ActivityPub: Add basic, read-only support for Outboxes, Notes, and Create/Announce Activities (#2197)

* Clean up collapsible components

* Expose user Outboxes and AS2 representations of statuses

* Save work thus far.

* Fix bad merge.

* Save my work

* Clean up pagination.

* First test working.

* Add tests.

* Add Forbidden error template.

* Revert yarn.lock changes.

* Fix code style deviations and use localized instead of hardcoded English text.

20 files changed, 190 insertions, 1 deletions

diff --git a/app/controllers/accounts_controller.rb b/app/controllers/accounts_controller.rb
index 8eda96336..d79ed142a 100644
--- a/app/controllers/accounts_controller.rb
+++ b/app/controllers/accounts_controller.rb
@@ -15,7 +15,9 @@ class AccountsController < ApplicationController
         render xml: AtomSerializer.render(AtomSerializer.new.feed(@account, @entries.to_a))
       end
 
-      format.activitystreams2
+      format.activitystreams2 do
+        headers['Access-Control-Allow-Origin'] = '*'
+      end
     end
   end
 
diff --git a/app/controllers/api/activitypub/activities_controller.rb b/app/controllers/api/activitypub/activities_controller.rb
new file mode 100644
index 000000000..03f27c7f6
--- /dev/null
+++ b/app/controllers/api/activitypub/activities_controller.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class Api::Activitypub::ActivitiesController < ApiController
+  # before_action :set_follow, only: [:show_follow]
+  before_action :set_status, only: [:show_status]
+
+  respond_to :activitystreams2
+
+  # Show a status in AS2 format, as either an Announce (reblog) or a Create (post) activity.
+  def show_status
+    headers['Access-Control-Allow-Origin'] = '*'
+
+    return forbidden unless @status.permitted?
+
+    if @status.reblog?
+      render :show_status_announce
+    else
+      render :show_status_create
+    end
+  end
+
+  private
+
+  def set_status
+    @status = Status.find(params[:id])
+  end
+end
diff --git a/app/controllers/api/activitypub/notes_controller.rb b/app/controllers/api/activitypub/notes_controller.rb
new file mode 100644
index 000000000..722961ec6
--- /dev/null
+++ b/app/controllers/api/activitypub/notes_controller.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class Api::Activitypub::NotesController < ApiController
+  before_action :set_status
+
+  respond_to :activitystreams2
+
+  def show
+    headers['Access-Control-Allow-Origin'] = '*'
+
+    forbidden unless @status.permitted?
+  end
+
+  private
+
+  def set_status
+    @status = Status.find(params[:id])
+  end
+end
diff --git a/app/controllers/api/activitypub/outbox_controller.rb b/app/controllers/api/activitypub/outbox_controller.rb
new file mode 100644
index 000000000..05d779910
--- /dev/null
+++ b/app/controllers/api/activitypub/outbox_controller.rb
@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+class Api::Activitypub::OutboxController < ApiController
+  before_action :set_account
+
+  respond_to :activitystreams2
+
+  def show
+    headers['Access-Control-Allow-Origin'] = '*'
+
+    @statuses = Status.as_outbox_timeline(@account).paginate_by_max_id(limit_param(DEFAULT_STATUSES_LIMIT), params[:max_id], params[:since_id])
+    @statuses = cache_collection(@statuses)
+
+    set_maps(@statuses)
+
+    # Since the statuses are in reverse chronological order, last is the lowest ID.
+    @next_path = api_activitypub_outbox_url(max_id: @statuses.last.id) if @statuses.size == limit_param(DEFAULT_STATUSES_LIMIT)
+
+    unless @statuses.empty?
+      if @statuses.first.id == 1
+        @prev_path = api_activitypub_outbox_url
+      elsif params[:max_id]
+        @prev_path = api_activitypub_outbox_url(since_id: @statuses.first.id)
+      end
+    end
+
+    @paginated = @next_path || @prev_path
+
+    set_pagination_headers(@next_path, @prev_path)
+  end
+
+  private
+
+  def cache_collection(raw)
+    super(raw, Status)
+  end
+
+  def set_account
+    @account = Account.find(params[:id])
+  end
+end
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 92755bcd3..ad2be71ee 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -62,6 +62,13 @@ class ApplicationController < ActionController::Base
     end
   end
 
+  def forbidden
+    respond_to do |format|
+      format.any  { head 403 }
+      format.html { render 'errors/403', layout: 'error', status: 403 }
+    end
+  end
+
   def unprocessable_entity
     respond_to do |format|
       format.any  { head 422 }
diff --git a/app/helpers/activitystreams2_builder_helper.rb b/app/helpers/activitystreams2_builder_helper.rb
new file mode 100644
index 000000000..eeada56f2
--- /dev/null
+++ b/app/helpers/activitystreams2_builder_helper.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module Activitystreams2BuilderHelper
+  # Gets a usable name for an account, using display name or username.
+  def account_name(account)
+    account.display_name.empty? ? account.username : account.display_name
+  end
+end
diff --git a/app/models/status.rb b/app/models/status.rb
index b75bd0a7b..918a58405 100644
--- a/app/models/status.rb
+++ b/app/models/status.rb
@@ -140,6 +140,10 @@ class Status < ApplicationRecord
       account.nil? ? filter_timeline_default(query) : filter_timeline_default(filter_timeline(query, account))
     end
 
+    def as_outbox_timeline(account)
+      where(account: account, visibility: :public)
+    end
+
     def favourites_map(status_ids, account_id)
       Favourite.select('status_id').where(status_id: status_ids).where(account_id: account_id).map { |f| [f.status_id, true] }.to_h
     end
diff --git a/app/views/accounts/show.activitystreams2.rabl b/app/views/accounts/show.activitystreams2.rabl
index dabae3f29..2c0a4ad3a 100644
--- a/app/views/accounts/show.activitystreams2.rabl
+++ b/app/views/accounts/show.activitystreams2.rabl
@@ -6,3 +6,4 @@ attributes display_name: :name, username: :preferredUsername, note: :summary
 
 node(:icon)   { |account| full_asset_url(account.avatar.url(:original)) }
 node(:image)  { |account| full_asset_url(account.header.url(:original)) }
+node(:outbox) { |account| api_activitypub_outbox_url(account.id) }
diff --git a/app/views/activitypub/types/announce.activitystreams2.rabl b/app/views/activitypub/types/announce.activitystreams2.rabl
new file mode 100644
index 000000000..4a29aa134
--- /dev/null
+++ b/app/views/activitypub/types/announce.activitystreams2.rabl
@@ -0,0 +1,3 @@
+extends 'activitypub/intransient.activitystreams2.rabl'
+
+node(:type) { 'Announce' }
diff --git a/app/views/activitypub/types/collection.activitystreams2.rabl b/app/views/activitypub/types/collection.activitystreams2.rabl
new file mode 100644
index 000000000..9e7e14e2b
--- /dev/null
+++ b/app/views/activitypub/types/collection.activitystreams2.rabl
@@ -0,0 +1,5 @@
+extends 'activitypub/intransient.activitystreams2.rabl'
+
+node(:type)       { 'Collection' }
+node(:items)      { [] }
+node(:totalItems) { 0 }
diff --git a/app/views/activitypub/types/create.activitystreams2.rabl b/app/views/activitypub/types/create.activitystreams2.rabl
new file mode 100644
index 000000000..e41a056a7
--- /dev/null
+++ b/app/views/activitypub/types/create.activitystreams2.rabl
@@ -0,0 +1,3 @@
+extends 'activitypub/intransient.activitystreams2.rabl'
+
+node(:type) { 'Create' }
diff --git a/app/views/activitypub/types/note.activitystreams2.rabl b/app/views/activitypub/types/note.activitystreams2.rabl
new file mode 100644
index 000000000..39c74d4ba
--- /dev/null
+++ b/app/views/activitypub/types/note.activitystreams2.rabl
@@ -0,0 +1,3 @@
+extends 'activitypub/intransient.activitystreams2.rabl'
+
+node(:type) { 'Note' }
diff --git a/app/views/activitypub/types/ordered_collection.activitystreams2.rabl b/app/views/activitypub/types/ordered_collection.activitystreams2.rabl
new file mode 100644
index 000000000..2cda6f4d0
--- /dev/null
+++ b/app/views/activitypub/types/ordered_collection.activitystreams2.rabl
@@ -0,0 +1,3 @@
+extends 'activitypub/types/collection.activitystreams2.rabl'
+
+node(:type) { 'OrderedCollection' }
diff --git a/app/views/activitypub/types/ordered_collection_page.activitystreams2.rabl b/app/views/activitypub/types/ordered_collection_page.activitystreams2.rabl
new file mode 100644
index 000000000..f498fe8e5
--- /dev/null
+++ b/app/views/activitypub/types/ordered_collection_page.activitystreams2.rabl
@@ -0,0 +1,4 @@
+extends 'activitypub/types/ordered_collection.activitystreams2.rabl'
+
+node(:type)     { 'OrderedCollectionPage' }
+node(:current)  { request.original_url }
diff --git a/app/views/api/activitypub/activities/_show_status.activitystreams2.rabl b/app/views/api/activitypub/activities/_show_status.activitystreams2.rabl
new file mode 100644
index 000000000..472bf5dbd
--- /dev/null
+++ b/app/views/api/activitypub/activities/_show_status.activitystreams2.rabl
@@ -0,0 +1,4 @@
+object @status
+
+node(:actor)     { |status| TagManager.instance.url_for(status.account) }
+node(:published) { |status| status.created_at.to_time.xmlschema }
\ No newline at end of file
diff --git a/app/views/api/activitypub/activities/show_status_announce.activitystreams2.rabl b/app/views/api/activitypub/activities/show_status_announce.activitystreams2.rabl
new file mode 100644
index 000000000..44ac1ba2f
--- /dev/null
+++ b/app/views/api/activitypub/activities/show_status_announce.activitystreams2.rabl
@@ -0,0 +1,8 @@
+extends 'activitypub/types/announce.activitystreams2.rabl'
+extends 'api/activitypub/activities/_show_status.activitystreams2.rabl'
+
+object @status
+
+node(:name)   { |status| t('activitypub.activity.announce.name', account_name: account_name(status.account)) }
+node(:url)    { |status| TagManager.instance.url_for(status) }
+node(:object) { |status| api_activitypub_status_url(status.reblog_of_id) }
diff --git a/app/views/api/activitypub/activities/show_status_create.activitystreams2.rabl b/app/views/api/activitypub/activities/show_status_create.activitystreams2.rabl
new file mode 100644
index 000000000..ff4d39eca
--- /dev/null
+++ b/app/views/api/activitypub/activities/show_status_create.activitystreams2.rabl
@@ -0,0 +1,8 @@
+extends 'activitypub/types/create.activitystreams2.rabl'
+extends 'api/activitypub/activities/_show_status.activitystreams2.rabl'
+
+object @status
+
+node(:name)   { |status| t('activitypub.activity.create.name', account_name: account_name(status.account)) }
+node(:url)    { |status| TagManager.instance.url_for(status) }
+node(:object) { |status| api_activitypub_note_url(status) }
diff --git a/app/views/api/activitypub/notes/show.activitystreams2.rabl b/app/views/api/activitypub/notes/show.activitystreams2.rabl
new file mode 100644
index 000000000..d962f4438
--- /dev/null
+++ b/app/views/api/activitypub/notes/show.activitystreams2.rabl
@@ -0,0 +1,11 @@
+extends 'activitypub/types/note.activitystreams2.rabl'
+
+object @status
+
+attributes :content
+
+node(:name)         { |status| status.content }
+node(:url)          { |status| TagManager.instance.url_for(status) }
+node(:attributedTo) { |status| TagManager.instance.url_for(status.account) }
+node(:inReplyTo)    { |status| api_activitypub_note_url(status.thread) } if @status.thread
+node(:published)    { |status| status.created_at.to_time.xmlschema }
diff --git a/app/views/api/activitypub/outbox/show.activitystreams2.rabl b/app/views/api/activitypub/outbox/show.activitystreams2.rabl
new file mode 100644
index 000000000..a498f74bc
--- /dev/null
+++ b/app/views/api/activitypub/outbox/show.activitystreams2.rabl
@@ -0,0 +1,23 @@
+if @paginated
+  extends 'activitypub/types/ordered_collection_page.activitystreams2.rabl'
+else
+  extends 'activitypub/types/ordered_collection.activitystreams2.rabl'
+end
+
+object @account
+
+node(:items) do
+  @statuses.map { |status| api_activitypub_status_url(status) }
+end
+
+node(:totalItems) { @statuses.count }
+node(:next)       { @next_path } if @next_path
+node(:prev)       { @prev_path } if @prev_path
+
+node(:name)       { |account| t('activitypub.outbox.name', account_name: account_name(account)) }
+node(:summary)    { |account| t('activitypub.outbox.summary', account_name: account_name(account)) }
+node(:updated) do |account|
+  times = @statuses.map { |status| status.updated_at.to_time }
+  times << account.created_at.to_time
+  times.max.xmlschema
+end
diff --git a/app/views/errors/403.html.haml b/app/views/errors/403.html.haml
new file mode 100644
index 000000000..c6e421f4f
--- /dev/null
+++ b/app/views/errors/403.html.haml
@@ -0,0 +1,5 @@
+- content_for :page_title do
+  = t('errors.403')
+
+- content_for :content do
+  = t('errors.403')
\ No newline at end of file