add new model for post replacements, add undo functionality

app/models/post.rb

@@ -7,8 +7,6 @@ class Post < ActiveRecord::Base
   class RevertError < Exception ; end
   class SearchError < Exception ; end
 
-  DELETION_GRACE_PERIOD = 30.days
-
   before_validation :initialize_uploader, :on => :create
   before_validation :merge_old_changes
   before_validation :normalize_tags
@@ -51,6 +49,7 @@ class Post < ActiveRecord::Base
   has_many :approvals, :class_name => "PostApproval", :dependent => :destroy
   has_many :disapprovals, :class_name => "PostDisapproval", :dependent => :destroy
   has_many :favorites, :dependent => :destroy
+  has_many :replacements, class_name: "PostReplacement"
 
   if PostArchive.enabled?
     has_many :versions, lambda {order("post_versions.updated_at ASC")}, :class_name => "PostArchive", :dependent => :destroy
@@ -1430,50 +1429,9 @@ class Post < ActiveRecord::Base
       ModAction.log("undeleted post ##{id}")
     end
 
-    def replace!(url, replacer = CurrentUser.user)
+    def replace!(url)
-      # TODO for posts with notes we need to rescale the notes if the dimensions change.
+      replacement = replacements.create(replacement_url: url)
-      if notes.size > 0
+      replacement.process!
-        raise NotImplementedError.new("Replacing images with notes not yet supported.")
-      end
-
-      # TODO for ugoiras we need to replace the frame data.
-      if is_ugoira?
-        raise NotImplementedError.new("Replacing ugoira images not yet supported.")
-      end
-
-      # TODO images hosted on s3 need to be deleted from s3 instead of the local filesystem.
-      if Danbooru.config.use_s3_proxy?(self)
-        raise NotImplementedError.new("Replacing S3 hosted images not yet supported.")
-      end
-
-      transaction do
-        upload = Upload.create!(source: url, rating: self.rating, tag_string: self.tag_string)
-        upload.process_upload
-        upload.update(status: "completed", post_id: id)
-
-        # queue the deletion *before* updating the post so that we use the old
-        # md5/file_ext to delete the old files. if saving the post fails,
-        # this is rolled back so the job won't run.
-        Post.delay(queue: "default", run_at: Time.now + DELETION_GRACE_PERIOD).delete_files(id, file_path, large_file_path, preview_file_path)
-
-        self.md5 = upload.md5
-        self.file_ext = upload.file_ext
-        self.image_width = upload.image_width
-        self.image_height = upload.image_height
-        self.file_size = upload.file_size
-        self.source = upload.source
-        self.tag_string = upload.tag_string
-
-        comments.create!({creator: User.system, body: presenter.comment_replacement_message(replacer), do_not_bump_post: true}, without_protection: true)
-        ModAction.log(presenter.modaction_replacement_message)
-
-        save!
-      end
-
-      # point of no return: these things can't be rolled back, so we do them
-      # only after the transaction successfully commits.
-      distribute_files
-      update_iqdb_async
     end
   end
 

app/models/post_replacement.rb

@@ -0,0 +1,64 @@
+class PostReplacement < ActiveRecord::Base
+  DELETION_GRACE_PERIOD = 30.days
+
+  belongs_to :post
+  belongs_to :creator, class_name: "User"
+  before_validation :initialize_fields
+  attr_accessible :replacement_url
+
+  def initialize_fields
+    self.creator = CurrentUser.user
+    self.original_url = post.source
+  end
+
+  def undo!
+    undo_replacement = post.replacements.create(replacement_url: original_url)
+    undo_replacement.process!
+  end
+
+  def process!
+    # TODO for posts with notes we need to rescale the notes if the dimensions change.
+    if post.notes.any?
+      raise NotImplementedError.new("Replacing images with notes not yet supported.")
+    end
+
+    # TODO for ugoiras we need to replace the frame data.
+    if post.is_ugoira?
+      raise NotImplementedError.new("Replacing ugoira images not yet supported.")
+    end
+
+    # TODO images hosted on s3 need to be deleted from s3 instead of the local filesystem.
+    if Danbooru.config.use_s3_proxy?(post)
+      raise NotImplementedError.new("Replacing S3 hosted images not yet supported.")
+    end
+
+    transaction do
+      upload = Upload.create!(source: replacement_url, rating: post.rating, tag_string: post.tag_string)
+      upload.process_upload
+      upload.update(status: "completed", post_id: post.id)
+
+      # queue the deletion *before* updating the post so that we use the old
+      # md5/file_ext to delete the old files. if saving the post fails,
+      # this is rolled back so the job won't run.
+      Post.delay(queue: "default", run_at: Time.now + DELETION_GRACE_PERIOD).delete_files(post.id, post.file_path, post.large_file_path, post.preview_file_path)
+
+      post.md5 = upload.md5
+      post.file_ext = upload.file_ext
+      post.image_width = upload.image_width
+      post.image_height = upload.image_height
+      post.file_size = upload.file_size
+      post.source = upload.source
+      post.tag_string = upload.tag_string
+
+      post.comments.create!({creator: User.system, body: post.presenter.comment_replacement_message(creator), do_not_bump_post: true}, without_protection: true)
+      ModAction.log(post.presenter.modaction_replacement_message)
+
+      post.save!
+    end
+
+    # point of no return: these things can't be rolled back, so we do them
+    # only after the transaction successfully commits.
+    post.distribute_files
+    post.update_iqdb_async
+  end
+end

db/migrate/20170512221200_create_post_replacements.rb

@@ -0,0 +1,14 @@
+class CreatePostReplacements < ActiveRecord::Migration
+  def change
+    create_table :post_replacements do |t|
+    	t.integer :post_id, null: false
+    	t.integer :creator_id, null: false
+    	t.text :original_url, null: false
+    	t.text :replacement_url, null: false
+      t.timestamps null: false
+    end
+
+    add_index :post_replacements, :post_id
+    add_index :post_replacements, :creator_id
+  end
+end

db/structure.sql

@@ -2686,6 +2686,40 @@ CREATE SEQUENCE post_flags_id_seq
 ALTER SEQUENCE post_flags_id_seq OWNED BY post_flags.id;
 
 
+--
+-- Name: post_replacements; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE post_replacements (
+    id integer NOT NULL,
+    post_id integer NOT NULL,
+    creator_id integer NOT NULL,
+    original_url text NOT NULL,
+    replacement_url text NOT NULL,
+    created_at timestamp without time zone NOT NULL,
+    updated_at timestamp without time zone NOT NULL
+);
+
+
+--
+-- Name: post_replacements_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE post_replacements_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+
+--
+-- Name: post_replacements_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE post_replacements_id_seq OWNED BY post_replacements.id;
+
+
 --
 -- Name: post_updates; Type: TABLE; Schema: public; Owner: -
 --
@@ -4265,6 +4299,13 @@ ALTER TABLE ONLY post_disapprovals ALTER COLUMN id SET DEFAULT nextval('post_dis
 ALTER TABLE ONLY post_flags ALTER COLUMN id SET DEFAULT nextval('post_flags_id_seq'::regclass);
 
 
+--
+-- Name: id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY post_replacements ALTER COLUMN id SET DEFAULT nextval('post_replacements_id_seq'::regclass);
+
+
 --
 -- Name: id; Type: DEFAULT; Schema: public; Owner: -
 --
@@ -4658,6 +4699,14 @@ ALTER TABLE ONLY post_flags
     ADD CONSTRAINT post_flags_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: post_replacements_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY post_replacements
+    ADD CONSTRAINT post_replacements_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: post_votes_pkey; Type: CONSTRAINT; Schema: public; Owner: -
 --
@@ -6780,6 +6829,20 @@ CREATE INDEX index_post_flags_on_post_id ON post_flags USING btree (post_id);
 CREATE INDEX index_post_flags_on_reason_tsvector ON post_flags USING gin (to_tsvector('english'::regconfig, reason));
 
 
+--
+-- Name: index_post_replacements_on_creator_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_post_replacements_on_creator_id ON post_replacements USING btree (creator_id);
+
+
+--
+-- Name: index_post_replacements_on_post_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_post_replacements_on_post_id ON post_replacements USING btree (post_id);
+
+
 --
 -- Name: index_post_votes_on_post_id; Type: INDEX; Schema: public; Owner: -
 --
@@ -7471,3 +7534,5 @@ INSERT INTO schema_migrations (version) VALUES ('20170416224142');
 
 INSERT INTO schema_migrations (version) VALUES ('20170428220448');
 
+INSERT INTO schema_migrations (version) VALUES ('20170512221200');
+

test/unit/post_test.rb

@@ -1,10 +1,12 @@
 require 'test_helper'
 require 'helpers/pool_archive_test_helper'
 require 'helpers/saved_search_test_helper'
+require 'helpers/iqdb_test_helper'
 
 class PostTest < ActiveSupport::TestCase
   include PoolArchiveTestHelper
   include SavedSearchTestHelper
+  include IqdbTestHelper
 
   def assert_tag_match(posts, query)
     assert_equal(posts.map(&:id), Post.tag_match(query).pluck(:id))
@@ -1588,6 +1590,7 @@ class PostTest < ActiveSupport::TestCase
 
   context "Replacing: " do
     setup do
+      mock_iqdb_service!
       Delayed::Worker.delay_jobs = true                    # don't delete the old images right away
       Danbooru.config.stubs(:use_s3_proxy?).returns(false) # don't fail on post ids < 10000
 
@@ -1612,11 +1615,38 @@ class PostTest < ActiveSupport::TestCase
 
     context "replacing a post from a generic source" do
       setup do
+        @post.update(source: "https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png")
         @post.replace!("https://www.google.com/intl/en_ALL/images/logo.gif")
         @upload = Upload.last
         @mod_action = ModAction.last
       end
 
+      context "that is then undone" do
+        setup do
+          Timecop.travel(Time.now + PostReplacement::DELETION_GRACE_PERIOD + 1.day) do
+            Delayed::Worker.new.work_off
+          end
+
+          @replacement = @post.replacements.first
+          @replacement.undo!
+          @post.reload
+        end
+
+        should "update the attributes" do
+          assert_equal(272, @post.image_width)
+          assert_equal(92, @post.image_height)
+          assert_equal(5969, @post.file_size)
+          assert_equal("png", @post.file_ext)
+          assert_equal("8f9327db2597fa57d2f42b4a6c5a9855", @post.md5)
+          assert_equal("8f9327db2597fa57d2f42b4a6c5a9855", Digest::MD5.file(@post.file_path).hexdigest)
+          assert_equal("https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png", @post.source)
+        end
+      end
+
+      should "create a post replacement record" do
+        assert_equal(@post.id, PostReplacement.last.post_id)
+      end
+
       should "correctly update the attributes" do
         assert_equal(@post.id, @upload.post.id)
         assert_equal("completed", @upload.status)
@@ -1670,7 +1700,7 @@ class PostTest < ActiveSupport::TestCase
         assert(File.exists?(old_preview_file_path))
         assert(File.exists?(old_large_file_path))
 
-        Timecop.travel(Time.now + Post::DELETION_GRACE_PERIOD + 1.day) do
+        Timecop.travel(Time.now + PostReplacement::DELETION_GRACE_PERIOD + 1.day) do
           Delayed::Worker.new.work_off
         end