Code refactor, support multiple gateways and non-SAML authentication (#9)

* Code refactor

* Update README.md

GPClient/portalauthenticator.h

@@ -0,0 +1,52 @@
+#ifndef PORTALAUTHENTICATOR_H
+#define PORTALAUTHENTICATOR_H
+
+#include "portalconfigresponse.h"
+#include "normalloginwindow.h"
+#include "samlloginwindow.h"
+#include "preloginresponse.h"
+
+#include <QObject>
+
+class PortalAuthenticator : public QObject
+{
+    Q_OBJECT
+public:
+    explicit PortalAuthenticator(const QString& portal);
+    ~PortalAuthenticator();
+
+    void authenticate();
+
+signals:
+    void success(const PortalConfigResponse&, const GPGateway&);
+    void fail(const QString& msg);
+    void preloginFailed(const QString& msg);
+
+private slots:
+    void onPreloginFinished();
+    void onPerformNormalLogin(const QString &username, const QString &password);
+    void onLoginWindowRejected();
+    void onSAMLLoginSuccess(const QMap<QString, QString> &samlResult);
+    void onFetchConfigFinished();
+
+private:
+    QString portal;
+    QString preloginUrl;
+    QString configUrl;
+    QString username;
+    QString password;
+
+    PreloginResponse preloginResponse;
+
+    bool isAutoLogin { false };
+
+    NormalLoginWindow *normalLoginWindow{ nullptr };
+
+    void tryAutoLogin();
+    void normalAuth();
+    void samlAuth();
+    void fetchConfig(QString username, QString password, QString preloginCookie = "");
+    void emitFail(const QString& msg = "");
+};
+
+#endif // PORTALAUTHENTICATOR_H