Add basic OEmbed provider API, fix #247

app/controllers/api/oembed_controller.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class Api::OembedController < ApiController
+  respond_to :json
+
+  def show
+    @stream_entry = stream_entry_from_url(params[:url])
+    @width        = [300, params[:maxwidth].to_i].min
+    @height       = [200, params[:maxheight].to_i].min
+  end
+
+  private
+
+  def stream_entry_from_url(url)
+    params = Rails.application.routes.recognize_path(url)
+
+    raise ActiveRecord::NotFound unless params[:controller] == 'stream_entries' && params[:action] == 'show'
+
+    StreamEntry.find(params[:id])
+  end
+end

app/helpers/api/oembed_helper.rb

@@ -0,0 +1,2 @@
+module Api::OembedHelper
+end

app/views/api/oembed/show.json.rabl

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+object @stream_entry
+
+node(:type) { 'rich' }
+node(:version) { '1.0' }
+node(:title, &:title)
+node(:author_name) { |entry| entry.account.display_name.blank? ? entry.account.username : entry.account.display_name }
+node(:author_url) { |entry| account_url(entry.account) }
+node(:provider_name) { Rails.configuration.x.local_domain }
+node(:provider_url) { root_url }
+node(:cache_age) { 86_400 }
+node(:html, &:content)
+node(:width) { @width }
+node(:height) { @height }

app/views/stream_entries/show.html.haml

@@ -1,8 +1,13 @@
 - content_for :header_tags do
   %link{ rel: 'alternate', type: 'application/atom+xml', href: account_stream_entry_url(@account, @stream_entry, format: 'atom') }/
+  %link{ rel: 'alternate', type: 'application/json+oembed', href: api_oembed_url(url: account_stream_entry_url(@account, @stream_entry), format: 'json') }/
+
   %meta{ name: 'og:site_name', content: 'Mastodon' }/
   %meta{ name: 'og:type', content: 'article' }/
+  %meta{ name: 'og:title', content: "#{@account.username} on #{Rails.configuration.x.local_domain}" }/
   %meta{ name: 'og:article:author', content: @account.username }/
+  %meta{ name: 'og:description', content: @stream_entry.activity.content }/
+  %meta{ name: 'og:image', content: @stream_entry.activity.is_a?(Status) && @stream_entry.activity.media_attachments.size > 0 ? full_asset_url(@stream_entry.activity.media_attachments.first.file.url(:preview)) : full_asset_url(@account.avatar.url(:large)) }/
 
 .activity-stream.activity-stream-headless
   = render partial: @type, locals: { @type.to_sym => @stream_entry.activity, include_threads: true }