From 6cc5fed93007a4f226129e53c08e05246e254c43 Mon Sep 17 00:00:00 2001
From: Ethan Dalool <git@voussoir.net>
Date: Fri, 2 Oct 2020 12:31:39 -0700
Subject: [PATCH] Improve error handling surrounding most_recent_video.

---
 ycdl/exceptions.py |  3 +++
 ycdl/objects.py    | 11 ++++++++---
 ycdl/ycdldb.py     |  4 ++--
 ycdl/ytrss.py      |  7 ++-----
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/ycdl/exceptions.py b/ycdl/exceptions.py
index 7c18b7e..d177f13 100644
--- a/ycdl/exceptions.py
+++ b/ycdl/exceptions.py
@@ -52,6 +52,9 @@ class NoSuchChannel(YCDLException):
 class NoSuchVideo(YCDLException):
     error_message = 'Video {} does not exist.'
 
+class NoVideos(YCDLException):
+    error_message = 'Channel {} has no videos.'
+
 # VIDEO ERRORS #####################################################################################
 
 class InvalidVideoState(YCDLException):
diff --git a/ycdl/objects.py b/ycdl/objects.py
index 2f1f4c0..94dae6c 100644
--- a/ycdl/objects.py
+++ b/ycdl/objects.py
@@ -27,7 +27,10 @@ class Channel(Base):
         self.automark = db_row['automark'] or "pending"
 
     def _rss_assisted_videos(self):
-        most_recent_video = self.get_most_recent_video_id()
+        try:
+            most_recent_video = self.get_most_recent_video_id()
+        except exceptions.NoVideos as exc:
+            raise exceptions.RSSAssistFailed(f'Channel has no videos to reference.') from exc
         new_ids = ytrss.get_user_videos_since(self.id, most_recent_video)
         videos = self.ycdldb.youtube.get_videos(new_ids)
         return videos
@@ -42,8 +45,10 @@ class Channel(Base):
     def get_most_recent_video_id(self):
         query = 'SELECT id FROM videos WHERE author_id == ? ORDER BY published DESC LIMIT 1'
         bindings = [self.id]
-        most_recent_video = self.ycdldb.sql_select_one(query, bindings)[0]
-        return most_recent_video
+        row = self.ycdldb.sql_select_one(query, bindings)
+        if row is None:
+            raise exceptions.NoVideos(self)
+        return row[0]
 
     def has_pending(self):
         query = 'SELECT 1 FROM videos WHERE author_id == ? AND state == "pending" LIMIT 1'
diff --git a/ycdl/ycdldb.py b/ycdl/ycdldb.py
index df26b58..02f4291 100644
--- a/ycdl/ycdldb.py
+++ b/ycdl/ycdldb.py
@@ -184,10 +184,10 @@ class YCDLDBChannelMixin:
 
         def assisted():
             for channel in self.get_channels():
-                most_recent_video = channel.get_most_recent_video_id()
                 try:
+                    most_recent_video = channel.get_most_recent_video_id()
                     new_ids = ytrss.get_user_videos_since(channel.id, most_recent_video)
-                except exceptions.RSSAssistFailed:
+                except (exceptions.NoVideos, exceptions.RSSAssistFailed):
                     traditional(channel)
                     continue
                 yield from new_ids
diff --git a/ycdl/ytrss.py b/ycdl/ytrss.py
index 0efe6a3..c6db7ad 100644
--- a/ycdl/ytrss.py
+++ b/ycdl/ytrss.py
@@ -20,15 +20,12 @@ def get_user_videos(uid):
     try:
         return _get_user_videos(uid)
     except Exception:
-        raise exceptions.RSSAssistFailed() from exc
+        raise exceptions.RSSAssistFailed(f'Failed to fetch RSS videos.') from exc
 
 def get_user_videos_since(uid, most_recent_video):
     video_ids = get_user_videos(uid)
     try:
         index = video_ids.index(most_recent_video)
-        # log.debug(f'RSS contained {most_recent_video}.')
     except ValueError:
-        message = f'RSS didn\'t contain {most_recent_video}.'
-        # log.debug(message)
-        raise exceptions.RSSAssistFailed(message)
+        raise exceptions.RSSAssistFailed(f'RSS didn\'t contain {most_recent_video}.')
     return video_ids[:index]