Add models to represent "Collections" (#36977)

app/models/collection.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: collections
+#
+#  id                       :bigint(8)        not null, primary key
+#  description              :text             not null
+#  discoverable             :boolean          not null
+#  local                    :boolean          not null
+#  name                     :string           not null
+#  original_number_of_items :integer
+#  sensitive                :boolean          not null
+#  uri                      :string
+#  created_at               :datetime         not null
+#  updated_at               :datetime         not null
+#  account_id               :bigint(8)        not null
+#  tag_id                   :bigint(8)
+#
+class Collection < ApplicationRecord
+  MAX_ITEMS = 25
+
+  belongs_to :account
+  belongs_to :tag, optional: true
+
+  has_many :collection_items, dependent: :delete_all
+
+  validates :name, presence: true
+  validates :description, presence: true
+  validates :uri, presence: true, if: :remote?
+  validates :original_number_of_items,
+            presence: true,
+            numericality: { greater_than_or_equal: 0 },
+            if: :remote?
+  validate :tag_is_usable
+  validate :items_do_not_exceed_limit
+
+  def remote?
+    !local?
+  end
+
+  private
+
+  def tag_is_usable
+    return if tag.blank?
+
+    errors.add(:tag, :unusable) unless tag.usable?
+  end
+
+  def items_do_not_exceed_limit
+    errors.add(:collection_items, :too_many, count: MAX_ITEMS) if collection_items.size > MAX_ITEMS
+  end
+end

app/models/collection_item.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+# == Schema Information
+#
+# Table name: collection_items
+#
+#  id                        :bigint(8)        not null, primary key
+#  activity_uri              :string
+#  approval_last_verified_at :datetime
+#  approval_uri              :string
+#  object_uri                :string
+#  position                  :integer          default(1), not null
+#  state                     :integer          default("pending"), not null
+#  created_at                :datetime         not null
+#  updated_at                :datetime         not null
+#  account_id                :bigint(8)
+#  collection_id             :bigint(8)        not null
+#
+class CollectionItem < ApplicationRecord
+  belongs_to :collection
+  belongs_to :account, optional: true
+
+  enum :state,
+       { pending: 0, accepted: 1, rejected: 2, revoked: 3 },
+       validate: true
+
+  delegate :local?, :remote?, to: :collection
+
+  validates :position, numericality: { only_integer: true, greater_than: 0 }
+  validates :activity_uri, presence: true, if: :local_item_with_remote_account?
+  validates :approval_uri, absence: true, unless: :local?
+  validates :account, presence: true, if: :accepted?
+  validates :object_uri, presence: true, if: -> { account.nil? }
+
+  scope :ordered, -> { order(position: :asc) }
+
+  def local_item_with_remote_account?
+    local? && account&.remote?
+  end
+end

app/models/concerns/account/associations.rb

@@ -13,6 +13,8 @@ module Account::Associations
         has_many :account_warnings
         has_many :aliases, class_name: 'AccountAlias'
         has_many :bookmarks
+        has_many :collections
+        has_many :collection_items
         has_many :conversations, class_name: 'AccountConversation'
         has_many :custom_filters
         has_many :favourites