interface for deleting duplicates

src/main/java/com/commafeed/backend/dao/FeedDAO.java

@@ -7,10 +7,15 @@ import javax.ejb.Stateless;
 import javax.persistence.Query;
 import javax.persistence.TypedQuery;
 import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Expression;
 import javax.persistence.criteria.JoinType;
+import javax.persistence.criteria.Path;
 import javax.persistence.criteria.Predicate;
 import javax.persistence.criteria.Root;
 import javax.persistence.criteria.SetJoin;
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import javax.xml.bind.annotation.XmlRootElement;
 
 import org.apache.commons.codec.digest.DigestUtils;
 import org.apache.commons.lang.StringUtils;
@@ -26,6 +31,13 @@ import com.google.common.collect.Lists;
 @Stateless
 public class FeedDAO extends GenericDAO<Feed> {
 
+	@XmlRootElement
+	@XmlAccessorType(XmlAccessType.FIELD)
+	public static class FeedCount {
+		public String normalizedUrlHash;
+		public List<Feed> feeds;
+	}
+
 	private List<Predicate> getUpdatablePredicates(Root<Feed> root,
 			Date threshold) {
 
@@ -123,4 +135,29 @@ public class FeedDAO extends GenericDAO<Feed> {
 		return deleted;
 
 	}
+
+	public List<FeedCount> findDuplicates(int offset, int limit) {
+		CriteriaQuery<String> query = builder.createQuery(String.class);
+		Root<Feed> root = query.from(getType());
+
+		Path<String> hashPath = root.get(Feed_.normalizedUrlHash);
+		Expression<Long> count = builder.count(hashPath);
+
+		query.select(hashPath);
+
+		query.groupBy(hashPath);
+		query.having(builder.greaterThan(count, 1l));
+
+		TypedQuery<String> q = em.createQuery(query);
+		limit(q, offset, limit);
+		List<String> normalizedUrlHashes = q.getResultList();
+
+		List<FeedCount> result = Lists.newArrayList();
+		for (String hash : normalizedUrlHashes) {
+			FeedCount fc = new FeedCount();
+			fc.normalizedUrlHash = hash;
+			fc.feeds = findByField(Feed_.normalizedUrlHash, hash);
+		}
+		return result;
+	}
 }

src/main/java/com/commafeed/frontend/rest/resources/AdminREST.java

@@ -21,6 +21,7 @@ import com.commafeed.backend.DatabaseCleaner;
 import com.commafeed.backend.MetricsBean;
 import com.commafeed.backend.StartupBean;
 import com.commafeed.backend.dao.FeedDAO;
+import com.commafeed.backend.dao.FeedDAO.FeedCount;
 import com.commafeed.backend.dao.UserDAO;
 import com.commafeed.backend.dao.UserRoleDAO;
 import com.commafeed.backend.feeds.FeedRefreshTaskGiver;
@@ -38,8 +39,8 @@ import com.commafeed.frontend.SecurityCheck;
 import com.commafeed.frontend.model.UserModel;
 import com.commafeed.frontend.model.request.FeedMergeRequest;
 import com.commafeed.frontend.model.request.IDRequest;
-import com.google.api.client.util.Lists;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
 import com.wordnik.swagger.annotations.Api;
@@ -268,17 +269,36 @@ public class AdminREST extends AbstractResourceREST {
 		return Response.ok(map).build();
 	}
 
+	@Path("/cleanup/findDuplicateFeeds")
+	@GET
+	@ApiOperation(value = "Find duplicate feeds")
+	public Response findDuplicateFeeds(@QueryParam("page") int page,
+			@QueryParam("limit") int limit) {
+		List<FeedCount> list = feedDAO.findDuplicates(limit * page, limit);
+		return Response.ok(list).build();
+	}
+
 	@Path("/cleanup/merge")
 	@POST
 	@ApiOperation(value = "Merge feeds", notes = "Merge feeds together")
-	public Response mergeFeeds(@ApiParam(required = true) FeedMergeRequest request) {
+	public Response mergeFeeds(
+			@ApiParam(required = true) FeedMergeRequest request) {
 		Feed into = feedDAO.findById(request.getIntoFeedId());
+		if (into == null) {
+			return Response.status(Status.BAD_REQUEST)
+					.entity("'into feed' not found").build();
+		}
 
 		List<Feed> feeds = Lists.newArrayList();
 		for (Long feedId : request.getFeedIds()) {
 			Feed feed = feedDAO.findById(feedId);
 			feeds.add(feed);
 		}
+		
+		if (feeds.isEmpty()) {
+			return Response.status(Status.BAD_REQUEST)
+					.entity("'from feeds' empty").build();
+		}
 
 		cleaner.mergeFeeds(into, feeds);
 		return Response.ok().build();