Fixing chained parents by simplifying the tree on unsplit

Author: Neko-Box-Coder

internal/views/splits.go

@@ -479,9 +479,35 @@ func (n *Node) Unsplit() bool {
 	if n.parent.IsLeaf() {
 		return n.parent.Unsplit()
 	}
+
+	n.parent.simplify()
 	return true
 }
 
+// simplify removes unnecessary intermediate parents that have only one child
+func (n *Node) simplify() {
+	if n.parent == nil || len(n.children) != 1 {
+		return
+	}
+
+	ind := 0
+	for i, c := range n.parent.children {
+		if c.id == n.id {
+			ind = i
+		}
+	}
+
+	n.parent.children[ind] = n.children[0]
+	n.parent.children[ind].parent = n.parent
+	if n.children[0].IsLeaf() {
+		n.parent.children[ind].Kind = n.Kind
+	}
+
+	// Since the node changes its parent, it also changes its siblings,
+	// so propW and propH need to be updated.
+	n.parent.markSizes()
+}
+
 // String returns the string form of the node and all children (used for debugging)
 func (n *Node) String() string {
 	var strf func(n *Node, ident int) string