import * as Errors from '../Errors.js'

/** @internal */
export function withTimeout<data>(
  fn: withTimeout.Fn<data>,
  options: withTimeout.Options,
): Promise<data> {
  const { errorInstance = new TimeoutError(), timeout, signal } = options
  // Fast path: no timeout, skip allocating Promise wrapper and AbortController.
  if (!(timeout > 0)) return fn({ signal: null })
  return new Promise((resolve, reject) => {
    void (async () => {
      let timeoutId: any
      let timedOut = false
      const controller = signal ? new AbortController() : null
      try {
        timeoutId = setTimeout(() => {
          timedOut = true
          if (controller) controller.abort()
          else reject(errorInstance)
        }, timeout)
        resolve(await fn({ signal: controller?.signal ?? null }))
      } catch (err) {
        if (timedOut || (err as Error)?.name === 'AbortError')
          reject(errorInstance)
        else reject(err)
      } finally {
        clearTimeout(timeoutId)
      }
    })()
  })
}

/** @internal */
export declare namespace withTimeout {
  type Fn<data> = ({
    signal,
  }: {
    signal: AbortController['signal'] | null
  }) => Promise<data>

  type Options = {
    // The error instance to throw when the timeout is reached.
    errorInstance?: Error | undefined
    // The timeout (in ms).
    timeout: number
    // Whether or not the timeout should use an abort signal.
    signal?: boolean | undefined
  }

  type ErrorType = TimeoutError | Errors.GlobalErrorType
}

/** @internal */

/**
 * Thrown when an operation times out.
 * @internal
 */
export class TimeoutError extends Errors.BaseError {
  override readonly name = 'Promise.TimeoutError'

  constructor() {
    super('Operation timed out.')
  }
}