HomeList.kt

@Composable
fun HomeList(taskViewModel: ListViewModel = viewModel()) {
    val coroutineScope = rememberCoroutineScope()
    val scaffoldState = rememberScaffoldState()

    val onShowSnackbar: (Task) -> Unit = { task ->
        coroutineScope.launch {
            val snackbarResult = scaffoldState.snackbarHostState.showSnackbar(
                message = "${task.title} completed",
                actionLabel = "Undo"
            )
            when (snackbarResult) {
                SnackbarResult.Dismissed -> Timber.d("Snackbar dismissed")
                SnackbarResult.ActionPerformed -> taskViewModel.onCheckedChange(task)
            }
        }
    }

    Scaffold(
        scaffoldState = scaffoldState,
        topBar = { HomeTopBar() }
    ) {
        val list by remember(taskViewModel) { taskViewModel.taskList }.collectAsState()

        LazyColumn {
            items(
                items = list,
                key = { it.id },
                itemContent = { task ->
                    ListItem(
                        task = task,
                        onCheckedChange = { task ->
                            taskViewModel.onCheckedChange(task)
                            onShowSnackbar(task)
                        }
                    )
                }
            )
        }
    }
}

@Composable
private fun ListItem(task: Task, onCheckedChange: (Task) -> Unit) {
    Row(
        modifier = Modifier
            .fillMaxWidth()
            .height(64.dp)
            .padding(8.dp),
        verticalAlignment = Alignment.CenterVertically
    ) {
        Checkbox(
            checked = task.isCompleted,
            onCheckedChange = { onCheckedChange(task) }
        )
        Spacer(Modifier.width(8.dp))
        Text(
            text = task.title,
            style = MaterialTheme.typography.body1,
            overflow = TextOverflow.Ellipsis,
            maxLines = 1
        )
    }
}

@Composable
private fun HomeTopBar() {
    TopAppBar {
        Box(modifier = Modifier.fillMaxSize()) {
            Text(
                modifier = Modifier.align(Alignment.Center),
                style = MaterialTheme.typography.h5,
                text = "My tasks"
            )
        }
    }
}

data class Task(val id: Long, val title: String, var isCompleted: Boolean)

class ListViewModel : ViewModel() {

    private val list = mutableListOf(
        Task(1L, "Buy milk", false),
        Task(2L, "Watch 'Call Me By Your Name'", false),
        Task(3L, "Listen 'Local Natives'", false),
        Task(4L, "Study about 'fakes instead of mocks'", false),
        Task(5L, "Congratulate Rafael", false),
        Task(6L, "Watch Kotlin YouTube Channel", false)
    )

    private val _taskList: MutableStateFlow<List<Task>> = MutableStateFlow(list)

    val taskList: StateFlow<List<Task>>
        get() = _taskList.stateIn(viewModelScope, SharingStarted.WhileSubscribed(), listOf())

    fun onCheckedChange(task: Task) {
        list.find { it.id == task.id }?.isCompleted = task.isCompleted.not()
        _taskList.value = list.filter { it.isCompleted.not() }
    }
}