mut self) {
        let ids: Vec<NodeId> = self.nodes.keys().copied().collect();
        for id in &ids {
            if let Some(n) = self.nodes.get_mut(id) {
                let n = Arc::make_mut(n);
                n.id = *id;
            }
        }
        // Drop dangling children and children claimed by another parent.
        let parents: BTreeMap<NodeId, Option<NodeId>> = self.nodes.iter().map(|(k, n)| (*k, n.parent)).collect();
        for id in &ids {
            let Some(n) = self.nodes.get(id) else { continue };
            let keep: Vec<NodeId> = n.children.iter().copied().filter(|c| parents.get(c).copied().flatten() == Some(*id)).collect();
            if keep != n.children
                && let Some(n) = self.nodes.get_mut(id)
            {
                Arc::make_mut(n).children = keep;
            }
        }
        // Orphans (parent missing or not listing them) are removed.
        loop {
            let orphan = self.nodes.iter().find_map(|(k, n)| {
                if n.is_page() {
                    return None;
                }
                match n.parent {
                    Some(p) if self.nodes.get(&p).is_some_and(|pn| pn.children.contains(k)) => None,
                    _ => Some(*k),
                }
            });
            let Some(o) = orphan else { break };
            for d in self.subtree(o) {
                self.nodes.remove(&d);
            }
        }
        let store = self.libraries.store.filter(|s| self.nodes.get(s).is_some_and(|n| n.is_page()));
        if store != self.libraries.store {
            Arc::make_mut(&mut self.libraries).store = store;
        }
        self.pages.retain(|p| self.nodes.get(p).is_some_and(|n| n.is_page()) && Some(*p) != store);
        for (k, n) in self.nodes.iter() {
            if n.is_page() && !self.pages.contains(k) && Some(*k) != store {
                self.pages.push(*k);
            }
        }
        if self.pages.is_empty() {
            let p = self.add_page("Page 1");
            self.current_page = Some(p);
        }
        if let Some(max) = self.nodes.keys().max()
            && self.next_id <= max.0
        {
            self.next_id = max.0.saturating_add(1);
        }
        if self.current_page.is_none_or(|p| !self.pages.contains(&p)) {
            self.current_page = self.pages.first().copied();
        }
    }

    /// Hit test: the topmost visible, unlocked node under `pt` on `page` for a click.
    /// `deep` selects the innermost leaf (Cmd-click); otherwise top-level children of frames
    /// resolve like Figma's click-through rules (see [`geometry::select_target`]).
    pub fn hit_test(&self, page: NodeId, pt: Point, tolerance: f64) -> Option<NodeId> {
        geometry::hit_leaf(self, page, pt, tolerance)
    }
}

fn remap_action(a: &mut proto::Action, map: &BTreeMap<NodeId, NodeId>) {
    use proto::Action::*;
    match a {
        Navigate { dest, .. } | ScrollTo { dest } | OpenOverlay { dest, .. } | SwapOverlay { dest } | ChangeTo { dest } => {
            if let Some(m) = map.get(dest) {
                *dest = *m;
            }
        }
        _ => {}
    }
}

#[cfg(test)]
mod colors_tests;
#[cfg(test)]
mod diff_tests;
#[cfg(test)]
mod tests;