import type { SimEvent } from '../../types/events.ts';
import { ComponentType } from '../../types/components.ts';
import type { SimComponent, SimContext, ComponentConfig, ComponentMetrics } from '../../types/components.ts';
import type { QueueConfig } from '../../types/configs.ts';
/**
 * Queue component: buffers work units in FIFO order with configurable
 * capacity limits and load-shedding behavior.
 *
 * Validates: Requirements 5.1, 5.2, 5.3, 5.4, 5.5
 */
export declare class Queue implements SimComponent {
    readonly id: string;
    readonly type = ComponentType.QUEUE;
    readonly config: ComponentConfig;
    private queueConfig;
    private buffer;
    private bufferHead;
    private inFlightCount;
    private pendingOrigins;
    private totalEnqueued;
    private totalDequeued;
    private totalRejected;
    constructor(id: string, queueConfig: QueueConfig);
    /**
     * Process an incoming event.
     *
     * 'arrival': Check capacity/load-shedding → reject or enqueue.
     * 'departure': Forward response to origin, dequeue next and send downstream.
     */
    handleEvent(event: SimEvent, context: SimContext): SimEvent[];
    /**
     * Handle an arrival: reject if full or load-shedding threshold exceeded,
     * otherwise enqueue and forward to downstream if idle.
     */
    /** Logical length of the FIFO buffer (excludes already-dequeued head elements) */
    private get bufferLength();
    private handleArrival;
    /**
     * Handle a departure from downstream: forward response to origin,
     * then dequeue and send next item downstream.
     */
    private handleDeparture;
    /**
     * Dequeue the next item (FIFO: front, LIFO: back) and send it as an arrival
     * to the downstream component.
     * Respects maxConcurrency: won't send if already at the in-flight limit.
     */
    private sendNextToDownstream;
    /**
     * Record the current queue depth metric (Req 5.5).
     */
    private recordQueueDepth;
    /** Return current metrics snapshot */
    getMetrics(): ComponentMetrics;
    /** Reset component to initial state */
    reset(): void;
}
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