defmodule Ash.Resource.Relationships.BelongsTo do
  @moduledoc "Represents a belongs_to relationship on a resource"

  defstruct [
    filterable?: true,
    validate_destination_attribute?: true,
    cardinality: :one,
    type: :belongs_to

  @type t :: %__MODULE__{
          type: :belongs_to,
          cardinality: :one,
          writable?: boolean,
          name: atom,
          read_action: atom,
          filter: Ash.Filter.t() | nil,
          source: Ash.Resource.t(),
          destination: Ash.Resource.t(),
          allow_nil?: boolean,
          primary_key?: boolean,
          define_attribute?: boolean,
          attribute_type: term,
          writable?: boolean,
          attribute_writable?: boolean,
          destination_attribute: atom,
          private?: boolean,
          filterable?: boolean,
          source_attribute: atom | nil,
          description: String.t()

  import Ash.Resource.Relationships.SharedOptions

  alias Spark.OptionsHelpers

  @global_opts shared_options()
               |> OptionsHelpers.set_default!(:destination_attribute, :id)
               |> OptionsHelpers.append_doc!(:source_attribute, "Defaults to <name>_id")
               |> Keyword.delete(:could_be_related_at_creation?)

  @opt_schema Spark.OptionsHelpers.merge_schemas(
                  primary_key?: [
                    type: :boolean,
                    default: false,
                      "Whether the generated attribute is, or is part of, the primary key of a resource."
                  allow_nil?: [
                    type: :boolean,
                    default: true,
                      "Whether this relationship must always be present, e.g: must be included on creation, and never removed (it may be modified). The generated attribute will not allow nil values."
                  attribute_writable?: [
                    type: :boolean,
                    default: false,
                    doc: """
                    Whether the generated attribute will be marked as public & writable.
                  define_attribute?: [
                    type: :boolean,
                    default: true,
                      "If set to `false` an attribute is not created on the resource for this relationship, and one must be manually added in `attributes`, invalidating many other options."
                  attribute_type: [
                    type: :any,
                    default: Application.compile_env(:ash, :default_belongs_to_type, :uuid),
                    doc: "The type of the generated created attribute. See `Ash.Type` for more."
                "Relationship Options"

  @doc false
  def opt_schema, do: @opt_schema