PathWatch.kt

/**
 * Creates a flow WatchEvent from a watchService
 */
fun WatchService.eventFlow() : Flow<List<WatchEvent<out Any>>> = flow {
    while (currentCoroutineContext().isActive) {
        coroutineScope {
            var key: WatchKey? = null
            val job = launch {
                runInterruptible(Dispatchers.IO) {
                    key = take()
                }
            }
            job.join()
            val currentKey = key
            if (currentKey != null) {
                emit(currentKey.pollEvents())
                currentKey.reset()
            }
        }
    }
}

/**
 * Returns a flow with the files inside a folder (with a given glob)
 */
fun Path.listDirectoryEntriesFlow(glob: String): Flow<List<Path>> {
    val watchService = watch()
    return watchService.eventFlow()
        .map { listDirectoryEntries(glob) }
        .onStart { emit(listDirectoryEntries(glob)) }
        .onCompletion { watchService.close() }
        .flowOn(Dispatchers.IO)
}

/**
 * Creates a new WatchService for any Event
 */
fun Path.watch() : WatchService {
    return watch(StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_MODIFY,
        StandardWatchEventKinds.OVERFLOW, StandardWatchEventKinds.ENTRY_DELETE)
}

/**
 * Creates a new watch service
 */
fun Path.watch(vararg events: WatchEvent.Kind<out Any>) = fileSystem.newWatchService()!!.apply { register(this, events)