karl-marx/src/main/scala/org/congressodeiradicali/karlmarx/JARPluginLoader.scala

/*
    This file is part of karl-marx.

    karl-marx is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    karl-marx is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with karl-marx.  If not, see <https://www.gnu.org/licenses/>.
 */

package org.congressodeiradicali.karlmarx

import java.io.File
import java.net.URL
import java.util.Properties
import java.util.jar.JarFile

import scala.reflect.internal.util.ScalaClassLoader.URLClassLoader
import scala.util.{Failure, Success, Try}

class JARPluginLoader extends PluginLoader {

  final val MANIFEST_LOCATION = "plugin-manifest.properties"
  // manifest structure is
  // package=some.package
  // class=PluginClassName


  override def loadFromFile(file: File): Try[Plugin] = {
    val jarFile = new JarFile(file)
    val manifestInputStream = jarFile.getInputStream(jarFile.getEntry(MANIFEST_LOCATION))

    val props = new Properties()
    props.load(manifestInputStream)

    manifestInputStream.close()

    val `package` = props.getProperty("package")
    val `class`   = props.getProperty("class")

    val fullClassName = s"${`package`}.${`class`}"

    try {
      val url = file.toURI.toURL
      val jarUrl = s"jar:${url.toString}!/"
      val urls = Seq[URL](new URL(jarUrl))
      val ucl = new URLClassLoader(urls, null)

      // TODO deprecation
      val plugin = Class.forName(fullClassName, true, ucl).newInstance().asInstanceOf[Plugin]
      Success(plugin)
    } catch {
      case e: Throwable => Failure(e)
    }

  }

}