/**
 * Circuit Breaker Pattern - Protect against failing external services
 */
import { AsyncFunction, Logger } from "../types/common";
import { CircuitState, CircuitBreakerOptions, CircuitBreakerStats } from "../types/circuit-breaker";
/**
 * Internal options (without execute field)
 */
interface CircuitBreakerInternalOptions {
    failureThreshold?: number;
    openDuration?: number;
    halfOpenMaxAttempts?: number;
    timeout?: number;
    shouldCountFailure?: (error: Error) => boolean;
    logger?: Logger;
    onStateChange?: (oldState: CircuitState, newState: CircuitState) => void;
    onOpen?: () => void;
    onClose?: () => void;
    onHalfOpen?: () => void;
}
/**
 * Circuit Breaker - Protects application from failing services
 */
export declare class CircuitBreaker<TResult = any, TArgs extends any[] = any[]> {
    private readonly fn;
    private state;
    private consecutiveFailures;
    private totalFailures;
    private totalSuccesses;
    private totalCalls;
    private lastFailureTime;
    private lastSuccessTime;
    private halfOpenAttempts;
    private nextAttemptTime;
    private readonly failureThreshold;
    private readonly openDuration;
    private readonly halfOpenMaxAttempts;
    private readonly timeout;
    private readonly shouldCountFailure;
    private readonly logger;
    private readonly onStateChange?;
    private readonly onOpen?;
    private readonly onClose?;
    private readonly onHalfOpen?;
    constructor(fn: AsyncFunction<TResult, TArgs>, options?: CircuitBreakerInternalOptions);
    /**
     * Execute function with circuit breaker protection
     */
    execute(...args: TArgs): Promise<TResult>;
    /**
     * Execute function with timeout
     */
    private executeWithTimeout;
    /**
     * Handle successful execution
     */
    private onSuccess;
    /**
     * Handle failed execution
     */
    private onFailure;
    /**
     * Change circuit state
     */
    private changeState;
    /**
     * Get circuit statistics
     */
    getStats(): CircuitBreakerStats;
    /**
     * Reset circuit to closed state
     */
    reset(): void;
    /**
     * Get current state
     */
    getState(): CircuitState;
}
/**
 * Callable circuit breaker type (Vercel-style)
 */
export interface CallableCircuitBreaker<TResult = any, TArgs extends any[] = any[]> {
    (...args: TArgs): Promise<TResult>;
    getState(): CircuitState;
    getStats(): CircuitBreakerStats;
    reset(): void;
}
/**
 * Define a circuit breaker with Vercel-style callable API
 *
 * @example
 * ```typescript
 * const breaker = defineCircuitBreaker({
 *   execute: async () => callAPI(),
 *   failureThreshold: 5,
 *   openDuration: 60000
 * });
 *
 * const result = await breaker(); // Direct call
 * console.log(breaker.getState()); // Check state
 * ```
 */
export declare function defineCircuitBreaker<TResult = any, TArgs extends any[] = any[]>(options: CircuitBreakerOptions<TResult>): CallableCircuitBreaker<TResult, TArgs>;
/**
 * @deprecated Use `defineCircuitBreaker` instead for better alignment with Vercel AI SDK patterns
 * @see defineCircuitBreaker
 */
export declare const circuitBreaker: typeof defineCircuitBreaker;
export {};
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