feat: add RelevantForm #918 (#1344)

### What problem does this PR solve?

feat: add RelevantForm #918

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/flow/form-hooks.ts

@@ -0,0 +1,62 @@
+import { useCallback } from 'react';
+import { Operator } from './constant';
+import useGraphStore from './store';
+
+const ExcludedNodesMap = {
+  // exclude some nodes downstream of the classification node
+  [Operator.Categorize]: [Operator.Categorize, Operator.Answer, Operator.Begin],
+  [Operator.Relevant]: [Operator.Begin],
+};
+
+export const useBuildFormSelectOptions = (
+  operatorName: Operator,
+  selfId?: string, // exclude the current node
+) => {
+  const nodes = useGraphStore((state) => state.nodes);
+
+  const buildCategorizeToOptions = useCallback(
+    (toList: string[]) => {
+      const excludedNodes: Operator[] = ExcludedNodesMap[operatorName] ?? [];
+      return nodes
+        .filter(
+          (x) =>
+            excludedNodes.every((y) => y !== x.data.label) &&
+            x.id !== selfId &&
+            !toList.some((y) => y === x.id), // filter out selected values ​​in other to fields from the current drop-down box options
+        )
+        .map((x) => ({ label: x.data.name, value: x.id }));
+    },
+    [nodes, operatorName, selfId],
+  );
+
+  return buildCategorizeToOptions;
+};
+
+export const useHandleFormSelectChange = (nodeId?: string) => {
+  const { addEdge, deleteEdgeBySourceAndSourceHandle } = useGraphStore(
+    (state) => state,
+  );
+  const handleSelectChange = useCallback(
+    (name?: string) => (value?: string) => {
+      if (nodeId && name) {
+        if (value) {
+          addEdge({
+            source: nodeId,
+            target: value,
+            sourceHandle: name,
+            targetHandle: null,
+          });
+        } else {
+          // clear selected value
+          deleteEdgeBySourceAndSourceHandle({
+            source: nodeId,
+            sourceHandle: name,
+          });
+        }
+      }
+    },
+    [addEdge, nodeId, deleteEdgeBySourceAndSourceHandle],
+  );
+
+  return { handleSelectChange };
+};