Support serial chrono order.

Fixes gpodder#35

bin/gpo

@@ -43,6 +43,9 @@
     list                       List all subscribed podcasts
     update [URL]               Check for new episodes (all or only at URL)
 
+    episodic URL               Set feed to episodic (newest episodes first)
+    serial URL                 Set feed to serial (oldest episodes first)
+
   - Episode management -
 
     download [URL]             Download new episodes (all or only from URL)
@@ -488,12 +491,14 @@ class gPodderCli(object):
 
             title, url, status = podcast.title, podcast.url, \
                 feed_update_status_msg(podcast)
+            strategy = 'episodic (newest first)' if podcast.download_strategy != podcast.STRATEGY_CHRONO else 'serial (oldest first)'
             episodes = self._episodesList(podcast)
             episodes = '\n      '.join(episodes)
             self._pager("""
     Title: %(title)s
     URL: %(url)s
     Feed update is %(status)s
+    Feed Order: %(strategy)s
 
     Episodes:
       %(episodes)s
@@ -564,10 +569,11 @@ class gPodderCli(object):
         return True
 
     def _format_podcast(self, podcast):
+        strategy = '' if podcast.download_strategy != podcast.STRATEGY_CHRONO else '(serial)'
         if not podcast.pause_subscription:
-            return ' '.join(('#', ingreen(podcast.title)))
+            return ' '.join(('#', ingreen(podcast.title), strategy))
 
-        return ' '.join(('#', inred(podcast.title), '-', _('Subscription suspended')))
+        return ' '.join(('#', inred(podcast.title), strategy, '-', _('Subscription suspended')))
 
     def list(self):
         """List all podcast subscriptions
@@ -931,10 +937,49 @@ class gPodderCli(object):
             if not podcast.pause_subscription:
                 podcast.pause_subscription = True
                 podcast.save()
+                self._model.load_podcast(url)
             self._error(_('Subscription suspended: %(url)s') % {'url': url})
 
         return True
 
+    @FirstArgumentIsPodcastURL
+    def episodic(self, url):
+        """Define a podcast as episodic (newest episodes first)
+
+        episodic http://example.net/podcast/latest.atom
+
+        Use {serial} to change podcast to oldest episodes first
+        """
+        podcast = self._get_podcast(url)
+
+        if podcast is not None:
+            if podcast.download_strategy != podcast.STRATEGY_DEFAULT:
+                podcast.download_strategy = podcast.STRATEGY_DEFAULT
+                podcast.save()
+                podcast.update()
+            self._error(_('Podcast now set to episodic: %(url)s') % {'url': url})
+
+        return True
+
+    @FirstArgumentIsPodcastURL
+    def serial(self, url):
+        """Define a podcast as serial (oldest episodes first)
+
+        serial http://example.net/podcast/latest.atom
+
+        Use {episodic} to change podcast to newest episodes first
+        """
+        podcast = self._get_podcast(url)
+
+        if podcast is not None:
+            if podcast.download_strategy != podcast.STRATEGY_CHRONO:
+                podcast.download_strategy = podcast.STRATEGY_CHRONO
+                podcast.save()
+                podcast.update()
+            self._error(_('Podcast now set to serial: %(url)s') % {'url': url})
+
+        return True
+
     @FirstArgumentIsPodcastURL
     def enable(self, url):
         """Resume subscription of a given feed

src/gpodder/model.py

@@ -483,7 +483,7 @@ class PodcastChannel(PodcastModelFields, PodcastModelMixin):
     UNICODE_TRANSLATE = {ord('ö'): 'o', ord('ä'): 'a', ord('ü'): 'u'}
 
     # Enumerations for download strategy
-    STRATEGY_DEFAULT, STRATEGY_LATEST = list(range(2))
+    STRATEGY_DEFAULT, STRATEGY_LATEST, STRATEGY_CHRONO = list(range(3))
 
     MAX_FOLDERNAME_LENGTH = 60
     SECONDS_PER_WEEK = 7*24*60*60
@@ -507,7 +507,7 @@ def __init__(self, model):
         if self.id:
             self._children = sorted(self.db.load_episodes(self, self),
                                     key=lambda e: (e.published, e.id),
-                                    reverse=True)
+                                    reverse=self.download_strategy != PodcastChannel.STRATEGY_CHRONO)
             self._determine_common_prefix()
 
     def one_line_description(self):
@@ -761,8 +761,11 @@ def _consume_custom_feed(self, custom_feed):
         for episode in self.episodes:
             self.model.core.cover_downloader.get_cover(self, download=True, episode=episode)
 
-        # Sort episodes by pubdate, descending
-        self.episodes.sort(key=lambda e: e.published, reverse=True)
+        self._order_episodes()
+
+    def _order_episodes(self):
+        # Sort episodes by pubdate, descending if default, ascending if chrono
+        self.episodes.sort(key=lambda e: e.published, reverse=self.download_strategy != PodcastChannel.STRATEGY_CHRONO)
 
     def update(self):
         if self._updating:
@@ -781,6 +784,9 @@ def update(self):
             if self.save_dir:
                 self.model.core.cover_downloader.get_cover(self, download=True)
 
+            # Make sure episodes are in correct order
+            self._order_episodes()
+
             self.save()
 
             # Re-determine the common prefix for all episodes
@@ -798,7 +804,7 @@ def save(self):
         if self.download_folder is None:
             self.get_save_dir()
 
-        super().save(self.db.db)
+        super().save(self.db.db)       
 
         self.model._append_podcast(self)