Support for addon dependencies and soft-dependencies

common/src/main/java/de/bluecolored/bluemap/common/BlueMapService.java

@@ -153,11 +153,7 @@ public synchronized Map<String, BmMap> getOrLoadMaps(Predicate<String> filter) t
             try {
                 loadMap(entry.getKey(), entry.getValue());
             } catch (ConfigurationException ex) {
-                Logger.global.logWarning(ex.getFormattedExplanation());
-                Throwable cause = ex.getRootCause();
-                if (cause != null) {
-                    Logger.global.logError("Detailed error:", ex);
-                }
+                ex.printLog(Logger.global);
             }
         }
         return Collections.unmodifiableMap(maps);

common/src/main/java/de/bluecolored/bluemap/common/addons/Addon.java

@@ -0,0 +1,39 @@
+/*
+ * This file is part of BlueMap, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.bluecolored.bluemap.common.addons;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+import java.nio.file.Path;
+
+@RequiredArgsConstructor
+@Getter
+public class Addon {
+
+    private final AddonInfo addonInfo;
+    private final Path jarFile;
+
+}

common/src/main/java/de/bluecolored/bluemap/common/addons/AddonInfo.java

@@ -24,13 +24,59 @@
  */
 package de.bluecolored.bluemap.common.addons;
 
+import com.google.gson.FieldNamingPolicy;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import de.bluecolored.bluemap.common.config.ConfigurationException;
 import lombok.Getter;
+import org.jetbrains.annotations.Nullable;
 
+import java.io.IOException;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+
+@SuppressWarnings({"FieldMayBeFinal", "unused"})
 @Getter
 public class AddonInfo {
     public static final String ADDON_INFO_FILE = "bluemap.addon.json";
 
+    private static final Gson GSON = new GsonBuilder()
+            .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_DASHES)
+            .create();
+
     private String id;
     private String entrypoint;
+    private Set<String> dependencies = Set.of();
+    private Set<String> softDependencies = Set.of();
+
+    public static @Nullable AddonInfo load(Path addonJarFile) throws ConfigurationException {
+        try (FileSystem fileSystem = FileSystems.newFileSystem(addonJarFile, (ClassLoader) null)) {
+            for (Path root : fileSystem.getRootDirectories()) {
+                Path addonInfoFile = root.resolve(ADDON_INFO_FILE);
+                if (!Files.exists(addonInfoFile)) continue;
+
+                try (Reader reader = Files.newBufferedReader(addonInfoFile, StandardCharsets.UTF_8)) {
+                    AddonInfo addonInfo = GSON.fromJson(reader, AddonInfo.class);
+
+                    if (addonInfo.getId() == null)
+                        throw new ConfigurationException("'id' is missing");
+
+                    if (addonInfo.getEntrypoint() == null)
+                        throw new ConfigurationException("'entrypoint' is missing");
+
+                    return addonInfo;
+                }
+            }
+        } catch (IOException e) {
+            throw new ConfigurationException("There was an exception trying to access the file.", e);
+        }
+
+        return null;
+    }
 
 }

common/src/main/java/de/bluecolored/bluemap/common/addons/AddonLoader.java

@@ -0,0 +1,194 @@
+/*
+ * This file is part of BlueMap, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) Blue (Lukas Rieger) <https://bluecolored.de>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.bluecolored.bluemap.common.addons;
+
+import de.bluecolored.bluemap.common.config.ConfigurationException;
+import de.bluecolored.bluemap.core.BlueMap;
+import de.bluecolored.bluemap.core.logger.Logger;
+import lombok.Singular;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public final class AddonLoader {
+    public static final AddonLoader INSTANCE = new AddonLoader();
+
+    private final Map<String, LoadedAddon> loadedAddons = new ConcurrentHashMap<>();
+
+    public void tryLoadAddons(Path root) {
+        if (!Files.exists(root)) return;
+        try (Stream<Path> files = Files.list(root)) {
+
+            // find all addons and load addon-info
+            Map<String, Addon> availableAddons = files
+                    .filter(Files::isRegularFile)
+                    .filter(f -> f.getFileName().toString().endsWith(".jar"))
+                    .map(this::tryLoadAddonInfo)
+                    .filter(Objects::nonNull)
+                    .collect(Collectors.toMap(addon -> addon.getAddonInfo().getId(), addon -> addon));
+
+            // remove addons that have missing required dependencies
+            while (!availableAddons.isEmpty()) {
+                Addon addonToRemove = availableAddons.values().stream()
+                        .filter(a -> !availableAddons.keySet().containsAll(a.getAddonInfo().getDependencies()))
+                        .findAny()
+                        .orElse(null);
+                if (addonToRemove == null) break;
+                String id = addonToRemove.getAddonInfo().getId();
+                availableAddons.remove(id);
+                new ConfigurationException("Missing required dependencies %s to load addon '%s' (%s)".formatted(
+                        Arrays.toString(addonToRemove.getAddonInfo().getDependencies().toArray(String[]::new)),
+                        id,
+                        addonToRemove.getJarFile()
+                )).printLog(Logger.global);
+            }
+
+            // topography sort and load addons based on their dependencies
+            Map<String, Long> dependenciesToLoad = new HashMap<>();
+            Queue<String> loadNext = new ArrayDeque<>();
+            for (Addon addon : availableAddons.values()) {
+                long dependencyCount =
+                        addon.getAddonInfo().getDependencies().size() +
+                        addon.getAddonInfo().getSoftDependencies().stream()
+                                .filter(availableAddons::containsKey)
+                                .count();
+                String id = addon.getAddonInfo().getId();
+                if (dependencyCount == 0) loadNext.add(id);
+                else dependenciesToLoad.put(id, dependencyCount);
+            }
+
+            while (!loadNext.isEmpty()) {
+                String id = loadNext.poll();
+                Addon addon = availableAddons.get(id);
+
+                try {
+                    loadAddon(addon);
+                    for (Addon dependant : availableAddons.values()) {
+                        AddonInfo info = dependant.getAddonInfo();
+                        if (info.getDependencies().contains(id) || info.getSoftDependencies().contains(id)) {
+                            Long count = dependenciesToLoad.get(info.getId());
+                            if (count == null) continue;
+                            if (--count <= 0) {
+                                dependenciesToLoad.remove(info.getId());
+                                loadNext.add(info.getId());
+                            } else {
+                                dependenciesToLoad.put(info.getId(), count);
+                            }
+                        }
+                    }
+                } catch (ConfigurationException ex) {
+                    new ConfigurationException("Failed to load addon '%s' (%s)".formatted(id, addon.getJarFile()), ex)
+                            .printLog(Logger.global);
+                }
+            }
+
+            // failed to resolve dependencies, possibly a cyclic reference
+            // try to load anyway in case a soft dependency is involved
+            for (String id : dependenciesToLoad.keySet()) {
+                Addon addon = availableAddons.remove(id);
+                try {
+                    if (addon != null) loadAddon(addon);
+                } catch (ConfigurationException ex) {
+                    new ConfigurationException("Failed to load addon '%s' (%s)".formatted(id, addon.getJarFile()), ex)
+                            .printLog(Logger.global);
+                }
+            }
+
+        } catch (IOException e) {
+            Logger.global.logError("Failed to load addons from '%s'".formatted(root), e);
+        }
+    }
+
+    private @Nullable Addon tryLoadAddonInfo(Path jarFile) {
+        try {
+            AddonInfo addonInfo = AddonInfo.load(jarFile);
+            if (addonInfo == null) return null;
+            return new Addon(addonInfo, jarFile);
+        } catch (ConfigurationException e) {
+            new ConfigurationException("Failed to load addon info from '%s'.".formatted(jarFile), e)
+                    .printLog(Logger.global);
+            return null;
+        }
+    }
+
+    private synchronized void loadAddon(Addon addon) throws ConfigurationException {
+        AddonInfo addonInfo = addon.getAddonInfo();
+        Path jarFile = addon.getJarFile();
+
+        Logger.global.logInfo("Loading BlueMap Addon: %s (%s)".formatted(addonInfo.getId(), jarFile));
+
+        try {
+            Set<ClassLoader> dependencyClassLoaders = new LinkedHashSet<>();
+            for (String dependencyId : addon.getAddonInfo().getDependencies()) {
+                LoadedAddon loadedAddon = loadedAddons.get(dependencyId);
+                if (loadedAddon == null) throw new IllegalStateException("Required dependency '%s' is not loaded."
+                        .formatted(addon.getAddonInfo().getId()));
+                dependencyClassLoaders.add(loadedAddon.getClassLoader());
+            }
+            for (String dependencyId : addon.getAddonInfo().getSoftDependencies()) {
+                LoadedAddon loadedAddon = loadedAddons.get(dependencyId);
+                if (loadedAddon == null) continue;
+                dependencyClassLoaders.add(loadedAddon.getClassLoader());
+            }
+
+            ClassLoader parent = BlueMap.class.getClassLoader();
+            if (!dependencyClassLoaders.isEmpty())
+                parent = new CombinedClassLoader(parent, dependencyClassLoaders.toArray(ClassLoader[]::new));
+
+            ClassLoader addonClassLoader = new URLClassLoader(
+                    new URL[]{ jarFile.toUri().toURL() },
+                    parent
+            );
+            Class<?> entrypointClass = addonClassLoader.loadClass(addonInfo.getEntrypoint());
+
+            // create addon instance
+            Object instance = entrypointClass.getConstructor().newInstance();
+            LoadedAddon loadedAddon = new LoadedAddon(
+                    addonInfo,
+                    jarFile,
+                    addonClassLoader,
+                    instance
+            );
+
+            loadedAddons.put(addonInfo.getId(), loadedAddon);
+
+            // run addon
+            if (instance instanceof Runnable runnable)
+                runnable.run();
+
+        } catch (Exception e) {
+            throw new ConfigurationException("There was an exception trying to initialize the addon!", e);
+        }
+    }
+
+}