import { ApiResponse } from '../../services/api/apisauce'

export const TRANSIENT_PROBLEMS = new Set([
  'NETWORK_ERROR',
  'TIMEOUT_ERROR',
  'CONNECTION_ERROR',
])
export const RETRY_BACKOFF_MS = [0, 800, 2400]

const sleep = (ms: number) =>
  ms <= 0 ? Promise.resolve() : new Promise<void>(r => setTimeout(r, ms))

// Retry transient network errors so a brief drop on a flaky mobile connection
// doesn't surface as a save failure. Non-transient errors return immediately.
// Exported for unit testing.
export async function retryTransient<T, U>(
  fn: () => Promise<ApiResponse<T, U>>,
): Promise<ApiResponse<T, U>> {
  let last: ApiResponse<T, U> | undefined
  for (let attempt = 0; attempt < RETRY_BACKOFF_MS.length; attempt++) {
    await sleep(RETRY_BACKOFF_MS[attempt])
    last = await fn()
    if (last.ok) return last
    if (!last.problem || !TRANSIENT_PROBLEMS.has(last.problem)) return last
  }
  return last as ApiResponse<T, U>
}