From bb1cfc76d985cb96e0561c3b5b197f286d8f6398 Mon Sep 17 00:00:00 2001
From: Ellen Emilia Anna Zscheile <fogti+devel@ytrizja.de>
Date: Mon, 31 Mar 2025 01:34:12 +0200
Subject: [PATCH] fix(planar-incr-embed): discover all possible paths,
 including the variants re: weak entries

---
 crates/planar-incr-embed/src/planarr/mod.rs   | 38 ++++++++++---------
 ...ar_incr_embed__planarr__tests__weak00.snap | 27 +++++++++++++
 crates/planar-incr-embed/src/planarr/tests.rs | 17 +++++++++
 3 files changed, 65 insertions(+), 17 deletions(-)
 create mode 100644 crates/planar-incr-embed/src/planarr/snapshots/planar_incr_embed__planarr__tests__weak00.snap

diff --git a/crates/planar-incr-embed/src/planarr/mod.rs b/crates/planar-incr-embed/src/planarr/mod.rs
index 37b8507..cb08ad4 100644
--- a/crates/planar-incr-embed/src/planarr/mod.rs
+++ b/crates/planar-incr-embed/src/planarr/mod.rs
@@ -180,25 +180,29 @@ where
     // 2. handle rest
     Some((
         start_idx,
-        it.filter_map(move |(section_idx, (ni, eps))| {
+        it.flat_map(move |(section_idx, (ni, eps))| {
             // find possible insertion point
             // (at most one of `eps.len()+1` positions)
-            let mut pos = if stack.is_empty() { Some(0) } else { None };
-            for (n, i) in eps.iter().enumerate() {
-                handle_lifo_relaxed(&mut stack, i);
-                if pos.is_none() && stack.is_empty() {
-                    pos = Some(n + 1);
-                }
-            }
-            pos.map(|insert_pos| {
-                (
-                    ni,
-                    OtherEnd {
-                        section_idx,
-                        insert_pos,
-                    },
-                )
-            })
+            (if stack.is_empty() { Some(0) } else { None })
+                .into_iter()
+                .chain(eps.iter().enumerate().filter_map(|(n, i)| {
+                    handle_lifo_relaxed(&mut stack, i);
+                    if stack.is_empty() {
+                        Some(n + 1)
+                    } else {
+                        None
+                    }
+                }))
+                .map(move |insert_pos| {
+                    (
+                        ni.clone(),
+                        OtherEnd {
+                            section_idx,
+                            insert_pos,
+                        },
+                    )
+                })
+                .collect::<Vec<_>>()
         }),
     ))
 }
diff --git a/crates/planar-incr-embed/src/planarr/snapshots/planar_incr_embed__planarr__tests__weak00.snap b/crates/planar-incr-embed/src/planarr/snapshots/planar_incr_embed__planarr__tests__weak00.snap
new file mode 100644
index 0000000..88c70c2
--- /dev/null
+++ b/crates/planar-incr-embed/src/planarr/snapshots/planar_incr_embed__planarr__tests__weak00.snap
@@ -0,0 +1,27 @@
+---
+source: crates/planar-incr-embed/src/planarr/tests.rs
+expression: "s_.find_all_other_ends(&0, 0, false).unwrap().1.collect::<Vec<_>>()"
+---
+[
+  [
+    1,
+    {
+      "section_idx": 1,
+      "insert_pos": 2
+    }
+  ],
+  [
+    2,
+    {
+      "section_idx": 2,
+      "insert_pos": 0
+    }
+  ],
+  [
+    2,
+    {
+      "section_idx": 2,
+      "insert_pos": 1
+    }
+  ]
+]
diff --git a/crates/planar-incr-embed/src/planarr/tests.rs b/crates/planar-incr-embed/src/planarr/tests.rs
index 4df1bbd..730be77 100644
--- a/crates/planar-incr-embed/src/planarr/tests.rs
+++ b/crates/planar-incr-embed/src/planarr/tests.rs
@@ -148,3 +148,20 @@ fn simple01() {
     assert_eq!(s_.insert_path(&1, 2, &2, 'd'), Ok(1));
     assert_compact_json_snapshot!(s.0);
 }
+
+#[test]
+fn weak00() {
+    let mut s = PlanarArrangement::<_, _, ()>::from_node_indices(0..3);
+    let mut s_ = s.as_mut();
+    s_.0[2].1.reversed = true;
+    s_.0[2].1.with_borrow_mut(|j| {
+        j.inner.push(RelaxedPath::Weak(()));
+    });
+    assert_eq!(s_.insert_path(&0, 0, &1, 'a'), Ok(0));
+    assert_eq!(s_.insert_path(&0, 0, &1, 'b'), Ok(0));
+    assert_compact_json_snapshot!(s_
+        .find_all_other_ends(&0, 0, false)
+        .unwrap()
+        .1
+        .collect::<Vec<_>>());
+}