Feat: Initialize the data pipeline canvas. #9869 (#9870)

### What problem does this PR solve?
Feat: Initialize the data pipeline canvas. #9869

### Type of change


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

web/src/pages/data-flow/canvas/node/use-build-switch-handle-positions.ts

@@ -0,0 +1,59 @@
+import { ISwitchCondition, RAGFlowNodeType } from '@/interfaces/database/flow';
+import { useUpdateNodeInternals } from '@xyflow/react';
+import get from 'lodash/get';
+import { useEffect, useMemo } from 'react';
+import { SwitchElseTo } from '../../constant';
+import { generateSwitchHandleText } from '../../utils';
+
+export const useBuildSwitchHandlePositions = ({
+  data,
+  id,
+}: {
+  id: string;
+  data: RAGFlowNodeType['data'];
+}) => {
+  const updateNodeInternals = useUpdateNodeInternals();
+
+  const conditions: ISwitchCondition[] = useMemo(() => {
+    return get(data, 'form.conditions', []);
+  }, [data]);
+
+  const positions = useMemo(() => {
+    const list: Array<{
+      text: string;
+      top: number;
+      idx: number;
+      condition?: ISwitchCondition;
+    }> = [];
+
+    [...conditions, ''].forEach((x, idx) => {
+      let top = idx === 0 ? 53 : list[idx - 1].top + 10 + 14 + 16 + 16; // case number (Case 1) height + flex gap
+      if (idx >= 1) {
+        const previousItems = conditions[idx - 1]?.items ?? [];
+        if (previousItems.length > 0) {
+          // top += 12; // ConditionBlock padding
+          top += previousItems.length * 26; // condition variable height
+          // top += (previousItems.length - 1) * 25; // operator height
+        }
+      }
+
+      list.push({
+        text:
+          idx < conditions.length
+            ? generateSwitchHandleText(idx)
+            : SwitchElseTo,
+        idx,
+        top,
+        condition: typeof x === 'string' ? undefined : x,
+      });
+    });
+
+    return list;
+  }, [conditions]);
+
+  useEffect(() => {
+    updateNodeInternals(id);
+  }, [id, updateNodeInternals, conditions]);
+
+  return { positions };
+};