import { HttpRequest } from '../types';
import { IAuthProvider, AuthContext } from './IAuthProvider';
export declare class OAuth2Provider implements IAuthProvider {
    readonly name = "oauth2";
    /** Token cache keyed by cache key (tokenUrl + clientId + grantType) */
    private tokenCache;
    /** Buffer time before token expiry to refresh (in milliseconds) */
    private readonly expiryBufferMs;
    canHandle(request: HttpRequest): boolean;
    applyAuth(request: HttpRequest, context: AuthContext): Promise<HttpRequest>;
    /**
     * Clear the token cache
     */
    clearTokenCache(): void;
    /**
     * Check if cached token is still valid
     */
    private isTokenValid;
    /**
     * Generate cache key from auth config
     */
    private generateCacheKey;
    /**
     * Fetch token from authorization server
     */
    private fetchToken;
    /**
     * Add client_credentials grant parameters
     */
    private addClientCredentialsParams;
    /**
     * Add password grant parameters
     */
    private addPasswordParams;
    /**
     * Add refresh_token grant parameters
     */
    private addRefreshTokenParams;
    /**
     * Replace variable placeholders with actual values
     */
    private replaceVariables;
}