added the ability to check if a like is alredy present

git-svn-id: http://svn.research-infrastructures.eu/public/d4science/gcube/trunk/portal/social-networking-library@117281 82a268e6-3cf1-43bd-a215-b396298e98cf

src/main/java/org/gcube/portal/databook/server/DBCassandraAstyanaxImpl.java

@@ -520,6 +520,34 @@ public final class DBCassandraAstyanaxImpl implements DatabookStore {
 		}
 		return toReturn;
 	}
+
+	/**
+	 * helper method that return whether the user 
+	 * @param userid  user identifier
+	 * @param feedid the feed identifier
+	 * @return true if the feed id liked already
+	 */
+	private boolean isFeedLiked(String userid, String feedid) {
+		OperationResult<Rows<String, String>> result = null;
+		try {
+			result = conn.getKeyspace().prepareQuery(cf_UserLikedFeeds)
+					.getKeySlice(userid)
+					.execute();
+		} catch (ConnectionException e) {
+			e.printStackTrace();
+		}
+
+		// Iterate rows and their columns looking for the feeid id
+		for (Row<String, String> row : result.getResult()) {
+			for (Column<String> column : row.getColumns()) {
+				if (column.getStringValue().compareTo(feedid)==0)	
+					return true;
+			}
+		}
+		return false;
+	}
+
+
 	/**
 	 * helper method that retrieve all the feed Ids belonging to an application
 	 * @param appid  application identifier
@@ -1309,25 +1337,31 @@ public final class DBCassandraAstyanaxImpl implements DatabookStore {
 			e.printStackTrace();
 			return false;
 		} 
-		// Inserting data
+		if (isFeedLiked(like.getUserid(), feedId)) {
-		MutationBatch m = conn.getKeyspace().prepareMutationBatch();
+			_log.info("User " + like.getUserid() +  " already liked Feed " + feedId);
-		//an entry in the feed CF
+			return true;
-		m.withRow(cf_Likes, like.getKey().toString())
+		}
-		.putColumn("Timestamp", like.getTime().getTime()+"", null)
+		else {
-		.putColumn("Userid", like.getUserid(), null)
+			// Inserting data
-		.putColumn("Feedid",like.getFeedid(), null)
+			MutationBatch m = conn.getKeyspace().prepareMutationBatch();
-		.putColumn("FullName",like.getFullName(), null)
+			//an entry in the feed CF
-		.putColumn("ThumbnailURL", like.getThumbnailURL(), null);
+			m.withRow(cf_Likes, like.getKey().toString())
-		//and an entry in the UserLikesCF
+			.putColumn("Timestamp", like.getTime().getTime()+"", null)
-		m.withRow(cf_UserLikedFeeds, like.getUserid()).putColumn(like.getKey(), like.getFeedid(), null);
+			.putColumn("Userid", like.getUserid(), null)
+			.putColumn("Feedid",like.getFeedid(), null)
+			.putColumn("FullName",like.getFullName(), null)
+			.putColumn("ThumbnailURL", like.getThumbnailURL(), null);
+			//and an entry in the UserLikesCF
+			m.withRow(cf_UserLikedFeeds, like.getUserid()).putColumn(like.getKey(), like.getFeedid(), null);
 
-		try {
+			try {
-			m.execute();
+				m.execute();
-		} catch (ConnectionException e) {
+			} catch (ConnectionException e) {
-			e.printStackTrace();
+				e.printStackTrace();
-			return false;
+				return false;
-		}	
+			}	
-		return updateFeedLikesCount(toLike, true);
+			return updateFeedLikesCount(toLike, true);
+		}
 	}
 	/**
 	 * {@inheritDoc}
@@ -1721,7 +1755,7 @@ public final class DBCassandraAstyanaxImpl implements DatabookStore {
 						if (column.getStringValue().compareTo(status[i].toString())==0)
 							invitesIds.add(column.getName());
 					}
-					
+
 				}
 			}
 			else {