import type { RedisReconnectStrategy } from "../options/options.js";

/**
 * Compute the next backoff delay in milliseconds for the configured
 * exponential reconnect strategy. Capped at `maxDelayMs`. Pure function,
 * trivially deterministic — the broker drives an external timer.
 */
export function nextReconnectDelayMs(
    attempt: number,
    strategy: RedisReconnectStrategy
): number {
    if (attempt < 0) return strategy.initialDelayMs;
    const raw = strategy.initialDelayMs * strategy.multiplier ** attempt;
    return Math.min(raw, strategy.maxDelayMs);
}

/**
 * Decide whether the reconnect loop should give up. Once `attempt` reaches
 * the configured maximum, the broker raises `WS_BROKER_REDIS.RECONNECT_FAILED`
 * and surfaces `down` health.
 */
export function shouldGiveUp(
    attempt: number,
    strategy: RedisReconnectStrategy
): boolean {
    return attempt >= strategy.maxAttempts;
}