FIX: automatically bust cache for share ai assets (#942)

* FIX: automatically bust cache for share ai assets CDNs can be configured to strip query params in Discourse hosting. This is generally safe, but in this case we had no way of busting the cache using the path. New design properly caches and properly breaks busts the cache if asset changes so we don't need to worry about versions * one day I will set up conditional lint on save :)
2025-02-16 16:34:45 +00:00 · 2024-11-22 11:23:15 +11:00 · 2024-11-22 11:23:15 +11:00 · 86cf4ccba7
commit 86cf4ccba7
parent 2c78961bed
6 changed files with 79 additions and 9 deletions
--- a/app/controllers/discourse_ai/ai_bot/shared_ai_conversations_controller.rb
+++ b/app/controllers/discourse_ai/ai_bot/shared_ai_conversations_controller.rb
@ -7,7 +7,8 @@ module DiscourseAi
      requires_login only: %i[create update destroy]
      before_action :require_site_settings!

-      skip_before_action :preload_json, :check_xhr, only: %i[show]
+      skip_before_action :preload_json, :check_xhr, only: %i[show asset]
+      skip_before_action :verify_authenticity_token, only: ["asset"]

      def create
        ensure_allowed_create!
@ -50,6 +51,30 @@ module DiscourseAi
        end
      end

+      def asset
+        no_cookies
+
+        name = params[:name]
+        path, content_type =
+          if name == "share"
+            %w[share.css text/css]
+          elsif name == "highlight"
+            %w[highlight.min.js application/javascript]
+          else
+            raise Discourse::NotFound
+          end
+
+        content = File.read(DiscourseAi.public_asset_path("ai-share/#{path}"))
+
+        # note, path contains a ":version" which automatically busts the cache
+        # based on file content, so this is safe
+        response.headers["Last-Modified"] = 10.years.ago.httpdate
+        response.headers["Content-Length"] = content.bytesize.to_s
+        immutable_for 1.year
+
+        render plain: content, disposition: :nil, content_type: content_type
+      end
+
      def preview
        ensure_allowed_preview!
        data = SharedAiConversation.build_conversation_data(@topic, include_usernames: true)
--- a/app/helpers/discourse_ai/ai_bot/shared_ai_conversations_helper.rb
+++ b/app/helpers/discourse_ai/ai_bot/shared_ai_conversations_helper.rb
@ -2,13 +2,29 @@
 module DiscourseAi
  module AiBot
    module SharedAiConversationsHelper
-      # bump up version when assets change
-      # long term we may want to change this cause it is hard to remember
-      # to bump versions, but for now this does the job
-      VERSION = "1"
+      # keeping it here for caching
+      def self.share_asset_url(asset_name)
+        if !%w[share.css highlight.js].include?(asset_name)
+          raise StandardError, "unknown asset type #{asset_name}"
+        end

-      def share_asset_url(short_path)
-        ::UrlHelper.absolute("/plugins/discourse-ai/ai-share/#{short_path}?#{VERSION}")
+        @urls ||= {}
+        url = @urls[asset_name]
+        return url if url
+
+        path = asset_name
+        path = "highlight.min.js" if asset_name == "highlight.js"
+
+        content = File.read(DiscourseAi.public_asset_path("ai-share/#{path}"))
+        sha1 = Digest::SHA1.hexdigest(content)
+
+        url = "/discourse-ai/ai-bot/shared-ai-conversations/asset/#{sha1}/#{asset_name}"
+
+        @urls[asset_name] = GlobalPath.cdn_path(url)
+      end
+
+      def share_asset_url(asset_name)
+        DiscourseAi::AiBot::SharedAiConversationsHelper.share_asset_url(asset_name)
      end
    end
  end
--- a/app/views/discourse_ai/ai_bot/shared_ai_conversations/show.html.erb
+++ b/app/views/discourse_ai/ai_bot/shared_ai_conversations/show.html.erb
@ -10,7 +10,7 @@
    <meta name="twitter:title" content="<%= I18n.t("discourse_ai.share_ai.title", title: @shared_conversation.title, site_name: SiteSetting.title) %>">
    <meta name="twitter:description" content="<%= @shared_conversation.formatted_excerpt %>">
    <meta name="viewport" content="width=device-width">
-    <link rel="stylesheet" href="<%= ::UrlHelper.absolute("/plugins/discourse-ai/ai-share/share.css?v=1") %>">
+    <link rel="stylesheet" href="<%= share_asset_url("share.css")  %>">
  </head>
  <body>
    <header class="site-header">
@ -54,7 +54,7 @@
        </article>
      <% end %>
    </section>
-    <script src="<%= share_asset_url("highlight.min.js") %>" nonce="<%= csp_nonce_placeholder %>" ></script>
+    <script src="<%= share_asset_url("highlight.js") %>" nonce="<%= csp_nonce_placeholder %>" ></script>
    <script nonce="<%= csp_nonce_placeholder %>">
      document.querySelectorAll('pre code').forEach((el) => {
        hljs.highlightElement(el);
--- a/config/routes.rb
+++ b/config/routes.rb
@ -30,6 +30,7 @@ DiscourseAi::Engine.routes.draw do
    post "/" => "shared_ai_conversations#create"
    delete "/:share_key" => "shared_ai_conversations#destroy"
    get "/:share_key" => "shared_ai_conversations#show"
+    get "/asset/:version/:name" => "shared_ai_conversations#asset"
    get "/preview/:topic_id" => "shared_ai_conversations#preview"
  end

--- a/plugin.rb
+++ b/plugin.rb
@ -43,6 +43,10 @@ register_asset "stylesheets/modules/ai-bot/common/ai-artifact.scss"

 module ::DiscourseAi
  PLUGIN_NAME = "discourse-ai"
+
+  def self.public_asset_path(name)
+    File.expand_path(File.join(__dir__, "public", name))
+  end
 end

 Rails.autoloaders.main.push_dir(File.join(__dir__, "lib"), namespace: ::DiscourseAi)
--- a/spec/requests/ai_bot/shared_ai_conversations_controller_spec.rb
+++ b/spec/requests/ai_bot/shared_ai_conversations_controller_spec.rb
@ -294,6 +294,30 @@ RSpec.describe DiscourseAi::AiBot::SharedAiConversationsController do
    end
  end

+  describe "GET asset" do
+    let(:helper) { Class.new { extend DiscourseAi::AiBot::SharedAiConversationsHelper } }
+
+    it "renders highlight js correctly" do
+      get helper.share_asset_url("highlight.js")
+
+      expect(response).to be_successful
+      expect(response.headers["Content-Type"]).to eq("application/javascript; charset=utf-8")
+
+      js = File.read(DiscourseAi.public_asset_path("ai-share/highlight.min.js"))
+      expect(response.body).to eq(js)
+    end
+
+    it "renders css correctly" do
+      get helper.share_asset_url("share.css")
+
+      expect(response).to be_successful
+      expect(response.headers["Content-Type"]).to eq("text/css; charset=utf-8")
+
+      css = File.read(DiscourseAi.public_asset_path("ai-share/share.css"))
+      expect(response.body).to eq(css)
+    end
+  end
+
  describe "GET preview" do
    it "denies preview from logged out users" do
      get "#{path}/preview/#{user_pm_share.id}.json"