Method startAuth

ui-linux/src/oauthservice.cpp:162–247

}

void OAuthService::startAuth(const QString &provider, const QString &tokenPath)
{
    cancel(); // clean up any previous attempt

    m_provider = provider;
    m_tokenPath = tokenPath;

    // Generate PKCE values (used for Google Drive)
    m_state = generateRandomString(32);
    m_codeVerifier = generateRandomString(64);
    QString codeChallenge = computeCodeChallenge(m_codeVerifier);

    // OneDrive uses rclone's fixed port 53682, Google Drive uses dynamic port
    m_server = new QTcpServer(this);
    
    if (provider == "onedrive") {
        // rclone's Azure AD app only has http://localhost:53682/ registered
        if (!m_server->listen(QHostAddress::LocalHost, 53682)) {
            emit authFailed(provider, "Failed to start local HTTP server on port 53682: " + m_server->errorString());
            delete m_server;
            m_server = nullptr;
            return;
        }
        m_redirectUri = "http://localhost:53682/";
    } else if (provider == "gdrive") {
        // Fixed port for Google Drive, ugh
        if (!m_server->listen(QHostAddress::LocalHost, 53692)) {
            emit authFailed(provider, "Failed to start local HTTP server on port 53692: " + m_server->errorString());
            delete m_server;
            m_server = nullptr;
            return;
        }
        m_redirectUri = "http://localhost:53692/callback";
    } else {
        // Other providers use dynamic port
        if (!m_server->listen(QHostAddress::LocalHost, 0)) {
            emit authFailed(provider, "Failed to start local HTTP server: " + m_server->errorString());
            delete m_server;
            m_server = nullptr;
            return;
        }
        m_redirectUri = QString("http://localhost:%1/callback").arg(m_server->serverPort());
    }
    
    m_port = m_server->serverPort();
    connect(m_server, &QTcpServer::newConnection, this, &OAuthService::onNewConnection);

    emit statusMessage(QString("Listening on %1").arg(m_redirectUri));

    // Build auth URL
    QUrl authUrl;
    QUrlQuery params;

    if (provider == "gdrive") {
        authUrl.setUrl(GDRIVE_AUTH_URL);
        params.addQueryItem("client_id", GDRIVE_CLIENT_ID);
        params.addQueryItem("redirect_uri", m_redirectUri);
        params.addQueryItem("response_type", "code");