Preserve the last seen timestamp

So that we can mark posts from bots as read.  Otherwise we could end up
sending empty messages until another human posts.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

slack/chat.py

@@ -57,6 +57,9 @@ class Message:
         links = []
         count = 0
         for line in self.__text:
+            if len(line) == 0:
+                continue
+
             line, link = _text_parse_tags(line)
             while line.count("[#####]") > 0:
                 line = line.replace("[#####]", "[%s]" % count, 1)
@@ -65,6 +68,8 @@ class Message:
             lines += [ "" ] + textwrap.wrap(line)
             links += link
 
+        if len(lines) == 0:
+            return ""
         text = "\n	".join(lines)
         if len(links) > 0:
             text += "\n	__________"

slack/threads.py

@@ -51,11 +51,11 @@ class Thread:
             self.fetch_info()
 
         # Read original message list
-        o_list = []
-        for message in self.do_fetch_messages(self.__last_ts):
-            if message["text"] != None and len(message["text"]) > 0:
-                o_list += [ chat.Message(message) ]
+        messages = self.do_fetch_messages(self.__last_ts)
+        o_list = [ chat.Message(msg) for msg in messages ]
         o_list.sort()
+        if len(o_list) == 0:
+            return o_list
 
         # Merge together messages from the same user
         m_list = [ o_list[0] ]