Provide Python plugin support

comixed-app/src/main/resources/application.properties

@@ -10,6 +10,9 @@ server.servlet.context-path=/
 # image caching directory
 comixed.images.cache.location=${user.home}/.comixed/image-cache
 
+# plugin directory
+comixed.plugins.location=${user.home}/.comixed/plugins
+
 # H2 JPA Configuration
 spring.datasource.url=jdbc:h2:file:~/.comixed/comixed;create=true
 spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy

comixed-plugins/pom.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+         xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>org.comixed</groupId>
+    <artifactId>comixed</artifactId>
+    <version>0.7.0-0</version>
+    <relativePath>..</relativePath>
+  </parent>
+  <groupId>org.comixed</groupId>
+  <artifactId>comixed-plugins</artifactId>
+  <version>0.7.0-0</version>
+  <name>comixed-plugins</name>
+  <url>http://maven.apache.org</url>
+  <dependencies>
+    <dependency>
+      <groupId>org.python</groupId>
+      <artifactId>jython-standalone</artifactId>
+      <version>2.7.0</version>
+    </dependency>
+    <dependency>
+      <groupId>org.comixed</groupId>
+      <artifactId>comixed-services</artifactId>
+      <version>${comixed.version}</version>
+    </dependency>
+    <dependency>
+      <groupId>mysql</groupId>
+      <artifactId>mysql-connector-java</artifactId>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>build-helper-maven-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>add-sources</id>
+            <phase>generate-resources</phase>
+            <goals>
+              <goal>add-resource</goal>
+            </goals>
+            <configuration>
+              <resources>
+                <resource>
+                  <directory>src/main/python</directory>
+                  <targetPath>python</targetPath>
+                  <includes>**/*.py</includes>
+                </resource>
+              </resources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

comixed-plugins/src/main/java/org/comixed/plugins/PluginException.java

@@ -0,0 +1,36 @@
+/*
+ * ComiXed - A digital comic book library management application.
+ * Copyright (C) 2020, The ComiXed Project
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses>
+ */
+
+package org.comixed.plugins;
+
+import java.io.IOException;
+
+/**
+ * <code>PluginException</code> is thrown when an error occurs during the run of a plugin.
+ *
+ * @author Darryl L. Pierce
+ */
+public class PluginException extends Exception {
+  public PluginException(String message) {
+    super(message);
+  }
+
+  public PluginException(String message, IOException cause) {
+    super(message, cause);
+  }
+}

comixed-plugins/src/main/java/org/comixed/plugins/PluginManager.java

@@ -0,0 +1,146 @@
+/*
+ * ComiXed - A digital comic book library management application.
+ * Copyright (C) 2020, The ComiXed Project
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses>
+ */
+
+package org.comixed.plugins;
+
+import java.io.*;
+import java.util.Collection;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+import lombok.extern.log4j.Log4j2;
+import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
+import org.apache.commons.compress.archivers.zip.ZipFile;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.IOUtils;
+import org.comixed.plugins.model.Plugin;
+import org.comixed.utils.FileTypeIdentifier;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.stereotype.Component;
+
+/**
+ * <code>PluginManager</code> handles retrieving and launching the plugins.
+ *
+ * @author Darryl L. Pierce
+ */
+@Component
+@EnableConfigurationProperties
+@Log4j2
+public class PluginManager implements InitializingBean {
+  @Autowired private ObjectFactory<Plugin> pluginObjectFactory;
+  @Autowired private FileTypeIdentifier fileTypeIdentifier;
+
+  @Value("${comixed.plugins.location}")
+  String pluginLocation;
+
+  /** the key is the plugin name, the value is a map of a plugin filename to the file's contents */
+  Map<String, Map<String, byte[]>> plugins = new HashMap<>();
+
+  /**
+   * Returns a {@link Plugin} by name.
+   *
+   * @param name the plugin name
+   * @return the plugin's classname
+   * @throws PluginException if an error occurs retrieve the plugin
+   */
+  public Plugin loadPlugin(String name) throws PluginException {
+    log.debug("Loading plugin details");
+    Map<String, byte[]> pluginEntries = this.plugins.get(name);
+    if (pluginEntries == null) throw new PluginException("no such plugin: " + name);
+    log.debug("Rehydrating plugin");
+    Plugin result = this.pluginObjectFactory.getObject();
+    result.setEntries(pluginEntries);
+    return result;
+  }
+
+  @Override
+  public void afterPropertiesSet() throws Exception {
+    log.debug("initial loading of plugins");
+    this.loadPlugins();
+  }
+
+  public void loadPlugins() throws PluginException {
+    log.debug("Clearing plugin list");
+    this.plugins.clear();
+    File pluginDirectory = new File(this.pluginLocation);
+    if (!pluginDirectory.exists()) {
+      log.debug("Plugin directory does not exist: {}", pluginDirectory.getAbsolutePath());
+      return;
+    }
+    if (!pluginDirectory.isDirectory())
+      throw new PluginException("Not a directory: " + this.pluginLocation);
+
+    Collection<File> pluginFiles =
+        FileUtils.listFiles(pluginDirectory, new String[] {"cxp"}, false);
+    log.debug("Found {} file{} to process", pluginFiles.size(), pluginFiles.size() == 1 ? "" : "s");
+    int processed = 0;
+    for (File pluginFile : pluginFiles) {
+      try (InputStream input = new BufferedInputStream(new FileInputStream(pluginFile))) {
+        String fileType = this.fileTypeIdentifier.subtypeFor(input);
+        if (!fileType.equalsIgnoreCase("zip")) {
+          log.debug("{} is not a zip file; skipping", pluginFile.getName());
+        } else {
+          this.loadPluginDetails(pluginFile);
+          processed++;
+        }
+      } catch (IOException error) {
+        log.error("could not determine file type: " + pluginFile.getAbsolutePath());
+      }
+    }
+
+    log.debug("Processed {} plugin{}", processed, processed == 1 ? "" : "s");
+  }
+
+  private void loadPluginDetails(File pluginFile) throws PluginException {
+    log.debug("Loading plugin file: {}", pluginFile.getAbsolutePath());
+    if (!pluginFile.exists())
+      throw new PluginException("No such plugin file: " + pluginFile.getAbsolutePath());
+    if (!pluginFile.isFile())
+      throw new PluginException("Plugin points to directory: " + pluginFile.getAbsolutePath());
+
+    Map<String, byte[]> pluginEntries = new HashMap<>();
+
+    log.debug("opening archive");
+    try (ZipFile zipfile = new ZipFile(pluginFile); ) {
+      log.debug("retrieving the list of archive entries");
+      Enumeration<ZipArchiveEntry> zipfileEntries = zipfile.getEntries();
+      while (zipfileEntries.hasMoreElements()) {
+        ZipArchiveEntry zipfileEntry = zipfileEntries.nextElement();
+        String filename = zipfileEntry.getName();
+        long filesize = zipfileEntry.getSize();
+        byte[] content = new byte[(int) filesize];
+        log.debug("Loading plugin file: {} ({} bytes)", filename, filesize);
+        IOUtils.readFully(zipfile.getInputStream(zipfileEntry), content);
+        pluginEntries.put(filename, content);
+      }
+    } catch (IOException error) {
+      throw new PluginException("failed to load plugin: " + pluginFile.getName(), error);
+    }
+
+    log.debug("storing plugin details");
+    Plugin plugin = this.pluginObjectFactory.getObject();
+    plugin.setEntries(pluginEntries);
+    if (this.plugins.containsKey(plugin.getName()))
+      throw new PluginException("plugin already exists with name: " + plugin.getName());
+    this.plugins.put(plugin.getName(), pluginEntries);
+  }
+}

comixed-plugins/src/main/java/org/comixed/plugins/interpreters/AbstractPluginInterpreter.java

@@ -0,0 +1,39 @@
+/*
+ * ComiXed - A digital comic book library management application.
+ * Copyright (C) 2020, The ComiXed Project
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses>
+ */
+
+package org.comixed.plugins.interpreters;
+
+import org.comixed.plugins.PluginException;
+import org.comixed.plugins.model.Plugin;
+
+/**
+ * <code>AbstractPluginInterpreter</code> defines a base type for providing concrete implementations
+ * of {@link PluginInterpreter}.
+ *
+ * @author Darryl L. Pierce
+ */
+public abstract class AbstractPluginInterpreter implements PluginInterpreter {
+  @Override
+  public void initialize() throws PluginException {}
+
+  @Override
+  public void start(Plugin plugin) throws PluginException {}
+
+  @Override
+  public void finish() throws PluginException {}
+}

comixed-plugins/src/main/java/org/comixed/plugins/interpreters/PluginInterpreter.java

@@ -0,0 +1,52 @@
+/*
+ * ComiXed - A digital comic book library management application.
+ * Copyright (C) 2020, The ComiXed Project
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses>
+ */
+
+package org.comixed.plugins.interpreters;
+
+import org.comixed.plugins.PluginException;
+import org.comixed.plugins.model.Plugin;
+
+/**
+ * <code>PluginInterpreter</code> defines a type that provides the interpreter for a plugin's
+ * execution environment.
+ *
+ * @author Darryl L. Pierce
+ */
+public interface PluginInterpreter {
+  /**
+   * Invoked to initialize the plugin's runtime environemnt.
+   *
+   * @throws PluginException if an error occurs
+   */
+  void initialize() throws PluginException;
+
+  /**
+   * Invoked to begin execution of the plugin.
+   *
+   * @param plugin the plugin
+   * @throws PluginException if an error occurs
+   */
+  void start(Plugin plugin) throws PluginException;
+
+  /**
+   * Invoked after the plugin has finished executing and is destroyed.
+   *
+   * @throws PluginException if an error occurs
+   */
+  void finish() throws PluginException;
+}