typecheck2

package example

import com.fasterxml.jackson.databind.JsonNode
import com.fasterxml.jackson.databind.ObjectMapper

import java.util.stream.Stream
import java.util.stream.StreamSupport

import org.w3c.dom.Document
import org.w3c.dom.Element
import org.w3c.dom.Node
import org.w3c.dom.NodeList
import javax.xml.parsers.DocumentBuilderFactory
import java.io.ByteArrayInputStream
import java.io.InputStream
import java.io.StringReader

data class Event(val id: Int)

val stringToEvent: (String) -> Event = { s -> Event(s.toInt()) }
val dummyToEvent: (Document) -> Event = { _ -> Event(1) }
val jsonToEvent: (JsonNode) -> Event = { j -> Event(j.get("id").asInt()) }

fun elementGen(opt: String): Any {
    return when(opt) {
        "string" -> "1"
        "json" -> {
            val mapper = ObjectMapper()
            mapper.readTree("{\"id\": 1 }")
        }
        "xml" -> {
            val xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<id>1</id>"
            val src = ByteArrayInputStream(xml.toByteArray())
            DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(src)
        }
        else -> throw RuntimeException("Option not supported")
    }
}

fun main(args : Array<String>) {

    val parser = when (args[0]) {
        "string" -> stringToEvent   // I get
                                    // /home/gbenincasa/develop/ihmc/higherOrderFun/src/main/kotlin/Example.kt: (49, 11): Out-projected type 'Function1<*, Event>' prohibits the use of 'public abstract operator fun invoke(p1: P1): R defined in kotlin.Function1'
                                    // However tt builds if I remove this line
        "json" -> jsonToEvent
        "xml" -> dummyToEvent
        else -> throw RuntimeException("Option not supported")
    }

    print(parser(elementGen(args[0])))
}