set up dependency stuff

common/src/main/java/com/dfsek/terra/addons/loading/AddonClassLoader.java

@@ -51,7 +51,7 @@ public class AddonClassLoader extends URLClassLoader {
 
                 set.add((Class<? extends TerraAddon>) clazz);
             } catch(ClassNotFoundException e) {
-                e.printStackTrace();
+                throw new IllegalStateException(e); // this should literally never happen, if it does something is very wrong
             }
         }
 

common/src/main/java/com/dfsek/terra/addons/loading/AddonLoadException.java

@@ -1,6 +1,8 @@
 package com.dfsek.terra.addons.loading;
 
 public class AddonLoadException extends Exception {
+    private static final long serialVersionUID = -4949084729296580176L;
+
     public AddonLoadException(String message) {
         super(message);
     }

common/src/main/java/com/dfsek/terra/addons/loading/pre/AddonPool.java

@@ -0,0 +1,32 @@
+package com.dfsek.terra.addons.loading.pre;
+
+import com.dfsek.terra.addons.loading.AddonLoadException;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class AddonPool {
+    private final Map<String, PreLoadAddon> pool = new HashMap<>();
+
+    public void add(PreLoadAddon addon) throws AddonLoadException {
+        if(pool.containsKey(addon.getId()))
+            throw new AddonLoadException("Duplicate addon ID: " + addon.getId());
+        pool.put(addon.getId(), addon);
+    }
+
+    public PreLoadAddon get(String id) {
+        return pool.get(id);
+    }
+
+    public void buildAll() throws AddonLoadException {
+        for(PreLoadAddon value : pool.values()) {
+            value.rebuildDependencies(this, value, true);
+        }
+    }
+
+    public Set<PreLoadAddon> getAddons() {
+        return new HashSet<>(pool.values());
+    }
+}

common/src/main/java/com/dfsek/terra/addons/loading/pre/CircularDependencyException.java

@@ -0,0 +1,15 @@
+package com.dfsek.terra.addons.loading.pre;
+
+import com.dfsek.terra.addons.loading.AddonLoadException;
+
+public class CircularDependencyException extends AddonLoadException {
+    private static final long serialVersionUID = 7398510879124125121L;
+
+    public CircularDependencyException(String message) {
+        super(message);
+    }
+
+    public CircularDependencyException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

common/src/main/java/com/dfsek/terra/addons/loading/pre/DependencyMissingException.java

@@ -0,0 +1,15 @@
+package com.dfsek.terra.addons.loading.pre;
+
+import com.dfsek.terra.addons.loading.AddonLoadException;
+
+public class DependencyMissingException extends AddonLoadException {
+    private static final long serialVersionUID = -8419489102208521583L;
+
+    public DependencyMissingException(String message) {
+        super(message);
+    }
+
+    public DependencyMissingException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

common/src/main/java/com/dfsek/terra/addons/loading/pre/PreLoadAddon.java

@@ -0,0 +1,48 @@
+package com.dfsek.terra.addons.loading.pre;
+
+import com.dfsek.terra.addons.addon.TerraAddon;
+import com.dfsek.terra.addons.annotations.Addon;
+import com.dfsek.terra.addons.annotations.Depends;
+import com.dfsek.terra.addons.loading.AddonLoadException;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class PreLoadAddon {
+    private final List<PreLoadAddon> depends = new ArrayList<>();
+    private final Class<? extends TerraAddon> addonClass;
+    private final String id;
+    private final String[] dependencies;
+
+    public PreLoadAddon(Class<? extends TerraAddon> addonClass) {
+        this.addonClass = addonClass;
+        this.id = addonClass.getAnnotation(Addon.class).value();
+        Depends depends = addonClass.getAnnotation(Depends.class);
+        this.dependencies = depends == null ? new String[] {} : depends.value();
+    }
+
+    public List<PreLoadAddon> getDepends() {
+        return depends;
+    }
+
+    public void rebuildDependencies(AddonPool pool, PreLoadAddon origin, boolean levelG1) throws AddonLoadException {
+        if(this.equals(origin) && !levelG1)
+            throw new CircularDependencyException("Detected circular dependency in addon \"" + id + "\", dependencies: " + Arrays.toString(dependencies));
+
+        for(String dependency : dependencies) {
+            PreLoadAddon preLoadAddon = pool.get(dependency);
+            if(preLoadAddon == null) throw new DependencyMissingException("Dependency " + dependency + " was not found.");
+            depends.add(preLoadAddon);
+            preLoadAddon.rebuildDependencies(pool, origin, false);
+        }
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public Class<? extends TerraAddon> getAddonClass() {
+        return addonClass;
+    }
+}

common/src/main/java/com/dfsek/terra/registry/AddonRegistry.java

@@ -1,19 +1,16 @@
 package com.dfsek.terra.registry;
 
 import com.dfsek.terra.addons.addon.TerraAddon;
-import com.dfsek.terra.addons.annotations.Addon;
-import com.dfsek.terra.addons.annotations.Depends;
 import com.dfsek.terra.addons.loading.AddonClassLoader;
 import com.dfsek.terra.addons.loading.AddonLoadException;
+import com.dfsek.terra.addons.loading.pre.AddonPool;
+import com.dfsek.terra.addons.loading.pre.PreLoadAddon;
 import com.dfsek.terra.api.core.TerraPlugin;
 
 import java.io.File;
 import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Set;
 
 public class AddonRegistry extends TerraRegistry<TerraAddon> {
     private final TerraPlugin main;
@@ -30,67 +27,61 @@ public class AddonRegistry extends TerraRegistry<TerraAddon> {
 
     @Override
     public boolean add(String name, TerraAddon addon) {
+        if(contains(name)) throw new IllegalArgumentException("Addon " + name + " is already registered.");
         addon.initialize();
         main.getLogger().info("Loaded addon " + addon.getName() + " v" + addon.getVersion() + ", by " + addon.getAuthor());
         return super.add(name, addon);
     }
 
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+
     public boolean loadAll() {
         boolean valid = true;
         File addonsFolder = new File(main.getDataFolder(), "addons");
         addonsFolder.mkdirs();
 
-        Map<String, Class<? extends TerraAddon>> addonIDs = new HashMap<>();
+        AddonPool pool = new AddonPool();
 
         try {
             for(File jar : addonsFolder.listFiles(file -> file.getName().endsWith(".jar"))) {
-
                 main.getLogger().info("Loading Addon(s) from: " + jar.getName());
-
+                for(Class<? extends TerraAddon> addonClass : AddonClassLoader.fetchAddonClasses(jar)) {
-                Set<Class<? extends TerraAddon>> addonClasses = AddonClassLoader.fetchAddonClasses(jar);
+                    pool.add(new PreLoadAddon(addonClass));
-
-                for(Class<? extends TerraAddon> addonClass : addonClasses) {
-                    String id = addonClass.getAnnotation(Addon.class).value();
-                    if(addonIDs.containsKey(id))
-                        throw new AddonLoadException("Duplicate addon ID: " + id);
-                    addonIDs.put(id, addonClass);
                 }
             }
 
-            for(Map.Entry<String, Class<? extends TerraAddon>> entry : addonIDs.entrySet()) {
+            pool.buildAll();
-                Class<? extends TerraAddon> addonClass = entry.getValue();
-
-                Depends dependencies = addonClass.getAnnotation(Depends.class);
-
-                if(dependencies != null) {
-                    for(String dependency : dependencies.value()) {
-                        if(!addonIDs.containsKey(dependency))
-                            throw new AddonLoadException("Addon " + entry.getKey() + " specifies dependency " + dependency + ", which is not loaded. Please install " + dependency + " to use " + entry.getKey());
-                    }
-                }
 
+            for(PreLoadAddon addon : pool.getAddons()) {
+                Class<? extends TerraAddon> addonClass = addon.getAddonClass();
                 Constructor<? extends TerraAddon> constructor;
+
                 try {
                     constructor = addonClass.getConstructor();
                 } catch(NoSuchMethodException e) {
                     throw new AddonLoadException("Addon class has no valid constructor: " + addonClass.getCanonicalName(), e);
                 }
-                TerraAddon addon;
+                TerraAddon loadedAddon;
                 try {
-                    addon = constructor.newInstance();
+                    loadedAddon = constructor.newInstance();
                 } catch(InstantiationException | IllegalAccessException | InvocationTargetException e) {
-                    throw new AddonLoadException("Failed to instantiate addon: " + addonClass.getCanonicalName(), e);
+                    throw new AddonLoadException("Failed to load addon \" + " + addon.getId() + "\": ", e);
                 }
                 try {
-                    addChecked(addon.getName(), addon);
+                    addChecked(loadedAddon.getName(), loadedAddon);
                 } catch(IllegalArgumentException e) {
-                    throw new AddonLoadException("Duplicate addon ID; addon with ID " + addon.getName() + " is already loaded.");
+                    valid = false;
+                    main.getLogger().severe("Duplicate addon ID; addon with ID " + loadedAddon.getName() + " is already loaded.");
+                    main.getLogger().severe("Existing addon class: " + get(loadedAddon.getName()).getClass().getCanonicalName());
+                    main.getLogger().severe("Duplicate addon class: " + addonClass.getCanonicalName());
                 }
             }
-        } catch(IOException | AddonLoadException e) {
+        } catch(AddonLoadException | IOException e) {
             e.printStackTrace();
             valid = false;
-            main.getLogger().severe("Addons failed to load. Please ensure all addons are properly installed.");
         }
 
         return valid;

platforms/bukkit/src/main/java/com/dfsek/terra/bukkit/TerraBukkitPlugin.java

@@ -141,7 +141,12 @@ public class TerraBukkitPlugin extends JavaPlugin implements TerraPlugin {
         LangUtil.load(config.getLanguage(), this); // Load language.
         debugLogger.setDebug(isDebug());
 
-        addonRegistry.loadAll();
+        if(!addonRegistry.loadAll()) {
+            getLogger().severe("Failed to load addons. Please correct addon installations to continue.");
+            Bukkit.getPluginManager().disablePlugin(this);
+            return;
+        }
+
         registry.loadAll(this); // Load all config packs.
 
         PluginCommand c = Objects.requireNonNull(getCommand("terra"));

platforms/bukkit/src/main/java/com/dfsek/terra/bukkit/population/SerializationUtil.java

@@ -41,7 +41,7 @@ public final class SerializationUtil {
             try {
                 if(result.getName().contains(oldNameSpace)) {
                     String newClassName = result.getName().replace(oldNameSpace, newNameSpace);
-                    Class localClass = Class.forName(newClassName);
+                    Class<?> localClass = Class.forName(newClassName);
 
                     Field nameField = ObjectStreamClass.class.getDeclaredField("name");
                     nameField.setAccessible(true);