Improve pluralization of translated strings

Switch a few strings containing numeric variables to ngettext from
gettext, to ensure they can be properly translated. Use "num" more
consistently as the placeholder for numeric variables in strings
marked with ngettext, to make things easier for translators.

securedrop/journalist_app/forms.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-from flask_babel import lazy_gettext as gettext
+from flask_babel import lazy_gettext as gettext, ngettext
 from flask_wtf import FlaskForm
 from flask_wtf.file import FileField, FileAllowed, FileRequired
 from wtforms import Field
@@ -13,27 +13,37 @@
 
 def otp_secret_validation(form: FlaskForm, field: Field) -> None:
     strip_whitespace = field.data.replace(' ', '')
-    if len(strip_whitespace) != 40:
-        raise ValidationError(gettext(
-            'HOTP secrets are 40 characters long - '
-            'you have entered {num_chars}.'.format(
-                num_chars=len(strip_whitespace)
-            )))
+    input_length = len(strip_whitespace)
+    if input_length != 40:
+        raise ValidationError(
+            ngettext(
+                'HOTP secrets are 40 characters long - you have entered {num}.',
+                'HOTP secrets are 40 characters long - you have entered {num}.',
+                input_length
+            ).format(num=input_length)
+        )
 
 
 def minimum_length_validation(form: FlaskForm, field: Field) -> None:
     if len(field.data) < Journalist.MIN_USERNAME_LEN:
         raise ValidationError(
-            gettext('Must be at least {min_chars} '
-                    'characters long.'
-                    .format(min_chars=Journalist.MIN_USERNAME_LEN)))
+            ngettext(
+                'Must be at least {num} characters long.',
+                'Must be at least {num} characters long.',
+                Journalist.MIN_USERNAME_LEN
+            ).format(num=Journalist.MIN_USERNAME_LEN)
+        )
 
 
 def name_length_validation(form: FlaskForm, field: Field) -> None:
     if len(field.data) > Journalist.MAX_NAME_LEN:
-        raise ValidationError(gettext(
-            'Cannot be longer than {max_chars} characters.'
-            .format(max_chars=Journalist.MAX_NAME_LEN)))
+        raise ValidationError(
+            ngettext(
+                'Cannot be longer than {num} characters.',
+                'Cannot be longer than {num} characters.',
+                Journalist.MAX_NAME_LEN
+            ).format(num=Journalist.MAX_NAME_LEN)
+        )
 
 
 def check_invalid_usernames(form: FlaskForm, field: Field) -> None:

securedrop/journalist_app/utils.py

@@ -111,10 +111,10 @@ def validate_user(
             # ngettext is needed although we always have period > 1
             # see https://github.com/freedomofpress/securedrop/issues/2422
             login_flashed_msg += ngettext(
-                "Please wait at least {seconds} second "
-                "before logging in again.",
-                "Please wait at least {seconds} seconds "
-                "before logging in again.", period).format(seconds=period)
+                "Please wait at least {num} second before logging in again.",
+                "Please wait at least {num} seconds before logging in again.",
+                period
+            ).format(num=period)
         else:
             try:
                 user = Journalist.query.filter_by(
@@ -239,10 +239,15 @@ def bulk_delete(
         except ValueError:
             deletion_errors += 1
 
-    flash(ngettext("Submission deleted.",
-                   "{num} submissions deleted.".format(
-                       num=len(items_selected)),
-                   len(items_selected)), "notification")
+    num_selected = len(items_selected)
+    flash(
+        ngettext(
+            "Submission deleted.",
+            "{num} submissions deleted.",
+            num_selected
+        ).format(num=num_selected),
+        "notification"
+    )
     if deletion_errors > 0:
         current_app.logger.error("Disconnected submission entries (%d) were detected",
                                  deletion_errors)

securedrop/journalist_templates/_source_row.html

@@ -20,11 +20,11 @@
     {% endif %}
   </div>
   <div class="submission-count">
-    <span><i class="far fa-file-archive"></i> {{ ngettext('1 doc', '{doc_num} docs', docs).format(doc_num=docs) }}</span>
-    <span><i class="far fa-file-alt"></i> {{ ngettext('1 message', '{msg_num} messages', msgs).format(msg_num=msgs) }}</span>
+    <span><i class="far fa-file-archive"></i> {{ ngettext('1 doc', '{num} docs', docs).format(num=docs) }}</span>
+    <span><i class="far fa-file-alt"></i> {{ ngettext('1 message', '{num} messages', msgs).format(num=msgs) }}</span>
     {% if source.num_unread > 0 %}
       <span class="unread">
-        <a class="btn small" href="/download_unread/{{ source.filesystem_id }}"><i class="fa fa-download"></i> {{ ngettext('1 unread', '{num_unread} unread', source.num_unread).format(num_unread=source.num_unread) }}</a>
+        <a class="btn small" href="/download_unread/{{ source.filesystem_id }}"><i class="fa fa-download"></i> {{ ngettext('1 unread', '{num} unread', source.num_unread).format(num=source.num_unread)}}</a>
       </span>
     {% endif %}
   </div>

securedrop/journalist_templates/delete.html

@@ -2,7 +2,7 @@
 {% block body %}
 
 {% with count=items_selected|length %}
-<p>{{ ngettext('The following file has been selected for <strong>permanent deletion</strong>:', 'The following {files} files have been selected for <strong>permanent deletion</strong>:', count).format(files=count)|safe }}</p>
+<p>{{ ngettext('The following file has been selected for <strong>permanent deletion</strong>:', 'The following {num} files have been selected for <strong>permanent deletion</strong>:', count).format(num=count)|safe }}</p>
 {% endwith %}
 
 <form action="/bulk" method="post">