From 9a035825131cb73425b20ec48e806a2a9e75c3ac Mon Sep 17 00:00:00 2001
From: evazion <noizave@gmail.com>
Date: Sat, 4 Jul 2020 17:46:58 -0500
Subject: [PATCH] Add OpenSearch suggestion support.

Add autocomplete support when searching Danbooru from the Chrome address
bar. If you type "danb<tab>" in the address bar then search for a tag,
then autocomplete results from Danbooru will appear as search
suggestions in Chrome.

Note that the "Autocomplete searches and URLs" Chrome setting must be
enabled for this to work.

Ref:

* http://dev.chromium.org/tab-to-search
* https://developer.mozilla.org/en-US/docs/Archive/Add-ons/Supporting_search_suggestions_in_search_plugins
* https://github.com/dewitt/opensearch/blob/master/mediawiki/Specifications/OpenSearch/Extensions/Suggestions/1.1/Draft%201.wiki
---
 app/controllers/autocomplete_controller.rb      | 16 ++++++++++++++++
 app/views/static/opensearch.xml.erb             |  1 +
 test/functional/autocomplete_controller_test.rb | 17 +++++++++++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 app/controllers/autocomplete_controller.rb
 create mode 100644 test/functional/autocomplete_controller_test.rb

diff --git a/app/controllers/autocomplete_controller.rb b/app/controllers/autocomplete_controller.rb
new file mode 100644
index 000000000..37fa3565b
--- /dev/null
+++ b/app/controllers/autocomplete_controller.rb
@@ -0,0 +1,16 @@
+class AutocompleteController < ApplicationController
+  respond_to :xml, :json
+
+  def index
+    @tags = Tag.names_matches_with_aliases(params[:query], params.fetch(:limit, 10).to_i)
+
+    if request.variant.opensearch?
+      expires_in 1.hour
+      results = [params[:query], @tags.map(&:pretty_name)]
+      respond_with(results)
+    else
+      # XXX
+      respond_with(@tags.map(&:attributes))
+    end
+  end
+end
diff --git a/app/views/static/opensearch.xml.erb b/app/views/static/opensearch.xml.erb
index 3c67241f8..8652a2f9c 100644
--- a/app/views/static/opensearch.xml.erb
+++ b/app/views/static/opensearch.xml.erb
@@ -4,4 +4,5 @@
   <Description><%= Danbooru.config.app_name %> search</Description>
   <Image height="16" width="16" type="image/x-icon"><%= root_url %>favicon.ico</Image>
   <Url type="text/html" template="<%= posts_url %>?tags={searchTerms}&amp;utm_source=opensearch"/>
+  <Url type="application/x-suggestions+json" template="<%= autocomplete_index_url(format: :json) %>?query={searchTerms}&amp;type=tags&amp;variant=opensearch"/>
 </OpenSearchDescription>
diff --git a/test/functional/autocomplete_controller_test.rb b/test/functional/autocomplete_controller_test.rb
new file mode 100644
index 000000000..51c064029
--- /dev/null
+++ b/test/functional/autocomplete_controller_test.rb
@@ -0,0 +1,17 @@
+require "test_helper"
+
+class AutocompleteControllerTest < ActionDispatch::IntegrationTest
+  context "Autocomplete controller" do
+    context "index action" do
+      setup do
+        create(:tag, name: "azur_lane")
+      end
+
+      should "work for opensearch queries" do
+        get autocomplete_index_path(query: "azur", variant: "opensearch"), as: :json
+        assert_response :success
+        assert_equal(["azur", ["azur lane"]], response.parsed_body)
+      end
+    end
+  end
+end