[SSG] Fix generate_site. parse_file for new file format.

Change sort order. Move argument parsing outside main. Better error
reporting. Better exit codes.

nova.py

@@ -30,7 +30,7 @@ class EpisodeList(UserList):
 
     def sort(self, *_args, **_kwargs):
         "Sorts the EpisodeList"
-        super().sort(key=lambda x: x.date, reverse=True)
+        super().sort(key=lambda x: x.date, reverse=False)
 
     def generate_thumbnails(self):
         "Generates thumbnails for all the videos"
@@ -88,20 +88,21 @@ class EpisodeList(UserList):
             with open(html, "w") as file:
                 file.write(episode.render(self.template, thumbnail))
 
-            last = self.data[-1]
-            last_name = self.output + gen_name(last.date, last.slug) + ".html"
-            shutil.copy2(last_name, self.output + "index.html")
+        last = self.data[-1]
+        last_name = f"{self.output}{gen_name(last.date, last.slug)}.html"
+        shutil.copy2(last_name, self.output + "index.html")
 
 
 class Episode:
     "Represents one episode of podcast"
-    def __init__(self, date, slug, title, show_notes, video_src, audio_src):
+    def __init__(self, date, slug, title, show_notes, video_src, audio_src, config):
         self.date = date
         self.slug = slug
         self.title = title.strip()
         self.show_notes = markdown.markdown(show_notes)
         self.video = video_src
         self.audio = audio_src
+        self.config = config
 
     def render(self, template, thumbnail_src):
         "Renders the Episode with the given template"
@@ -130,10 +131,35 @@ def parse_args():
     return input_dir, output_dir
 
 
-def main():
+class ParseError(ValueError):
+    "Error raised while parsing a file"
+
+
+def parse_file(file, array_keys=("categories")):
+    "Parses a file"
+    config = {}
+    kv_re = re.compile(r"(?P<key>\w+):\s*(?P<value>.*)")
+    while line := file.readline():
+        if line.rstrip("\n") == "---":
+            break
+        if line.strip() == "":
+            continue
+        if match := kv_re.match(line):
+            if match.group("key").strip().lower() in array_keys:
+                config[match.group("key")] = [i.strip() for i in
+                                              match.group("value").split(",")]
+            else:
+                config[match.group("key")] = match.group("value")
+        else:
+            raise ParseError(f"Invalid line {line}")
+
+    return (config, file.read())
+
+
+def main(args):
     "Main method"
     root = path.dirname(sys.argv[0]).rstrip("/") + "/"
-    input_dir, output_dir = parse_args()
+    input_dir, output_dir = args
 
     # Input validation
     paths = [
@@ -142,9 +168,9 @@ def main():
         input_dir + "videos",
         input_dir + "audio",
     ]
-    if not all(path.isdir(i) for i in paths):
-        print("Invalid Input", file=sys.stderr)
-        return
+    if not all(path.isdir((fail := i)) for i in paths):
+        print(f"Invalid Input. {fail} is not a directory.", file=sys.stderr)
+        return 1
 
     if not path.isdir(output_dir):
         os.mkdir(output_dir)
@@ -170,16 +196,21 @@ def main():
         date = datetime.strptime(match.group("date"), "%Y-%M-%d")
         slug = match.group("slug")
         with open(input_dir + "md/" + file) as episode:
-            title = episode.readline()
-            show_notes = episode.read()
+            try:
+                config, show_notes = parse_file(episode)
+            except ParseError as err:
+                print(f"Error while parsing file: {file}")
+                print(err)
+                return 2
         podcast.append(
             Episode(
                 date,
                 slug,
-                title,
+                config["title"],
                 show_notes,
                 input_dir + "videos/" + gen_name(date, slug) + ".mp4",
-                input_dir + "audio/" + gen_name(date, slug) + ".mp3"
+                input_dir + "audio/" + gen_name(date, slug) + ".mp3",
+                config
             )
         )
 
@@ -189,7 +220,8 @@ def main():
     podcast.generate_atom()
     podcast.generate_site(root)
     shutil.copytree(input_dir + "overrides", output_dir, dirs_exist_ok=True)
+    return 0
 
 
 if __name__ == "__main__":
-    main()
+    sys.exit(main(parse_args()))