[gi-docgen/tintou/opensearch] generate: Add support for OpenSearch

[Corentin Noël <corentinnoel src gnome org>]

commit 9b205f19b4b69064407af4519157f76755c8263f
Author: Corentin Noël <corentin noel collabora com>
Date:   Thu Nov 4 12:21:35 2021 +0100

    generate: Add support for OpenSearch
    
    If the `docs_url` key is used and the search is enabled, an OpenSearch
    file is created to allow better integration with the browsers.

 docs/project-configuration.rst     |  2 ++
 gidocgen/config.py                 |  4 ++++
 gidocgen/gdgenerate.py             | 26 +++++++++++++++++++++++++-
 gidocgen/templates/basic/base.html |  5 +++++
 4 files changed, 36 insertions(+), 1 deletion(-)
---
diff --git a/docs/project-configuration.rst b/docs/project-configuration.rst
index 9da5c84..728a8d4 100644
--- a/docs/project-configuration.rst
+++ b/docs/project-configuration.rst
@@ -62,6 +62,8 @@ The following keys are used, if found:
 ``search_index`` = ``b``
   Whether gi-docgen should generate a search index file for the namespace.
 
+``docs_url`` = ``s``
+  The website that will provide this documentation.
 
 The ``theme`` section
 ~~~~~~~~~~~~~~~~~~~~~
diff --git a/gidocgen/config.py b/gidocgen/config.py
index 3da1709..58fdec8 100644
--- a/gidocgen/config.py
+++ b/gidocgen/config.py
@@ -73,6 +73,10 @@ class GIDocConfig:
     def website_url(self):
         return self.library.get('website_url', '')
 
+    @property
+    def docs_url(self):
+        return self.library.get('docs_url', '')
+
     @property
     def browse_url(self):
         return self.library.get('browse_url', '')
diff --git a/gidocgen/gdgenerate.py b/gidocgen/gdgenerate.py
index 325c11a..269fa39 100644
--- a/gidocgen/gdgenerate.py
+++ b/gidocgen/gdgenerate.py
@@ -2660,6 +2660,26 @@ def gen_types_hierarchy(config, theme_config, output_dir, jinja_env, repository)
         "href": content["output_file"],
     }
 
+def gen_opensearch(config, repository, namespace, symbols, content_files):
+    desc = etree.Element('OpenSearchDescription')
+    desc.set("xmlns", "http://a9.com/-/spec/opensearch/1.1/";)
+    desc.set("xmlns:moz", "http://www.mozilla.org/2006/browser/search/";)
+    sub = etree.SubElement(desc, 'ShortName')
+    sub.text=f"{namespace.name}"
+    sub = etree.SubElement(desc, 'Description')
+    sub.text=f"{namespace.name}-{namespace.version} Reference Manual"
+    sub = etree.SubElement(desc, 'InputEncoding')
+    sub.text="UTF-8"
+    if config.logo_url:
+        sub = etree.SubElement(desc, 'Image')
+        sub.text=config.logo_url
+    sub = etree.SubElement(desc, 'Url', type="text/html")
+    sub.set("type", "text/html")
+    sub.set("template", f"{config.docs_url}/?q={{searchTerms}}")
+    sub = etree.SubElement(desc, 'moz:SearchForm')
+    sub.text=f"{config.docs_url}"
+
+    return etree.ElementTree(desc)
 
 def gen_devhelp(config, repository, namespace, symbols, content_files):
     book = etree.Element('book')
@@ -2944,7 +2964,11 @@ def gen_reference(config, options, repository, templates_dir, theme_config, cont
         res = gen_devhelp(config, repository, namespace, template_symbols, content_files)
         res.write(devhelp_file, encoding="UTF-8")
 
-    if config.search_index:
+    if config.search_index and config.docs_url:
+        opensearch_file = os.path.join(ns_dir, "opensearch.xml")
+        log.info(f"Creating OpenSearch file for {namespace.name}-{namespace.version}: {opensearch_file}")
+        res = gen_opensearch(config, repository, namespace, template_symbols, content_files)
+        res.write(opensearch_file, encoding="UTF-8")
         gdgenindices.gen_indices(config, repository, content_dirs, ns_dir)
 
     copy_files = []
diff --git a/gidocgen/templates/basic/base.html b/gidocgen/templates/basic/base.html
index 963a73e..36598ba 100644
--- a/gidocgen/templates/basic/base.html
+++ b/gidocgen/templates/basic/base.html
@@ -34,6 +34,11 @@ SPDX-License-Identifier: Apache-2.0 OR GPL-3.0-or-later
   {% if CONFIG.site_url %}
   <link rel="canonical" href="{{ CONFIG.site_url }}"/>
   {% endif %}
+  {% if CONFIG.search_index %}
+  {% if CONFIG.docs_url %}
+  <link rel="search" type="application/opensearchdescription+xml" title="{{ namespace.name }}" 
href="opensearch.xml">
+  {% endif %}
+  {% endif %}
 
   <link rel="stylesheet" href="style.css" type="text/css" />