import { AxiosRequestConfig, AxiosError, AxiosInstance } from 'axios';

declare const AXIOS_RETRYER_REQUEST_PRIORITIES: {
    readonly CRITICAL: 4;
    readonly HIGHEST: 3;
    readonly HIGH: 2;
    readonly MEDIUM: 1;
    readonly LOW: 0;
};
type AxiosRetryerRequestPriority = (typeof AXIOS_RETRYER_REQUEST_PRIORITIES)[keyof typeof AXIOS_RETRYER_REQUEST_PRIORITIES];

type RetryEventArgs<TEvents extends object, K extends keyof TEvents> = NonNullable<TEvents[K]> extends (...args: infer TArgs) => unknown ? TArgs : never;
type RetryEventListener<TEvents extends object, K extends keyof TEvents> = (...args: RetryEventArgs<TEvents, K>) => void;
/**
 * Terminal request error payload emitted by `onRequestError`.
 */
interface AxiosRetryerRequestErrorEvent {
    /** Final Axios error object that caused request failure. */
    error: AxiosError;
    /** Final Axios request config that failed. */
    config: AxiosRequestConfig;
    /** HTTP status if available, otherwise `null` for network-level failures. */
    status: number | null;
    /** Request identifier if available. */
    requestId?: string;
    /** Total attempts performed including the initial attempt. */
    attempts: number;
    /** Whether the final error shape is considered retryable by the active strategy. */
    retryable: boolean;
}
/**
 * Queue-entry payload emitted by `onRequestQueued`.
 */
interface AxiosRetryerRequestQueuedEvent {
    /** Request identifier generated or assigned by RetryManager. */
    requestId: string;
    /** Request config entering the queue. */
    config: AxiosRequestConfig;
    /** Resolved priority used for queue ordering. */
    priority: AxiosRetryerRequestPriority;
    /** Queue size immediately after this request was enqueued. */
    queueSize: number;
}
/**
 * Queue-dispatch payload emitted by `onRequestDispatched`.
 */
interface AxiosRetryerRequestDispatchedEvent {
    /** Request identifier generated or assigned by RetryManager. */
    requestId: string;
    /** Request config dispatched from the queue. */
    config: AxiosRequestConfig;
    /** Resolved priority used for queue ordering. */
    priority: AxiosRetryerRequestPriority;
    /** Time spent waiting in the queue before dispatch (milliseconds). */
    queuedForMs: number;
}
/**
 * Success payload emitted by `onRequestSucceeded`.
 */
interface AxiosRetryerRequestSucceededEvent {
    /** Request identifier generated or assigned by RetryManager. */
    requestId?: string;
    /** Final request config that succeeded. */
    config: AxiosRequestConfig;
    /** Final HTTP status code. */
    status: number;
    /** Total attempts performed including the initial attempt. */
    attempts: number;
}
/**
 * Core events exposed by RetryManager without any plugins attached.
 */
interface CoreRetryEvents {
    /**
     * Triggered when the retry process begins.
     */
    onRetryProcessStarted?: () => void;
    /**
     * Triggered before each retry attempt.
     * @param config The Axios request configuration being retried.
     */
    beforeRetry?: (config: AxiosRequestConfig) => void;
    /**
     * Triggered after a retry attempt.
     * @param config The Axios request configuration being retried.
     * @param success Whether the retry was successful.
     * @param error If the retry failed, the error that caused the failure.
     */
    afterRetry?: (config: AxiosRequestConfig, success: boolean, error?: AxiosError) => void;
    /**
     * Triggered when a retry is scheduled and waiting for the specified delay.
     * @param delayMs The delay in milliseconds.
     * @param config The Axios request configuration.
     */
    onRetryScheduled?: (delayMs: number, config: AxiosRequestConfig) => void;
    /**
     * Triggered for each failed retry attempt.
     * @param config The failed Axios request configuration.
     */
    onFailure?: (config: AxiosRequestConfig) => void;
    /**
     * Triggered when a request enters the queue.
     *
     * @param payload Queue entry metadata for this request.
     */
    onRequestQueued?: (payload: AxiosRetryerRequestQueuedEvent) => void;
    /**
     * Triggered when a queued request is dispatched from the queue to the network layer.
     *
     * @param payload Dispatch metadata including queue wait duration.
     */
    onRequestDispatched?: (payload: AxiosRetryerRequestDispatchedEvent) => void;
    /**
     * Triggered when a request succeeds (initial attempt or after retries).
     *
     * @param payload Success metadata for this request.
     */
    onRequestSucceeded?: (payload: AxiosRetryerRequestSucceededEvent) => void;
    /**
     * Triggered once when a request fails terminally (all retries exhausted or no-retry terminal path).
     * Unlike `onFailure`, this event is emitted only for the final failure.
     *
     * @param payload Terminal error context for application-level handling.
     */
    onRequestError?: (payload: AxiosRetryerRequestErrorEvent) => void;
    /**
     * Triggered when all retries are completed.
     */
    onRetryProcessFinished?: () => void;
    /**
     * Triggered when an in-flight retry delay timer is cancelled — either because
     * the user aborted the request (`source: 'user'`) or because the system shut
     * the request down (`source: 'system'`, e.g. plugin destroy, queue clear).
     */
    onRetryTimerCancelled?: (payload: {
        requestId: string;
        source: 'user' | 'system';
    }) => void;
    /**
     * Triggered when a request cancelled.
     * @param requestId Id of the cancelled request.
     */
    onRequestCancelled?: (requestId: string) => void;
    /**
     * Called when a request fails due to network or connection issues, meaning
     * no valid server response was received (e.g., user is offline).
     *
     * @param request - The Axios request config that encountered a connection error.
     */
    onInternetConnectionError?: (request: AxiosRequestConfig) => void;
    /**
     * Triggered when a blocking request (at or above `blockingPriorityThreshold`) fails terminally.
     * Only fires when `blockingPriorityThreshold` is configured.
     *
     * @param config The Axios request config of the failed blocking request.
     */
    onBlockingRequestFailed?: (config: AxiosRequestConfig) => void;
    /**
     * Triggered when every in-flight blocking request (at or above `blockingPriorityThreshold`)
     * has **succeeded** (terminal success) and none remain in the internal blocker set.
     * Not emitted when a blocker fails (`onBlockingRequestFailed`) or is cancelled.
     * Only fires when `blockingPriorityThreshold` is configured.
     */
    onAllBlockingRequestsResolved?: () => void;
}
type RetryManagerEvents<TPluginEvents extends object = Record<never, never>> = {
    [K in keyof CoreRetryEvents | keyof TPluginEvents]: K extends keyof TPluginEvents ? K extends keyof CoreRetryEvents ? CoreRetryEvents[K] & TPluginEvents[K] : TPluginEvents[K] : K extends keyof CoreRetryEvents ? CoreRetryEvents[K] : never;
};

/**
 * AxiosRetryer metrics
 * */
interface AxiosRetryerMetrics {
    totalRequests: number;
    successfulRetries: number;
    failedRetries: number;
    completelyFailedRequests: number;
    canceledRequests: number;
    completelyFailedCriticalRequests: number;
    errorTypes: {
        network: number;
        server5xx: number;
        client4xx: number;
        cancelled: number;
    };
    retryAttemptsDistribution: Record<string, number>;
    requestCountsByPriority: Record<string, number>;
    retryPrioritiesDistribution: Record<string, {
        total: number;
        successes: number;
        failures: number;
    }>;
    queueWaitDuration: number;
    retryDelayDuration: number;
}
/**
 * Represents the distribution of different error types encountered
 */
interface ErrorTypesDistribution {
    /** Number of network-related errors (e.g., connection failures) */
    network: number;
    /** Number of 5xx server errors */
    server5xx: number;
    /** Number of 4xx client errors */
    client4xx: number;
    /** Number of canceled requests */
    cancelled: number;
}
/**
 * Represents metrics for a specific request priority level
 */
interface PriorityMetrics {
    /** The priority level (higher numbers indicate higher priority) */
    priority: number;
    /** Total number of retry attempts for this priority */
    total: number;
    /** Number of successful retries for this priority */
    successes: number;
    /** Number of failed retries for this priority */
    failures: number;
    /** Success rate percentage for this priority (0-100) */
    successRate: number;
    /** Failure rate percentage for this priority (0-100) */
    failureRate: number;
}
/**
 * AxiosRetryer detailed metrics
 * */
interface AxiosRetryerDetailedMetrics {
    /** Total number of requests made through the retryer */
    totalRequests: number;
    /** Number of successfully completed retries */
    successfulRetries: number;
    /** Number of failed retry attempts */
    failedRetries: number;
    /** Requests that failed all retry attempts */
    completelyFailedRequests: number;
    /** Requests canceled before completion */
    canceledRequests: number;
    /** Critical priority requests that failed all retries */
    completelyFailedCriticalRequests: number;
    /** Distribution of error types encountered */
    errorTypesDistribution: ErrorTypesDistribution;
    /** Distribution of retry attempts across all requests */
    retryAttemptsDistribution: Record<number, number>;
    /** Count of requests by priority level */
    requestCountsByPriority: Record<number, number>;
    /** Average time spent in queue (seconds) */
    avgQueueWait: number;
    /** Average delay between retry attempts (seconds) */
    avgRetryDelay: number;
    /** Detailed metrics grouped by request priority */
    priorityMetrics: PriorityMetrics[];
    /** Timer health and accumulation metrics */
    timerHealth: {
        /** Number of active internal timers */
        activeTimers: number;
        /** Number of active retry timers */
        activeRetryTimers: number;
        /** Health score (0 = excellent, 100+ = potential issues) */
        healthScore: number;
    };
}
/**
 * Interface for pluggable metrics recording.
 * The core library ships with no-op metrics by default.
 * Use MetricsPlugin for full metrics collection.
 */
interface MetricsRecorder {
    reset(): void;
    buildDetailedMetrics(timerStats: {
        activeTimers: number;
        activeRetryTimers: number;
    }): AxiosRetryerDetailedMetrics;
    emitMetricsUpdated?(): void;
}

/**
 * Logger interface used by RetryManager and its collaborators.
 * Supply a custom implementation via {@link RetryManagerOptions.logger}
 * to redirect or suppress log output.
 */
interface Logger {
    log(message: string, data?: unknown): void;
    error(message: string, error?: unknown): void;
    warn(message: string, data?: unknown): void;
    debug(message: string, meta?: unknown): void;
}
/**
 * Context object passed to plugins during initialization and teardown.
 * Provides the plugin-facing view of RetryManager capabilities including
 * plugin-only wiring hooks that are not part of the public manager API.
 */
interface PluginContext<TPluginEvents extends object = Record<never, never>> {
    /** The Axios instance managed by RetryManager. */
    readonly axiosInstance: AxiosInstance;
    /** Returns the configured logger. */
    getLogger(): Logger;
    /** Subscribe to a manager or plugin event. */
    on<K extends keyof RetryManagerEvents<TPluginEvents>>(event: K, listener: RetryEventListener<RetryManagerEvents<TPluginEvents>, K>): void;
    /** Unsubscribe from a manager or plugin event. */
    off<K extends keyof RetryManagerEvents<TPluginEvents>>(event: K, listener: RetryEventListener<RetryManagerEvents<TPluginEvents>, K>): boolean;
    /** Fire all listeners registered for this event. */
    emit<K extends keyof RetryManagerEvents<TPluginEvents>>(event: K, ...args: RetryEventArgs<RetryManagerEvents<TPluginEvents>, K>): void;
    /**
     * Identical to `emit` — fires all listeners registered for this event.
     *
     * Kept for backward compatibility with existing plugins. There is no semantic
     * distinction from `emit`: prefer `emit` in new code.
     */
    triggerAndEmit<K extends keyof RetryManagerEvents<TPluginEvents>>(event: K, ...args: RetryEventArgs<RetryManagerEvents<TPluginEvents>, K>): void;
    /** Cancel a specific in-flight or queued request by its ID. */
    cancelRequest(requestId: string): void;
    /** Cancel all active and queued requests. */
    cancelAllRequests(): void;
    /** Cancel only requests currently waiting in the queue. */
    cancelQueuedRequests(): void;
    /**
     * Register a queue gate that must approve each request before it is dispatched.
     * Used by plugins that need to block request processing under certain conditions.
     */
    registerQueueGate(name: string, canProcess: (request: AxiosRequestConfig) => boolean): void;
    /** Remove a previously registered queue gate. */
    unregisterQueueGate(name: string): boolean;
    /** Trigger a queue drain pass. Useful after a gate condition changes. */
    refreshQueue(): void;
    /**
     * Register or unregister a metrics recorder.
     * Pass `null` to detach. Used by MetricsPlugin to expose metric data to the RetryManager's getMetrics() method.
     */
    registerMetricsRecorder(recorder: MetricsRecorder | null): void;
    /**
     * Return active timer counts.
     * Used by MetricsPlugin to populate the timerHealth section of detailed metrics.
     */
    getTimerStats(): {
        activeTimers: number;
        activeRetryTimers: number;
    };
    /**
     * Release lifecycle tracking for a request config and mark its queue slot complete.
     * Used by TokenRefreshPlugin when a tracked request is intercepted for token refresh.
     */
    releaseRequestTracking(config: AxiosRequestConfig): void;
}
/**
 * AxiosRetryer plugin interface that can be attached with {@link RetryManager.use} and removed with {@link RetryManager.unuse}
 * */
interface RetryPlugin<TPluginEvents extends object = Record<never, never>> {
    /**
     * Plugin name. Should be unique
     * */
    name: string;
    /**
     * Plugin version (e.g. 1.0.0)
     * */
    version: string;
    /**
     * Phantom covariant marker for TypeScript to infer `TPluginEvents` at call sites
     * such as `manager.use(plugin)`. Never set this at runtime; implementations may
     * simply omit it (it is always `undefined`).
     * */
    readonly _events?: Readonly<TPluginEvents>;
    /**
     * Called when the plugin is attached and initialized.
     * @param context Plugin context providing manager capabilities and plugin-only wiring hooks.
     * */
    initialize: (context: PluginContext<TPluginEvents>) => void;
    /**
     * Called before the plugin is removed.
     * @param context Plugin context providing manager capabilities and plugin-only wiring hooks.
     * */
    onBeforeDestroyed?: (context: PluginContext<TPluginEvents>) => void;
}

interface MetricsPluginEvents {
    onMetricsUpdated?: (metrics: AxiosRetryerDetailedMetrics) => void;
}

/**
 * Plugin that enables detailed metrics collection for the RetryManager.
 *
 * Without this plugin, `getMetrics()` returns empty/zero metrics.
 * Install this plugin to track request counts, retry distributions,
 * error types, queue wait times, and priority breakdowns.
 *
 * @example
 * ```typescript
 * import { MetricsPlugin } from 'axios-retryer/plugins/MetricsPlugin';
 *
 * const metricsPlugin = new MetricsPlugin();
 * manager.use(metricsPlugin);
 *
 * // Later: read collected metrics
 * const metrics = manager.getMetrics();
 * ```
 */
declare class MetricsPlugin implements RetryPlugin<MetricsPluginEvents> {
    name: string;
    version: string;
    readonly _events?: Readonly<MetricsPluginEvents>;
    private context;
    private metrics;
    private collector;
    private readonly recorder;
    private readonly onRequestQueuedListener;
    private readonly onRequestDispatchedListener;
    private readonly onRequestCancelledListener;
    private readonly beforeRetryListener;
    private readonly afterRetryListener;
    private readonly onRetryScheduledListener;
    private readonly onFailureListener;
    private readonly onBlockingRequestFailedListener;
    private readonly onRequestSucceededListener;
    constructor();
    initialize(context: PluginContext<MetricsPluginEvents>): void;
    onBeforeDestroyed(context: PluginContext<MetricsPluginEvents>): void;
    getMetrics(): AxiosRetryerDetailedMetrics;
    resetMetrics(): void;
    private emitMetricsUpdated;
}

declare class MetricsCollector implements MetricsRecorder {
    private readonly getMetricsState;
    private queueWaitHistory;
    private retryDelayHistory;
    constructor(getMetricsState: () => AxiosRetryerMetrics);
    recordRequestStart(priority: AxiosRetryerRequestPriority): void;
    recordQueueWait(durationMs: number): void;
    recordRetrySuccess(priority: AxiosRetryerRequestPriority): void;
    recordRetryFailure(priority: AxiosRetryerRequestPriority, error: AxiosError): void;
    recordRetryAttempt(attempt: number, priority: AxiosRetryerRequestPriority): void;
    recordRetryDelay(durationMs: number): void;
    reset(): void;
    recordCancellation(includeErrorType?: boolean): void;
    recordTerminalFailure(isCritical: boolean): void;
    buildDetailedMetrics(timerStats: {
        activeTimers: number;
        activeRetryTimers: number;
    }): AxiosRetryerDetailedMetrics;
    private getPriorityMetrics;
    private recordDuration;
    private pruneDurationHistory;
    private getWindowAverage;
}

/**
 * Creates a MetricsPlugin instance.
 * Functional alternative to using the `new MetricsPlugin()` constructor.
 *
 * @returns A configured MetricsPlugin instance
 *
 * @example
 * ```typescript
 * import { createMetricsPlugin } from 'axios-retryer/plugins/MetricsPlugin';
 *
 * const metricsPlugin = createMetricsPlugin();
 * manager.use(metricsPlugin);
 * ```
 */
declare function createMetricsPlugin(): MetricsPlugin;

export { MetricsCollector, MetricsPlugin, createMetricsPlugin };
export type { MetricsPluginEvents, MetricsRecorder };