Add service to add item to a collection (#37192)

app/models/account.rb

@@ -455,6 +455,10 @@ class Account < ApplicationRecord
     save!
   end
 
+  def featureable?
+    local? && discoverable?
+  end
+
   private
 
   def prepare_contents

app/models/collection_item.rb

@@ -32,6 +32,8 @@ class CollectionItem < ApplicationRecord
   validates :account, presence: true, if: :accepted?
   validates :object_uri, presence: true, if: -> { account.nil? }
 
+  before_validation :set_position, on: :create
+
   scope :ordered, -> { order(position: :asc) }
   scope :with_accounts, -> { includes(account: [:account_stat, :user]) }
   scope :not_blocked_by, ->(account) { where.not(accounts: { id: account.blocking }) }
@@ -39,4 +41,12 @@ class CollectionItem < ApplicationRecord
   def local_item_with_remote_account?
     local? && account&.remote?
   end
+
+  private
+
+  def set_position
+    return if position_changed?
+
+    self.position = self.class.where(collection_id:).maximum(:position).to_i + 1
+  end
 end

app/policies/account_policy.rb

@@ -64,4 +64,8 @@ class AccountPolicy < ApplicationPolicy
   def review?
     role.can?(:manage_taxonomies)
   end
+
+  def feature?
+    record.featureable? && !current_account.blocking?(record) && !record.blocking?(current_account)
+  end
 end

app/services/add_account_to_collection_service.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class AddAccountToCollectionService
+  def call(collection, account)
+    raise ArgumentError unless collection.local?
+
+    @collection = collection
+    @account = account
+
+    raise Mastodon::NotPermittedError, I18n.t('accounts.errors.cannot_be_added_to_collections') unless AccountPolicy.new(@collection.account, @account).feature?
+
+    create_collection_item
+  end
+
+  private
+
+  def create_collection_item
+    @collection.collection_items.create!(
+      account: @account,
+      state: :accepted
+    )
+  end
+end

config/locales/en.yml

@@ -7,6 +7,8 @@ en:
     hosted_on: Mastodon hosted on %{domain}
     title: About
   accounts:
+    errors:
+      cannot_be_added_to_collections: This account cannot be added to collections.
     followers:
       one: Follower
       other: Followers

spec/models/account_spec.rb

@@ -781,4 +781,37 @@ RSpec.describe Account do
       expect(subject.reload.followers_count).to eq 15
     end
   end
+
+  describe '#featureable?' do
+    subject { Fabricate.build(:account, domain: (local ? nil : 'example.com'), discoverable:) }
+
+    context 'when account is local' do
+      let(:local) { true }
+
+      context 'when account is discoverable' do
+        let(:discoverable) { true }
+
+        it 'returns `true`' do
+          expect(subject.featureable?).to be true
+        end
+      end
+
+      context 'when account is not discoverable' do
+        let(:discoverable) { false }
+
+        it 'returns `false`' do
+          expect(subject.featureable?).to be false
+        end
+      end
+    end
+
+    context 'when account is remote' do
+      let(:local) { false }
+      let(:discoverable) { true }
+
+      it 'returns `false`' do
+        expect(subject.featureable?).to be false
+      end
+    end
+  end
 end

spec/models/collection_item_spec.rb

@@ -38,4 +38,23 @@ RSpec.describe CollectionItem do
       it { is_expected.to validate_presence_of(:object_uri) }
     end
   end
+
+  describe 'Creation' do
+    let(:collection) { Fabricate(:collection) }
+    let(:other_collection) { Fabricate(:collection) }
+    let(:account) { Fabricate(:account) }
+    let(:other_account) { Fabricate(:account) }
+
+    it 'automatically sets the `position` if absent' do
+      first_item = collection.collection_items.create(account:)
+      second_item = collection.collection_items.create(account: other_account)
+      unrelated_item = other_collection.collection_items.create(account:)
+      custom_item = other_collection.collection_items.create(account: other_account, position: 7)
+
+      expect(first_item.position).to eq 1
+      expect(second_item.position).to eq 2
+      expect(unrelated_item.position).to eq 1
+      expect(custom_item.position).to eq 7
+    end
+  end
 end

spec/policies/account_policy_spec.rb

@@ -156,4 +156,36 @@ RSpec.describe AccountPolicy do
       end
     end
   end
+
+  permissions :feature? do
+    context 'when account is featureable?' do
+      it 'permits' do
+        expect(subject).to permit(alice, john)
+      end
+    end
+
+    context 'when account is not featureable' do
+      before { allow(alice).to receive(:featureable?).and_return(false) }
+
+      it 'denies' do
+        expect(subject).to_not permit(john, alice)
+      end
+    end
+
+    context 'when account is blocked' do
+      before { alice.block!(john) }
+
+      it 'denies' do
+        expect(subject).to_not permit(alice, john)
+      end
+    end
+
+    context 'when account is blocking' do
+      before { john.block!(alice) }
+
+      it 'denies' do
+        expect(subject).to_not permit(alice, john)
+      end
+    end
+  end
 end

spec/services/add_account_to_collection_service_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AddAccountToCollectionService do
+  subject { described_class.new }
+
+  let(:collection) { Fabricate.create(:collection) }
+
+  describe '#call' do
+    context 'when given a featurable account' do
+      let(:account) { Fabricate(:account) }
+
+      it 'creates a new CollectionItem in the `accepted` state' do
+        expect do
+          subject.call(collection, account)
+        end.to change(collection.collection_items, :count).by(1)
+
+        new_item = collection.collection_items.last
+        expect(new_item.state).to eq 'accepted'
+        expect(new_item.account).to eq account
+      end
+    end
+
+    context 'when given an account that is not featureable' do
+      let(:account) { Fabricate(:account, discoverable: false) }
+
+      it 'raises an error' do
+        expect do
+          subject.call(collection, account)
+        end.to raise_error(Mastodon::NotPermittedError)
+      end
+    end
+  end
+end