Merge pull request #63 from rails/variants

On-demand variants

21 files changed, 296 insertions, 53 deletions

diff --git a/Gemfile b/Gemfile
index 7154892086..953b85ccfe 100644
--- a/Gemfile
+++ b/Gemfile
@@ -18,4 +18,6 @@ gem "httparty"
 gem "aws-sdk", "~> 2", require: false
 gem "google-cloud-storage", "~> 1.3", require: false
 
+gem 'mini_magick'
+
 gem "rubocop", require: false
diff --git a/Gemfile.lock b/Gemfile.lock
index 5b283272f7..e18acab95b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,6 +2,16 @@ GIT
   remote: https://github.com/rails/rails.git
   revision: 5c16dd35a23f75038baf1527143ee44accf081ff
   specs:
+    actioncable (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      nio4r (~> 2.0)
+      websocket-driver (~> 0.6.1)
+    actionmailer (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      actionview (= 5.2.0.alpha)
+      activejob (= 5.2.0.alpha)
+      mail (~> 2.5, >= 2.5.4)
+      rails-dom-testing (~> 2.0)
     actionpack (5.2.0.alpha)
       actionview (= 5.2.0.alpha)
       activesupport (= 5.2.0.alpha)
@@ -29,15 +39,30 @@ GIT
       i18n (~> 0.7)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
+    rails (5.2.0.alpha)
+      actioncable (= 5.2.0.alpha)
+      actionmailer (= 5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      actionview (= 5.2.0.alpha)
+      activejob (= 5.2.0.alpha)
+      activemodel (= 5.2.0.alpha)
+      activerecord (= 5.2.0.alpha)
+      activesupport (= 5.2.0.alpha)
+      bundler (>= 1.3.0)
+      railties (= 5.2.0.alpha)
+      sprockets-rails (>= 2.0.0)
+    railties (5.2.0.alpha)
+      actionpack (= 5.2.0.alpha)
+      activesupport (= 5.2.0.alpha)
+      method_source
+      rake (>= 0.8.7)
+      thor (>= 0.18.1, < 2.0)
 
 PATH
   remote: .
   specs:
     activestorage (0.1)
-      actionpack (>= 5.2.0.alpha)
-      activejob (>= 5.2.0.alpha)
-      activerecord (>= 5.2.0.alpha)
-      activesupport (>= 5.2.0.alpha)
+      rails (>= 5.2.0.alpha)
 
 GEM
   remote: https://rubygems.org/
@@ -101,15 +126,20 @@ GEM
       multi_json (~> 1.10)
     loofah (2.0.3)
       nokogiri (>= 1.5.9)
+    mail (2.6.5)
+      mime-types (>= 1.16, < 4)
     memoist (0.16.0)
+    method_source (0.8.2)
     mime-types (3.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0521)
+    mini_magick (4.8.0)
     mini_portile2 (2.2.0)
     minitest (5.10.2)
     multi_json (1.12.1)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
+    nio4r (2.1.0)
     nokogiri (1.8.0)
       mini_portile2 (~> 2.2.0)
     os (0.9.6)
@@ -147,12 +177,23 @@ GEM
       faraday (~> 0.9)
       jwt (~> 1.5)
       multi_json (~> 1.10)
+    sprockets (3.7.1)
+      concurrent-ruby (~> 1.0)
+      rack (> 1, < 3)
+    sprockets-rails (3.2.0)
+      actionpack (>= 4.0)
+      activesupport (>= 4.0)
+      sprockets (>= 3.0.0)
     sqlite3 (1.3.13)
+    thor (0.19.4)
     thread_safe (0.3.6)
     tzinfo (1.2.3)
       thread_safe (~> 0.1)
     uber (0.1.0)
     unicode-display_width (1.3.0)
+    websocket-driver (0.6.5)
+      websocket-extensions (>= 0.1.0)
+    websocket-extensions (0.1.2)
 
 PLATFORMS
   ruby
@@ -168,9 +209,10 @@ DEPENDENCIES
   byebug
   google-cloud-storage (~> 1.3)
   httparty
+  mini_magick
   rake
   rubocop
   sqlite3
 
 BUNDLED WITH
-   1.15.1
+   1.15.2
diff --git a/README.md b/README.md
index 27678a8fe1..b56999cae7 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,13 @@ class MessagesController < ApplicationController
 end
 ```
 
+Variation of image attachment:
+
+```erb
+<%# Hitting the variant URL will lazy transform the original blob and then redirect to its new service location %>
+<%= image_tag url_for(user.avatar.variant(resize: "100x100")) %>
+```
+
 ## Installation
 
 1. Add `gem "activestorage", git: "https://github.com/rails/activestorage.git"` to your Gemfile.
@@ -70,6 +77,7 @@ end
 3. Run `rails activestorage:install` to create needed directories, migrations, and configuration.
 4. Configure the storage service in `config/environments/*` with `config.active_storage.service = :local`
    that references the services configured in `config/storage_services.yml`.
+5. Optional: Add `gem "mini_magick"` to your Gemfile if you want to use variants.
 
 ## Todos
 
diff --git a/Rakefile b/Rakefile
index f0baf50163..a41e07f373 100644
--- a/Rakefile
+++ b/Rakefile
@@ -3,6 +3,7 @@ require "bundler/gem_tasks"
 require "rake/testtask"
 
 Rake::TestTask.new do |test|
+  test.libs << "app/controllers"
   test.libs << "test"
   test.test_files = FileList["test/**/*_test.rb"]
   test.warning = false
diff --git a/activestorage.gemspec b/activestorage.gemspec
index 884d3287e6..9546b60783 100644
--- a/activestorage.gemspec
+++ b/activestorage.gemspec
@@ -9,10 +9,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = ">= 2.3.0"
 
-  s.add_dependency "activesupport", ">= 5.2.0.alpha"
-  s.add_dependency "activerecord", ">= 5.2.0.alpha"
-  s.add_dependency "actionpack", ">= 5.2.0.alpha"
-  s.add_dependency "activejob", ">= 5.2.0.alpha"
+  s.add_dependency "rails", ">= 5.2.0.alpha"
 
   s.add_development_dependency "bundler", "~> 1.15"
 
diff --git a/lib/active_storage/direct_uploads_controller.rb b/app/controllers/active_storage/direct_uploads_controller.rb
index 99ff27f903..dccd864e8d 100644
--- a/lib/active_storage/direct_uploads_controller.rb
+++ b/app/controllers/active_storage/direct_uploads_controller.rb
@@ -1,6 +1,3 @@
-require "action_controller"
-require "active_storage/blob"
-
 class ActiveStorage::DirectUploadsController < ActionController::Base
   def create
     blob = ActiveStorage::Blob.create_before_direct_upload!(blob_args)
diff --git a/lib/active_storage/disk_controller.rb b/app/controllers/active_storage/disk_controller.rb
index 16a295d00d..16a295d00d 100644
--- a/lib/active_storage/disk_controller.rb
+++ b/app/controllers/active_storage/disk_controller.rb
diff --git a/app/controllers/active_storage/variants_controller.rb b/app/controllers/active_storage/variants_controller.rb
new file mode 100644
index 0000000000..dde7e1458f
--- /dev/null
+++ b/app/controllers/active_storage/variants_controller.rb
@@ -0,0 +1,25 @@
+class ActiveStorage::VariantsController < ActionController::Base
+  def show
+    if blob_key = decode_verified_blob_key
+      redirect_to processed_variant_for(blob_key).url(disposition: disposition_param)
+    else
+      head :not_found
+    end
+  end
+
+  private
+    def decode_verified_blob_key
+      ActiveStorage::VerifiedKeyWithExpiration.decode(params[:encoded_blob_key])
+    end
+
+    def processed_variant_for(blob_key)
+      ActiveStorage::Variant.new(
+        ActiveStorage::Blob.find_by!(key: blob_key),
+        ActiveStorage::Variation.decode(params[:variation_key])
+      ).processed
+    end
+
+    def disposition_param
+      params[:disposition].presence_in(%w( inline attachment )) || 'inline'
+    end
+end
diff --git a/config/routes.rb b/config/routes.rb
new file mode 100644
index 0000000000..d25f2c82f0
--- /dev/null
+++ b/config/routes.rb
@@ -0,0 +1,16 @@
+Rails.application.routes.draw do
+  get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
+  post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
+
+  get  "/rails/active_storage/variants/:encoded_blob_key/:variation_key/*filename" => "active_storage/variants#show", as: :rails_blob_variation
+
+  direct :rails_variant do |variant|
+    encoded_blob_key = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
+    variation_key    = variant.variation.key
+    filename         = variant.blob.filename
+
+    route_for(:rails_blob_variation, encoded_blob_key, variation_key, filename)
+  end
+
+  resolve('ActiveStorage::Variant') { |variant| route_for(:rails_variant, variant) }
+end
diff --git a/lib/active_storage/blob.rb b/lib/active_storage/blob.rb
index 1a15361747..6bd3941cd8 100644
--- a/lib/active_storage/blob.rb
+++ b/lib/active_storage/blob.rb
@@ -1,6 +1,7 @@
 require "active_storage/service"
 require "active_storage/filename"
 require "active_storage/purge_job"
+require "active_storage/variant"
 
 # Schema: id, key, filename, content_type, metadata, byte_size, checksum, created_at
 class ActiveStorage::Blob < ActiveRecord::Base
@@ -31,8 +32,9 @@ class ActiveStorage::Blob < ActiveRecord::Base
     end
   end
 
-  # We can't wait until the record is first saved to have a key for it
+
   def key
+    # We can't wait until the record is first saved to have a key for it
     self[:key] ||= self.class.generate_unique_secure_token
   end
 
@@ -40,6 +42,11 @@ class ActiveStorage::Blob < ActiveRecord::Base
     ActiveStorage::Filename.new(self[:filename])
   end
 
+  def variant(transformations)
+    ActiveStorage::Variant.new(self, ActiveStorage::Variation.new(transformations))
+  end
+
+
   def url(expires_in: 5.minutes, disposition: :inline)
     service.url key, expires_in: expires_in, disposition: disposition, filename: filename
   end
diff --git a/lib/active_storage/engine.rb b/lib/active_storage/engine.rb
index 5f0b62809e..b32ae34516 100644
--- a/lib/active_storage/engine.rb
+++ b/lib/active_storage/engine.rb
@@ -14,17 +14,6 @@ module ActiveStorage
       end
     end
 
-    initializer "active_storage.routes" do
-      require "active_storage/disk_controller"
-      require "active_storage/direct_uploads_controller"
-
-      config.after_initialize do |app|
-        app.routes.prepend do
-          eval(File.read(File.expand_path("../routes.rb", __FILE__)))
-        end
-      end
-    end
-
     initializer "active_storage.attached" do
       require "active_storage/attached"
 
@@ -33,32 +22,42 @@ module ActiveStorage
       end
     end
 
-    config.after_initialize do |app|
-      if config_choice = app.config.active_storage.service
-        config_file = Pathname.new(Rails.root.join("config/storage_services.yml"))
-        raise("Couldn't find Active Storage configuration in #{config_file}") unless config_file.exist?
+    initializer "active_storage.verifiers" do
+      require "active_storage/verified_key_with_expiration"
+      require "active_storage/variation"
 
-        require "yaml"
-        require "erb"
+      config.after_initialize do |app|
+        ActiveStorage::VerifiedKeyWithExpiration.verifier = \
+        ActiveStorage::Variation.verifier = \
+          Rails.application.message_verifier('ActiveStorage')
+      end
+    end
+
+    initializer "active_storage.services" do
+      config.after_initialize do |app|
+        if config_choice = app.config.active_storage.service
+          config_file = Pathname.new(Rails.root.join("config/storage_services.yml"))
+          raise("Couldn't find Active Storage configuration in #{config_file}") unless config_file.exist?
+
+          require "yaml"
+          require "erb"
 
-        configs =
-          begin
-            YAML.load(ERB.new(config_file.read).result) || {}
-          rescue Psych::SyntaxError => e
-            raise "YAML syntax error occurred while parsing #{config_file}. " \
-                  "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
-                  "Error: #{e.message}"
-          end
+          configs =
+            begin
+              YAML.load(ERB.new(config_file.read).result) || {}
+            rescue Psych::SyntaxError => e
+              raise "YAML syntax error occurred while parsing #{config_file}. " \
+                    "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. " \
+                    "Error: #{e.message}"
+            end
 
-        ActiveStorage::Blob.service =
-          begin
-            ActiveStorage::Service.configure config_choice, configs
-          rescue => e
-            raise e, "Cannot load `Rails.config.active_storage.service`:\n#{e.message}", e.backtrace
-          end
-      else
-        raise "No storage service specified for current env (#{Rails.env}). " \
-              "Add config.active_storage.service = :local into your config/environments/#{Rails.env}.rb."
+          ActiveStorage::Blob.service =
+            begin
+              ActiveStorage::Service.configure config_choice, configs
+            rescue => e
+              raise e, "Cannot load `Rails.config.active_storage.service`:\n#{e.message}", e.backtrace
+            end
+        end
       end
     end
   end
diff --git a/lib/active_storage/routes.rb b/lib/active_storage/routes.rb
deleted file mode 100644
index 748427a776..0000000000
--- a/lib/active_storage/routes.rb
+++ /dev/null
@@ -1,2 +0,0 @@
-get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
-post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
diff --git a/lib/active_storage/variant.rb b/lib/active_storage/variant.rb
new file mode 100644
index 0000000000..435033f980
--- /dev/null
+++ b/lib/active_storage/variant.rb
@@ -0,0 +1,35 @@
+require "active_storage/blob"
+require "mini_magick"
+
+# Image blobs can have variants that are the result of a set of transformations applied to the original.
+class ActiveStorage::Variant
+  attr_reader :blob, :variation
+  delegate :service, to: :blob
+
+  def initialize(blob, variation)
+    @blob, @variation = blob, variation
+  end
+
+  def processed
+    process unless service.exist?(key)
+    self
+  end
+
+  def key
+    "variants/#{blob.key}/#{variation.key}"
+  end
+
+  def url(expires_in: 5.minutes, disposition: :inline)
+    service.url key, expires_in: expires_in, disposition: disposition, filename: blob.filename
+  end
+
+
+  private
+    def process
+      service.upload key, transform(service.download(blob.key))
+    end
+
+    def transform(io)
+      File.open MiniMagick::Image.read(io).tap { |image| variation.transform(image) }.path
+    end
+end
diff --git a/lib/active_storage/variation.rb b/lib/active_storage/variation.rb
new file mode 100644
index 0000000000..abff288ac1
--- /dev/null
+++ b/lib/active_storage/variation.rb
@@ -0,0 +1,53 @@
+require "active_support/core_ext/object/inclusion"
+
+# A set of transformations that can be applied to a blob to create a variant.
+class ActiveStorage::Variation
+  class_attribute :verifier
+
+  ALLOWED_TRANSFORMATIONS = %i(
+    resize rotate format flip fill monochrome orient quality roll scale sharpen shave shear size thumbnail
+    transparent transpose transverse trim background bordercolor compress crop
+  )
+
+  attr_reader :transformations
+
+  class << self
+    def decode(key)
+      new verifier.verify(key)
+    end
+    
+    def encode(transformations)
+      verifier.generate(transformations)
+    end
+  end
+
+  def initialize(transformations)
+    @transformations = transformations
+  end
+
+  def transform(image)
+    transformations.each do |(method, argument)|
+      next unless eligible_transformation?(method)
+
+      if eligible_argument?(argument)
+        image.public_send(method, argument)
+      else
+        image.public_send(method)
+      end
+    end
+  end
+
+  def key
+    self.class.encode(transformations)
+  end
+
+  private
+    def eligible_transformation?(method)
+      method.to_sym.in?(ALLOWED_TRANSFORMATIONS)
+    end
+
+    # FIXME: Consider whitelisting allowed arguments as well?
+    def eligible_argument?(argument)
+      argument.present? && argument != true
+    end
+end
diff --git a/lib/active_storage/verified_key_with_expiration.rb b/lib/active_storage/verified_key_with_expiration.rb
index e429ee21ce..4a46483db5 100644
--- a/lib/active_storage/verified_key_with_expiration.rb
+++ b/lib/active_storage/verified_key_with_expiration.rb
@@ -1,5 +1,5 @@
 class ActiveStorage::VerifiedKeyWithExpiration
-  class_attribute :verifier, default: defined?(Rails) ? Rails.application.message_verifier("ActiveStorage") : nil
+  class_attribute :verifier
 
   class << self
     def encode(key, expires_in: nil)
diff --git a/test/controllers/variants_controller.rb b/test/controllers/variants_controller.rb
new file mode 100644
index 0000000000..6753584d4d
--- /dev/null
+++ b/test/controllers/variants_controller.rb
@@ -0,0 +1,24 @@
+require "test_helper"
+require "database/setup"
+
+require "active_storage/variants_controller"
+require "active_storage/verified_key_with_expiration"
+
+class ActiveStorage::VariantsControllerTest < ActionController::TestCase
+  setup do
+    @routes = Routes
+    @controller = ActiveStorage::VariantsController.new
+
+    @blob = create_image_blob filename: "racecar.jpg"
+  end
+
+  test "showing variant inline" do
+    get :show, params: {
+      filename: @blob.filename,
+      encoded_blob_key: ActiveStorage::VerifiedKeyWithExpiration.encode(@blob.key, expires_in: 5.minutes),
+      variation_key: ActiveStorage::Variation.encode(resize: "100x100") }
+
+    assert_redirected_to /racecar.jpg\?disposition=inline/
+    assert_same_image "racecar-100x100.jpg", @blob.variant(resize: "100x100")
+  end
+end
diff --git a/test/fixtures/files/racecar-100x100-monochrome.jpg b/test/fixtures/files/racecar-100x100-monochrome.jpg
new file mode 100644
index 0000000000..39e683747e
--- /dev/null
+++ b/test/fixtures/files/racecar-100x100-monochrome.jpg
diff --git a/test/fixtures/files/racecar-100x100.jpg b/test/fixtures/files/racecar-100x100.jpg
new file mode 100644
index 0000000000..2a515a4912
--- /dev/null
+++ b/test/fixtures/files/racecar-100x100.jpg
diff --git a/test/fixtures/files/racecar.jpg b/test/fixtures/files/racecar.jpg
new file mode 100644
index 0000000000..934b4caa22
--- /dev/null
+++ b/test/fixtures/files/racecar.jpg
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 03593b12c7..20b22049b3 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+$LOAD_PATH << File.expand_path("../../app/controllers", __FILE__)
+
 require "bundler/setup"
 require "active_support"
 require "active_support/test_case"
@@ -15,7 +17,6 @@ rescue Errno::ENOENT
   {}
 end
 
-
 require "active_storage/service/disk_service"
 require "tmpdir"
 ActiveStorage::Blob.service = ActiveStorage::Service::DiskService.new(root: Dir.mktmpdir("active_storage_tests"))
@@ -24,20 +25,35 @@ ActiveStorage::Service.logger = ActiveSupport::Logger.new(STDOUT)
 require "active_storage/verified_key_with_expiration"
 ActiveStorage::VerifiedKeyWithExpiration.verifier = ActiveSupport::MessageVerifier.new("Testing")
 
+require "active_storage/variation"
+ActiveStorage::Variation.verifier = ActiveSupport::MessageVerifier.new("Testing")
+
 class ActiveSupport::TestCase
   private
     def create_blob(data: "Hello world!", filename: "hello.txt", content_type: "text/plain")
       ActiveStorage::Blob.create_after_upload! io: StringIO.new(data), filename: filename, content_type: content_type
     end
+
+    def create_image_blob(filename: "racecar.jpg", content_type: "image/jpeg")
+      ActiveStorage::Blob.create_after_upload! \
+        io: File.open(File.expand_path("../fixtures/files/#{filename}", __FILE__)),
+        filename: filename, content_type: content_type
+    end
+
+    def assert_same_image(fixture_filename, variant)
+      assert_equal \
+        File.binread(File.expand_path("../fixtures/files/#{fixture_filename}", __FILE__)),
+        File.binread(variant.service.send(:path_for, variant.key))
+    end
 end
 
 require "action_controller"
 require "action_controller/test_case"
-
 class ActionController::TestCase
   Routes = ActionDispatch::Routing::RouteSet.new.tap do |routes|
     routes.draw do
-      eval(File.read(File.expand_path("../../lib/active_storage/routes.rb", __FILE__)))
+      # FIXME: Hacky way to avoid having to instantiate the real engine
+      eval(File.readlines(File.expand_path("../../config/routes.rb", __FILE__)).slice(1..-2).join("\n"))
     end
   end
 end
diff --git a/test/variant_test.rb b/test/variant_test.rb
new file mode 100644
index 0000000000..5294b87135
--- /dev/null
+++ b/test/variant_test.rb
@@ -0,0 +1,23 @@
+require "test_helper"
+require "database/setup"
+require "active_storage/variant"
+
+class ActiveStorage::VariantTest < ActiveSupport::TestCase
+  setup do
+    @blob = create_image_blob filename: "racecar.jpg"
+  end
+
+  test "resized variation" do
+    variant = @blob.variant(resize: "100x100").processed
+
+    assert_match /racecar.jpg/, variant.url    
+    assert_same_image "racecar-100x100.jpg", variant    
+  end
+
+  test "resized and monochrome variation" do
+    variant = @blob.variant(resize: "100x100", monochrome: true).processed
+
+    assert_match /racecar.jpg/, variant.url
+    assert_same_image "racecar-100x100-monochrome.jpg", variant    
+  end
+end