Jetpack's Android navigation made simple

ExampleRoute1.kt

package com.github.firezenk

import androidx.navigation.NavGraphBuilder
import androidx.navigation.NavHostController
import androidx.navigation.NavType
import androidx.navigation.compose.composable
import com.github.firezenk.Route
import com.github.firezenk.exampleRoute2

internal val exampleRoute1 = Route("ExampleRoute1", linkedMapOf(
    "arg1" to NavType.StringType
))

context(NavHostController)
internal fun NavGraphBuilder.exampleRoute1() {
    composable(
        route = exampleRoute1.asString,
        arguments = exampleRoute1.args
    ) {
        FadeInOutAnimation {
            Example1Screen(
                arg1 = it.arguments?.getString(exampleRoute1.args[0].name)!!,
                openExample2 = { arg1, arg2 -> exampleRoute2.navigate(arg1, arg2) },
                goBack = { this@NavHostController.popBackStack() }
            )
        }
    }
}

ExampleRoute2.kt

package com.github.firezenk

import androidx.navigation.NavGraphBuilder
import androidx.navigation.NavHostController
import androidx.navigation.NavType
import androidx.navigation.compose.composable
import com.github.firezenk.Route

internal val exampleRoute2 = Route("ExampleRoute2", linkedMapOf(
    "arg1" to NavType.StringType
    "arg2" to NavType.IntType
))

context(NavHostController)
internal fun NavGraphBuilder.exampleRoute2() {
    composable(
        route = exampleRoute2.asString,
        arguments = exampleRoute2.args
    ) {
        FadeInOutAnimation {
            Example2Screen(
                arg1 = it.arguments?.getString(exampleRoute2.args[0].name)!!,
                arg2 = it.arguments?.getInt(exampleRoute2.args[1].name)!!,
                goBack = { this@NavHostController.popBackStack() }
            )
        }
    }
}

Navigation.kt

package com.github.firezenk

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.runtime.Composable
import androidx.navigation.NavHostController
import androidx.navigation.compose.NavHost
import androidx.navigation.compose.rememberNavController
import com.github.firezenk.R
import com.github.firezenk.startRoute
import com.github.firezenk.exampleRoute1
import com.github.firezenk.exampleRoute2

class Navigation : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            val navController = rememberNavController()
            AppNavHost(navController) { finish() }
        }
    }
}

@Composable
fun AppNavHost(navController: NavHostController, goFinish: () -> Unit) {
    NavHost(
        navController = navController,
        startDestination = startRoute.asString,
    ) {
        with(navController) {
            exampleRoute1()
            exampleRoute2()
            // more routes here
        }
    }
}

RouteExt.kt

package com.github.firezenk

import androidx.navigation.NamedNavArgument
import androidx.navigation.NavHostController
import androidx.navigation.NavType
import androidx.navigation.navArgument

class Route(root: String, argsPairs: LinkedHashMap<String, NavType<*>> = linkedMapOf()) {

    val args: MutableList<NamedNavArgument> = mutableListOf<NamedNavArgument>().apply {
        addAll(argsPairs.map { (name, navType) ->
            navArgument(name) { type = navType }
        })
    }

    val asString: String = if (args.isEmpty()) root else {
        val argsString = args.joinToString(separator = "/") { "{${it.name}}" }
        "$root/$argsString"
    }

    /**
     * Navigate to the route, passing the arguments as ordered varargs
     * @param args: The arguments to be passed to the route
     */
    context(NavHostController)
    fun navigate(vararg args: Any) {
        val route = asString.split("/").mapIndexed { index, token ->
            if (token.startsWith("{") && token.endsWith("}")) args[index - 1] else token
        }.joinToString("/")
        this@NavHostController.navigate(route)
    }
}

StartRoute.kt

package com.github.firezenk

import androidx.navigation.NavGraphBuilder
import androidx.navigation.NavHostController
import androidx.navigation.compose.composable
import com.github.firezenk.Route
import com.github.firezenk.exampleRoute1
import com.github.firezenk.exampleRoute2

internal val startRoute = Route("Start")

context(NavHostController)
internal fun NavGraphBuilder.startRoute() {
    composable(startRoute.asString) {
        StartScreen(
            openExample1 = { exampleRoute1.navigate(it) },
            openExample2 = { arg1, arg2 -> exampleRoute2.navigate(arg1, arg2) },
            goBack = { this@NavHostController.popBackStack() }
        )
    }
}