add mod loading for jars included in plugins

api/src/main/java/space/vectrix/ignite/Blackboard.java

@@ -48,6 +48,7 @@ public final class Blackboard {
   public static final BlackboardMap.@NotNull Key<Path> GAME_JAR = key("ignite.jar", Path.class, Paths.get("./server.jar"));
   public static final BlackboardMap.@NotNull Key<String> GAME_TARGET = key("ignite.target", String.class, "org.bukkit.craftbukkit.Main");
   public static final BlackboardMap.@NotNull Key<Path> GAME_LIBRARIES = key("ignite.libraries", Path.class, Paths.get("./libraries"));
+  public static final BlackboardMap.@NotNull Key<Path> PLUGINS_DIRECTORY = key("ignite.plugins", Path.class, Paths.get("./plugins"));
   public static final BlackboardMap.@NotNull Key<Path> MODS_DIRECTORY = key("ignite.mods", Path.class, Paths.get("./mods"));
   // formatting:on
 

launcher/src/main/java/space/vectrix/ignite/IgniteBootstrap.java

@@ -102,6 +102,7 @@ private void run(final String@NotNull [] args) {
     Blackboard.compute(Blackboard.GAME_JAR, () -> Paths.get(System.getProperty(Blackboard.GAME_JAR.name())));
     Blackboard.compute(Blackboard.GAME_TARGET, () -> System.getProperty(Blackboard.GAME_TARGET.name()));
     Blackboard.compute(Blackboard.GAME_LIBRARIES, () -> Paths.get(System.getProperty(Blackboard.GAME_LIBRARIES.name())));
+    Blackboard.compute(Blackboard.PLUGINS_DIRECTORY, () -> Paths.get(System.getProperty(Blackboard.PLUGINS_DIRECTORY.name())));
     Blackboard.compute(Blackboard.MODS_DIRECTORY, () -> Paths.get(System.getProperty(Blackboard.MODS_DIRECTORY.name())));
 
     // Get a suitable game locator and game provider.

launcher/src/main/java/space/vectrix/ignite/mod/ModResourceLocator.java

@@ -25,15 +25,20 @@
 package space.vectrix.ignite.mod;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
 import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.util.ArrayList;
+import java.util.Enumeration;
 import java.util.List;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.stream.Collectors;
 import org.jetbrains.annotations.NotNull;
+import org.tinylog.Logger;
 import space.vectrix.ignite.Blackboard;
 import space.vectrix.ignite.IgniteBootstrap;
 import space.vectrix.ignite.util.IgniteConstants;
@@ -56,7 +61,14 @@ public final class ModResourceLocator {
     resources.add(this.createLauncherResource());
     resources.add(this.createGameResource());
 
-    // Retrieve the mods from the mods directory.
+    // Retrieve the mods from the mods directory, or inside plugins.
+    this.scanModsDirectory(resources);
+    this.scanPluginsDirectory(resources);
+
+    return resources;
+  }
+
+  private void scanModsDirectory(final @NotNull List<ModResourceImpl> resources) {
     final Path modDirectory = Blackboard.raw(Blackboard.MODS_DIRECTORY);
     try {
       if(modDirectory == null) {
@@ -69,23 +81,58 @@ public final class ModResourceLocator {
       }
 
       //noinspection resource
-      for(final Path childDirectory : Files.walk(modDirectory).collect(Collectors.toList())) {
+      for(final Path childDirectory : Files.walk(modDirectory, 1).collect(Collectors.toList())) {
+        if(!Files.isRegularFile(childDirectory) || !childDirectory.getFileName().toString().endsWith(".jar")) {
+          continue;
+        }
+
+        this.tryLoadMod(childDirectory, resources);
+      }
+    } catch(final Throwable throwable) {
+      throw new RuntimeException("Failed to walk the mods directory!", throwable);
+    }
+  }
+
+  private void scanPluginsDirectory(final @NotNull List<ModResourceImpl> resources) {
+    final Path modDirectory = Blackboard.raw(Blackboard.MODS_DIRECTORY);
+    final Path pluginDirectory = Blackboard.raw(Blackboard.PLUGINS_DIRECTORY);
+    try {
+      if(modDirectory == null
+        || pluginDirectory == null
+        || Files.notExists(pluginDirectory)
+        || Files.notExists(modDirectory)) {
+        return;
+      }
+
+      final Path destinationPath = modDirectory.resolve("_plugins");
+
+      //noinspection resource
+      for(final Path childDirectory : Files.walk(pluginDirectory, 1).collect(Collectors.toList())) {
         if(!Files.isRegularFile(childDirectory) || !childDirectory.getFileName().toString().endsWith(".jar")) {
           continue;
         }
 
         try(final JarFile jarFile = new JarFile(childDirectory.toFile())) {
-          final JarEntry jarEntry = jarFile.getJarEntry(IgniteConstants.MOD_CONFIG);
-          if(jarEntry == null) continue;
+          final Enumeration<JarEntry> entries = jarFile.entries();
 
-          resources.add(new ModResourceImpl(ModResourceLocator.JAVA_LOCATOR, childDirectory, jarFile.getManifest()));
+          while (entries.hasMoreElements()) {
+            final JarEntry entry = entries.nextElement();
+
+            if(entry.getName().endsWith(".mixin.jar")) {
+              Logger.debug("Located mixin jar '{}' in plugin '{}'. Extracting to temporary mod directory...", entry.getName(), jarFile.getName());
+              final Path modPath = this.extractModFromPlugin(
+                childDirectory.getFileName().toString(),
+                jarFile, entry, destinationPath
+              );
+
+              this.tryLoadMod(modPath, resources);
+            }
+          }
         }
       }
     } catch(final Throwable throwable) {
-      throw new RuntimeException("Failed to walk the mods directory!", throwable);
+      throw new RuntimeException("Failed to walk the plugins directory!", throwable);
     }
-
-    return resources;
   }
 
   private @NotNull ModResourceImpl createLauncherResource() {
@@ -111,4 +158,39 @@ public final class ModResourceLocator {
       throw new RuntimeException("Failed to get game manifest!", exception);
     }
   }
+
+  private Path extractModFromPlugin(final @NotNull String jarName,
+                                    final @NotNull JarFile jarFile,
+                                    final @NotNull JarEntry jarEntry,
+                                    final @NotNull Path destinationDirectory) {
+    final String baseJarName = jarName.substring(0, jarName.length() - ".jar".length());
+    final Path outputPath = destinationDirectory.resolve(baseJarName).resolve(jarEntry.getName());
+
+    if(Files.notExists(outputPath)) {
+      //noinspection ResultOfMethodCallIgnored
+      outputPath.toFile().mkdirs();
+    }
+
+    try {
+      try(InputStream inputStream = jarFile.getInputStream(jarEntry)) {
+        Files.copy(inputStream, outputPath, StandardCopyOption.REPLACE_EXISTING);
+      }
+    } catch (final IOException exception) {
+      throw new RuntimeException(exception);
+    }
+
+    return outputPath;
+  }
+
+  private void tryLoadMod(final @NotNull Path modPath, final @NotNull List<ModResourceImpl> resources) throws IOException {
+    try(final JarFile jarFile = new JarFile(modPath.toFile())) {
+      final JarEntry jarEntry = jarFile.getJarEntry(IgniteConstants.MOD_CONFIG);
+      if(jarEntry == null) {
+        Logger.warn("'{}' was in the mods directory, but could not load due to a missing '{}'.", jarFile.getName(), IgniteConstants.MOD_CONFIG);
+        return;
+      }
+
+      resources.add(new ModResourceImpl(ModResourceLocator.JAVA_LOCATOR, modPath, jarFile.getManifest()));
+    }
+  }
 }

launcher/src/main/java/space/vectrix/ignite/mod/ModsImpl.java

@@ -111,6 +111,11 @@ public boolean locateResources() {
       final ModResource resource = container.resource();
 
       if(!resource.locator().equals(ModResourceLocator.LAUNCHER_LOCATOR) && !resource.locator().equals(ModResourceLocator.GAME_LOCATOR)) {
+        if(this.containers.containsKey(container.id())) {
+          Logger.error("Mod container with the identifier '{}' already exists!", container.id());
+          continue;
+        }
+
         try {
           IgniteAgent.addJar(container.resource().path());
         } catch(final IOException exception) {