Don't create blacklist duplicates

app/src/main/java/dummydomain/yetanothercallblocker/EditBlacklistItemActivity.java

@@ -222,7 +222,13 @@ public class EditBlacklistItemActivity extends AppCompatActivity {
             }
         } else {
             if (TextUtils.isEmpty(name) && TextUtils.isEmpty(pattern)) {
-                LOG.warn("save() not creating a new item because fields are empty");
+                LOG.info("save() not creating a new item because fields are empty");
+                return;
+            }
+
+            if (blacklistDao.findByNameAndPattern(name, pattern) != null) {
+                LOG.info("save() not creating a new item because" +
+                        " an item with the same name and pattern exists");
                 return;
             }
 

app/src/main/java/dummydomain/yetanothercallblocker/data/db/BlacklistDao.java

@@ -51,6 +51,13 @@ public class BlacklistDao {
                 .orderAsc(BlacklistItemDao.Properties.Pattern));
     }
 
+    public BlacklistItem findByNameAndPattern(String name, String pattern) {
+        return first(getBlacklistItemDao().queryBuilder()
+                .where(BlacklistItemDao.Properties.Name.eq(name))
+                .where(BlacklistItemDao.Properties.Pattern.eq(pattern))
+                .orderAsc(BlacklistItemDao.Properties.Pattern));
+    }
+
     public void save(BlacklistItem blacklistItem) {
         getBlacklistItemDao().save(blacklistItem);
     }