Implement clear cache feature (issue sopeco#57)

Implemented the feature and made it available in the context menu when
at least one project is selected. Currently there is a bug when
right-clicking on the project which has not been selected before. This
problem is addressed in sopeco#63.

Change-Id: Ic4c9cc663c06f9d49532f370789dbd762c3d8789
Signed-off-by: Denis Knoepfle <[email protected]>

org.spotter.eclipse.ui/plugin.xml

@@ -261,6 +261,12 @@
             id="org.spotter.eclipse.ui.commands.run"
             name="Run">
       </command>
+      <command
+            defaultHandler="org.spotter.eclipse.ui.handlers.ClearCacheHandler"
+            description="Clear cache containing data retrieved from DS Service"
+            id="org.spotter.eclipse.ui.commands.clearCache"
+            name="Clear Cache">
+      </command>
       <command
             defaultHandler="org.spotter.eclipse.ui.handlers.ServiceClientSettingsHandler"
             description="Open DynamicSpotter Service Client Settings"
@@ -362,6 +368,13 @@
                style="push"
                tooltip="Run selected DynamicSpotter Project">
          </command>
+         <command
+               commandId="org.spotter.eclipse.ui.commands.clearCache"
+               icon="icons/clear-cache.png"
+               label="Clear Cache"
+               style="push"
+               tooltip="Clear cache containing data retrieved from DS Service">
+         </command>
          <command
                commandId="org.spotter.eclipse.ui.commands.serviceClientSettings"
                icon="icons/conn-settings.png"

org.spotter.eclipse.ui/src/org/spotter/eclipse/ui/handlers/ClearCacheHandler.java

@@ -0,0 +1,60 @@
+/**
+ * Copyright 2014 SAP AG
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.spotter.eclipse.ui.handlers;
+
+import org.eclipse.core.commands.AbstractHandler;
+import org.eclipse.core.commands.ExecutionEvent;
+import org.eclipse.core.commands.ExecutionException;
+import org.eclipse.core.resources.IProject;
+import org.spotter.eclipse.ui.Activator;
+import org.spotter.eclipse.ui.util.DialogUtils;
+
+/**
+ * A handler for the clear cache command which clears the cache containing data
+ * retrieved from the DS service.
+ * 
+ * @author Denis Knoepfle
+ * 
+ */
+public class ClearCacheHandler extends AbstractHandler {
+
+	/**
+	 * The id of the corresponding clear cache command.
+	 */
+	public static final String CLEAR_CACHE_COMMAND_ID = "org.spotter.eclipse.ui.commands.clearCache";
+
+	@Override
+	public Object execute(ExecutionEvent event) throws ExecutionException {
+		Activator activator = Activator.getDefault();
+		for (IProject project : activator.getSelectedProjects()) {
+			String projectName = project.getName();
+			activator.getClient(projectName).clearCache();
+		}
+
+		DialogUtils.openInformation("This feature is not fully implemented yet and only "
+				+ "clears the extensions cache without checking if any open "
+				+ "editors/views are still in a valid state in case the extensions have "
+				+ "changed on the server side.");
+
+		return null;
+	}
+
+	@Override
+	public boolean isEnabled() {
+		return !Activator.getDefault().getSelectedProjects().isEmpty();
+	}
+
+}