import { PolyProviderError } from "./types";
import { sleep } from "@/lib/utils";

export interface RetryOptions {
  maxAttempts?: number;
  baseDelayMs?: number;
  maxDelayMs?: number;
  signal?: AbortSignal;
  onRetry?: (attempt: number, error: PolyProviderError, delayMs: number) => void;
}

/**
 * Exponential backoff with full jitter. Only retries errors flagged `retryable`
 * (429 / 5xx / network / timeout). Auth, invalid request and unsupported-parameter
 * errors are never retried. Respects Retry-After when present.
 */
export async function withRetry<T>(fn: (attempt: number) => Promise<T>, normalize: (e: unknown) => PolyProviderError, opts: RetryOptions = {}): Promise<T> {
  const max = opts.maxAttempts ?? 3;
  const base = opts.baseDelayMs ?? 500;
  const cap = opts.maxDelayMs ?? 8_000;
  let attempt = 0;
  while (true) {
    attempt++;
    try {
      return await fn(attempt);
    } catch (raw) {
      const err = normalize(raw);
      if (!err.retryable || attempt >= max || opts.signal?.aborted || err.code === "CANCELLED") throw err;
      const backoff = Math.min(cap, base * 2 ** (attempt - 1));
      const delay = err.retryAfterMs ?? Math.round(Math.random() * backoff);
      opts.onRetry?.(attempt, err, delay);
      await sleep(delay, opts.signal);
    }
  }
}