package org.openrndr.extra.olive

import java.io.InputStream
import java.io.Reader
import javax.script.ScriptEngineManager

internal class LoadException(message: String? = null, cause: Throwable? = null) : RuntimeException(message, cause)

internal class KtsObjectLoader(classLoader: ClassLoader? = Thread.currentThread().contextClassLoader) {

    private val engine = ScriptEngineManager(classLoader).getEngineByExtension("kts")

    init {
        if (engine == null) {
            throw RuntimeException("could not create scripting engine")
        }
    }

    inline fun <R> safeEval(noinline evaluation: () -> R?) = try {
        evaluation()
    } catch (e: Exception) {
        throw LoadException("Cannot load script", e)
    }

    inline fun <reified T> Any?.castOrError() = takeIf { it is T }?.let { it as T }
        ?: throw IllegalArgumentException("Cannot cast $this to expected type ${T::class}")

    inline fun <reified T> load(script: String): T = safeEval { engine.eval(script) }.castOrError()

    inline fun <reified T> load(reader: Reader): T = safeEval { engine.eval(reader) }.castOrError()

    inline fun <reified T> load(inputStream: InputStream): T = load(inputStream.reader())

    inline fun <reified T> loadAll(vararg inputStream: InputStream): List<T> = inputStream.map(::load)
}