Add coursier to resolve and fetch dependencies for plugins

build.sbt

@@ -89,6 +89,9 @@ libraryDependencies += "com.fazecast" % "jSerialComm" % "[2.0.0,3.0.0)"
 // Socket.io
 libraryDependencies += "io.socket" % "socket.io-client" % "1.0.0"
 
+// Coursier
+libraryDependencies += "io.get-coursier" %% "coursier" % "2.0.0-RC3-2"
+
 // ---------------------------------------------------------------------------------------------------------------------
 // PLUGIN FRAMEWORK DEFINITIONS
 // ---------------------------------------------------------------------------------------------------------------------

src/main/scala/org/codeoverflow/chatoverflow/framework/PluginType.scala

@@ -1,25 +1,31 @@
 package org.codeoverflow.chatoverflow.framework
 
+import java.io.File
+
 import org.codeoverflow.chatoverflow.WithLogger
 import org.codeoverflow.chatoverflow.api.APIVersion
 import org.codeoverflow.chatoverflow.api.plugin.{Plugin, PluginManager}
 import org.codeoverflow.chatoverflow.framework.PluginCompatibilityState.PluginCompatibilityState
 
+import scala.concurrent.Future
+
 /**
-  * A plugin type is a container for all information about a plugin, everything in the 'plugin.xml' and the actual class.
-  * The plugins functionality and meta information can be accessed through this interface.
-  *
-  * @param name            the name of the plugin, used for identifying
-  * @param author          the author of the plugin, used for identifying
-  * @param version         the version of the plugin
-  * @param majorAPIVersion the major api version, with which the plugin was developed
-  * @param minorAPIVersion the minor api version, with which the plugin was developed
-  * @param pluginClass     the class of the plugin, used to create instances of this plugin.
-  *                        Needs to have a constructor with the signature of one PluginManager,
-  *                        otherwise instances can't be created from it.
-  */
+ * A plugin type is a container for all information about a plugin, everything in the 'plugin.xml' and the actual class.
+ * The plugins functionality and meta information can be accessed through this interface.
+ *
+ * @param name               the name of the plugin, used for identifying
+ * @param author             the author of the plugin, used for identifying
+ * @param version            the version of the plugin
+ * @param majorAPIVersion    the major api version, with which the plugin was developed
+ * @param minorAPIVersion    the minor api version, with which the plugin was developed
+ * @param pluginClass        the class of the plugin, used to create instances of this plugin.
+ *                           Needs to have a constructor with the signature of one PluginManager,
+ *                           otherwise instances can't be created from it.
+ * @param pluginDependencies A future that completes when all dependencies, that the plugin has, are available and
+ *                           that returns a seq of the required dependencies files in the local coursier cache.
+ */
 class PluginType(name: String, author: String, version: String, majorAPIVersion: Int, minorAPIVersion: Int,
-                 metadata: PluginMetadata, pluginClass: Class[_ <: Plugin]) extends WithLogger {
+                 metadata: PluginMetadata, pluginClass: Class[_ <: Plugin], pluginDependencies: Future[Seq[File]]) extends WithLogger {
 
   private var pluginVersionState = PluginCompatibilityState.Untested
 
@@ -126,4 +132,12 @@ class PluginType(name: String, author: String, version: String, majorAPIVersion:
     * @return the PluginMetadata instance of this plugin
     */
   def getMetadata: PluginMetadata = metadata
+
+  /**
+   * Returns the future that will result in a sequence of jar files that represents the dependencies
+   * of this plugin including all sub-dependencies.
+   *
+   * @return the dependency future
+   */
+  def getDependencyFuture: Future[Seq[File]] = pluginDependencies
 }

src/main/scala/org/codeoverflow/chatoverflow/framework/helper/CoursierUtils.scala

@@ -0,0 +1,58 @@
+package org.codeoverflow.chatoverflow.framework.helper
+
+import java.io.{File, InputStream}
+
+import coursier.Fetch
+import coursier.cache.{CacheLogger, FileCache}
+import coursier.core.Dependency
+import coursier.maven.PomParser
+import org.codeoverflow.chatoverflow.WithLogger
+
+import scala.io.Source
+
+/**
+ * A utility object containing some common code for use with Coursier.
+ */
+object CoursierUtils extends WithLogger {
+
+  private object CoursierLogger extends CacheLogger {
+    override def downloadedArtifact(url: String, success: Boolean): Unit = {
+      logger debug (if (success)
+        s"Successfully downloaded $url"
+      else
+        s"Failed to download $url")
+    }
+  }
+
+  private val cache = FileCache().noCredentials.withLogger(CoursierLogger)
+
+  /**
+   * Extracts all dependencies out of the provided pom. Throws an exception if the pom is invalid.
+   *
+   * @param is the InputStream from which the pom is read
+   * @return a seq of all found dependencies
+   */
+  def parsePom(is: InputStream): Seq[Dependency] = {
+    val pomFile = Source.fromInputStream(is)
+    val parser = coursier.core.compatibility.xmlParseSax(pomFile.mkString, new PomParser)
+
+    parser.project match {
+      case Right(deps) => deps.dependencies.map(_._2)
+      case Left(errorMsg) => throw new IllegalArgumentException(s"Pom couldn't be parsed: $errorMsg")
+    }
+  }
+
+  /**
+   * Resolves and fetches all passed dependencies and gives back a seq of all local files of these dependencies.
+   *
+   * @param dependencies all dependencies that you want to be fetched
+   * @return all local files for the passed dependencies
+   */
+  def fetchDependencies(dependencies: Seq[Dependency]): Seq[File] = {
+    // IntelliJ may warn you that a implicit is missing. This is one of the many bugs in IntelliJ, the code compiles fine.
+    Fetch()
+      .withCache(cache)
+      .addDependencies(dependencies: _*)
+      .run()
+  }
+}

src/main/scala/org/codeoverflow/chatoverflow/framework/helper/PluginClassLoader.scala

@@ -3,8 +3,11 @@ package org.codeoverflow.chatoverflow.framework.helper
 import java.net.{URL, URLClassLoader}
 
 /**
-  * This plugin class loader does only exist for plugin security policy checks.
-  *
-  * @param urls Takes an array of urls an creates a simple URLClassLoader with it
-  */
-class PluginClassLoader(urls: Array[URL]) extends URLClassLoader(urls)
+ * This plugin class loader does only exist for plugin security policy checks and
+ * to expose the addURL method to the package inorder to add all required dependencies after dependency resolution.
+ *
+ * @param urls Takes an array of urls an creates a simple URLClassLoader with it
+ */
+class PluginClassLoader(urls: Array[URL]) extends URLClassLoader(urls) {
+  private[helper] override def addURL(url: URL): Unit = super.addURL(url) // just exposes this method to be package-private instead of protected
+}

src/main/scala/org/codeoverflow/chatoverflow/framework/helper/PluginLoader.scala

@@ -10,6 +10,9 @@ import org.reflections.scanners.SubTypesScanner
 import org.reflections.util.ConfigurationBuilder
 
 import scala.collection.JavaConverters._
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.Future
+import scala.util.{Failure, Success}
 import scala.xml.{Node, SAXParseException, XML}
 
 /**
@@ -80,7 +83,8 @@ class PluginLoader(private val jar: File) extends WithLogger {
         majorString.toInt,
         minorString.toInt,
         PluginMetadata.fromXML(p),
-        cls
+        cls,
+        resolveDependencies(getString(p, "name"))
       ))
     } catch {
       // thrown by getString
@@ -144,4 +148,29 @@ class PluginLoader(private val jar: File) extends WithLogger {
         None
     }
   }
+
+  /**
+   * Creates a future which gets all dependencies from the included dependencies.pom, if existing, fetches them
+   * and adds their jar files to the classloader.
+   *
+   * @param pluginName the name of the plugin, only used for logging
+   * @return a future of all required jars for this plugin
+   */
+  private def resolveDependencies(pluginName: String): Future[Seq[File]] = {
+    val pomIs = classloader.getResourceAsStream("dependencies.pom")
+    if (pomIs == null) {
+      return Future(Seq())
+    }
+
+    Future(CoursierUtils.parsePom(pomIs))
+      .map(dependencies => dependencies.filter(_.module.name.value != "chatoverflow-api_2.12"))
+      .map(dependencies => CoursierUtils.fetchDependencies(dependencies))
+      .andThen {
+        case Success(jarFiles) =>
+          jarFiles.foreach(jar => classloader.addURL(jar.toURI.toURL))
+          logger info s"Dependencies for the plugin $pluginName successfully resolved and fetched if missing."
+        case Failure(exception) =>
+          logger warn s"Couldn't resolve and fetch dependencies for the plugin in $pluginName: $exception"
+      }
+  }
 }