improve extension binding and added api to query extensions

scm-webapp/src/main/java/sonia/scm/plugin/ExtensionCollector.java

@@ -0,0 +1,333 @@
+/**
+ * Copyright (c) 2014, Sebastian Sdorra All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer. 2. Redistributions in
+ * binary form must reproduce the above copyright notice, this list of
+ * conditions and the following disclaimer in the documentation and/or other
+ * materials provided with the distribution. 3. Neither the name of SCM-Manager;
+ * nor the names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://bitbucket.org/sdorra/scm-manager
+ *
+ */
+
+
+
+package sonia.scm.plugin;
+
+//~--- non-JDK imports --------------------------------------------------------
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Multimap;
+import com.google.common.collect.Sets;
+import com.google.inject.Module;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+//~--- JDK imports ------------------------------------------------------------
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
+/**
+ *
+ * @author Sebastian Sdorra
+ */
+@SuppressWarnings("unchecked")
+public final class ExtensionCollector
+{
+
+  /**
+   * the logger for ExtensionCollector
+   */
+  private static final Logger logger =
+    LoggerFactory.getLogger(ExtensionCollector.class);
+
+  //~--- constructors ---------------------------------------------------------
+
+  /**
+   * Constructs ...
+   *
+   *
+   * @param modules
+   */
+  ExtensionCollector(Iterable<ScmModule> modules)
+  {
+    for (ScmModule module : modules)
+    {
+      collectRootElements(module);
+    }
+
+    for (ScmModule module : modules)
+    {
+      collectExtensions(module);
+    }
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param epe
+   *
+   * @return
+   */
+  public Collection<Class> byExtensionPoint(ExtensionPointElement epe)
+  {
+    Collection<Class> collection = extensions.get(epe);
+    if ( collection == null ){
+      collection = Collections.EMPTY_SET;
+    }
+    return collection;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param clazz
+   *
+   * @return
+   */
+  public Collection<Class> byExtensionPoint(Class clazz)
+  {
+    Collection<Class> exts;
+    ExtensionPointElement epe = extensionPointIndex.get(clazz);
+
+    if (epe != null)
+    {
+      exts = byExtensionPoint(epe);
+    }
+    else
+    {
+      exts = Collections.EMPTY_SET;
+    }
+
+    return exts;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param epe
+   *
+   * @return
+   */
+  public Class oneByExtensionPoint(ExtensionPointElement epe)
+  {
+    return Iterables.getFirst(byExtensionPoint(epe), null);
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param clazz
+   *
+   * @return
+   */
+  public Class oneByExtensionPoint(Class clazz)
+  {
+    return Iterables.getFirst(byExtensionPoint(clazz), null);
+  }
+
+  //~--- get methods ----------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Iterable<ExtensionPointElement> getExtensionPointElements()
+  {
+    return extensionPointIndex.values();
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Multimap<ExtensionPointElement, Class> getExtensions()
+  {
+    return extensions;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Set<Module> getInjectionModules()
+  {
+    return injectionModules;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Set<Class> getLooseExtensions()
+  {
+    return looseExtensions;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Set<Class> getRestProviders()
+  {
+    return restProviders;
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @return
+   */
+  public Set<Class> getRestResources()
+  {
+    return restResources;
+  }
+
+  //~--- methods --------------------------------------------------------------
+
+  /**
+   * Method description
+   *
+   *
+   * @param extension
+   */
+  private void appendExtension(Class extension)
+  {
+    boolean found = false;
+
+    for (Entry<Class, ExtensionPointElement> e : extensionPointIndex.entrySet())
+    {
+      if (e.getKey().isAssignableFrom(extension))
+      {
+        extensions.put(e.getValue(), extension);
+        found = true;
+
+        break;
+      }
+    }
+
+    if (!found)
+    {
+      looseExtensions.add(extension);
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param extension
+   */
+  private void appendModule(Class extension)
+  {
+    try
+    {
+      injectionModules.add((Module) extension.newInstance());
+    }
+    catch (IllegalAccessException | InstantiationException ex)
+    {
+      logger.error("could not create instance of module", ex);
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param module
+   */
+  private void collectExtensions(ScmModule module)
+  {
+    for (Class extension : module.getExtensions())
+    {
+      if (Module.class.isAssignableFrom(extension))
+      {
+        appendModule(extension);
+      }
+      else
+      {
+        appendExtension(extension);
+      }
+    }
+  }
+
+  /**
+   * Method description
+   *
+   *
+   * @param module
+   */
+  private void collectRootElements(ScmModule module)
+  {
+    for (ExtensionPointElement epe : module.getExtensionPoints())
+    {
+      extensionPointIndex.put(epe.getClazz(), epe);
+    }
+    restProviders.addAll(Lists.newArrayList(module.getRestProviders()));
+    restResources.addAll(Lists.newArrayList(module.getRestResources()));
+  }
+
+  //~--- fields ---------------------------------------------------------------
+
+  /** Field description */
+  private final Set<Class> looseExtensions = Sets.newHashSet();
+
+  /** Field description */
+  private final Set<Module> injectionModules = Sets.newHashSet();
+
+  /** Field description */
+  private final Set<Class> restProviders = Sets.newHashSet();
+
+  /** Field description */
+  private final Set<Class> restResources = Sets.newHashSet();
+
+  /** Field description */
+  private final Multimap<ExtensionPointElement, Class> extensions =
+    HashMultimap.create();
+
+  /** Field description */
+  private final Map<Class, ExtensionPointElement> extensionPointIndex =
+    Maps.newHashMap();
+}