feat(ui): extract logic for finding candidate fields to own function

invokeai/frontend/web/src/features/nodes/store/util/getFirstValidConnection.ts

@@ -116,3 +116,75 @@ export const getFirstValidConnection = (
 
   return null;
 };
+
+export const getTargetCandidateFields = (
+  source: string,
+  sourceHandle: string,
+  target: string,
+  nodes: AnyNode[],
+  edges: Edge[],
+  templates: Templates,
+  edgePendingUpdate: Edge | null
+): FieldInputTemplate[] => {
+  const sourceNode = nodes.find((n) => n.id === source);
+  const targetNode = nodes.find((n) => n.id === target);
+  if (!sourceNode || !targetNode) {
+    return [];
+  }
+
+  const sourceTemplate = templates[sourceNode.data.type];
+  const targetTemplate = templates[targetNode.data.type];
+  if (!sourceTemplate || !targetTemplate) {
+    return [];
+  }
+
+  const sourceField = sourceTemplate.outputs[sourceHandle];
+
+  if (!sourceField) {
+    return [];
+  }
+
+  const targetCandidateFields = map(targetTemplate.inputs).filter((field) => {
+    const c = { source, sourceHandle, target, targetHandle: field.name };
+    const r = validateConnection(c, nodes, edges, templates, edgePendingUpdate, true);
+    return r.isValid;
+  });
+
+  return targetCandidateFields;
+};
+
+export const getSourceCandidateFields = (
+  target: string,
+  targetHandle: string,
+  source: string,
+  nodes: AnyNode[],
+  edges: Edge[],
+  templates: Templates,
+  edgePendingUpdate: Edge | null
+): FieldOutputTemplate[] => {
+  const targetNode = nodes.find((n) => n.id === target);
+  const sourceNode = nodes.find((n) => n.id === source);
+  if (!sourceNode || !targetNode) {
+    return [];
+  }
+
+  const sourceTemplate = templates[sourceNode.data.type];
+  const targetTemplate = templates[targetNode.data.type];
+  if (!sourceTemplate || !targetTemplate) {
+    return [];
+  }
+
+  const targetField = targetTemplate.inputs[targetHandle];
+
+  if (!targetField) {
+    return [];
+  }
+
+  const sourceCandidateFields = map(sourceTemplate.outputs).filter((field) => {
+    const c = { source, sourceHandle: field.name, target, targetHandle };
+    const r = validateConnection(c, nodes, edges, templates, edgePendingUpdate, true);
+    return r.isValid;
+  });
+
+  return sourceCandidateFields;
+};