/**
 * Create a new AbortController that also aborts the given {@link signal} is aborted.
 *
 * This can be used for a operation that is controlled by an {@link AbortSignal} from its caller but
 * that also needs to create its own {@link AbortController} to control its own operations.
 */
export function dependentAbortController(signal?: AbortSignal): AbortController {
    const controller = new AbortController()

    if (signal?.aborted) {
        controller.abort()
    } else if (signal) {
        const abortHandler = (): void => {
            signal.removeEventListener('abort', abortHandler)
            controller.abort()
        }
        signal.addEventListener('abort', abortHandler)
    }

    return controller
}

/**
 * Helper function to add an `abort` event listener (and properly remove it).
 */
export function onAbort(signal: AbortSignal | undefined, handler: () => void): void {
    if (signal) {
        const handlerWithRemoval = (): void => {
            signal.removeEventListener('abort', handlerWithRemoval)
            handler()
        }
        signal.addEventListener('abort', handlerWithRemoval)
    }
}