decentralised_book_index/lib/decentralised_book_index/metadata/book.ex

defmodule DecentralisedBookIndex.Metadata.Book do
  use Ash.Resource,
    otp_app: :decentralised_book_index,
    domain: DecentralisedBookIndex.Metadata,
    data_layer: AshPostgres.DataLayer

  require Ash.Query
  alias DecentralisedBookIndex.Metadata

  postgres do
    table "books"
    repo DecentralisedBookIndex.Repo
  end

  actions do
    defaults [:read, :update, :destroy]

    create :create do
      primary? true
      accept [:title, :description, :format, :language, :page_count, :published, :publisher_id, :book_editions_registry_id]
      argument :bids, {:array, :map}
      argument :author_roles, {:array, :map}

      change fn changeset, _ ->
        registry_id = Ash.Changeset.get_attribute(changeset, :book_editions_registry_id)

        if registry_id == nil do
          {:ok, registry} = DecentralisedBookIndex.Metadata.create_book_editions_registry()

          Ash.Changeset.force_change_attribute(changeset, :book_editions_registry_id, registry.id)
        else
          changeset
        end
      end

      change manage_relationship(:bids, type: :direct_control, order_is_key: :order)
      change manage_relationship(:author_roles, type: :direct_control, order_is_key: :order)
    end

    create :add_book_to_related_editions_registry do
      accept [:title, :description, :format, :language, :page_count, :published, :publisher_id]

      argument :related_book_id, :uuid do
        allow_nil? false
      end

      argument :bids, {:array, :map}
      argument :author_roles, {:array, :map}

      change fn changeset, context ->
        related_book_id = changeset.arguments.related_book_id

        if related_book_id == nil do
          Ash.Changeset.add_error(changeset, :related_book_id, "Related book is empty")
        else
          {:ok, related_book} = DecentralisedBookIndex.Metadata.get_book_by_id(related_book_id)

          Ash.Changeset.force_change_attribute(changeset, :book_editions_registry_id, related_book.book_editions_registry_id)
        end
      end

      change manage_relationship(:bids, type: :direct_control, order_is_key: :order)
      change manage_relationship(:author_roles, type: :direct_control, order_is_key: :order)
    end

    read :by_id do
      argument :id, :uuid, allow_nil?: false
      get? true
      filter expr(id == ^arg(:id))
    end

    read :by_bid do
      argument :type, :string, allow_nil?: false
      argument :bid, :string, allow_nil?: false
      get? true
      filter expr(exists(bids, type == ^arg(:type) and bid == ^arg(:bid)))
    end

    read :get_alternative_editions do
      argument :book, :struct, allow_nil?: false

      prepare fn query, context ->
        book = query.arguments.book

        DecentralisedBookIndex.Metadata.Book
        |> Ash.Query.filter(book_editions_registry_id == ^book.book_editions_registry_id
                            and id != ^book.id)
      end
    end

    read :get_author_books do
      argument :author, :struct, allow_nil?: false

      prepare fn query, context ->
        author = query.arguments.author

        {:ok, author_ids} = Metadata.get_author_ids(author)

        Metadata.Book
        |> Ash.Query.filter(expr(exists(author_roles, author_id in ^author_ids)))
      end
    end
  end

  attributes do
    uuid_primary_key :id

    attribute :title, :string do
      allow_nil? false
      public? true
    end

    attribute :description, :string do
      allow_nil? false
      public? true
    end

    attribute :published, :date do
      allow_nil? false
      public? true
    end

    attribute :language, :string do
      allow_nil? false
      public? true
    end

    attribute :format, :string do
      allow_nil? false
      public? true
    end

    attribute :page_count, :integer do
      allow_nil? false
      public? true
    end

    timestamps()
  end

  relationships do
    belongs_to :book_editions_registry, Metadata.BookEditionsRegistry

    belongs_to :publisher, Metadata.Publisher

    has_many :author_roles, Metadata.AuthorRole do
      sort order: :asc
      public? true
    end

    has_many :bids, Metadata.BookId do
      sort order: :asc
      public? true
    end
  end
end