2 files changed, 177 insertions, 1 deletions
diff --git a/src/main/java/moe/nea/firmament/init/AutoDiscoveryPlugin.java b/src/main/java/moe/nea/firmament/init/AutoDiscoveryPlugin.java
new file mode 100644
index 0000000..e3644c0
--- /dev/null
+++ b/src/main/java/moe/nea/firmament/init/AutoDiscoveryPlugin.java
@@ -0,0 +1,173 @@
+package moe.nea.firmament.init;
+
+
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+
+public class AutoDiscoveryPlugin {
+    private static final List<AutoDiscoveryPlugin> mixinPlugins = new ArrayList<>();
+
+    public static List<AutoDiscoveryPlugin> getMixinPlugins() {
+        return mixinPlugins;
+    }
+
+    private String mixinPackage;
+
+    public void setMixinPackage(String mixinPackage) {
+        this.mixinPackage = mixinPackage;
+        mixinPlugins.add(this);
+    }
+
+    /**
+     * Resolves the base class root for a given class URL. This resolves either the JAR root, or the class file root.
+     * In either case the return value of this + the class name will resolve back to the original class url, or to other
+     * class urls for other classes.
+     */
+    public URL getBaseUrlForClassUrl(URL classUrl) {
+        String string = classUrl.toString();
+        if (classUrl.getProtocol().equals("jar")) {
+            try {
+                return new URL(string.substring(4).split("!")[0]);
+            } catch (MalformedURLException e) {
+                throw new RuntimeException(e);
+            }
+        }
+        if (string.endsWith(".class")) {
+            try {
+                return new URL(string.replace("\\", "/")
+                                     .replace(getClass().getCanonicalName()
+                                                        .replace(".", "/") + ".class", ""));
+            } catch (MalformedURLException e) {
+                throw new RuntimeException(e);
+            }
+        }
+        return classUrl;
+    }
+
+    /**
+     * Get the package that contains all the mixins. This value is set using {@link #setMixinPackage}.
+     */
+    public String getMixinPackage() {
+        return mixinPackage;
+    }
+
+    /**
+     * Get the path inside the class root to the mixin package
+     */
+    public String getMixinBaseDir() {
+        return mixinPackage.replace(".", "/");
+    }
+
+    /**
+     * A list of all discovered mixins.
+     */
+    private List<String> mixins = null;
+
+    /**
+     * Try to add mixin class ot the mixins based on the filepath inside of the class root.
+     * Removes the {@code .class} file suffix, as well as the base mixin package.
+     * <p><b>This method cannot be called after mixin initialization.</p>
+     *
+     * @param className the name or path of a class to be registered as a mixin.
+     */
+    public void tryAddMixinClass(String className) {
+        if (!className.endsWith(".class")) return;
+        String norm = (className.substring(0, className.length() - ".class".length()))
+            .replace("\\", "/")
+            .replace("/", ".");
+        if (norm.startsWith(getMixinPackage() + ".") && !norm.endsWith(".")) {
+            mixins.add(norm.substring(getMixinPackage().length() + 1));
+        }
+    }
+
+    private void tryDiscoverFromContentFile(URL url) {
+        Path file;
+        try {
+            file = Paths.get(getBaseUrlForClassUrl(url).toURI());
+        } catch (URISyntaxException e) {
+            throw new RuntimeException(e);
+        }
+        System.out.println("Base directory found at " + file);
+        if (!Files.exists(file)) {
+            System.out.println("Skipping non-existing mixin root: " + file);
+            return;
+        }
+        if (Files.isDirectory(file)) {
+            walkDir(file);
+        } else {
+            walkJar(file);
+        }
+        System.out.println("Found mixins: " + mixins);
+
+    }
+
+    /**
+     * Search through the JAR or class directory to find mixins contained in {@link #getMixinPackage()}
+     */
+    public List<String> getMixins() {
+        if (mixins != null) return mixins;
+        System.out.println("Trying to discover mixins");
+        mixins = new ArrayList<>();
+        URL classUrl = getClass().getProtectionDomain().getCodeSource().getLocation();
+        System.out.println("Found classes at " + classUrl);
+        tryDiscoverFromContentFile(classUrl);
+        var classRoots = System.getProperty("firmament.classroots");
+        if (classRoots != null && !classRoots.isBlank()) {
+            System.out.println("Found firmament class roots: " + classRoots);
+            for (String s : classRoots.split(File.pathSeparator)) {
+                if (s.isBlank()) {
+                    continue;
+                }
+                try {
+                    tryDiscoverFromContentFile(new File(s).toURI().toURL());
+                } catch (MalformedURLException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        }
+        return mixins;
+    }
+
+    /**
+     * Search through directory for mixin classes based on {@link #getMixinBaseDir}.
+     *
+     * @param classRoot The root directory in which classes are stored for the default package.
+     */
+    private void walkDir(Path classRoot) {
+        System.out.println("Trying to find mixins from directory");
+        try (Stream<Path> classes = Files.walk(classRoot.resolve(getMixinBaseDir()))) {
+            classes.map(it -> classRoot.relativize(it).toString())
+                   .forEach(this::tryAddMixinClass);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Read through a JAR file, trying to find all mixins inside.
+     */
+    private void walkJar(Path file) {
+        System.out.println("Trying to find mixins from jar file");
+        try (ZipInputStream zis = new ZipInputStream(Files.newInputStream(file))) {
+            ZipEntry next;
+            while ((next = zis.getNextEntry()) != null) {
+                tryAddMixinClass(next.getName());
+                zis.closeEntry();
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}
diff --git a/src/main/java/moe/nea/firmament/init/MixinPlugin.java b/src/main/java/moe/nea/firmament/init/MixinPlugin.java
index ea8709b..e7a02b5 100644
--- a/src/main/java/moe/nea/firmament/init/MixinPlugin.java
+++ b/src/main/java/moe/nea/firmament/init/MixinPlugin.java
@@ -12,9 +12,12 @@ import java.util.Set;
 
 public class MixinPlugin implements IMixinConfigPlugin {
 
+    AutoDiscoveryPlugin autoDiscoveryPlugin = new AutoDiscoveryPlugin();
+
     @Override
     public void onLoad(String mixinPackage) {
         MixinExtrasBootstrap.init();
+        autoDiscoveryPlugin.setMixinPackage(mixinPackage);
     }
 
     @Override
@@ -37,7 +40,7 @@ public class MixinPlugin implements IMixinConfigPlugin {
 
     @Override
     public List<String> getMixins() {
-        return null;
+        return autoDiscoveryPlugin.getMixins();
     }
 
     @Override