//! Direct Selection (A) and Group Selection tools.
//!
//! Direct Selection: click an anchor to select it (Shift toggles), click a segment to select the
//! segment independently of its endpoint anchors, drag to move selected anchors (the one pressed on snaps to
//! anchors, segments and Smart Guides, or with them off Snap to Point; Shift keeps the move at 45°
//! steps; Alt on an anchor or a segment picks the whole path and Alt-drag copies it; an Alt-click
//! on a path selected whole adds its group, and each further Alt-click adds the next group up, as
//! Group Selection's clicks do), drag a direction handle to
//! reshape (Shift keeps it at 45° steps round its anchor, Alt moves it alone; smart guides snap
//! it), marquee to select anchors (Shift-drag toggles them: the selected ones inside are
//! deselected, the others selected; with Alt held at the press, as Group Selection for the drag,
//! it selects every object it touches, whole), drag a corner widget of any path (a star, a pen
//! path) to round its corners
//! (the selected ones when anchors are selected; Alt-click cycles their kind, double-click opens
//! the Corners dialog).
//! Group Selection: click selects the leaf; each further click on it adds the next enclosing group;
//! its marquee works as Direct Selection's, and E pressed during the drag makes it select only the
//! objects entirely inside it (members of groups too), whole.
//! In isolation mode both pick only the isolated object and what is inside it: anchors, segments,
//! paths and groups outside it stay put.
//! Both move objects selected as a whole as the Selection tool does, snapping alike. When the
//! selection also holds direct-selected anchors or segments, a drag from an object moves those
//! anchors and the objects selected whole, as an anchor drag does, and while Alt is held it
//! copies the selected objects.
//! Both pick the key objects of a blend, and click or drag ruler guides ([`crate::rulerguide`]).
//! A Cmd/Ctrl+Shift double-click with either one releases the ruler guide or guide path under the
//! pointer ([`release_guide_at`]).
//! Direct Selection also edits a blend's spine: drag its points (a key object on a point moves
//! with it) and, once a point is clicked, its handles; and the points of selected gradient meshes
//! and mesh envelopes and their handles ([`MeshEdit`]): Shift-clicks and the marquee pick several,
//! a click on a gradient mesh's line picks its two ends and one inside a patch the four points
//! around it, a drag of picked points moves them all, the arrow keys nudge them, and a solid fill
//! colour or the Transparency panel's opacity goes to a gradient mesh's picked points. Dragging a
//! corner or an edge of area
//! type's frame reshapes the type area (`text.reshapeArea`): the text reflows at its size. A click
//! on a frame anchor or a marquee selects frame anchors (Shift toggles them). While the selection
//! holds only area type with selected frame anchors, those show filled, a drag of one of them moves
//! them all, and the arrow keys nudge them; otherwise the type is selected whole. Dragging an anchor of type on
//! a path's path reshapes the path (`text.reshapePath`): the text reflows along it.
//! Dragging the brackets of selected type on a path moves or flips it ([`crate::pathtype`]).
//! A press on a selected object's centre point (Attributes panel › Show Center) selects the object
//! whole, and a drag from it moves the object.
//!
//! A press on the stroke of a path that isn't selected as a whole selects that segment's two anchors
//! (the fill, or Alt, selects the whole path); dragging the segment bends it if it's curved, else
//! moves its anchors.

use std::borrow::Cow;
use std::collections::{BTreeMap, BTreeSet};

use serde_json::{Value, json};
use vectorcraft_doc::hit::{HitKind, compound_part_at, hit_test, selected_hidden_at};
use vectorcraft_doc::{AnchorRef, Node, NodeId, NodeKind, Selection};
use vectorcraft_geom::{Anchor, PathData, Point, Rect, Vec2};

use crate::bbox::move_delta;
use crate::corners::{self, CornerDrag, over_widget};
use crate::guides::{HandleSnap, Leave, PointSnap, Targets};
use crate::meshedit::{MeshEdit, grid_of};
use crate::pathtype::{self, BracketDrag, over_bracket};
use crate::rulerguide::GuideEdit;
use crate::select::{MoveSnap, hold_point, is_area_type, is_path_type, matrix_json, release_guide_at};
use crate::{Action, Cursor, Mods, Overlay, PointerEvent, PointerKind, Tool, ToolContext, ToolKey};

#[derive(Clone, Debug)]
enum State {
    Idle,
    /// Dragging the selected anchors, which move alike: `grab` is where the anchor pressed on (or
    /// the point of a straight segment nearest the pointer pressed on it) was, the point that
    /// snaps.
    MoveAnchors {
        start: Point,
        grab: Point,
        began: bool,
    },
    /// Moving (Alt: copying) the selected objects; `grab`: the anchor an Alt-press picked the
    /// path by, which snaps as a dragged anchor does; else `hold`, where the press took hold of
    /// the object ([`hold_point`]), snaps as the Selection tool's does.
    MoveObject {
        start: Point,
        grab: Option<Point>,
        hold: Point,
        began: bool,
        /// Group Selection: Shift-click on a selected object toggles it off on release.
        deselect: Option<NodeId>,
    },
    /// Dragging a curved segment: it follows the pointer (`path.reshapeSegment`).
    Segment {
        id: NodeId,
        si: usize,
        seg: usize,
        t: f64,
        start: Point,
        began: bool,
    },
    Handle {
        id: NodeId,
        si: usize,
        ai: usize,
        out: bool,
    },
    Marquee {
        start: Point,
        cur: Point,
        /// Shift: the anchors inside leave the selection if selected, else join it.
        toggle: bool,
        /// Group Selection, E pressed an odd number of times during the drag: the marquee selects
        /// only the objects that lie entirely inside it, whole.
        enclosed: bool,
        /// Direct Selection with Alt held at the press, which makes it the Group Selection tool
        /// for the drag: the marquee selects every object it touches, whole (#4890).
        whole: bool,
    },
    Corner(CornerDrag),
    /// Dragging a bracket of type on a path.
    Bracket(BracketDrag),
    /// Dragging a point of a blend's spine from `from`.
    SpinePoint {
        id: NodeId,
        anchor: usize,
        from: Point,
        start: Point,
        began: bool,
    },
    /// Dragging a curved segment of a selected blend's spine: it follows the pointer
    /// (`object.blend.spine.reshapeSegment`, #1111).
    SpineSegment {
        id: NodeId,
        seg: usize,
        t: f64,
        start: Point,
        began: bool,
    },
    /// Dragging a handle of the clicked spine point.
    SpineHandle {
        id: NodeId,
        anchor: usize,
        out: bool,
    },
    /// Dragging a mesh point or handle ([`MeshEdit`]).
    Mesh,
    /// Dragging anchors of area type's frames (a corner, the two ends of an edge, or the selected
    /// frame anchors), or an anchor of type on a path's path: each object with its anchors.
    TypeArea {
        items: FrameAnchors,
        start: Point,
        began: bool,
    },
}

/// Anchors of the frames of area type (or of the path of type on a path), each object with its
/// anchors.
type FrameAnchors = Vec<(NodeId, Vec<AnchorRef>)>;

/// What [`DirectSelectionTool::notify`] hears after a press or a marquee selected frame anchors:
/// the selected objects to keep them with.
const FRAME_PICKED: &str = "frameAnchors";

/// The params of `text.reshapeArea` or `text.reshapePath` moving `items` by `d`.
fn reshape_params(items: &[(NodeId, Vec<AnchorRef>)], d: Vec2) -> Value {
    match items {
        [(id, anchors)] => json!({"id": id.0, "anchors": anchors_json(anchors), "dx": d.x, "dy": d.y}),
        _ => {
            let items: Vec<Value> = items.iter().map(|(id, v)| json!({"id": id.0, "anchors": anchors_json(v)})).collect();
            json!({"items": items, "dx": d.x, "dy": d.y})
        }
    }
}

/// How far (pt) a snap must move a dragged point for the arrow to say it snapped.
const SNAPPED: f64 = 1e-9;

/// Whether a drag step snapped: the snapped move `d` left where the pointer alone put it
/// (`unsnapped`). With Shift the constraint (General › Constrain Angle) moves it too, so only a
/// snap's guide tells then.
fn snapped(d: Vec2, unsnapped: Vec2, shift: bool, guides: &[Overlay]) -> bool {
    if shift { !guides.is_empty() } else { (d - unsnapped).hypot() > SNAPPED }
}

pub struct DirectSelectionTool {
    group: bool,
    state: State,
    /// The spine point last clicked (blend, anchor): its handles show and can be dragged.
    spine: Option<(NodeId, usize)>,
    mesh: MeshEdit,
    /// Smart guides of the handle, anchors or objects being dragged.
    guides: Vec<Overlay>,
    /// What the dragged anchors snap to, gathered when the drag begins.
    anchor_snap: Option<PointSnap>,
    /// With one open path's end anchor dragged along a straight segment, that segment's other end:
    /// the dragged end may land square to a straight path or grazing a curve (Smart Guides ›
    /// Geometric Guides). Set when the drag begins.
    line_end: Option<Leave>,
    /// What the anchor holding paths moved whole snaps to while Alt makes a copy: the original left
    /// behind too. Gathered with [`Self::anchor_snap`], before the previews move the original.
    copy_snap: Option<PointSnap>,
    /// What the dragged handle snaps to.
    handle_snap: HandleSnap,
    /// What the objects being moved snap to, gathered when the move begins.
    move_snap: Option<MoveSnap>,
    /// What the point holding a move of objects snaps to while the move takes direct-selected
    /// anchors along (`path.moveAnchors`): each move of objects sets it when it begins, to the
    /// targets of an anchor drag when anchors are selected, else to `None`.
    partial_snap: Option<PointSnap>,
    /// With Snap to Grid or Snap to Pixel on, what such a move from a fill snaps instead of the
    /// point it holds: the box around the selected anchors and the objects selected whole.
    partial_grid: Option<MoveSnap>,
    /// The drag snapped to a point or a guide at its last step: the arrow turns hollow.
    snapped: bool,
    /// The anchor under the pointer (Highlight anchors on mouse over): its path, where it is.
    hover: Option<(NodeId, Point)>,
    guide: GuideEdit,
    /// The already selected anchor the press landed on: a click (no drag) selects it alone, as a
    /// drag moves every selected anchor with it.
    click: Option<(NodeId, usize, usize)>,
    /// A click on a whole path picks the segment on release; a drag still moves the whole path.
    click_segment: Option<(NodeId, usize, usize)>,
    /// An Alt-click on a path selected whole adds this enclosing group on release, as a Group
    /// Selection click does; an Alt-drag still copies the selection.
    click_group: Option<NodeId>,
    /// The selected anchors of area type's frames, picked by a click or a marquee: they show
    /// filled, a drag of one moves them all, and the arrow keys nudge them. They stay selected
    /// while the document and its selection are at `frame_revision`, the revision after they were
    /// picked or the tool last moved them.
    frame: BTreeMap<NodeId, BTreeSet<AnchorRef>>,
    frame_revision: (u64, u64),
    /// The already selected frame anchor the press landed on without Shift: a click (no drag)
    /// selects it alone, as a drag moves every selected frame anchor with it.
    frame_click: Option<(NodeId, AnchorRef)>,
}

impl DirectSelectionTool {
    pub fn new(group: bool) -> Self {
        Self {
            group,
            state: State::Idle,
            spine: None,
            mesh: MeshEdit::default(),
            guides: vec![],
            anchor_snap: None,
            line_end: None,
            copy_snap: None,
            handle_snap: HandleSnap::default(),
            move_snap: None,
            partial_snap: None,
            partial_grid: None,
            snapped: false,
            hover: None,
            guide: GuideEdit::default(),
            click: None,
            click_segment: None,
            click_group: None,
            frame: BTreeMap::new(),
            frame_revision: (0, 0),
            frame_click: None,
        }
    }

    /// The selected frame anchors that still apply, each object with its anchors. They apply while
    /// nothing else changed the document or the selection since they were picked (a drag of them
    /// changes it as it goes), and only while the selection holds nothing else: every selected
    /// object is editable area type with selected frame anchors, and no path anchors or ruler
    /// guides are selected. Otherwise the type is selected whole.
    fn frame_anchors(&self, cx: &ToolContext) -> FrameAnchors {
        let dragging = matches!(self.state, State::TypeArea { began: true, .. });
        if self.group
            || self.frame.is_empty()
            || (!dragging && cx.revision != self.frame_revision)
            || !cx.selection.anchors.is_empty()
            || !cx.selection.guides.is_empty()
        {
            return vec![];
        }
        let editable = cx.doc.editable();
        let v: FrameAnchors = self
            .frame
            .iter()
            .filter_map(|(id, set)| {
                let n = cx
                    .doc
                    .node(*id)
                    .filter(|n| cx.selection.contains(*id) && is_area_type(n) && editable(*id) && in_scope(cx.doc, cx.isolation, *id))?;
                let frame = editable_path(n)?;
                let v: Vec<AnchorRef> =
                    set.iter().copied().filter(|(si, ai)| frame.subpaths.get(*si).is_some_and(|sp| *ai < sp.anchors.len())).collect();
                (!v.is_empty()).then_some((*id, v))
            })
            .collect();
        if v.len() == cx.selection.objects.len() { v } else { vec![] }
    }

    /// The move an arrow key nudges the selected frame anchors by (General › Keyboard Increment,
    /// ten times with Shift, along General › Constrain Angle's axes), with those anchors.
    fn frame_nudge(&self, cx: &ToolContext, key: ToolKey, mods: Mods) -> Option<(FrameAnchors, Vec2)> {
        if !matches!(self.state, State::Idle) {
            return None;
        }
        let d = cx.arrow_nudge(key, mods)?;
        let items = self.frame_anchors(cx);
        (!items.is_empty()).then_some((items, d))
    }

    /// An arrow key's nudge of the picked points of the selected meshes.
    fn mesh_nudge(&self, cx: &ToolContext, key: ToolKey, mods: Mods) -> Option<Vec<Action>> {
        if !matches!(self.state, State::Idle) {
            return None;
        }
        self.mesh.nudge(cx, key, mods, &|id| cx.selection.contains(id))
    }

    /// Is `key` the E that Group Selection takes while a marquee is being dragged? Direct
    /// Selection takes no letter.
    fn claims_letter(&self, key: ToolKey) -> bool {
        self.group && key == ToolKey::Letter('e') && matches!(self.state, State::Marquee { .. })
    }
}

/// Whether `id` may be picked while `scope` is isolated: it is that object, or it sits inside it.
/// With no isolation, everything may be picked.
pub(crate) fn in_scope(doc: &vectorcraft_doc::Document, scope: Option<NodeId>, id: NodeId) -> bool {
    scope.is_none_or(|scope| doc.ancestry(id).is_some_and(|anc| anc.contains(&scope)))
}

/// Visit the nodes Direct Selection may pick. In isolation mode that is the isolated object and
/// its contents; art around it is locked and the walk does not reach it. A Shaper Group's original
/// shapes, its first child, are left out unless they are the isolated object (Construction mode),
/// as clicks leave them out.
fn walk_pickable<'a>(doc: &'a vectorcraft_doc::Document, scope: Option<NodeId>, mut f: impl FnMut(&'a Node)) {
    fn walk<'a>(n: &'a Node, f: &mut impl FnMut(&'a Node)) {
        f(n);
        for c in n.children().into_iter().flatten().skip(usize::from(n.extras().shaper.is_some())) {
            walk(c, f);
        }
    }
    if let Some(id) = scope
        && let Some(n) = doc.node(id)
    {
        walk(n, &mut f);
    } else if scope.is_none() {
        for l in &doc.layers {
            walk(l, &mut f);
        }
    }
}

/// The spines of the editable blends, topmost first: (blend, spine).
pub(crate) fn spines(cx: &ToolContext) -> Vec<(NodeId, PathData)> {
    let mut v = vec![];
    walk_pickable(cx.doc, cx.isolation, |n| {
        if let NodeKind::Blend { children, spec } = &n.kind
            && let Some((path, _)) = vectorcraft_doc::live::blend_spine(children, spec)
        {
            v.push((n.id, path));
        }
    });
    v.reverse();
    let editable = cx.doc.editable();
    v.retain(|(id, _)| editable(*id));
    v
}

/// The spine point under `p`: (blend, anchor, where it is).
fn hit_spine_point(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, usize, Point)> {
    spines(cx).into_iter().find_map(|(id, path)| {
        let (_, ai, a) = path.anchors().find(|(_, _, a)| a.p.distance(p) <= tol)?;
        Some((id, ai, a.p))
    })
}

/// The segment of a selected blend's spine passing within `tol` of `p`: (blend, segment, t, whether
/// it is straight).
pub(crate) fn hit_spine_segment(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, usize, f64, bool)> {
    spines(cx).into_iter().filter(|(id, _)| cx.selection.contains(*id)).find_map(|(id, path)| {
        let (si, seg, t, _, dist) = path.nearest(p)?;
        (dist <= tol).then(|| (id, seg, t, path.subpaths.get(si).is_some_and(|sp| sp.segment_is_line(seg))))
    })
}

/// The spine point `sel` and whether `p` is on its outgoing handle's end (`Some(true)`) or its
/// incoming one's.
fn hit_spine_handle(cx: &ToolContext, sel: (NodeId, usize), p: Point, tol: f64) -> Option<bool> {
    let a = spine_anchor(cx, sel)?;
    if a.has_out() && a.h_out.distance(p) <= tol {
        return Some(true);
    }
    (a.has_in() && a.h_in.distance(p) <= tol).then_some(false)
}

/// Anchor `sel.1` of blend `sel.0`'s spine.
fn spine_anchor(cx: &ToolContext, (id, ai): (NodeId, usize)) -> Option<vectorcraft_geom::Anchor> {
    match &cx.doc.node(id)?.kind {
        NodeKind::Blend { children, spec } => vectorcraft_doc::live::blend_spine(children, spec)?.0.subpaths.first()?.anchors.get(ai).copied(),
        _ => None,
    }
}

/// The anchors Direct Selection edits on `n`, in document space: a path's, area type's frame or
/// type on a path's path.
fn editable_path(n: &Node) -> Option<Cow<'_, PathData>> {
    match &n.kind {
        NodeKind::Path { path, .. } => Some(Cow::Borrowed(path)),
        NodeKind::Text(t) => t.area_frame().or_else(|| t.type_path()).map(Cow::Owned),
        _ => None,
    }
}

/// The editable objects `f` accepts, topmost first.
fn anchor_owners(cx: &ToolContext, f: fn(&Node) -> bool) -> Vec<NodeId> {
    let mut v = vec![];
    walk_pickable(cx.doc, cx.isolation, |n| {
        if f(n) {
            v.push(n.id)
        }
    });
    v.reverse();
    let editable = cx.doc.editable();
    v.retain(|id| editable(*id));
    v
}

/// Where a line's end anchor `grab`bed for a drag leaves from, when it is one: the only anchor
/// selected, the end of an open subpath whose one segment is straight, and no other art moving
/// with it. That segment's other end stays put, so the end snaps square to straight paths and
/// grazing curves; mid-line anchors and ends of curved segments do not (Illustrator limits Snap
/// to Tangent and Snap to Perpendicular to line endpoints).
fn line_end_leave(cx: &ToolContext, grab: Point) -> Option<Leave> {
    let sel = cx.selection;
    if !sel.segments.is_empty() || sel.anchors.len() != 1 {
        return None;
    }
    let (&id, set) = sel.anchors.iter().next()?;
    if set.len() != 1 || sel.objects.iter().any(|o| *o != id) {
        return None;
    }
    let &(si, ai) = set.iter().next()?;
    let sp = cx.doc.node(id)?.path_data()?.subpaths.get(si)?;
    let n = sp.anchors.len();
    if sp.closed || ai >= n || sp.anchors[ai].p.distance(grab) > 1e-6 {
        return None;
    }
    let (other, seg) = if n < 2 {
        return None;
    } else if ai == 0 {
        (1, 0)
    } else if ai == n - 1 {
        (n - 2, n - 2)
    } else {
        return None;
    };
    sp.segment_is_line(seg).then(|| Leave::contact(sp.anchors[other].p))
}

/// The anchor within `tol` of `p` nearest to it, of the topmost selected path or area type frame
/// that has one, else of the topmost visible one: (id, si, ai, where it is). Selected objects come
/// first so an object above can't take the press from the one being edited (#1508), as
/// [`hovered_anchor`] marks it. In normal viewmode, an opaque fill in front occludes unselected
/// objects behind it (#3405).
fn hit_anchor(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, usize, usize, Point)> {
    let mut owners = anchor_owners(cx, |n| matches!(n.kind, NodeKind::Path { .. }) || is_area_type(n) || is_path_type(n));
    owners.sort_by_key(|id| !cx.selection.contains(*id));

    // 1. Check selected objects first. Selected objects are NEVER occluded (#1508).
    let mut unselected_idx = owners.len();
    for (i, &id) in owners.iter().enumerate() {
        if !cx.selection.contains(id) {
            unselected_idx = i;
            break;
        }
        if let Some(pd) = cx.doc.node(id).and_then(editable_path)
            && let Some((si, ai, a)) = nearest_anchor(&pd, p, tol)
        {
            return Some((id, si, ai, a));
        }
    }

    // 2. For unselected objects: in normal viewmode, an opaque fill in front occludes
    // unselected objects behind it (#3405).
    let unselected = &owners[unselected_idx..];
    if unselected.is_empty() {
        return None;
    }

    let filter: Option<Box<dyn Fn(NodeId) -> bool>> = if !cx.outline
        && let Some(h) = hit_test(cx.doc, p, cx.selection_hit_options())
        && matches!(h.kind, HitKind::Fill)
    {
        let leaf = h.leaf;
        let ancestry = h.ancestry.clone();
        let part = cx.doc.node(leaf).and_then(|n| compound_part_at(n, p, tol));
        Some(Box::new(move |id| id == leaf || ancestry.contains(&id) || part == Some(id)))
    } else {
        None
    };

    unselected.iter().copied().find_map(|id| {
        if let Some(f) = &filter
            && !f(id)
        {
            return None;
        }
        let pd = cx.doc.node(id).and_then(editable_path)?;
        nearest_anchor(&pd, p, tol).map(|(si, ai, a)| (id, si, ai, a))
    })
}

/// Is `p` within a press's reach of an anchor of type on a path's path? The anchor wins over a
/// bracket standing on it (the end bracket on the last anchor, #3980); the bracket's stem above it
/// still drags the bracket.
fn over_path_type_anchor(cx: &ToolContext, p: Point) -> bool {
    hit_anchor(cx, p, cx.point_tol()).is_some_and(|(id, ..)| cx.doc.node(id).is_some_and(is_path_type))
}

/// The anchor of `pd` within `tol` of `p` nearest to it: (subpath, anchor, where it is).
fn nearest_anchor(pd: &PathData, p: Point, tol: f64) -> Option<(usize, usize, Point)> {
    pd.anchors().map(|(si, ai, a)| (si, ai, a.p)).filter(|(.., a)| a.distance(p) <= tol).min_by(|x, y| x.2.distance(p).total_cmp(&y.2.distance(p)))
}

/// The selected object whose centre point (Attributes panel › Show Center), drawn while it is
/// selected, is within `tol` of `p`: (object, where the point is).
fn hit_center(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, Point)> {
    let (symbols, editable) = (cx.doc.symbol_boxes(), cx.doc.editable());
    cx.selection.objects.iter().copied().filter(|id| editable(*id) && in_scope(cx.doc, cx.isolation, *id)).find_map(|id| {
        let c = cx.doc.node(id).filter(|n| n.shows_center())?.geometric_bounds_with(&symbols)?.center();
        (c.distance(p) <= tol).then_some((id, c))
    })
}

/// An edge of an area type frame under `p`, topmost first: (text, the edge's two anchors).
fn hit_frame_edge(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, Vec<AnchorRef>)> {
    anchor_owners(cx, is_area_type).into_iter().find_map(|id| {
        let frame = cx.doc.node(id).and_then(editable_path)?;
        let (si, seg, _, _, d) = frame.nearest(p)?;
        let n = frame.subpaths.get(si)?.anchors.len();
        (d <= tol && n > 0).then(|| (id, vec![(si, seg % n), (si, (seg + 1) % n)]))
    })
}

/// The anchors whose direction handles show, and drag, with the tools that edit anchors
/// ([`crate::catalog::edits_anchors`]): the direct-selected anchors of a path, every anchor of a
/// path selected as a whole. Selection & Anchor Display → Show handles when multiple anchors are
/// selected off, none while more than one anchor is selected.
fn handle_anchors(cx: &ToolContext) -> Vec<(NodeId, usize, usize, Anchor)> {
    let mut v = vec![];
    for &id in &cx.selection.objects {
        let Some(pd) = cx.doc.node(id).and_then(|n| n.path_data()) else { continue };
        let shown = cx.selection.partial(id);
        v.extend(pd.anchors().filter(|(si, ai, _)| shown.is_none_or(|set| set.contains(&(*si, *ai)))).map(|(si, ai, a)| {
            let mut a = *a;
            if let Some(sp) = pd.subpaths.get(si) {
                let (inside, outside) = cx.selection.handle_sides(id, si, ai, sp);
                if !inside {
                    a.h_in = a.p;
                }
                if !outside {
                    a.h_out = a.p;
                }
            }
            (id, si, ai, a)
        }));
    }
    if !cx.handles_multiple && v.len() > 1 {
        v.clear();
    }
    v
}

/// The end of a shown direction handle ([`handle_anchors`]) nearest to `p` within `tol`, and
/// nearer to it than the handle's anchor (a short handle leaves its anchor to be picked): (path,
/// subpath, anchor, is_out).
pub(crate) fn hit_handle(cx: &ToolContext, p: Point, tol: f64) -> Option<(NodeId, usize, usize, bool)> {
    let mut best: Option<((NodeId, usize, usize, bool), f64)> = None;
    for (id, si, ai, a) in handle_anchors(cx) {
        for (out, has, h) in [(true, a.has_out(), a.h_out), (false, a.has_in(), a.h_in)] {
            let d = h.distance(p);
            if has && d <= tol && d < a.p.distance(p) && best.is_none_or(|b| d < b.1) {
                best = Some(((id, si, ai, out), d));
            }
        }
    }
    best.map(|b| b.0)
}

fn anchors_json(v: &[AnchorRef]) -> Value {
    Value::Array(v.iter().map(|(s, a)| json!([s, a])).collect())
}

/// The segments of `path` that marquee `r` crosses with neither of their anchors inside it, as
/// (subpath, segment) pairs: the reference app selects a segment that a marquee is dragged "over
/// part of" (<http://web.archive.org/web/20211230015528/https://helpx.adobe.com/illustrator/using/selecting-objects.html>).
fn crossed_segments(path: &PathData, r: Rect) -> Vec<AnchorRef> {
    let mut out = vec![];
    for (si, sp) in path.subpaths.iter().enumerate() {
        let n = sp.anchors.len();
        let count = if sp.closed { n } else { n.saturating_sub(1) };
        for seg in 0..count {
            let (Some(a), Some(b)) = (sp.anchors.get(seg), sp.anchors.get((seg + 1) % n)) else { continue };
            if r.contains(a.p) || r.contains(b.p) {
                continue;
            }
            let piece = PathData::single(vectorcraft_geom::SubPath::new(vec![*a, *b], false));
            if vectorcraft_geom::hit::intersects_rect(&piece, r) {
                out.push((si, seg));
            }
        }
    }
    out
}

/// A segment of a path under the pointer.
struct SegmentHit {
    si: usize,
    seg: usize,
    t: f64,
    curved: bool,
}

/// The group a Group Selection click on a selected object adds, given the object's `ancestry`
/// (its layer and sublayers first, the object last). It walks up from the object and returns the
/// first ancestor below the layer and its sublayers that is not yet selected. The walk stops at the
/// isolated object, since the next group up is outside isolation mode, and at any layer or
/// sublayer, including one inside a group.
fn next_group(cx: &ToolContext, ancestry: &[NodeId]) -> Option<NodeId> {
    // Skip the layer and its sublayers: they are not objects.
    let layers = ancestry.iter().take_while(|id| cx.doc.node(**id).is_some_and(Node::is_layer)).count().max(1);
    ancestry
        .iter()
        .skip(layers)
        .rev()
        .copied()
        .take_while(|id| in_scope(cx.doc, cx.isolation, *id) && !cx.doc.node(*id).is_some_and(Node::is_layer))
        .find(|id| !cx.selection.contains(*id))
}

/// The segment of path `id` nearest to `p`, where the hit test found its stroke.
fn segment_at(cx: &ToolContext, id: NodeId, p: Point) -> Option<SegmentHit> {
    let pd = cx.doc.node(id)?.path_data()?;
    let (si, seg, t, ..) = pd.nearest(p)?;
    let sp = pd.subpaths.get(si)?;
    let n = sp.anchors.len();
    let (i0, i1) = (seg.checked_rem(n)?, (seg + 1).checked_rem(n)?);
    let (a, b) = (sp.anchors.get(i0)?, sp.anchors.get(i1)?);
    Some(SegmentHit { si, seg, t, curved: a.has_out() || b.has_in() })
}

impl Tool for DirectSelectionTool {
    fn id(&self) -> &'static str {
        if self.group { "groupSelection" } else { "directSelection" }
    }
    fn busy(&self) -> bool {
        !matches!(self.state, State::Idle) || self.guide.busy()
    }
    fn options(&self) -> Value {
        self.mesh.options()
    }
    /// Escape during a drag (anchors, handles, segments, objects, type areas, blend spines, mesh
    /// points, corner widgets, the brackets of type on a path, a marquee) cancels it: what it moved
    /// goes back and the tool waits for the next press (#1743).
    /// With Group Selection, E during a marquee drag makes the marquee select only the objects
    /// entirely inside it, whole, and E pressed again makes it select what it selects by default.
    /// The arrow keys nudge the selected frame anchors of area type.
    fn key(&mut self, cx: &ToolContext, key: ToolKey, mods: Mods) -> Vec<Action> {
        if let Some(out) = self.mesh_nudge(cx, key, mods) {
            return out;
        }
        if let Some((items, d)) = self.frame_nudge(cx, key, mods) {
            return vec![Action::Exec("text.reshapeArea".into(), reshape_params(&items, d)), Action::Notify(FRAME_PICKED.into())];
        }
        if self.claims_letter(key)
            && let State::Marquee { enclosed, .. } = &mut self.state
        {
            *enclosed = !*enclosed;
            return vec![];
        }
        if key == ToolKey::Escape && self.guide.busy() {
            return self.guide.cancel();
        }
        if key != ToolKey::Escape || matches!(self.state, State::Idle) {
            return vec![];
        }
        // A mesh point drag ends here too; the `Action::Cancel` below undoes it.
        self.mesh.cancel();
        // The frame anchors a cancelled drag held stay selected.
        let frame = matches!(self.state, State::TypeArea { .. }) && !self.frame.is_empty();
        self.state = State::Idle;
        self.guides.clear();
        (self.anchor_snap, self.copy_snap, self.move_snap) = (None, None, None);
        (self.click, self.click_segment, self.click_group, self.frame_click) = (None, None, None, None);
        if frame { vec![Action::Cancel, Action::Notify(FRAME_PICKED.into())] } else { vec![Action::Cancel] }
    }
    fn claims_key(&self, cx: &ToolContext, key: ToolKey) -> bool {
        self.claims_letter(key) || self.mesh_nudge(cx, key, Mods::default()).is_some() || self.frame_nudge(cx, key, Mods::default()).is_some()
    }
    fn notify(&mut self, cx: &ToolContext, what: &str) {
        if what == FRAME_PICKED {
            self.frame_revision = cx.revision;
        }
    }
    fn pointer(&mut self, cx: &ToolContext, ev: &PointerEvent) -> Vec<Action> {
        if let Some(out) = self.guide.pointer(cx, ev) {
            return out;
        }
        let p = ev.pos;
        // Anchors and handle ends are picked from a little further than segments and objects.
        let (tol, point) = (cx.pick_tol(), cx.point_tol());
        match (ev.kind, self.state.clone()) {
            (PointerKind::Down, _) if self.group => self.press_group(cx, ev, p, tol),
            (PointerKind::DoubleClick, _) if self.group => release_guide_at(cx, p, ev.mods).into_iter().collect(),
            (PointerKind::DoubleClick, _) if !self.group => self.double_click(cx, ev, p),
            (PointerKind::Move, State::Idle) => {
                self.hover = if self.group || !cx.highlight_anchors { None } else { hovered_anchor(cx, p) };
                vec![]
            }
            (PointerKind::Down, _) => {
                self.click = None;
                self.click_segment = None;
                self.click_group = None;
                self.frame_click = None;
                if let Some(c) = CornerDrag::hit(cx, ev, true) {
                    self.state = State::Corner(c);
                    return vec![];
                }
                if !over_path_type_anchor(cx, p)
                    && let Some(b) = BracketDrag::hit(cx, ev)
                {
                    self.state = State::Bracket(b);
                    return vec![];
                }
                if let Some(sel) = self.spine.filter(|(id, _)| cx.selection.contains(*id))
                    && let Some(out) = hit_spine_handle(cx, sel, p, point)
                {
                    self.state = State::SpineHandle { id: sel.0, anchor: sel.1, out };
                    return vec![Action::Begin("Reshape Spine".into())];
                }
                self.spine = None;
                self.snapped = false;
                if let Some(g) = self.mesh.hit(cx, &cx.selection.objects, p) {
                    self.state = State::Mesh;
                    return self.mesh.press(cx, &cx.selection.objects, g, p, ev.mods.shift);
                }
                // Shift keeps the picked mesh points: it adds to the selection.
                if !ev.mods.shift {
                    self.mesh.unfocus();
                }
                if let Some((id, si, ai, out)) = hit_handle(cx, p, point) {
                    self.state = State::Handle { id, si, ai, out };
                    self.handle_snap = HandleSnap::default();
                    return vec![Action::Begin("Reshape".into())];
                }
                if let Some((id, anchor, from)) = hit_spine_point(cx, p, point) {
                    self.spine = Some((id, anchor));
                    self.state = State::SpinePoint { id, anchor, from, start: p, began: false };
                    return if cx.selection.contains(id) { vec![] } else { vec![Action::Exec("select.set".into(), json!({"ids": [id.0]}))] };
                }
                if let Some((id, si, ai, grab)) = hit_anchor(cx, p, point) {
                    return self.press_anchor(cx, ev, p, (id, si, ai, grab));
                }
                if let Some((id, center)) = hit_center(cx, p, point) {
                    return self.press_center(cx, ev, p, id, center);
                }
                if let Some((id, anchors)) = hit_frame_edge(cx, p, tol) {
                    self.frame.clear();
                    return self.press_type_area(cx, id, vec![(id, anchors)], p, ev.mods.shift);
                }
                // A curved segment of a selected blend's spine reshapes, as a path's does.
                if let Some((id, seg, t, false)) = hit_spine_segment(cx, p, tol) {
                    self.state = State::SpineSegment { id, seg, t, start: p, began: false };
                    return vec![];
                }
                if let Some(out) = self.guide.press(cx, ev) {
                    self.state = State::Idle;
                    return out;
                }
                if let Some(h) = hit_test(cx.doc, p, cx.selection_hit_options()) {
                    return self.press_object(cx, ev, p, tol, h);
                }
                if let Some(out) = self.press_hidden(cx, ev, p) {
                    return out;
                }
                self.state = State::Marquee { start: p, cur: p, toggle: ev.mods.shift, enclosed: false, whole: ev.mods.alt };
                vec![]
            }
            (PointerKind::Drag, State::MoveAnchors { start, grab, began }) => self.drag_move_anchors(cx, ev, p, (start, grab, began)),
            (PointerKind::Drag, State::Segment { id, si, seg, t, start, began }) => {
                let mut out = vec![];
                if !began {
                    if p.distance(start) < cx.tol(3.0) {
                        return out;
                    }
                    out.push(Action::Begin("Reshape".into()));
                    self.state = State::Segment { id, si, seg, t, start, began: true };
                }
                let d = p - start;
                out.push(Action::Preview(
                    "path.reshapeSegment".into(),
                    json!({"id": id.0, "subpath": si, "segment": seg, "t": t, "dx": d.x, "dy": d.y, "perpendicular": ev.mods.shift}),
                ));
                out
            }
            (PointerKind::Drag, State::MoveObject { start, grab, hold, began, .. }) => self.drag_move_object(cx, ev, p, (start, grab, hold, began)),
            (PointerKind::Drag, State::TypeArea { items, start, began }) => {
                let mut out = vec![];
                let on_path = items.first().and_then(|(id, _)| cx.doc.node(*id)).is_some_and(is_path_type);
                if !began {
                    if p.distance(start) < cx.tol(3.0) {
                        return out;
                    }
                    out.push(Action::Begin(if on_path { "Reshape Type Path" } else { "Reshape Type Area" }.into()));
                }
                let d = move_delta(start, p, ev.mods.shift, cx.constrain_angle);
                let cmd = if on_path { "text.reshapePath" } else { "text.reshapeArea" };
                out.push(Action::Preview(cmd.into(), reshape_params(&items, d)));
                self.state = State::TypeArea { items, start, began: true };
                out
            }
            (PointerKind::Drag, State::Handle { id, si, ai, out }) => {
                let (q, guides) = self.handle_snap.snap(cx, (id, si, ai), p, ev.mods.shift);
                self.snapped = snapped(q.to_vec2(), p.to_vec2(), ev.mods.shift, &guides);
                self.guides = guides;
                vec![Action::Preview(
                    "path.setHandle".into(),
                    json!({"id": id.0, "subpath": si, "anchor": ai, "which": if out {"out"} else {"in"}, "x": q.x, "y": q.y, "independent": ev.mods.alt}),
                )]
            }
            (PointerKind::Drag, State::SpinePoint { id, anchor, from, start, began }) => {
                let mut out = vec![];
                if !began {
                    if p.distance(start) < cx.tol(3.0) {
                        return out;
                    }
                    out.push(Action::Begin("Reshape Spine".into()));
                    self.state = State::SpinePoint { id, anchor, from, start, began: true };
                }
                let q = from + move_delta(start, p, ev.mods.shift, cx.constrain_angle);
                out.push(Action::Preview("object.blend.spine.moveAnchor".into(), json!({"id": id.0, "anchor": anchor, "x": q.x, "y": q.y})));
                out
            }
            (PointerKind::Drag, State::SpineSegment { id, seg, t, start, began }) => {
                let mut out = vec![];
                if !began {
                    if p.distance(start) < cx.tol(3.0) {
                        return out;
                    }
                    out.push(Action::Begin("Reshape Spine".into()));
                    self.state = State::SpineSegment { id, seg, t, start, began: true };
                }
                let d = p - start;
                out.push(Action::Preview(
                    "object.blend.spine.reshapeSegment".into(),
                    json!({"id": id.0, "segment": seg, "t": t, "dx": d.x, "dy": d.y, "perpendicular": ev.mods.shift}),
                ));
                out
            }
            (PointerKind::Drag, State::SpineHandle { id, anchor, out }) => vec![Action::Preview(
                "object.blend.spine.moveAnchor".into(),
                json!({"id": id.0, "anchor": anchor, "handle": if out {"out"} else {"in"}, "x": p.x, "y": p.y, "independent": ev.mods.alt}),
            )],
            (PointerKind::Drag, State::Mesh) => self.mesh.drag_to(p).unwrap_or_default(),
            (PointerKind::Up, State::Mesh) => {
                self.state = State::Idle;
                self.mesh.release(cx).unwrap_or_default()
            }
            (PointerKind::Drag, State::Marquee { start, toggle, enclosed, whole, .. }) => {
                self.state = State::Marquee { start, cur: p, toggle, enclosed, whole };
                vec![]
            }
            (PointerKind::Drag, State::Corner(mut c)) => {
                let out = c.drag(cx, p);
                self.state = State::Corner(c);
                out
            }
            (PointerKind::Up, State::Corner(c)) => {
                self.state = State::Idle;
                c.finish()
            }
            (PointerKind::Drag, State::Bracket(mut b)) => {
                let out = b.drag(cx, p, ev.mods.cmd);
                self.state = State::Bracket(b);
                out
            }
            (PointerKind::Up, State::Bracket(b)) => {
                self.state = State::Idle;
                b.finish()
            }
            (
                PointerKind::Up,
                State::MoveAnchors { began, .. }
                | State::MoveObject { began, .. }
                | State::Segment { began, .. }
                | State::SpinePoint { began, .. }
                | State::SpineSegment { began, .. }
                | State::TypeArea { began, .. },
            ) => self.release_move(cx, began),
            (PointerKind::Up, State::Handle { .. } | State::SpineHandle { .. }) => {
                self.state = State::Idle;
                self.guides.clear();
                vec![Action::Commit]
            }
            (PointerKind::Up, State::Marquee { start, toggle, enclosed, whole, .. }) => self.release_marquee(cx, p, (start, toggle, enclosed, whole)),
            _ => vec![],
        }
    }
    fn overlays(&self, cx: &ToolContext) -> Vec<Overlay> {
        match &self.state {
            State::Marquee { start, cur, .. } => vec![Overlay::Marquee(Rect::from_points(*start, *cur))],
            State::Corner(c) => c.overlays(cx),
            _ => {
                let mut out = self.spine_overlays(cx);
                out.extend(self.mesh.overlays(cx, &|id| cx.selection.contains(id)));
                if !self.group {
                    out.extend(frame_overlays(cx, &self.frame_anchors(cx)));
                    out.extend(pathtype::overlays(cx));
                }
                if matches!(self.state, State::Handle { .. } | State::MoveAnchors { .. } | State::MoveObject { .. }) {
                    out.extend(self.guides.iter().cloned());
                }
                if let Some((id, p)) = self.hover.filter(|_| matches!(self.state, State::Idle)) {
                    out.push(Overlay::Anchor { p, color: cx.doc.layer_color(id), filled: false, size: 8.0 });
                }
                out.extend(self.guide.overlays(cx));
                out
            }
        }
    }
    fn cursor(&self, cx: &ToolContext, p: Point, m: Mods) -> Cursor {
        if !self.group && (matches!(self.state, State::Corner(_)) || over_widget(cx, p, true)) {
            return Cursor::CornerRadius;
        }
        if !self.group && (matches!(self.state, State::Bracket(_)) || over_bracket(cx, p) && !over_path_type_anchor(cx, p)) {
            return Cursor::PathBracket;
        }
        let rest = if self.group { Cursor::GroupSelection } else { Cursor::ArrowHollow };
        if !self.group {
            match self.state {
                // Alt-dragging leaves a copy behind.
                State::MoveObject { began: true, .. } if m.alt => return Cursor::SelectionCopy,
                // An Alt-marquee is Group Selection's until it is released.
                State::Marquee { whole: true, .. } => return Cursor::GroupSelection,
                // Bending a segment keeps the cursor that offered it.
                State::Segment { began: true, .. } | State::SpineSegment { began: true, .. } => return Cursor::ReshapeSegment,
                // A drag shows the filled arrow, hollow while it snaps to a point or a guide.
                State::Handle { .. }
                | State::SpineHandle { .. }
                | State::SpinePoint { began: true, .. }
                | State::TypeArea { began: true, .. }
                | State::MoveAnchors { began: true, .. }
                | State::MoveObject { began: true, .. } => {
                    return if self.snapped { Cursor::ArrowHollow } else { Cursor::Arrow };
                }
                // Alt makes it the Group Selection tool for the next press, unless the press takes
                // a handle, a mesh or spine point, a type frame's edge or a ruler guide.
                State::Idle if m.alt => {
                    let other = self.takes_point(cx, p)
                        || hovered_anchor(cx, p).is_none() && (hit_frame_edge(cx, p, cx.pick_tol()).is_some() || self.guide.cursor(cx, p).is_some());
                    if !other {
                        return Cursor::GroupSelection;
                    }
                }
                State::Idle => {
                    if let Some(c) = self.part_under(cx, p, m) {
                        return c;
                    }
                }
                _ => {}
            }
        }
        // A press on the highlighted anchor picks it, not the guide.
        self.guide.cursor(cx, p).filter(|_| self.hover.is_none() || self.guide.busy()).unwrap_or(rest)
    }
}

impl DirectSelectionTool {
    /// A press at `p` takes a mesh point or handle, a direction handle's end, the clicked spine
    /// point's handle or a spine point, before any anchor or segment.
    fn takes_point(&self, cx: &ToolContext, p: Point) -> bool {
        let point = cx.point_tol();
        self.mesh.hit(cx, &cx.selection.objects, p).is_some()
            || hit_handle(cx, p, point).is_some()
            || self.spine.is_some_and(|sel| hit_spine_handle(cx, sel, p, point).is_some())
            || hit_spine_point(cx, p, point).is_some()
    }

    /// The cursor for the path part a press at `p` takes, in the press's order: an anchor (its
    /// square filled when its path is selected), then a curved segment a drag reshapes (a path's
    /// not selected whole, or a selected blend's spine's). Handles, mesh and spine points, frame
    /// edges, ruler guides, straight segments and fills keep the plain cursor.
    fn part_under(&self, cx: &ToolContext, p: Point, m: Mods) -> Option<Cursor> {
        let tol = cx.pick_tol();
        if self.takes_point(cx, p) {
            return None;
        }
        // A selected path's anchors or the anchors of the path under the pointer, as Highlight
        // anchors on mouse over finds them: walking every path on each hover is too slow.
        if let Some((id, _)) = hovered_anchor(cx, p) {
            return Some(if cx.selection.contains(id) { Cursor::DirectAnchorSelected } else { Cursor::DirectAnchor });
        }
        if hit_frame_edge(cx, p, tol).is_some() {
            return None;
        }
        if matches!(hit_spine_segment(cx, p, tol), Some((.., false))) {
            return Some(Cursor::ReshapeSegment);
        }
        if m.shift || self.guide.cursor(cx, p).is_some() {
            return None;
        }
        let h = hit_test(cx.doc, p, cx.selection_hit_options())?;
        let whole = cx.selection.contains(h.leaf) && cx.selection.partial(h.leaf).is_none();
        let curved = matches!(h.kind, HitKind::Stroke | HitKind::Outline) && segment_at(cx, h.leaf, p).is_some_and(|s| s.curved);
        (!whole && curved).then_some(Cursor::ReshapeSegment)
    }
}

/// The anchor within a press's reach of `p` ([`ToolContext::point_tol`]), of a selected path or the
/// path under `p`: what Highlight anchors on mouse over marks (a press there picks it).
fn hovered_anchor(cx: &ToolContext, p: Point) -> Option<(NodeId, Point)> {
    let tol = cx.point_tol();
    let under =
        hit_test(cx.doc, p, cx.selection_hit_options()).map(|h| cx.doc.node(h.leaf).and_then(|n| compound_part_at(n, p, tol)).unwrap_or(h.leaf));
    cx.selection.objects.iter().copied().filter(|id| in_scope(cx.doc, cx.isolation, *id)).chain(under).find_map(|id| {
        let path = cx.doc.node(id).and_then(editable_path)?;
        nearest_anchor(&path, p, tol).map(|(.., a)| (id, a))
    })
}

/// The frame anchors of the selected area type and the path anchors of the selected type on a
/// path, which Direct Selection drags; the `selected` frame anchors are filled.
fn frame_overlays(cx: &ToolContext, selected: &[(NodeId, Vec<AnchorRef>)]) -> Vec<Overlay> {
    let mut out = vec![];
    for id in &cx.selection.objects {
        let Some(frame) = cx.doc.node(*id).filter(|n| is_area_type(n) || is_path_type(n)).and_then(editable_path) else { continue };
        let color = cx.doc.layer_color(*id);
        let picked = selected.iter().find(|(s, _)| s == id).map(|(_, v)| v.as_slice()).unwrap_or_default();
        out.extend(frame.anchors().map(|(si, ai, a)| Overlay::Anchor { p: a.p, color, filled: picked.contains(&(si, ai)), size: 5.0 }));
    }
    out
}

impl DirectSelectionTool {
    /// Press on a frame anchor of area type: Shift toggles it among the selected frame anchors;
    /// without Shift, one not among them becomes the only one, and one among them becomes the only
    /// one when the press is released without a drag. A drag moves them all.
    fn press_frame_anchor(&mut self, cx: &ToolContext, id: NodeId, anchor: AnchorRef, p: Point, shift: bool) -> Vec<Action> {
        let mut picked: BTreeMap<NodeId, BTreeSet<AnchorRef>> =
            self.frame_anchors(cx).into_iter().map(|(id, v)| (id, v.into_iter().collect())).collect();
        let on = picked.get(&id).is_some_and(|set| set.contains(&anchor));
        if shift {
            let set = picked.entry(id).or_default();
            if on {
                set.remove(&anchor);
            } else {
                set.insert(anchor);
            }
            if set.is_empty() {
                picked.remove(&id);
            }
        } else if !on {
            picked = BTreeMap::from([(id, BTreeSet::from([anchor]))]);
        }
        // The selected objects follow: the type is selected while it has selected frame anchors,
        // and a click that picks a new anchor without Shift selects that type alone.
        let mut out = vec![];
        let any = picked.contains_key(&id);
        if !shift && !on && cx.selection.objects != [id] {
            out.push(Action::Exec("select.set".into(), json!({"ids": [id.0]})));
        } else if shift && cx.selection.contains(id) != any {
            out.push(Action::Exec("select.toggle".into(), json!({"id": id.0})));
        }
        let items: FrameAnchors = picked.iter().map(|(id, set)| (*id, set.iter().copied().collect())).collect();
        self.state = if items.is_empty() { State::Idle } else { State::TypeArea { items, start: p, began: false } };
        self.frame = picked;
        self.frame_click = (on && !shift).then_some((id, anchor));
        out.push(Action::Notify(FRAME_PICKED.into()));
        out
    }

    /// Press on area type's frame anchors (a corner, or an edge's two ends) or an anchor of type
    /// on a path's path, of `id`: select the text and get ready to drag `items`.
    fn press_type_area(&mut self, cx: &ToolContext, id: NodeId, items: FrameAnchors, p: Point, shift: bool) -> Vec<Action> {
        self.state = State::TypeArea { items, start: p, began: false };
        if cx.selection.contains(id) {
            vec![]
        } else if shift {
            vec![Action::Exec("select.add".into(), json!({"ids": [id.0]}))]
        } else {
            vec![Action::Exec("select.set".into(), json!({"ids": [id.0]}))]
        }
    }

    /// The clicked spine point, filled, with its handles.
    fn spine_overlays(&self, cx: &ToolContext) -> Vec<Overlay> {
        let Some(sel) = self.spine.filter(|(id, _)| cx.selection.contains(*id)) else { return vec![] };
        let Some(a) = spine_anchor(cx, sel) else { return vec![] };
        let color = cx.doc.layer_color(sel.0);
        let mut out = vec![];
        for h in [a.h_in, a.h_out].into_iter().filter(|h| h.distance(a.p) > 1e-6) {
            out.push(Overlay::Line { a: a.p, b: h, color, dashed: false });
            out.push(Overlay::Handle { p: h, color });
        }
        out.push(Overlay::Anchor { p: a.p, color, filled: true, size: 5.0 });
        out
    }
}

#[cfg(test)]
mod tests;

impl DirectSelectionTool {
    /// A press where a clipping mask hides the art of a selected object (picked in the Layers
    /// panel, say) grabs the selection by it, as a press on its visible part does; `None`
    /// elsewhere, and with Shift (a marquee then adds to the selection).
    fn press_hidden(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point) -> Option<Vec<Action>> {
        if ev.mods.shift {
            return None;
        }
        selected_hidden_at(cx.doc, p, cx.selection_hit_options(), &cx.selection.objects)?;
        self.state = State::MoveObject { start: p, grab: None, hold: p, began: false, deselect: None };
        Some(vec![])
    }
    fn press_group(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point, tol: f64) -> Vec<Action> {
        if let Some(out) = self.guide.press(cx, ev) {
            self.state = State::Idle;
            return out;
        }
        let Some(mut h) = hit_test(cx.doc, p, cx.selection_hit_options()) else {
            if let Some(out) = self.press_hidden(cx, ev, p) {
                return out;
            }
            self.state = State::Marquee { start: p, cur: p, toggle: ev.mods.shift, enclosed: false, whole: false };
            return vec![];
        };
        // A compound path's paths are picked one at a time, below the compound path (#2441).
        if let Some(part) = cx.doc.node(h.leaf).and_then(|n| compound_part_at(n, p, tol)) {
            h.ancestry.push(part);
            h.leaf = part;
        }
        let target = if cx.selection.contains(h.leaf) { next_group(cx, &h.ancestry).unwrap_or(h.leaf) } else { h.leaf };
        let mut deselect = None;
        let mut out = vec![];
        if ev.mods.shift {
            // Shift on a selected member deselects what was hit (a compound path's part),
            // not the next ancestor a plain click would add (#2441).
            if cx.selection.contains(h.leaf) {
                deselect = Some(h.leaf);
            } else {
                out.push(Action::Exec("select.toggle".into(), json!({"id": target.0})));
            }
        } else if !cx.selection.contains(target) {
            if cx.selection.contains(h.leaf) {
                out.push(Action::Exec("select.add".into(), json!({"ids": [target.0]})));
            } else {
                out.push(Action::Exec("select.set".into(), json!({"ids": [target.0]})));
            }
        }
        self.state = State::MoveObject { start: p, grab: None, hold: hold_point(cx, &h, p), began: false, deselect };
        out
    }
    fn double_click(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point) -> Vec<Action> {
        self.state = State::Idle;
        if let Some(a) = corners::double_click(cx, p, true) {
            return vec![a];
        }
        if let Some(a) = release_guide_at(cx, p, ev.mods) {
            return vec![a];
        }
        if crate::rulerguide::guide_at(cx, p).is_some() {
            return vec![];
        }
        // A double-click edits what is drawn: not a clipping path's outline.
        let hit = hit_test(cx.doc, p, cx.hit_options());
        if hit.as_ref().and_then(|h| cx.doc.node(h.leaf)).is_some_and(|n| matches!(n.kind, NodeKind::Text(_))) {
            return vec![Action::SwitchTool("type".into())];
        }
        // Outside the isolated art it leaves isolation mode, as with the Selection tool (#4466).
        if hit.is_none() && cx.isolation.is_some() {
            return vec![Action::Exec("object.exitIsolation".into(), json!({}))];
        }
        vec![]
    }
    fn press_anchor(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point, (id, si, ai, grab): (NodeId, usize, usize, Point)) -> Vec<Action> {
        if cx.doc.node(id).is_some_and(is_area_type) {
            return self.press_frame_anchor(cx, id, (si, ai), p, ev.mods.shift);
        }
        if cx.doc.node(id).is_some_and(is_path_type) {
            return self.press_type_area(cx, id, vec![(id, vec![(si, ai)])], p, ev.mods.shift);
        }
        // Alt picks the whole path (and Alt-drag copies it), as on a segment. On a path
        // already selected whole, an Alt-click adds the next enclosing group on release.
        if ev.mods.alt {
            self.state = State::MoveObject { start: p, grab: Some(grab), hold: grab, began: false, deselect: None };
            let whole = cx.selection.contains(id) && cx.selection.partial(id).is_none();
            if whole && !ev.mods.shift {
                self.click_group = cx.doc.ancestry(id).and_then(|a| next_group(cx, &a));
            }
            return if whole { vec![] } else { vec![Action::Exec("select.set".into(), json!({"ids": [id.0]}))] };
        }
        // A path with all its anchors selected is stored whole (no partial entry).
        let already =
            cx.selection.contains(id) && !cx.selection.segments.contains_key(&id) && cx.selection.partial(id).is_none_or(|s| s.contains(&(si, ai)));
        // Paths all selected whole move as objects, held by this anchor, so Alt can turn
        // the copy on and off during the drag as with the Selection tool.
        self.state = if already && cx.selection.anchors.is_empty() {
            State::MoveObject { start: p, grab: Some(grab), hold: grab, began: false, deselect: None }
        } else {
            State::MoveAnchors { start: p, grab, began: false }
        };
        if ev.mods.shift {
            return vec![Action::Exec("select.anchors".into(), json!({"id": id.0, "anchors": [[si, ai]], "mode": "toggle"}))];
        }
        // Pressed among other selected anchors: a click selects this one alone (the
        // drag, which moves them all, keeps them).
        self.click = already.then_some((id, si, ai));
        if !already {
            return vec![Action::Exec("select.anchors".into(), json!({"id": id.0, "anchors": [[si, ai]], "mode": "set"}))];
        }
        vec![]
    }
    /// Press on the centre point of object `id`: it selects the object whole (Shift toggles it),
    /// as a press on its fill does, and a drag moves it held by that point (#4891).
    fn press_center(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point, id: NodeId, center: Point) -> Vec<Action> {
        self.state = State::MoveObject { start: p, grab: None, hold: center, began: false, deselect: None };
        self.frame.clear();
        if ev.mods.shift {
            return vec![Action::Exec("select.toggle".into(), json!({"id": id.0}))];
        }
        if cx.selection.partial(id).is_some() || cx.selection.segments.contains_key(&id) {
            return vec![Action::Exec("select.set".into(), json!({"ids": [id.0]}))];
        }
        vec![]
    }
    fn press_object(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point, tol: f64, mut h: vectorcraft_doc::hit::Hit) -> Vec<Action> {
        if let Some(part) = cx.doc.node(h.leaf).and_then(|n| compound_part_at(n, p, tol)) {
            h.ancestry.push(part);
            h.leaf = part;
        }
        // On a gradient mesh a click picks the point, the mesh line's two ends or the four points
        // around the patch under it (Shift toggles them), and selects the mesh; a drag moves the
        // picked points.
        if !ev.mods.alt
            && let Some(NodeKind::Mesh(m)) = cx.doc.node(h.leaf).map(|n| &n.kind)
            && let Some(points) = crate::meshedit::part_points(m, p, cx.point_tol(), tol)
        {
            let id = h.leaf;
            let mut out = match (ev.mods.shift, cx.selection.contains(id)) {
                (true, false) => vec![Action::Exec("select.add".into(), json!({"ids": [id.0]}))],
                (false, false) => vec![Action::Exec("select.set".into(), json!({"ids": [id.0]}))],
                _ => vec![],
            };
            self.frame.clear();
            self.state = State::Mesh;
            out.extend(self.mesh.press_points(cx, &cx.selection.objects, id, &points, p, ev.mods.shift));
            return out;
        }
        // A segment pick keeps its endpoints available for movement without selecting
        // the anchors themselves. Dragging reshapes a curve, else moves it. Alt picks
        // the whole path (and Alt-drag copies it), as with Group Selection.
        let whole = cx.selection.contains(h.leaf) && cx.selection.partial(h.leaf).is_none();
        if !ev.mods.alt
            && matches!(h.kind, HitKind::Stroke | HitKind::Outline)
            && let Some(s) = segment_at(cx, h.leaf, p)
        {
            if whole && !ev.mods.shift {
                self.click_segment = Some((h.leaf, s.si, s.seg));
            } else {
                let selected = cx.selection.segments.get(&h.leaf).is_some_and(|sel| sel.contains(&(s.si, s.seg)));
                self.state = if s.curved && !ev.mods.shift {
                    State::Segment { id: h.leaf, si: s.si, seg: s.seg, t: s.t, start: p, began: false }
                } else {
                    // Held by the segment itself, so the segment is what lands on a
                    // ruler guide or lines up, not the pressed spot beside it (#3701).
                    State::MoveAnchors { start: p, grab: hold_point(cx, &h, p), began: false }
                };
                if ev.mods.shift {
                    return vec![Action::Exec("select.segments".into(), json!({"id": h.leaf.0, "segments": [[s.si, s.seg]], "mode": "toggle"}))];
                }
                if selected {
                    return vec![];
                }
                return vec![Action::Exec("select.segments".into(), json!({"id": h.leaf.0, "segments": [[s.si, s.seg]]}))];
            }
        }
        // Clicking the fill selects the whole leaf path (all anchors). With Alt, a click
        // on a path already selected whole adds the next enclosing group on release,
        // as Group Selection's click does; each further Alt-click climbs one level.
        self.state = State::MoveObject { start: p, grab: None, hold: hold_point(cx, &h, p), began: false, deselect: None };
        if ev.mods.alt && whole && !ev.mods.shift {
            self.click_group = next_group(cx, &h.ancestry);
        }
        if ev.mods.shift {
            return vec![Action::Exec("select.toggle".into(), json!({"id": h.leaf.0}))];
        }
        self.frame.clear();
        if !cx.selection.contains(h.leaf) || cx.selection.partial(h.leaf).is_some() {
            return vec![Action::Exec("select.set".into(), json!({"ids": [h.leaf.0]}))];
        }
        vec![]
    }
    fn drag_move_anchors(&mut self, cx: &ToolContext, ev: &PointerEvent, p: Point, (start, grab, began): (Point, Point, bool)) -> Vec<Action> {
        let mut out = vec![];
        if !began {
            if p.distance(start) < cx.tol(3.0) {
                return out;
            }
            out.push(Action::Begin("Move".into()));
            self.state = State::MoveAnchors { start, grab, began: true };
            self.anchor_snap = Some(PointSnap::new(cx, || Targets::for_anchor_drag(cx.doc, cx.selection)));
            self.line_end = line_end_leave(cx, grab);
        }
        let mut d = move_delta(start, p, ev.mods.shift, cx.constrain_angle);
        let unsnapped = d;
        // The grabbed anchor snaps and the others follow it. Shift keeps the move at its
        // angle, and the anchor slides along it onto what Smart Guides find there (#886).
        self.guides.clear();
        if let Some(snap) = &self.anchor_snap {
            let shift = ev.mods.shift.then(|| Leave::segment(cx, grab, true));
            let (q, guides) = snap.snap_from(cx, grab + (p - start), shift.as_ref().or(self.line_end.as_ref()));
            (d, self.guides) = (q - grab, guides);
        }
        self.snapped = snapped(d, unsnapped, ev.mods.shift, &self.guides);
        out.push(Action::Preview("path.moveAnchors".into(), json!({"dx": d.x, "dy": d.y})));
        out
    }
    fn drag_move_object(
        &mut self,
        cx: &ToolContext,
        ev: &PointerEvent,
        p: Point,
        (start, grab, hold, began): (Point, Option<Point>, Point, bool),
    ) -> Vec<Action> {
        let mut out = vec![];
        if !began {
            if p.distance(start) < cx.tol(3.0) {
                return out;
            }
            // With direct-selected anchors or segments in the selection, the drag moves
            // them and the objects selected whole (`path.moveAnchors`), as an anchor drag
            // does, while Alt is up; the other anchors of a partly selected path stay in
            // place. The history names the move or the copy at the end.
            self.partial_snap = (!cx.selection.anchors.is_empty()).then(|| PointSnap::new(cx, || Targets::for_anchor_drag(cx.doc, cx.selection)));
            let grid = self.partial_snap.is_some() && grab.is_none() && (cx.snap_to_grid || cx.snap_to_pixel);
            self.partial_grid =
                grid.then(|| MoveSnap::grid_only(vectorcraft_effects::preview::anchor_bounds(cx.selection, cx.doc, cx.preview_bounds)));
            let copy = ev.mods.alt && self.partial_snap.is_none();
            out.push(Action::Begin(if copy { "Copy".into() } else { "Move".into() }));
            self.state = State::MoveObject { start, grab, hold, began: true, deselect: None };
            if grab.is_some() {
                // Alt can go down or up at any time: gather both while nothing has moved.
                self.anchor_snap = Some(PointSnap::new(cx, || Targets::for_anchor_drag(cx.doc, cx.selection)));
                self.copy_snap = Some(PointSnap::new(cx, || Targets::for_anchor_drag(cx.doc, &Selection::default())));
            } else {
                self.move_snap = Some(MoveSnap::new(cx));
            }
        }
        let mut d = move_delta(start, p, ev.mods.shift, cx.constrain_angle);
        let unsnapped = d;
        self.guides.clear();
        if !ev.mods.alt
            && let Some(snap) = &self.partial_snap
        {
            let held = grab.unwrap_or(hold);
            if let Some(grid) = &self.partial_grid {
                (d, self.guides) = if ev.mods.shift { grid.snap_along(cx, held, d, false) } else { grid.snap(cx, held, d, false) };
            } else {
                let shift = ev.mods.shift.then(|| Leave::segment(cx, held, true));
                let (q, guides) = snap.snap_from(cx, held + (p - start), shift.as_ref());
                (d, self.guides) = (q - held, guides);
            }
            self.snapped = snapped(d, unsnapped, ev.mods.shift, &self.guides);
            out.push(Action::Preview("path.moveAnchors".into(), json!({"dx": d.x, "dy": d.y})));
            return out;
        }
        let snap = if ev.mods.alt { &self.copy_snap } else { &self.anchor_snap };
        if let (Some(grab), Some(snap)) = (grab, snap) {
            let shift = ev.mods.shift.then(|| Leave::segment(cx, grab, true));
            let (q, guides) = snap.snap_from(cx, grab + (p - start), shift.as_ref());
            (d, self.guides) = (q - grab, guides);
        } else if let Some(snap) = &self.move_snap {
            (d, self.guides) = if ev.mods.shift { snap.snap_along(cx, hold, d, ev.mods.alt) } else { snap.snap(cx, hold, d, ev.mods.alt) };
        }
        self.snapped = snapped(d, unsnapped, ev.mods.shift, &self.guides);
        out.push(Action::Preview(
            "object.transform".into(),
            json!({"matrix": matrix_json(vectorcraft_geom::Affine::translate(d)), "copy": ev.mods.alt}),
        ));
        out
    }
    fn release_move(&mut self, cx: &ToolContext, began: bool) -> Vec<Action> {
        let deselect = match self.state {
            State::MoveObject { deselect, .. } => deselect,
            _ => None,
        };
        // The frame anchors a drag moved stay selected.
        let frame = matches!(self.state, State::TypeArea { .. }) && !self.frame.is_empty();
        self.state = State::Idle;
        self.guides.clear();
        (self.anchor_snap, self.copy_snap, self.move_snap) = (None, None, None);
        let group = self.click_group.take();
        // A click on one of several selected frame anchors selects it alone.
        if let (false, Some((id, anchor))) = (began, self.frame_click.take()) {
            self.frame = BTreeMap::from([(id, BTreeSet::from([anchor]))]);
            let mut out = vec![];
            if cx.selection.objects != [id] {
                out.push(Action::Exec("select.set".into(), json!({"ids": [id.0]})));
            }
            out.push(Action::Notify(FRAME_PICKED.into()));
            return out;
        }
        match (began, deselect, self.click.take(), self.click_segment.take()) {
            (true, ..) if frame => vec![Action::Commit, Action::Notify(FRAME_PICKED.into())],
            (true, ..) => vec![Action::Commit],
            (false, Some(id), _, _) => vec![Action::Exec("select.toggle".into(), json!({"id": id.0}))],
            (false, None, Some((id, si, ai)), _) => {
                vec![Action::Exec("select.anchors".into(), json!({"id": id.0, "anchors": [[si, ai]], "mode": "set"}))]
            }
            (false, None, None, Some((id, si, seg))) => {
                vec![Action::Exec("select.segments".into(), json!({"id": id.0, "segments": [[si, seg]]}))]
            }
            (false, None, None, None) => group.map(|g| Action::Exec("select.add".into(), json!({"ids": [g.0]}))).into_iter().collect(),
        }
    }
    fn release_marquee(&mut self, cx: &ToolContext, p: Point, (start, toggle, enclosed, whole): (Point, bool, bool, bool)) -> Vec<Action> {
        self.state = State::Idle;
        let r = Rect::from_points(start, p);
        if r.width() < cx.tol(3.0) && r.height() < cx.tol(3.0) {
            if toggle {
                return vec![];
            }
            self.frame.clear();
            return vec![Action::Exec("select.none".into(), json!({}))];
        }
        // With Group Selection's enclosed marquee, the tool selects the objects inside it
        // (members of groups too), each whole, as a click selects one; with an Alt-marquee, every
        // object it touches, each whole.
        if enclosed || whole {
            let mut touched = vectorcraft_doc::hit::marquee(cx.doc, r, cx.isolation, true);
            let editable = cx.doc.editable();
            touched.retain(|id| editable(*id));
            let picked = if enclosed { crate::select::inside(cx, r, touched) } else { touched };
            let ids: Vec<Value> = picked.into_iter().map(|id| json!(id.0)).collect();
            let art = Action::Exec(if toggle { "select.toggle" } else { "select.set" }.into(), json!({ "ids": ids }));
            return std::iter::once(art).chain(crate::rulerguide::marquee_select(cx, r, enclosed)).collect();
        }
        // Anchors inside the rect, on editable paths inside isolation mode.
        let mut sel: Vec<(NodeId, Vec<AnchorRef>)> = vec![];
        walk_pickable(cx.doc, cx.isolation, |n| {
            if let NodeKind::Path { path, .. } = &n.kind {
                let v: Vec<AnchorRef> = path.anchors().filter(|(_, _, a)| r.contains(a.p)).map(|(s, i, _)| (s, i)).collect();
                if !v.is_empty() {
                    sel.push((n.id, v));
                }
            }
        });
        let editable = cx.doc.editable();
        // Direct Selection: the frame anchors of area type inside the rect are selected
        // (with Shift, toggled), and the type with them, whole.
        let mut framed: Vec<(NodeId, BTreeSet<AnchorRef>)> = vec![];
        if !self.group {
            walk_pickable(cx.doc, cx.isolation, |n| {
                if is_area_type(n)
                    && let Some(frame) = editable_path(n)
                {
                    let inside: BTreeSet<AnchorRef> = frame.anchors().filter(|(_, _, a)| r.contains(a.p)).map(|(s, i, _)| (s, i)).collect();
                    if !inside.is_empty() {
                        framed.push((n.id, inside));
                    }
                }
            });
            framed.retain(|(id, _)| editable(*id));
        }
        // Direct Selection: the mesh points inside the rect are picked (with Shift, toggled), and
        // their meshes selected whole; with Shift a mesh is toggled only when it gains its first
        // picked point or loses its last one.
        let mut meshed: Vec<NodeId> = vec![];
        if !self.group {
            let mut inside: Vec<(NodeId, usize)> = vec![];
            walk_pickable(cx.doc, cx.isolation, |n| {
                if editable(n.id)
                    && let Some(grid) = grid_of(n)
                {
                    inside.extend(grid.points.iter().enumerate().filter(|(_, q)| r.contains(q.p)).map(|(i, _)| (n.id, i)));
                }
            });
            for (id, any) in self.mesh.marquee(&inside, toggle) {
                meshed.push(id);
                if !toggle || cx.selection.contains(id) != any {
                    sel.push((id, vec![]));
                }
            }
        }
        let mut marked: BTreeMap<NodeId, BTreeSet<AnchorRef>> =
            if toggle { self.frame_anchors(cx).into_iter().map(|(id, v)| (id, v.into_iter().collect())).collect() } else { BTreeMap::new() };
        for (id, inside) in &framed {
            let set = marked.entry(*id).or_default();
            *set = if toggle { set.symmetric_difference(inside).copied().collect() } else { inside.clone() };
            let any = !set.is_empty();
            if !any {
                marked.remove(id);
            }
            // With Shift the type is toggled only when it gains its first selected frame
            // anchor or loses its last one.
            if !toggle || cx.selection.contains(*id) != any {
                sel.push((*id, vec![]));
            }
        }
        // Objects without anchors to pick (type, images, symbols…) are selected whole when
        // the marquee touches them, as with the Selection tool (#927).
        for id in vectorcraft_doc::hit::marquee(cx.doc, r, cx.isolation, true) {
            let whole = cx.doc.node(id).is_some_and(|n| !matches!(n.kind, NodeKind::Path { .. } | NodeKind::Compound { .. }));
            if whole && !sel.iter().any(|(s, _)| *s == id) && !framed.iter().any(|(f, _)| *f == id) && !meshed.contains(&id) {
                sel.push((id, vec![]));
            }
        }
        sel.retain(|(id, _)| editable(*id));
        // Direct Selection: a segment the marquee crosses with neither of its anchors inside it is
        // selected, as a click on it selects it (#4654).
        let mut crossed: Vec<(NodeId, Vec<AnchorRef>)> = vec![];
        if !self.group {
            walk_pickable(cx.doc, cx.isolation, |n| {
                if let NodeKind::Path { path, .. } = &n.kind
                    && editable(n.id)
                {
                    let segs = crossed_segments(path, r);
                    if !segs.is_empty() {
                        crossed.push((n.id, segs));
                    }
                }
            });
        }
        self.frame = marked;
        let items: Vec<Value> = sel.iter().map(|(id, v)| json!({"id": id.0, "anchors": anchors_json(v)})).collect();
        let art = Action::Exec("select.anchorsMany".into(), json!({"items": items, "mode": if toggle { "toggle" } else { "set" }}));
        let mode = if toggle { "toggle" } else { "add" };
        let segments = crossed
            .iter()
            .map(|(id, segs)| Action::Exec("select.segments".into(), json!({"id": id.0, "segments": anchors_json(segs), "mode": mode})));
        let mut out: Vec<Action> = std::iter::once(art).chain(segments).chain(crate::rulerguide::marquee_select(cx, r, false)).collect();
        if !self.frame.is_empty() {
            out.push(Action::Notify(FRAME_PICKED.into()));
        }
        out
    }
}