Decompose - Global navigation events with channel

StackNavigator.kt

internal class StackComponent(context: ComponentContext): Component {

    private val results = Channel<NavResult<*>>(Channel.CONFLATED)

    inline fun <reified R> sendResult(result: R) {
        val config = stack.active.configuration

        // or popWhile - bring desired page to the front
        navigation.pop { 
            results.trySend(NavResult(config, result))
        }
    }

    suspend inline fun <reified D : Configuration, reified R> subscribe(
        noinline onResult: suspend (result: R) -> Unit
    ) = results
        .receiveAsFlow()
        .filter { it.from is D && it.value is R }
        .collectLatest { onResult(it.value as R) }
}


internal data class NavResult<T>(
    val from: Component,
    val value: T
)

// lambda that takes a lambda as a parameter. First lambda subscribes, parameter lambda handles the result.
// i.e. curry the result function.
typealias ResultReceiver<T> = @Composable ((action: (T) -> Unit) -> Unit)

internal inline fun <reified D : Component, reified R> StackComponent.resultReceiver(): ResultReceiver<R> =
    @Composable {
        val block by rememberUpdatedState(it)
        LaunchedEffect(Unit) { subscribe<D, R>(block) }
    }

internal inline fun <reified R> StackComponent.resultNavigator(): (R) -> Unit =
    { sendResult<R>(it) }

// feature module
// declare the screen
@Composable
fun SelectItemScreen(
    component: ItemsComponent,
    onBack: (Uuid?) -> Unit,
    onAddItem: ResultReceiver<Uuid>,
)
    
// call the screen
SelectItemScreen(
    component = component,
    onBack = stackComponent.resultNavigator(),
    onCreateItem = stackComponent.resultReceiver<CreateItemConfig, _>(),
)