final class AvatarUploader {


     func upload(imageData: Data ,responseHandler: @escaping (Error?) -> Void) {
        let request = createMultipartRequest(imageData: imageData)

        // return body as Data
        print("Fire....")
        let session = URLSession.shared
        print(request)
        let task = session.dataTask(with: request) { (data, response, error) in
            print("Complete")
            if error != nil {
                print("error upload : \(error)")
                responseHandler(error)
                return
            }
            do {
                if let json = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String: Any] {
                    responseHandler(nil)
                    print("SUCCESS")
            } else {
                    print("Invalid Json")
                }
            }
            catch {
                print(error)
                responseHandler(error)
            }
        }
        task.resume()
    }


    private func createMultipartRequest(imageData: Data) -> URLRequest {
        var request = URLRequest(url: URL(string: "https://canon-photos-dev.canon-cpc.gigsternetwork.com/graphql")!)
        request.httpMethod = "POST"
        let uuid = UUID().uuidString

        request.setValue("multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW", forHTTPHeaderField: "Content-Type")
        request.setValue("Bearer \(SessionHelper.shared.currentUser.token)", forHTTPHeaderField: "Authorization")

        var body = Data()

        body.append("Content-Disposition: form-data; name=\"operations\"\n\n".data(using: .utf8)!)
        let mutation =
        """
        {\"query\":
        \"mutation($userId: Int!, $file: PhotoUpload!) { setUserAvatar(userId: $userId, file: $file) { userImage } }\",
        \"variables\": {
        \"userId\": \(SessionHelper.shared.currentUser.userId),
        \"file\": null
        }
        }\n\n
        """
        body.append(mutation.data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"map\"\n\n".data(using: .utf8)!)
        body.append("{\"0\":[\"variables.file\"]}\n\n".data(using: .utf8)!)
        body.append("Content-Disposition: form-data; name=\"0\"; filename=\(uuid).jpeg\n\n".data(using: .utf8)!)

      //  body.append(imageData)

        body.append("------WebKitFormBoundary7MA4YWxkTrZu0gW--)".data(using: .utf8)!)

        print(String(data: body, encoding: .utf8))

        request.httpBody = body

        return request
    }


}