Simplify and fix classloaders handling on script evaluation

#KT-37558 fixed

libraries/scripting/jvm-host/src/kotlin/script/experimental/jvmhost/CompiledScriptJarsCache.kt

@@ -8,11 +8,8 @@ package kotlin.script.experimental.jvmhost
 import java.io.File
 import java.net.URLClassLoader
 import java.util.jar.JarInputStream
-import kotlin.script.experimental.api.CompiledScript
-import kotlin.script.experimental.api.ScriptCompilationConfiguration
-import kotlin.script.experimental.api.SourceCode
-import kotlin.script.experimental.api.hostConfiguration
-import kotlin.script.experimental.host.ScriptingHostConfiguration
+import kotlin.reflect.KClass
+import kotlin.script.experimental.api.*
 import kotlin.script.experimental.jvm.CompiledJvmScriptsCache
 import kotlin.script.experimental.jvm.baseClassLoader
 import kotlin.script.experimental.jvm.impl.KJvmCompiledScript
@@ -33,12 +30,7 @@ open class CompiledScriptJarsCache(val scriptToFile: (SourceCode, ScriptCompilat
                 it.manifest.mainAttributes.getValue("Main-Class")
             }
         }
-        val classLoader = URLClassLoader(
-            arrayOf(file.toURI().toURL()),
-            scriptCompilationConfiguration[ScriptCompilationConfiguration.hostConfiguration]?.get(ScriptingHostConfiguration.jvm.baseClassLoader)
-        )
-
-        return createScriptFromClassLoader(className, classLoader)
+        return KJvmCompiledScriptLazilyLoadedFromClasspath(className, listOf(file))
     }
 
     override fun store(
@@ -54,4 +46,40 @@ open class CompiledScriptJarsCache(val scriptToFile: (SourceCode, ScriptCompilat
 
         jvmScript.saveToJar(file)
     }
-}
+}
+
+private class KJvmCompiledScriptLazilyLoadedFromClasspath(
+    private val scriptClassFQName: String,
+    private val classPath: List<File>
+) : CompiledScript {
+
+    private var loadedScript: KJvmCompiledScript? = null
+
+    fun getScriptOrError(): KJvmCompiledScript = loadedScript ?: throw RuntimeException("Compiled script is not loaded yet")
+
+    override suspend fun getClass(scriptEvaluationConfiguration: ScriptEvaluationConfiguration?): ResultWithDiagnostics<KClass<*>> {
+        if (loadedScript == null) {
+            val actualEvaluationConfiguration = scriptEvaluationConfiguration ?: ScriptEvaluationConfiguration()
+            val baseClassLoader = actualEvaluationConfiguration[ScriptEvaluationConfiguration.jvm.baseClassLoader]
+            val classLoader = URLClassLoader(
+                classPath.map { it.toURI().toURL() }.toTypedArray(),
+                baseClassLoader
+            )
+            loadedScript = createScriptFromClassLoader(scriptClassFQName, classLoader)
+        }
+        return getScriptOrError().getClass(scriptEvaluationConfiguration)
+    }
+
+    override val compilationConfiguration: ScriptCompilationConfiguration
+        get() = getScriptOrError().compilationConfiguration
+
+    override val sourceLocationId: String?
+        get() = getScriptOrError().sourceLocationId
+
+    override val otherScripts: List<CompiledScript>
+        get() = getScriptOrError().otherScripts
+
+    override val resultField: Pair<String, KotlinType>?
+        get() = getScriptOrError().resultField
+}
+

libraries/scripting/jvm-host/src/kotlin/script/experimental/jvmhost/jvmScriptSaving.kt

@@ -14,7 +14,6 @@ import java.util.jar.Manifest
 import kotlin.script.experimental.api.*
 import kotlin.script.experimental.jvm.JvmDependency
 import kotlin.script.experimental.jvm.impl.*
-import kotlin.script.experimental.jvm.util.scriptCompilationClasspathFromContext
 import kotlin.script.experimental.jvm.util.scriptCompilationClasspathFromContextOrNull
 
 // TODO: generate execution code (main)