Proxito: support single language project (#10766)

The important changes are in the resolver and unresolver.

- A new option was added to the versioning scheme field.
- There are some extra validations in place, so users can't create translations if their project doesn't support them.
- The versioning scheme field is disabled on translations, since it doesn't any effect there.
- All usages of single_version were replaced with versioning scheme, except where it's still required for backwards compatibility (API, sphinx html_context).
- Some function/variables were renamed to use the new naming.
- Docs were added, not sure if I'm following diataxis right...
- single-version.rst was moved into `versioning-schemes.rst` and `guides/setup/versioning-schemes.rst`. A redirect is needed.

Some changes on templates need to be ported to ext-theme.

Closes #10307

docs/user/api/v3.rst

@@ -300,6 +300,7 @@ Project details
        ``versioning_scheme`` can be one of the following values:
 
        - ``multiple_versions_with_translations``
+       - ``multiple_versions_without_translations``
        - ``single_version_without_translations``
 
     .. note::

docs/user/guides/setup/index.rst

@@ -32,6 +32,10 @@ The following how-to guides help you solve common tasks and challenges in the se
     Is your version (flyout) menu overwhelmed and hard to navigate?
     Here's how to make it shorter.
 
+⏩️ :doc:`Changing the versioning scheme of your project </guides/setup/versioning-schemes>`
+    Change how the URLs of your documentation look like,
+    and if your project supports multiple versions or translations.
+
 .. seealso::
 
    :doc:`/tutorial/index`
@@ -50,3 +54,4 @@ The following how-to guides help you solve common tasks and challenges in the se
    Hiding a version </guides/hiding-a-version>
    Using a .readthedocs.yaml file in a sub-folder </guides/setup/monorepo>
    Using custom URL redirects in documentation projects </guides/redirects>
+   Changing the versioning scheme of your project </guides/setup/versioning-schemes>

docs/user/guides/setup/versioning-schemes.rst

@@ -0,0 +1,24 @@
+How to change the versioning scheme of your project
+===================================================
+
+In this guide, we show you how to change the versioning scheme of your project on Read the Docs.
+
+Changing the versioning scheme of your project will affect the URLs of your documentation,
+any existing links to your documentation will break.
+If you want to keep the old URLs working, you can create :doc:`redirects </user-defined-redirects>`.
+
+.. seealso::
+
+   :doc:`/versioning-schemes`
+     Reference of all the versioning schemes supported by Read the Docs.
+
+   :doc:`/versions`
+     General explanation of how versioning works on Read the Docs.
+
+Changing the versioning scheme
+------------------------------
+
+#. Go the :guilabel:`Admin` tab of your project.
+#. Click on :guilabel:`Advanced Settings`.
+#. Select the new versioning scheme in the :guilabel:`Versioning scheme` dropdown.
+#. Click on :guilabel:`Save`.

docs/user/reference/features.rst

@@ -19,8 +19,8 @@ Feature reference
   We support multiple versions and translations,
   integrated nicely into the URL of your documentation.
   This is served at ``/en/latest/`` by default.
-  If you only have 1 version and translation,
-  we also support :doc:`single version projects </single-version>` served at ``/``.
+  If you have only one version, or don't need translations,
+  you can change the :doc:`versioning scheme </versioning-schemes>` of your project.
 
 ⏩️ :doc:`/pull-requests`
   Your project can be configured to build and host documentation for every new pull request.
@@ -105,5 +105,5 @@ Feature reference
    /reference/environment-variables
    /security-log
    /server-side-search/index
-   /single-version
+   /versioning-schemes
    /science

docs/user/versioning-schemes.rst

@@ -0,0 +1,66 @@
+Versioning schemes
+==================
+
+The versioning scheme of your project defines the URL of your documentation,
+and if your project supports multiple versions or translations.
+
+Read the Docs supports three different versioning schemes:
+
+- `Multiple versions with translations`_.
+- `Multiple versions without translations`_.
+- `Single version without translations`_.
+
+.. seealso::
+
+   :doc:`/guides/setup/versioning-schemes`
+     How to configure your project to use a specific versioning scheme.
+
+   :doc:`/versions`
+     General explanation of how versioning works on Read the Docs.
+
+Multiple versions with translations
+-----------------------------------
+
+This is the default versioning scheme, it's the recommend one if your project has multiple versions,
+and has or plans to support translations.
+
+The URLs of your documentation will look like:
+
+- ``/en/latest/``
+- ``/en/1.5/``
+- ``/es/latest/install.html``
+- ``/es/1.5/contributing.html``
+
+Multiple versions without translations
+--------------------------------------
+
+Use this versioning scheme if you want to have multiple versions of your documentation,
+but don't want to have translations.
+
+The URLs of your documentation will look like:
+
+- ``/latest/``
+- ``/1.5/install.html``
+
+.. warning::
+
+   This means you can't have translations for your documentation.
+
+Single version without translations
+-----------------------------------
+
+Having a single version of a documentation project can be considered the better choice
+in cases where there should only always exist one unambiguous copy of your project.
+For example:
+
+- A research project may wish to *only* expose readers to their latest list of publications and research data.
+- A :abbr:`SaaS (Software as a Service)` application might only ever have one version live.
+
+The URLs of your documentation will look like:
+
+- ``/``
+- ``/install.html``
+
+.. warning::
+
+   This means you can't have translations or multiple versions for your documentation.

readthedocs/api/v2/templates/restapi/footer.html

@@ -37,7 +37,7 @@
 
       </dl>
       {% endif %}
-      {% if not project.single_version and versions|length >= 1 %}
+      {% if project.supports_multiple_versions and versions|length >= 1 %}
       <dl>
         <dt>{% trans "Versions" %}</dt>
         {% for version in versions %}

readthedocs/api/v3/tests/test_projects.py

@@ -440,6 +440,9 @@ def test_update_project(self):
         self.assertEqual(self.project.show_version_warning, False)
         self.assertEqual(self.project.is_single_version, True)
         self.assertEqual(self.project.external_builds_enabled, True)
+        self.assertEqual(
+            self.project.versioning_scheme, SINGLE_VERSION_WITHOUT_TRANSLATIONS
+        )
 
     def test_partial_update_project(self):
         data = {

readthedocs/core/resolver.py

@@ -7,6 +7,10 @@
 
 from readthedocs.builds.constants import EXTERNAL, INTERNAL
 from readthedocs.core.utils.url import unsafe_join_url_path
+from readthedocs.projects.constants import (
+    MULTIPLE_VERSIONS_WITHOUT_TRANSLATIONS,
+    SINGLE_VERSION_WITHOUT_TRANSLATIONS,
+)
 from readthedocs.subscriptions.constants import TYPE_CNAME
 from readthedocs.subscriptions.products import get_feature
 
@@ -59,7 +63,7 @@ def base_resolve_path(
         filename,
         version_slug=None,
         language=None,
-        single_version=None,
+        versioning_scheme=None,
         project_relationship=None,
         custom_prefix=None,
     ):
@@ -83,8 +87,10 @@ def base_resolve_path(
         if custom_prefix:
             path = unsafe_join_url_path(path, custom_prefix)
 
-        if single_version:
+        if versioning_scheme == SINGLE_VERSION_WITHOUT_TRANSLATIONS:
             path = unsafe_join_url_path(path, "{filename}")
+        elif versioning_scheme == MULTIPLE_VERSIONS_WITHOUT_TRANSLATIONS:
+            path = unsafe_join_url_path(path, "{version}/{filename}")
         else:
             path = unsafe_join_url_path(path, "{language}/{version}/{filename}")
 
@@ -102,7 +108,6 @@ def resolve_path(
         filename="",
         version_slug=None,
         language=None,
-        single_version=None,
     ):
         """Resolve a URL with a subset of fields defined."""
         version_slug = version_slug or project.get_default_version()
@@ -111,22 +116,23 @@ def resolve_path(
         filename = self._fix_filename(filename)
 
         parent_project, project_relationship = self._get_canonical_project(project)
-        single_version = bool(project.is_single_version or single_version)
 
-        # If the project is a subproject, we use the custom prefix
+        # If the project is a subproject, we use the custom prefix and versioning scheme
         # of the child of the relationship, this is since the project
         # could be a translation. For a project that isn't a subproject,
-        # we use the custom prefix of the parent project.
+        # we use the custom prefix and versioning scheme of the parent project.
         if project_relationship:
             custom_prefix = project_relationship.child.custom_prefix
+            versioning_scheme = project_relationship.child.versioning_scheme
         else:
             custom_prefix = parent_project.custom_prefix
+            versioning_scheme = parent_project.versioning_scheme
 
         return self.base_resolve_path(
             filename=filename,
             version_slug=version_slug,
             language=language,
-            single_version=single_version,
+            versioning_scheme=versioning_scheme,
             project_relationship=project_relationship,
             custom_prefix=custom_prefix,
         )
@@ -152,7 +158,6 @@ def resolve_version(self, project, version=None, filename="/"):
             filename=filename,
             version_slug=version.slug,
             language=project.language,
-            single_version=project.single_version,
         )
         protocol = "https" if use_https else "http"
         return urlunparse((protocol, domain, path, "", "", ""))