import { delay } from './delay';

export function exponentialBackoffDelay(currentFailureCount: number, minDelay: number, maxDelay: number, maxFailureCount: number) {
    let maxDelayRet = minDelay + ((maxDelay - minDelay) / maxFailureCount) * Math.max(currentFailureCount, maxFailureCount);
    return Math.round(Math.random() * maxDelayRet);
}

export async function backoff<T>(callback: () => Promise<T>,
    opts?: {
        onError?: (e: any, failuresCount: number) => void,
        minDelay?: number,
        maxDelay?: number,
        maxFailureCount?: number
    }): Promise<T> {
    let currentFailureCount = 0;
    const minDelay = opts && opts.minDelay !== undefined ? opts.minDelay : 250;
    const maxDelay = opts && opts.maxDelay !== undefined ? opts.maxDelay : 1000;
    const maxFailureCount = opts && opts.maxFailureCount !== undefined ? opts.maxFailureCount : 50;
    while (true) {
        try {
            return await callback();
        } catch (e) {
            if (currentFailureCount < maxFailureCount) {
                currentFailureCount++;
            }
            if (opts && opts.onError) {
                opts.onError(e, currentFailureCount);
            }
            let waitForRequest = exponentialBackoffDelay(currentFailureCount, minDelay, maxDelay, maxFailureCount);
            await delay(waitForRequest);
        }
    }
}