refactor API

common/src/main/java/com/dfsek/terra/addon/AddonClassLoader.java

@@ -0,0 +1,60 @@
+package com.dfsek.terra.addon;
+
+import com.dfsek.terra.api.addons.TerraAddon;
+import com.dfsek.terra.api.addons.annotations.Addon;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+public class AddonClassLoader extends URLClassLoader {
+    static {
+        ClassLoader.registerAsParallelCapable();
+    }
+
+    public AddonClassLoader(URL[] urls, ClassLoader parent) {
+        super(urls, parent);
+    }
+
+    public AddonClassLoader(URL[] urls) {
+        super(urls);
+    }
+
+    @SuppressWarnings("unchecked")
+    public static Set<Class<? extends TerraAddon>> fetchAddonClasses(File file) throws IOException {
+        JarFile jarFile = new JarFile(file);
+        Enumeration<JarEntry> entries = jarFile.entries();
+
+        AddonClassLoader loader = new AddonClassLoader(new URL[] {file.toURI().toURL()}, AddonClassLoader.class.getClassLoader());
+
+        Set<Class<? extends TerraAddon>> set = new HashSet<>();
+        while(entries.hasMoreElements()) {
+            JarEntry entry = entries.nextElement();
+
+            if(entry.isDirectory() || !entry.getName().endsWith(".class")) continue;
+            String className = entry.getName().substring(0, entry.getName().length() - 6).replace('/', '.');
+
+            try {
+                Class<?> clazz = loader.loadClass(className);
+
+                Addon addon = clazz.getAnnotation(Addon.class);
+
+                if(addon == null) continue;
+
+                if(!TerraAddon.class.isAssignableFrom(clazz)) throw new IllegalArgumentException("Addon class must extend TerraAddon.");
+
+                set.add((Class<? extends TerraAddon>) clazz);
+            } catch(ClassNotFoundException e) {
+                throw new IllegalStateException(e); // this should literally never happen, if it does something is very wrong
+            }
+        }
+
+        return set;
+    }
+}

common/src/main/java/com/dfsek/terra/addon/AddonPool.java

@@ -0,0 +1,32 @@
+package com.dfsek.terra.addon;
+
+import com.dfsek.terra.addon.exception.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/addon/PreLoadAddon.java

@@ -0,0 +1,51 @@
+package com.dfsek.terra.addon;
+
+import com.dfsek.terra.addon.exception.AddonLoadException;
+import com.dfsek.terra.addon.exception.CircularDependencyException;
+import com.dfsek.terra.addon.exception.DependencyMissingException;
+import com.dfsek.terra.api.addons.TerraAddon;
+import com.dfsek.terra.api.addons.annotations.Addon;
+import com.dfsek.terra.api.addons.annotations.Depends;
+
+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. Please install " + dependency + " to use " + id + ".");
+            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/addon/exception/AddonLoadException.java

@@ -0,0 +1,13 @@
+package com.dfsek.terra.addon.exception;
+
+public class AddonLoadException extends Exception {
+    private static final long serialVersionUID = -4949084729296580176L;
+
+    public AddonLoadException(String message) {
+        super(message);
+    }
+
+    public AddonLoadException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

common/src/main/java/com/dfsek/terra/addon/exception/CircularDependencyException.java

@@ -0,0 +1,13 @@
+package com.dfsek.terra.addon.exception;
+
+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/addon/exception/DependencyMissingException.java

@@ -0,0 +1,13 @@
+package com.dfsek.terra.addon.exception;
+
+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);
+    }
+}