/*
 * Copyright (C) 2015 by Christian Kamm <kamm@incasoftware.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 */

#pragma once

#include "owncloudgui.h"
#include <QObject>
#include <QString>
#include <QNetworkProxy>
#include <QAuthenticator>
#include <QPointer>
#include <QScopedPointer>
#include <QSettings>
#include <QSet>

namespace QKeychain {
class Job;
class ReadPasswordJob;
}

namespace OCC {

class ConfigFile;
class ProxyAuthDialog;

/**
 * @brief Handle proxyAuthenticationRequired signals from our QNetworkAccessManagers.
 *
 * The main complication here is that the slot needs to return credential information
 * synchronously - but running a dialog or getting password data from synchronous
 * storage are asynchronous operations. This leads to reentrant calls that are
 * fairly complicated to handle.
 */
class ProxyAuthHandler : public QObject
{
    Q_OBJECT

public:
    static ProxyAuthHandler *instance();

    ~ProxyAuthHandler() override;

public slots:
    /// Intended for QNetworkAccessManager::proxyAuthenticationRequired()
    void handleProxyAuthenticationRequired(const QNetworkProxy &proxy,
        QAuthenticator *authenticator);

private slots:
    void slotSenderDestroyed(QObject *);

private:
    ProxyAuthHandler();

    /// Runs the ProxyAuthDialog and returns true if new credentials were entered.
    bool getCredsFromDialog();

    /// Checks the keychain for credentials of the current proxy.
    bool getCredsFromKeychain();

    /// Stores the current credentials in the keychain.
    void storeCredsInKeychain();

    template<class T, typename PointerToMemberFunction>
    void execAwait(const T *sender,
                   PointerToMemberFunction signal,
                   int &counter,
                   const QEventLoop::ProcessEventsFlags flags = QEventLoop::AllEvents);

    [[nodiscard]] QString keychainUsernameKey() const;
    [[nodiscard]] QString keychainPasswordKey() const;

    /// The hostname:port of the current proxy, used for detecting switches
    /// to a different proxy.
    QString _proxy;

    QString _username;
    QString _password;

    /// If the user cancels the credential dialog, blocked will be set to
    /// true and we won't bother him again.
    bool _blocked = false;

    /// In several instances handleProxyAuthenticationRequired() can be called
    /// while it is still running. These counters detect what we're currently
    /// waiting for.
    int _waitingForDialog = 0;
    int _waitingForKeychain = 0;

    QPointer<ProxyAuthDialog> _dialog;

    /// The QSettings instance to securely store username/password in the keychain.
    QScopedPointer<QSettings> _settings;

    /// Pointer to the most-recently-run ReadPasswordJob, needed due to reentrancy.
    QScopedPointer<QKeychain::ReadPasswordJob> _readPasswordJob;

    /// For checking the proxy config settings.
    QScopedPointer<ConfigFile> _configFile;

    /// To distinguish between a new QNAM asking for credentials and credentials
    /// failing for an existing QNAM, we keep track of the senders of the
    /// proxyAuthRequired signal here.
    QSet<QObject *> _gaveCredentialsTo;
};

} // namespace OCC