better loading in util.read_localized_resource

The other code kinda assumed that we can turn the resource path into a
package by replacing the slashes (path separators) with dots. That
turned out to not really work in the end, especially if the resource
subfolders don't have a __init__.py in there.

This uses the .files() API (available in Python 3.9 and backported in
importlib_resources) to better handle folders in the resources.

3 files changed, 26 insertions, 16 deletions

diff --git a/MANIFEST.in b/MANIFEST.in
index 0d8bb87..38898e6 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,7 +1,7 @@
 include *.txt *.ini *.cfg *.rst
 recursive-include fietsboek *.ico *.png *.css *.gif *.jpg *.pt *.txt *.mak *.mako *.js *.html *.xml *.jinja2
 recursive-include fietsboek/static *
-recursive-include fietsboek/locale *.pot *.po *.mo
+recursive-include fietsboek/locale *.pot *.po *.mo *.html
 recursive-include tests *
 recursive-exclude * __pycache__
 recursive-exclude * *.py[co]
diff --git a/fietsboek/util.py b/fietsboek/util.py
index e24f96a..7ca0d62 100644
--- a/fietsboek/util.py
+++ b/fietsboek/util.py
@@ -2,8 +2,9 @@
 import random
 import string
 import datetime
-import importlib.resources
 
+# Compat for Python < 3.9
+import importlib_resources
 import babel
 import markdown
 import bleach
@@ -263,29 +264,37 @@ def check_password_constraints(password, repeat_password=None):
         raise ValueError(_("password_constraint.length"))
 
 
-def read_localized_resource(locale_name, path):
+def read_localized_resource(locale_name, path, raise_on_error=False):
     """Reads a localized resource.
 
     Localized resources are located in the ``fietsboek/locale/**`` directory.
-    Note that ``path`` may contain slashes, which are automatically replaced
-    with the right separators.
+    Note that ``path`` may contain slashes.
 
     If the resource could not be found, a placeholder string is returned instead.
 
     :param locale_name: Name of the locale.
     :type locale_name: str
+    :param raise_on_error: Raise an error instead of returning a placeholder.
+    :type raise_on_error: bool
+    :raises FileNotFoundError: If the path could not be found and
+        ``raise_on_error`` is ``True``.
     :return: The text content of the resource.
     :rtype: str
     """
-    parts = path.split("/")
-    package = ".".join(parts[:-1])
-    package = f"fietsboek.locale.{locale_name}.{package}"
-    try:
-        return importlib.resources.read_text(package, parts[-1])
-    except (FileNotFoundError, ModuleNotFoundError, NotADirectoryError):
-        # Second chance: If the locale is a specific form of a more general
-        # locale, try the general locale as well.
-        if "_" in locale_name:
-            main_locale = locale_name.split("_", 1)[0]
-            return read_localized_resource(main_locale, path)
+    locales = [locale_name]
+    # Second chance: If the locale is a specific form of a more general
+    # locale, try the general locale as well.
+    if "_" in locale_name:
+        locales.append(locale_name.split("_", 1)[0])
+
+    for locale in locales:
+        locale_dir = importlib_resources.files('fietsboek') / 'locale' / locale
+        resource_path = locale_dir / path
+        try:
+            return resource_path.read_text()
+        except (FileNotFoundError, ModuleNotFoundError, NotADirectoryError):
+            pass
+    if raise_on_error:
+        raise FileNotFoundError(f"Resource {path!r} not found")
+    else:
         return f"{locale_name}:{path}"
diff --git a/setup.py b/setup.py
index d6267a6..bcb2ab1 100644
--- a/setup.py
+++ b/setup.py
@@ -20,6 +20,7 @@ requires = [
     'SQLAlchemy',
     'transaction',
     'zope.sqlalchemy',
+    'importlib_resources',
     'Babel',
     'cryptography',
     'gpxpy',