src/utils/templateHandler.js

export const handleTemplateUpload = (file, previewImage) => {
  return new Promise((resolve, reject) => {
    if (!file) {
      reject(new Error('No file selected'));
      return;
    }

    const reader = new FileReader();
    reader.onload = (e) => {
      previewImage.src = e.target.result;
      resolve(e.target.result);
    };
    reader.onerror = () => reject(new Error('Failed to read file'));
    reader.readAsDataURL(file);
  });
};