fix: incorrect phase reduction order

src/utils/orderPhaseNodes.ts

@@ -0,0 +1,40 @@
+import type {PhaseNode} from "../pages/VisProgPage/visualProgrammingUI/nodes/PhaseNode.tsx";
+
+/**
+ * takes an array of phaseNodes and orders them according to their nextPhaseId attributes,
+ * starting with the phase that has isFirstPhase = true
+ *
+ * @param {PhaseNode[]} nodes an unordered phaseNode array
+ * @returns {PhaseNode[]} the ordered phaseNode array
+ */
+export default function orderPhaseNodeArray(nodes: PhaseNode[]) : PhaseNode[] {
+  // find the first phaseNode of the sequence
+  const start = nodes.find(node => node.data.isFirstPhase);
+  if (!start) {
+    throw new Error('No phaseNode with isFirstObject = true found');
+  }
+
+  // prepare for ordering of phaseNodes
+  const orderedPhaseNodes: PhaseNode[] = [];
+  const IdMap = new Map(nodes.map(node => [node.id, node]));
+  let currentNode: PhaseNode | undefined = start;
+
+  // populate orderedPhaseNodes array with the phaseNodes in the correct order
+  while (currentNode) {
+    orderedPhaseNodes.push(currentNode);
+
+    if (!currentNode.data.nextPhaseId) {
+      throw new Error("Incomplete phase sequence, program does not reach the end node");
+    }
+
+    if (currentNode.data.nextPhaseId === "end") break;
+
+    currentNode = IdMap.get(currentNode.data.nextPhaseId);
+
+    if (!currentNode) {
+      throw new Error(`Incomplete phase sequence, phaseNode with id "${orderedPhaseNodes.at(-1)?.data.nextPhaseId}" not found`);
+    }
+  }
+
+  return orderedPhaseNodes;
+}