export declare class OAuthService {
    private readonly gmailOAuth2Client;
    private readonly outlookScopes;
    private readonly gmailScopes;
    generateGmailAuthUrl(state: string): string;
    generateOutlookAuthUrl(state: string): string;
    exchangeGmailCode(code: string): Promise<any>;
    exchangeOutlookCode(code: string): Promise<any>;
    refreshGmailToken(refreshToken: string): Promise<any>;
    refreshOutlookToken(refreshToken: string): Promise<any>;
    generateState(prefix: string, additionalData?: any): string;
    parseState(state: string): {
        prefix: string;
        timestamp: number;
        random: string;
        data: any;
    };
}