simplify algorithm

sites/arbitrary.py

@@ -76,15 +76,24 @@ class Arbitrary(Site):
         else:
             # set of already processed urls. Stored to detect loops.
             found_content_urls = set()
-            content_url = definition.url
+            content_urls = [definition.url]
 
             def process_content_url(content_url):
                 if content_url in found_content_urls:
-                    return False
+                    return None
                 found_content_urls.add(content_url)
                 for chapter in self._chapter(content_url, definition):
                     story.add(chapter)
-                if definition.next_selector:
+                return content_url
+
+            while content_urls:
+                for temp_url in content_urls:
+                    # stop inner loop once a new link is found
+                    if content_url := process_content_url(temp_url):
+                        break
+                # reset url list
+                content_urls = []
+                if content_url and definition.next_selector:
                     soup, base = self._soup(content_url)
                     next_link = soup.select(definition.next_selector)
                     if next_link:
@@ -92,14 +101,7 @@ class Arbitrary(Site):
                             next_link_url = str(next_link_item.get('href'))
                             if base:
                                 next_link_url = self._join_url(base, next_link_url)
-                            content_url = self._join_url(content_url, next_link_url)
-                            # stop loop once a new link is found
-                            status = process_content_url(content_url)
-                            if status:
-                                break
-                return True
-
-            process_content_url(content_url)
+                            content_urls.append(self._join_url(content_url, next_link_url))
 
         if not story:
             raise SiteException("No story content found; check the content selectors")