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 { LoadBalancerConfig } from '../../types/configs.ts';
/**
 * LoadBalancer component: distributes incoming work units across downstream
 * components using a configurable strategy (round-robin, random, least-connections).
 *
 * Validates: Requirements 8.1, 8.2, 8.3
 */
export declare class LoadBalancer implements SimComponent {
    readonly id: string;
    readonly type = ComponentType.LOAD_BALANCER;
    readonly config: ComponentConfig;
    private lbConfig;
    private rrIndex;
    private connectionCounts;
    private failedDownstream;
    private errorRate;
    private workUnitToDownstream;
    private pendingOrigins;
    private totalForwarded;
    private totalFailed;
    constructor(id: string, lbConfig: LoadBalancerConfig);
    /**
     * Process an incoming event.
     *
     * 'arrival': Select a downstream component based on strategy, forward the work unit.
     * 'departure': Forward response back to origin, decrement connection count.
     */
    handleEvent(event: SimEvent, context: SimContext): SimEvent[];
    /**
     * Handle an arrival: select a downstream and forward the work unit.
     * Excludes failed downstream components (Req 8.2).
     * Returns failure if all downstream are failed (Req 8.3).
     */
    private handleArrival;
    /**
     * Handle a departure from downstream: forward response back to origin,
     * decrement connection count for least-connections tracking.
     */
    private handleDeparture;
    /**
     * Select a downstream component based on the configured strategy (Req 8.1).
     */
    private selectDownstream;
    /** Round-robin: cycle through available downstream in order */
    private selectRoundRobin;
    /** Random: use context.random() to pick a random downstream */
    private selectRandom;
    /** Least-connections: pick the downstream with the fewest active connections */
    private selectLeastConnections;
    setErrorRate(rate: number): void;
    /** Mark a downstream component as failed (Req 8.2) */
    setDownstreamFailed(componentId: string, failed: boolean): void;
    /** Return current metrics snapshot */
    getMetrics(): ComponentMetrics;
    /** Reset component to initial state */
    reset(): void;
}
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