Change .pot files to only contain at most 5 context lines

Crowdin did not like having many comments which caused the upload to
fail.

docs/_templates/gettext/message.pot_t

@@ -0,0 +1,33 @@
+# SOME DESCRIPTIVE TITLE.
+# Copyright (C) {{ copyright }}
+# This file is distributed under the same license as the {{ project }} package.
+# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
+#
+#, fuzzy
+msgid ""
+msgstr ""
+"Project-Id-Version: {{ project|e }} {{ version|e }}\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: {{ ctime|e }}\n"
+"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
+"Last-Translator: {{ last_translator|e }}\n"
+"Language-Team: {{ language_team|e }}\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+{% for message in messages %}
+{% if display_location -%}
+{% for source, line in message.locations[:5] -%}
+#: {{ relpath(source) }}:{{ line }}
+{% endfor -%}
+{% endif -%}
+
+{% if display_uuid -%}
+{% for uuid in message.uuids -%}
+#: {{ uuid }}
+{% endfor -%}
+{% endif -%}
+
+msgid "{{ message.text|e }}"
+msgstr ""
+{% endfor -%}

docs/extensions/builder.py

@@ -1,12 +1,18 @@
 from sphinx.builders.html import StandaloneHTMLBuilder
+from sphinx.builders.gettext import MessageCatalogBuilder, I18nBuilder, timestamp, ltz, should_write, GettextRenderer
+from sphinx.locale import __
+from sphinx.util import status_iterator
+from sphinx.util.osutil import ensuredir
 from sphinx.environment.adapters.indexentries import IndexEntries
 from sphinx.writers.html5 import HTML5Translator
+import datetime
+import os
+
 
 class DPYHTML5Translator(HTML5Translator):
     def visit_section(self, node):
         self.section_level += 1
-        self.body.append(
-            self.starttag(node, 'section'))
+        self.body.append(self.starttag(node, 'section'))
 
     def depart_section(self, node):
         self.section_level -= 1
@@ -20,6 +26,7 @@ class DPYHTML5Translator(HTML5Translator):
         super().depart_table(node)
         self.body.append('</div>')
 
+
 class DPYStandaloneHTMLBuilder(StandaloneHTMLBuilder):
     # This is mostly copy pasted from Sphinx.
     def write_genindex(self) -> None:
@@ -28,8 +35,7 @@ class DPYStandaloneHTMLBuilder(StandaloneHTMLBuilder):
         genindex = IndexEntries(self.env).create_index(self, group_entries=False)
         indexcounts = []
         for _k, entries in genindex:
-            indexcounts.append(sum(1 + len(subitems)
-                                   for _, (_, subitems, _) in entries))
+            indexcounts.append(sum(1 + len(subitems) for _, (_, subitems, _) in entries))
 
         genindexcontext = {
             'genindexentries': genindex,
@@ -38,40 +44,79 @@ class DPYStandaloneHTMLBuilder(StandaloneHTMLBuilder):
         }
 
         if self.config.html_split_index:
-            self.handle_page('genindex', genindexcontext,
-                             'genindex-split.html')
-            self.handle_page('genindex-all', genindexcontext,
-                             'genindex.html')
+            self.handle_page('genindex', genindexcontext, 'genindex-split.html')
+            self.handle_page('genindex-all', genindexcontext, 'genindex.html')
             for (key, entries), count in zip(genindex, indexcounts):
-                ctx = {'key': key, 'entries': entries, 'count': count,
-                       'genindexentries': genindex}
-                self.handle_page('genindex-' + key, ctx,
-                                 'genindex-single.html')
+                ctx = {'key': key, 'entries': entries, 'count': count, 'genindexentries': genindex}
+                self.handle_page('genindex-' + key, ctx, 'genindex-single.html')
         else:
             self.handle_page('genindex', genindexcontext, 'genindex.html')
 
 
+class DPYMessageCatalogBuilder(MessageCatalogBuilder):
+    def finish(self) -> None:
+        # Bypass MessageCatalogBuilder.finish
+        I18nBuilder.finish(self)
+
+        # This is mostly copy pasted from Sphinx
+        # However, this allows
+        context = {
+            'version': self.config.version,
+            'copyright': self.config.copyright,
+            'project': self.config.project,
+            'last_translator': self.config.gettext_last_translator,
+            'language_team': self.config.gettext_language_team,
+            'ctime': datetime.datetime.fromtimestamp(timestamp, ltz).strftime('%Y-%m-%d %H:%M%z'),
+            'display_location': self.config.gettext_location,
+            'display_uuid': self.config.gettext_uuid,
+        }
+        for textdomain, catalog in status_iterator(
+            self.catalogs.items(),
+            __("writing message catalogs... "),
+            "darkgreen",
+            len(self.catalogs),
+            self.app.verbosity,
+            lambda textdomain__: textdomain__[0],
+        ):
+            # noop if config.gettext_compact is set
+            ensuredir(os.path.join(self.outdir, os.path.dirname(textdomain)))
+
+            context['messages'] = list(catalog)
+            content = GettextRenderer(template_path='_templates/gettext', outdir=self.outdir).render(
+                'message.pot_t', context
+            )
+
+            pofn = os.path.join(self.outdir, textdomain + '.pot')
+            if should_write(pofn, content):
+                with open(pofn, 'w', encoding='utf-8') as pofile:
+                    pofile.write(content)
+
+
 def add_custom_jinja2(app):
     env = app.builder.templates.environment
     env.tests['prefixedwith'] = str.startswith
     env.tests['suffixedwith'] = str.endswith
 
+
 def add_builders(app):
     """This is necessary because RTD injects their own for some reason."""
     app.set_translator('html', DPYHTML5Translator, override=True)
     app.add_builder(DPYStandaloneHTMLBuilder, override=True)
+    app.add_builder(DPYMessageCatalogBuilder, override=True)
 
     try:
         original = app.registry.builders['readthedocs']
     except KeyError:
         pass
     else:
-        injected_mro = tuple(base if base is not StandaloneHTMLBuilder else DPYStandaloneHTMLBuilder
-                             for base in original.mro()[1:])
+        injected_mro = tuple(
+            base if base is not StandaloneHTMLBuilder else DPYStandaloneHTMLBuilder for base in original.mro()[1:]
+        )
         new_builder = type(original.__name__, injected_mro, {'name': 'readthedocs'})
         app.set_translator('readthedocs', DPYHTML5Translator, override=True)
         app.add_builder(new_builder, override=True)
 
+
 def setup(app):
     add_builders(app)
     app.connect('builder-inited', add_custom_jinja2)