Simple routing system for Kotlin Multiplatform

Router.kt

import kotlinx.coroutines.flow.StateFlow
import kotlin.reflect.KClass

interface Router<T : Any> {
    // null if the backStack was cleared and the app was closed
    val currentDirection: StateFlow<T?>

    // will push the new direction
    // if pop is not null, it will pop all previous direction down to the latest appearance of the pop kclass
    fun push(
        direction: T,
        pop: KClass<out T>? = null,
        inclusive: Boolean = false
    )

    fun pushPopLast(direction: T)

    fun pop()
}

SimpleRouter.kt

import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlin.reflect.KClass

class SimpleRouter<T : Any>(initialRoot: T) : Router<T> {
    private val backStack: MutableList<T> = mutableListOf<T>(initialRoot)

    private val _currentDirection: MutableStateFlow<T?> = MutableStateFlow(initialRoot)
    override val currentDirection: StateFlow<T?> = _currentDirection

    override fun push(
        direction: T,
        pop: KClass<out T>?,
        inclusive: Boolean
    ) {
        if(pop != null) {
            val last = backStack.findLast { pop.isInstance(it) }
            if(last != null) {
                val index = backStack.lastIndexOf(last) - if(inclusive) 0 else 1

                for(i in backStack.size-1 downTo index) {
                    backStack.removeLast()
                }
            }
        }

        pushDirection(direction)
    }

    override fun pushPopLast(direction: T) {
        backStack.removeLast()

        pushDirection(direction)
    }

    private fun pushDirection(direction: T) {
        backStack.add(direction)
        _currentDirection.value = direction
    }

    override fun pop() {
        backStack.removeLastOrNull()
        if(backStack.isEmpty()) {
            _currentDirection.value = null
        }
    }
}