Add 2FA support (#112)

GPClient/challengedialog.cpp

@@ -0,0 +1,38 @@
+#include <QtWidgets/QDialogButtonBox>
+#include <QtWidgets/QPushButton>
+
+#include "challengedialog.h"
+#include "ui_challengedialog.h"
+
+ChallengeDialog::ChallengeDialog(QWidget *parent) :
+    QDialog(parent),
+    ui(new Ui::ChallengeDialog)
+{
+    ui->setupUi(this);
+    ui->buttonBox->button(QDialogButtonBox::Ok)->setDisabled(true);
+}
+
+ChallengeDialog::~ChallengeDialog()
+{
+    delete ui;
+}
+
+void ChallengeDialog::setMessage(const QString &message)
+{
+    ui->challengeMessage->setText(message);
+}
+
+const QString ChallengeDialog::getChallenge()
+{
+    return ui->challengeInput->text();
+}
+
+void ChallengeDialog::on_challengeInput_textChanged(const QString &value)
+{
+    QPushButton *okBtn = ui->buttonBox->button(QDialogButtonBox::Ok);
+    if (value.isEmpty()) {
+        okBtn->setDisabled(true);
+    } else {
+        okBtn->setEnabled(true);
+    }
+}