Examples: Add multimodal app (#2328)

examples/multimodal-demo/src/hooks/useFileHandler.ts

@@ -0,0 +1,45 @@
+import { useState } from 'react';
+import { FileInfo } from '@/types';
+import { convertToBase64, getFileBuffer } from '@/utils/fileUtils';
+
+interface UseFileHandlerReturn {
+  selectedFile: FileInfo | null;
+  file: File | null;
+  fileData: string | Buffer | null;
+  setSelectedFile: (file: FileInfo | null) => void;
+  handleFile: (file: File) => Promise<void>;
+  clearFile: () => void;
+}
+
+export const useFileHandler = (): UseFileHandlerReturn => {
+  const [selectedFile, setSelectedFile] = useState<FileInfo | null>(null);
+  const [file, setFile] = useState<File | null>(null);
+  const [fileData, setFileData] = useState<string | Buffer | null>(null);
+
+  const handleFile = async (file: File) => {
+    setFile(file);
+    
+    if (file.type.startsWith('image/')) {
+      const base64Data = await convertToBase64(file);
+      setFileData(base64Data);
+    } else if (file.type.startsWith('audio/')) {
+      const bufferData = await getFileBuffer(file);
+      setFileData(bufferData);
+    }
+  };
+
+  const clearFile = () => {
+    setSelectedFile(null);
+    setFile(null);
+    setFileData(null);
+  };
+
+  return {
+    selectedFile,
+    file,
+    fileData,
+    setSelectedFile,
+    handleFile,
+    clearFile,
+  };
+};