fix: Tag fetching (#27)

While checking tags, if current tag isn't found in first page, script will now browse all API pages until either tag is found or there are no more pages.

tools/verify_versions.py

@@ -3,34 +3,66 @@
 import json
 
 def verify_all_mod_versions():
+    """
+    Ensure all mod versions are properly declared to GitHub.
+
+    For each mod entry of this repository's manifesto, this method will fetch information
+    from GitHub API and compare declared SHA ("CommitHash" member) to GitHub information,
+    to ensure tracability of verified mods.
+    """
+
     # Load local manifesto file
     f = open('verified-mods.json')
     manifesto = json.load(f)
 
     for mod in manifesto:
         print('Verifying "{}":'.format(mod))
 
-        # Build GitHub API link and fetch distant tags list
+        # Build GitHub API link
         words = manifesto[mod]['Repository'].split('/')
         tags_url = "https://api.github.com/repos/{}/{}/tags".format(words[-2], words[-1])
-        response = urlopen(tags_url) 
-        tags_data = json.loads(response.read())
 
         # Check all mod versions one-by-one
         for version in manifesto[mod]['Versions']:
+            distant_version = retrieve_tag_info(version['Version'], tags_url)
             local_hash = version['CommitHash']
-            matching_distant_versions = list(filter(lambda v: v['name'] == version['Version'], tags_data))
-
-            # There should be only one matching version
-            if len(matching_distant_versions) != 1:
-                sys.exit('\t❌  v{} (unknown distant version)'.format(version['Version']))
 
             # Compare manifesto commit hash with repository hash
-            distant_version = matching_distant_versions[0]
             if local_hash == distant_version['commit']['sha']:
                 print('\t✔️  v{}'.format(version['Version']))
             else:
                 sys.exit('\t❌  v{} (hash comparison failed)'.format(version['Version']))
 
+
+def retrieve_tag_info(tag_name, repository_url):
+    """
+    Retrieves tag information from distant API.
+
+    Since the GitHub API is paginated, (*i.e.* it does not list all data in a single page,
+    but rather serves pages holding 30 elements maximum), we need to browse all pages
+    until either the tag is found or the page is empty, meaning we didn't find the tag.
+    Page browsing is done by updating the `page` URL argument (`?page=1`, `?page=2` etc).
+
+    @param tag_name: the name of the mod release
+    @param repository_url: API URL used to access mod's tags data
+    @return: tag data, including commit SHA signature
+    """
+
+    i = 1
+    while True:
+        url = '{}?page={}'.format(repository_url, i)
+        response = urlopen(url)
+        tags_data = json.loads(response.read())
+
+        # If page is empty, it means the tag couldn't be found
+        if len(tags_data) == 0:
+            raise LookupError('Tag not found.')
+
+        # If there's one matching result, we found the tag!
+        matching_distant_versions = list(filter(lambda v: v['name'] == tag_name, tags_data))
+        if len(matching_distant_versions) == 1:
+            return matching_distant_versions[0]
+        i += 1
+
 if __name__ == "__main__":
     verify_all_mod_versions()