feat: manually mirror opencoze's code from bytedance

Change-Id: I09a73aadda978ad9511264a756b2ce51f5761adf

frontend/packages/workflow/variable/src/hooks/use-available-workflow-variables.tsx

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2025 coze-dev Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+import { useEffect, startTransition } from 'react';
+
+import {
+  ASTKind,
+  type ObjectType,
+  useCurrentScope,
+} from '@flowgram-adapter/free-layout-editor';
+import { useRefresh, useService } from '@flowgram-adapter/free-layout-editor';
+
+import { WorkflowVariableFacadeService, type WorkflowVariable } from '../core';
+
+export function useAvailableWorkflowVariables(): WorkflowVariable[] {
+  const scope = useCurrentScope();
+  const facadeService: WorkflowVariableFacadeService = useService(
+    WorkflowVariableFacadeService,
+  );
+  const refresh = useRefresh();
+
+  useEffect(() => {
+    const disposable = scope.available.onDataChange(() => {
+      startTransition(() => refresh());
+    });
+
+    return () => disposable.dispose();
+  }, []);
+
+  return scope.available.variables
+    .map(_variable => {
+      // 第一层为变量，因此需要分层处理
+      if (_variable.type.kind === ASTKind.Object) {
+        return ((_variable.type as ObjectType)?.properties || []).map(
+          _property => facadeService.getVariableFacadeByField(_property),
+        );
+      }
+      return [];
+    })
+    .flat();
+}