Add oEmbed endpoint

app/controllers/application_controller.rb

@@ -81,6 +81,10 @@ class ApplicationController < ActionController::Base
     end
   end
 
-  helper_method :profile_path
+  def profile_url(user)
+    root_url[0..-2] + profile_path(user)
+  end
+
+  helper_method :profile_path, :profile_url
 
 end

app/controllers/oembed_controller.rb

@@ -0,0 +1,70 @@
+class OembedController < ApplicationController
+
+  def show
+    url = URI.parse(params[:url])
+
+    if url.path =~ %r{^/a/(\d+)$}
+      id = $1
+      asciicast = AsciicastDecorator.new(Asciicast.find(id))
+      oembed = oembed_response(asciicast)
+
+      respond_to do |format|
+        format.json do
+          render json: oembed
+        end
+        format.xml do
+          render xml: oembed.to_xml(root: 'oembed')
+        end
+      end
+    else
+      head :bad_request
+    end
+  end
+
+  private
+
+  def oembed_response(asciicast)
+    width, height = asciicast.image_width, asciicast.image_height
+
+    if params[:maxwidth]
+      width, height = size_smaller_than(width, height, params[:maxwidth], params[:maxheight])
+    end
+
+    oembed = {
+      type: 'rich',
+      version: 1.0,
+      title: asciicast.title,
+      author_name: asciicast.user.display_name,
+      author_url: profile_url(asciicast.user),
+      provider_name: 'asciinema',
+      provider_url: root_url,
+      thumbnail_url: asciicast.image_url,
+      thumbnail_width: width,
+      thumbnail_height: height,
+      html: render_html(asciicast, width),
+      width: width,
+      height: height,
+    }
+  end
+
+  def render_html(asciicast, width)
+    render_to_string(
+      template: 'oembed/show.html.erb',
+      layout: false,
+      locals: { asciicast: asciicast, width: width }
+    ).chomp
+  end
+
+  def size_smaller_than(width, height, max_width, max_height)
+    fw = Rational(max_width, width)
+    fh = Rational(max_height, height)
+
+    if fw > 1 && fh > 1
+      [width, height]
+    else
+      f = [fw, fh].min
+      [(Rational(width) * f).to_i, (Rational(height) * f).to_i]
+    end
+  end
+
+end

app/uploaders/asciicast_uploader.rb

@@ -1,12 +1,10 @@
 class AsciicastUploader < BaseUploader
 
   def url
-    url = super
-
-    if url[0] == '/'
+    if CFG.carrierwave_storage == 'file'
       path
     else
-      url
+      super
     end
   end
 

app/views/oembed/show.html.erb

@@ -0,0 +1 @@
+<%= link_to image_tag(asciicast.image_url, width: width, alt: asciicast.title), asciicast_url(asciicast), target: '_blank' %>

config/routes.rb

@@ -15,6 +15,8 @@ Rails.application.routes.draw do
   get "/u/:id" => "users#show", as: :unnamed_user
   get "/~:username" => "users#show", as: :public_profile
 
+  get "/oembed" => "oembed#show", as: :oembed
+
   namespace :api do
     resources :asciicasts
   end

spec/api/oembed_spec.rb

@@ -0,0 +1,17 @@
+require 'rails_helper'
+
+describe "oEmbed provider" do
+
+  let(:asciicast) { create(:asciicast) }
+
+  it "responds with status 200 for JSON" do
+    get "/oembed?url=http://localhost:3000/a/#{asciicast.id}&format=json"
+    expect(response.status).to eq(200)
+  end
+
+  it "responds with status 200 for XML" do
+    get "/oembed?url=http://localhost:3000/a/#{asciicast.id}&format=xml"
+    expect(response.status).to eq(200)
+  end
+
+end