Type annotations for bookwyrm.isbn

bookwyrm/isbn/isbn.py

@@ -1,11 +1,20 @@
 """ Use the range message from isbn-international to hyphenate ISBNs """
 import os
+from typing import Optional
 from xml.etree import ElementTree
+from xml.etree.ElementTree import Element
+
 import requests
 
 from bookwyrm import settings
 
 
+def _get_rules(element: Element) -> list[Element]:
+    if (rules_el := element.find("Rules")) is not None:
+        return rules_el.findall("Rule")
+    return []
+
+
 class IsbnHyphenator:
     """Class to manage the range message xml file and use it to hyphenate ISBNs"""
 
@@ -15,58 +24,94 @@ class IsbnHyphenator:
     )
     __element_tree = None
 
-    def update_range_message(self):
+    def update_range_message(self) -> None:
         """Download the range message xml file and save it locally"""
         response = requests.get(self.__range_message_url)
         with open(self.__range_file_path, "w", encoding="utf-8") as file:
             file.write(response.text)
         self.__element_tree = None
 
-    def hyphenate(self, isbn_13):
+    def hyphenate(self, isbn_13: Optional[str]) -> Optional[str]:
         """hyphenate the given ISBN-13 number using the range message"""
         if isbn_13 is None:
             return None
+
         if self.__element_tree is None:
             self.__element_tree = ElementTree.parse(self.__range_file_path)
+
         gs1_prefix = isbn_13[:3]
         reg_group = self.__find_reg_group(isbn_13, gs1_prefix)
         if reg_group is None:
             return isbn_13  # failed to hyphenate
+
         registrant = self.__find_registrant(isbn_13, gs1_prefix, reg_group)
         if registrant is None:
             return isbn_13  # failed to hyphenate
+
         publication = isbn_13[len(gs1_prefix) + len(reg_group) + len(registrant) : -1]
         check_digit = isbn_13[-1:]
         return "-".join((gs1_prefix, reg_group, registrant, publication, check_digit))
 
-    def __find_reg_group(self, isbn_13, gs1_prefix):
-        for ean_ucc_el in self.__element_tree.find("EAN.UCCPrefixes").findall(
-            "EAN.UCC"
-        ):
-            if ean_ucc_el.find("Prefix").text == gs1_prefix:
-                for rule_el in ean_ucc_el.find("Rules").findall("Rule"):
-                    length = int(rule_el.find("Length").text)
+    def __find_reg_group(self, isbn_13: str, gs1_prefix: str) -> Optional[str]:
+        if self.__element_tree is None:
+            self.__element_tree = ElementTree.parse(self.__range_file_path)
+
+        ucc_prefixes_el = self.__element_tree.find("EAN.UCCPrefixes")
+        if ucc_prefixes_el is None:
+            return None
+
+        for ean_ucc_el in ucc_prefixes_el.findall("EAN.UCC"):
+            if (
+                prefix_el := ean_ucc_el.find("Prefix")
+            ) is not None and prefix_el.text == gs1_prefix:
+                for rule_el in _get_rules(ean_ucc_el):
+                    length_el = rule_el.find("Length")
+                    if length_el is None:
+                        continue
+                    length = int(text) if (text := length_el.text) else 0
                     if length == 0:
                         continue
-                    reg_grp_range = [
-                        int(x[:length]) for x in rule_el.find("Range").text.split("-")
-                    ]
+
+                    range_el = rule_el.find("Range")
+                    if range_el is None or range_el.text is None:
+                        continue
+
+                    reg_grp_range = [int(x[:length]) for x in range_el.text.split("-")]
                     reg_group = isbn_13[len(gs1_prefix) : len(gs1_prefix) + length]
                     if reg_grp_range[0] <= int(reg_group) <= reg_grp_range[1]:
                         return reg_group
                 return None
         return None
 
-    def __find_registrant(self, isbn_13, gs1_prefix, reg_group):
+    def __find_registrant(
+        self, isbn_13: str, gs1_prefix: str, reg_group: str
+    ) -> Optional[str]:
         from_ind = len(gs1_prefix) + len(reg_group)
-        for group_el in self.__element_tree.find("RegistrationGroups").findall("Group"):
-            if group_el.find("Prefix").text == "-".join((gs1_prefix, reg_group)):
-                for rule_el in group_el.find("Rules").findall("Rule"):
-                    length = int(rule_el.find("Length").text)
+
+        if self.__element_tree is None:
+            self.__element_tree = ElementTree.parse(self.__range_file_path)
+
+        reg_groups_el = self.__element_tree.find("RegistrationGroups")
+        if reg_groups_el is None:
+            return None
+
+        for group_el in reg_groups_el.findall("Group"):
+            if (
+                prefix_el := group_el.find("Prefix")
+            ) is not None and prefix_el.text == "-".join((gs1_prefix, reg_group)):
+                for rule_el in _get_rules(group_el):
+                    length_el = rule_el.find("Length")
+                    if length_el is None:
+                        continue
+                    length = int(text) if (text := length_el.text) else 0
                     if length == 0:
                         continue
+
+                    range_el = rule_el.find("Range")
+                    if range_el is None or range_el.text is None:
+                        continue
                     registrant_range = [
-                        int(x[:length]) for x in rule_el.find("Range").text.split("-")
+                        int(x[:length]) for x in range_el.text.split("-")
                     ]
                     registrant = isbn_13[from_ind : from_ind + length]
                     if registrant_range[0] <= int(registrant) <= registrant_range[1]:

bookwyrm/settings.py

@@ -1,5 +1,7 @@
 """ bookwyrm settings and configuration """
 import os
+from typing import AnyStr
+
 from environs import Env
 
 import requests
@@ -37,7 +39,7 @@ EMAIL_SENDER_DOMAIN = env("EMAIL_SENDER_DOMAIN", DOMAIN)
 EMAIL_SENDER = f"{EMAIL_SENDER_NAME}@{EMAIL_SENDER_DOMAIN}"
 
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
-BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+BASE_DIR: AnyStr = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 LOCALE_PATHS = [
     os.path.join(BASE_DIR, "locale"),
 ]

mypy.ini

@@ -13,6 +13,9 @@ implicit_reexport = True
 [mypy-bookwyrm.connectors.*]
 ignore_errors = False
 
+[mypy-bookwyrm.isbn.*]
+ignore_errors = False
+
 [mypy-celerywyrm.*]
 ignore_errors = False