Merge "Don't scroll to live content on initial content load" into main

) {

    val coroutineScope = rememberCoroutineScope()

    val liveContentKeys = remember { mutableListOf<String>() }

    var communalContentPending by remember { mutableStateOf(true) }

    LaunchedEffect(communalContent) {

        // Do nothing until any communal content comes in

        if (communalContentPending && communalContent.isEmpty()) {

            return@LaunchedEffect

        }

        val prevLiveContentKeys = liveContentKeys.toList()

        val newLiveContentKeys = communalContent.filter { it.isLiveContent() }.map { it.key }

        liveContentKeys.clear()

        liveContentKeys.addAll(communalContent.filter { it.isLiveContent() }.map { it.key })

        liveContentKeys.addAll(newLiveContentKeys)

        // Find the first updated content

        // Do nothing on first communal content since we don't have a delta

        if (communalContentPending) {

            communalContentPending = false

            return@LaunchedEffect

        }

        // Do nothing if there is no new live content

        val indexOfFirstUpdatedContent =

            liveContentKeys.indexOfFirst { !prevLiveContentKeys.contains(it) }

            newLiveContentKeys.indexOfFirst { !prevLiveContentKeys.contains(it) }

        if (indexOfFirstUpdatedContent < 0) {

            return@LaunchedEffect

        }

        // Scroll if current position is behind the first updated content

        if (indexOfFirstUpdatedContent in 0 until gridState.firstVisibleItemIndex) {

        // Scroll if the live content is not visible

        val lastVisibleItemIndex = gridState.layoutInfo.visibleItemsInfo.lastOrNull()?.index

        if (lastVisibleItemIndex != null && indexOfFirstUpdatedContent > lastVisibleItemIndex) {

            // Launching with a scope to prevent the job from being canceled in the case of a

            // recomposition during scrolling

            coroutineScope.launch { gridState.animateScrollToItem(indexOfFirstUpdatedContent) }

        _firstVisibleItemOffset = firstVisibleItemOffset

    }

    fun resetScrollPosition() {

        _firstVisibleItemIndex = 0

        _firstVisibleItemOffset = 0

    }

    val firstVisibleItemIndex: Int

        get() = _firstVisibleItemIndex