refactor isofy

src/cnaas_nms/tools/jinja_filters.py

@@ -34,6 +34,7 @@ def isofy_ipv4(ip_string, prefix=''):
     """Transform IPv4 address so it can be used as an ISO/NET address.
     All four blocks of the IP address are padded with zeros and split up into double octets.
     Example: 10.255.255.1 -> 0102.5525.5001.00
+    With prefix: 10.255.255.1, 47.0023.0000.0001.0000 -> 47.0023.0000.0001.0000.0102.5525.5001.00
     Args:
         ip_string: a valid IPv4 address
         prefix: first part of the ISO address (optional)
@@ -47,24 +48,15 @@ def isofy_ipv4(ip_string, prefix=''):
         if not prefix_valid:
             raise ValueError(f"{prefix} cannot be used as ISO prefix, please check formatting")
         prefix += '.'
-
+    # IP: split and fill with 0s
     ip_parts = ip_string.split('.')
     padded = [p.zfill(3) for p in ip_parts]
     joined = ''.join(padded)
-
-    chunksize = 2
-    ip_octets = [joined[i : i + chunksize] for i in range(0, len(joined), chunksize)]
-    ip_octets += ['00']
-
-    # format: add . after every other octet, starting at the end
-    ip_octets.reverse()
-    resultsize = 2 * len(ip_octets) - 1
-    result = resultsize * ['']
-    result[1::4] = len(result[1::4]) * '.'
-    result[0::2] = ip_octets
-    result.reverse()
-
-    iso_address = prefix + ''.join(result)
+    # IP: split to chunks à 4 chars
+    chunksize = 4
+    ip_chunks = [joined[i : i + chunksize] for i in range(0, len(joined), chunksize)]
+    # combine
+    iso_address = prefix + '.'.join(ip_chunks) + '.00'
     return iso_address