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use std::collections::BTreeSet;
use selene_core::{Change, DbString, EdgeId, LabelSet, NodeId, PropertyMap, db_string};
use super::{Mutator, remove_index_row, remove_node_labels};
use crate::adjacency::AdjacencyEntry;
use crate::error::{GraphError, GraphResult};
use crate::id_map::EngineIdMap;
use crate::store::RowIndex;
impl<'tx, 'g> Mutator<'tx, 'g> {
/// Delete an alive node and cascade delete incident edges.
pub fn delete_node(&mut self, id: NodeId) -> GraphResult<()> {
let row = self.require_live_node(id)?;
let incident = self.remove_node_row(id, row)?;
self.txn.changes.push(Change::NodeDeleted { id });
for edge_id in incident {
self.delete_edge_inner(edge_id, true)?;
}
Ok(())
}
/// Remove one node row from every in-memory structure (label index,
/// property/composite indexes, liveness) and return its incident edges.
///
/// This is the change-free removal core shared by [`Self::delete_node`] and
/// [`Self::truncate_node_type`]; callers own the changeset accounting (one
/// `NodeDeleted` for DETACH DELETE, one declarative truncate change plus
/// staged per-row tombstones for TRUNCATE). The returned incident set spans
/// edges of **every** edge type touching the node (derived from both
/// adjacency directions) so no dangling edge can survive.
pub(super) fn remove_node_row(
&mut self,
id: NodeId,
row: usize,
) -> GraphResult<BTreeSet<EdgeId>> {
let graph = self.txn.read();
let labels = graph
.node_store
.labels
.get(row)
.cloned()
.unwrap_or_default();
let props = graph
.node_store
.properties
.get(row)
.cloned()
.unwrap_or_default();
let mut incident = BTreeSet::new();
if let Some(outgoing) = graph.adjacency_out.get(&id) {
incident.extend(outgoing.iter().map(|edge| edge.edge_id));
}
if let Some(incoming) = graph.adjacency_in.get(&id) {
incident.extend(incoming.iter().map(|edge| edge.edge_id));
}
{
let graph = self.txn.guard_mut();
remove_node_labels(&mut graph.idx_label, row as u32, &labels);
crate::property_index::apply_node_delete(
&mut graph.property_index,
&labels,
&props,
row as u32,
)?;
crate::composite_property_index::apply_node_delete(
&mut graph.composite_property_index,
&labels,
&props,
row as u32,
)?;
crate::vector_index::apply_node_delete(
&mut graph.vector_index,
&labels,
&props,
row as u32,
)?;
crate::text_index::apply_node_delete(
&mut graph.text_index,
&labels,
&props,
row as u32,
id,
);
graph.node_store.labels.set(row, LabelSet::new());
graph.node_store.properties.set(row, PropertyMap::new());
graph.node_store.alive_mut().remove(row as u32);
// BRIEF-Item-4a: KEEP the real external id in row_to_id for the now
// dead row (and keep the id -> row map entry). A deleted id stays
// resolvable -> its dead row -> NodeNotAlive, identically across the
// live and recovery paths: the snapshot persists dead rows with their
// id (sections.rs) and STEP 9 encodes that id from this column. Only
// never-committed aborted-tx hole rows carry NodeId::TOMBSTONE
// (-> None -> NotFound, the accepted refinement).
// GRAPH-05: drop this node's own adjacency entries wholesale, O(1)
// each. The incident set was already captured above, so the
// per-edge cascade (`remove_edge_row`) only has to clear the
// *neighbor* side of each incident edge; a `get_mut` on this
// now-absent hub key no-ops. This is what turns a degree-`D` hub
// delete from O(D^2) (clone + linear-scan the shrinking hub entry
// once per incident edge) into O(D).
graph.adjacency_out.remove(&id);
graph.adjacency_in.remove(&id);
}
Ok(incident)
}
/// Delete an alive edge.
pub fn delete_edge(&mut self, id: EdgeId) -> GraphResult<()> {
self.delete_edge_inner(id, true)
}
/// Remove every node carrying `label` and all of their incident edges in one
/// declarative truncate.
///
/// Observationally identical to `MATCH (n:L) DETACH DELETE n`: every matched
/// node and every incident edge (of **any** edge type, derived from both
/// adjacency directions) is removed via the same change-free in-memory path
/// `delete_node`/`delete_edge_inner` use, so the resulting graph state is
/// byte-identical. The difference is the changeset: exactly **one**
/// declarative [`Change::NodesOfTypeTruncated`] is recorded regardless of the
/// number of rows removed (O(1) WAL write, deletion-reclamation audit
/// Item 11), while the per-row `NodeDeleted`/`EdgeDeleted` tombstones are
/// staged for provider/subscriber fan-out so derived state (e.g. extension
/// providers) is reclaimed without leaks. An absent label is a clean no-op
/// (no change is recorded), matching DETACH DELETE of zero matches; a second
/// truncate of the same label is therefore idempotent.
///
/// All logic lives in the mutator (the single write funnel, hard rule 11) so
/// future `DROP NODE TYPE CASCADE` and `DROP GRAPH` factory-reset paths can
/// reuse it without an N+1 change storm.
pub fn truncate_node_type(&mut self, label: DbString) -> GraphResult<()> {
// Snapshot the matched node rows and derive every incident edge BEFORE
// any removal, exactly as delete_node does — removal mutates the
// adjacency/label structures we are iterating.
let matched_rows: Vec<u32> = match self.txn.read().nodes_with_label(&label) {
Some(bitmap) => bitmap.iter().collect(),
None => return Ok(()),
};
if matched_rows.is_empty() {
return Ok(());
}
let mut node_tombstones = Vec::with_capacity(matched_rows.len());
let mut incident_edges = BTreeSet::new();
for row in matched_rows {
// Skip rows that are not alive (defensive: idx_label is kept in
// lockstep with liveness, but a dead row must never be re-removed).
if !self.txn.read().node_store.is_alive(row) {
continue;
}
let Some(id) = self.txn.read().node_id_for_row(RowIndex::new(row)) else {
continue;
};
incident_edges.append(&mut self.remove_node_row(id, row as usize)?);
node_tombstones.push(Change::NodeDeleted { id });
}
if node_tombstones.is_empty() {
return Ok(());
}
let mut expansion = node_tombstones;
for edge_id in incident_edges {
let row = self
.txn
.read()
.row_for_edge_id(edge_id)
.ok_or(GraphError::EdgeNotFound { id: edge_id })?
.get();
// An incident edge may already be gone if two truncated endpoints
// shared it; remove_edge_row is only called for still-alive rows.
if self.txn.read().edge_store.is_alive(row) {
self.remove_edge_row(edge_id, row as usize)?;
expansion.push(Change::EdgeDeleted { id: edge_id });
}
}
let index = self.txn.changes.len();
self.txn
.changes
.push(Change::NodesOfTypeTruncated { label });
self.txn.truncate_expansions.push((index, expansion));
Ok(())
}
/// Remove every edge carrying `label` in one declarative truncate.
///
/// Observationally identical to `MATCH ()-[e:L]->() DELETE e`: each matched
/// edge is removed via the same change-free path `delete_edge` uses, leaving
/// the graph dangling-free. Records exactly **one** declarative
/// [`Change::EdgesOfTypeTruncated`] (O(1) WAL) and stages per-row
/// `EdgeDeleted` tombstones for fan-out. Absent label is a clean idempotent
/// no-op.
pub fn truncate_edge_type(&mut self, label: DbString) -> GraphResult<()> {
let matched_rows: Vec<u32> = match self.txn.read().edges_with_label(&label) {
Some(bitmap) => bitmap.iter().collect(),
None => return Ok(()),
};
if matched_rows.is_empty() {
return Ok(());
}
let mut expansion = Vec::with_capacity(matched_rows.len());
for row in matched_rows {
if !self.txn.read().edge_store.is_alive(row) {
continue;
}
let Some(id) = self.txn.read().edge_id_for_row(RowIndex::new(row)) else {
continue;
};
self.remove_edge_row(id, row as usize)?;
expansion.push(Change::EdgeDeleted { id });
}
if expansion.is_empty() {
return Ok(());
}
let index = self.txn.changes.len();
self.txn
.changes
.push(Change::EdgesOfTypeTruncated { label });
self.txn.truncate_expansions.push((index, expansion));
Ok(())
}
fn delete_edge_inner(&mut self, id: EdgeId, record_change: bool) -> GraphResult<()> {
let row = self.require_live_edge(id)?;
self.remove_edge_row(id, row)?;
if record_change {
self.txn.changes.push(Change::EdgeDeleted { id });
}
Ok(())
}
/// Remove one edge row from every in-memory structure (liveness, edge-label
/// index, both adjacency directions) without recording any change.
///
/// Shared change-free core for [`Self::delete_edge_inner`] and the truncate
/// paths; callers own changeset accounting.
pub(super) fn remove_edge_row(&mut self, id: EdgeId, row: usize) -> GraphResult<()> {
let graph = self.txn.read();
let label = graph
.edge_store
.label
.get(row)
.cloned()
.ok_or(GraphError::EdgeNotFound { id })?;
let source = *graph
.edge_store
.source
.get(row)
.ok_or(GraphError::EdgeNotFound { id })?;
let target = *graph
.edge_store
.target
.get(row)
.ok_or(GraphError::EdgeNotFound { id })?;
let props = graph
.edge_store
.properties
.get(row)
.cloned()
.unwrap_or_default();
let graph = self.txn.guard_mut();
crate::property_index::apply_edge_delete(
&mut graph.edge_property_index,
&label,
&props,
row as u32,
)?;
graph.edge_store.alive_mut().remove(row as u32);
// BRIEF-Item-4a: keep the real id in row_to_id for the dead row (see
// remove_node_row); only never-committed holes carry EdgeId::TOMBSTONE.
remove_index_row(&mut graph.idx_edge_label, &label, row as u32);
// GRAPH-05: remove the edge from each endpoint's adjacency entry in
// place (no full-`SmallVec` clone), dropping the map key only when the
// entry becomes empty. In a node-delete cascade the hub endpoint's
// entry has already been dropped wholesale by `remove_node_row`, so its
// lookup no-ops and only the neighbor side is touched.
remove_edge_from_adjacency(&mut graph.adjacency_out, source, id);
remove_edge_from_adjacency(&mut graph.adjacency_in, target, id);
graph.edge_store.label.set(row, db_string("")?);
graph.edge_store.source.set(row, NodeId::TOMBSTONE);
graph.edge_store.target.set(row, NodeId::TOMBSTONE);
graph.edge_store.properties.set(row, PropertyMap::new());
Ok(())
}
}
/// Remove edge `edge_id` from one direction's adjacency `map` in place,
/// dropping the node's entry only when it becomes empty.
///
/// In-place via `imbl::HashMap::get_mut` (no full-`SmallVec` clone), so a
/// degree-`D` hub-delete cascade is O(D) rather than O(D^2). A missing key is a
/// no-op — e.g. the hub endpoint whose whole entry `remove_node_row` already
/// dropped. The empty-key removal preserves the "no present-but-empty entry"
/// invariant asserted by the consistency checks.
fn remove_edge_from_adjacency(
map: &mut EngineIdMap<NodeId, AdjacencyEntry>,
node: NodeId,
edge_id: EdgeId,
) {
// The `get_mut` borrow ends with the match expression (it yields a bool),
// so the conditional `remove` below is a fresh, non-overlapping borrow.
let now_empty = match map.get_mut(&node) {
Some(entry) => {
entry.remove(edge_id);
entry.is_empty()
}
None => false,
};
if now_empty {
map.remove(&node);
}
}