Allow to run multiple actions on demand in Kotlin script

run.main.kts

import kotlin.Function0
import kotlin.Function1
import kotlin.Function2
import kotlin.Function3
import kotlin.Function4
import kotlin.Function5
import kotlin.system.exitProcess

fun run(
    vararg functions: Pair<String, Function<Any>>,
) {
    val requestedKey = args.firstOrNull()
    val function: Function<*> = requestedKey?.let { key ->
        functions.firstOrNull { it.first == key }?.second
    } ?: { ->
        val actions = functions.joinToString(", ") { it.first }
        "Could not find the function $requestedKey, available ones: $actions"
    }
    val failSafe: Function1<Int, String?> = { nArgs ->
        if (args.size != nArgs + 1) "Expected $nArgs arguments but received ${args.size - 1}" else null
    }
    when (function) {
        is Function0<*> ->
            failSafe(0) ?: function.invoke()
        is Function1<*, *> ->
            failSafe(1) ?: (function as Function1<String, *>)
                .invoke(args[1])
        is Function2<*, *, *> ->
            failSafe(2) ?: (function as Function2<String, String, *>)
                .invoke(args[1], args[2])
        is Function3<*, *, *, *> ->
            failSafe(3) ?: (function as Function3<String, String, String, *>)
                .invoke(args[1], args[2], args[3])
        is Function4<*, *, *, *, *> ->
            failSafe(4) ?: (function as Function4<String, String, String, String, *>)
                .invoke(args[1], args[2], args[3], args[4])
        is Function5<*, *, *, *, *, *> ->
            failSafe(5) ?: (function as Function5<String, String, String, String, String, *>)
                .invoke(args[1], args[2], args[3], args[4], args[5])
        else -> function
    }.let {
        when (it) {
            is Unit -> 0
            is Int -> it.toInt()
            is String -> 1.apply { println(it) }
            else -> 1.apply { println("Unsupported return: $it") }
        }
    }.also(::exitProcess)
}

fun function(arg1: String, arg2: String) {
    println("Called function with $arg1 - $arg2")
}

run(
    "help" to { println("Show help message") },
    "run" to { success: String ->
        println("Success: $success")
        val status = success.toBoolean()
        println("Run with status: $status")
        if (status) 0 else 1
    },
    "fun" to ::function,
)