diffo

# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
#
# SPDX-License-Identifier: MIT

defmodule Diffo.Provider.BaseRelationship do
  @moduledoc """
  Ash Resource Fragment which is the shared foundation for TMF Relationship resources.

  Provides the common attributes, relationships, validations, and actions shared
  between `Diffo.Provider.Relationship` (TMF service/resource relationships) and
  `Diffo.Provider.AssignedToRelationship` (pool assignment relationships).

  ## Common attributes

  - `id` — uuid4 primary key
  - `type` — relationship type atom
  - `target_href` — denormalised target href (set by the `DetailRelationship` change)
  - `target_type` — denormalised target type (`:service` or `:resource`)
  - `created_at`, `updated_at` — timestamps

  ## Common Ash relationships

  - `belongs_to :source, Diffo.Provider.Instance`
  - `belongs_to :target, Diffo.Provider.Instance`
  """
  use Spark.Dsl.Fragment,
    of: Ash.Resource,
    otp_app: :diffo,
    domain: Diffo.Provider,
    data_layer: AshNeo4j.DataLayer,
    extensions: [AshJason.Resource]

  attributes do
    uuid_primary_key :id do
      description "a uuid4, unique to this relationship, generated by default"
      public? true
    end

    attribute :type, :atom do
      description "the type of the relationship from the source to the target"
      allow_nil? false
      public? true
    end

    attribute :target_href, :string do
      description "the target href, denormalised from the target instance"
      allow_nil? true
      writable? false
      public? true
    end

    attribute :target_type, :atom do
      description "the target type, denormalised from the target instance"
      allow_nil? true
      writable? false
      public? true
    end

    create_timestamp :created_at
    update_timestamp :updated_at
  end

  relationships do
    belongs_to :source, Diffo.Provider.Instance do
      description "the source instance which originates this relationship"
      allow_nil? false
      public? true
    end

    belongs_to :target, Diffo.Provider.Instance do
      description "the target instance which is the destination of this relationship"
      allow_nil? false
      public? true
    end
  end

  validations do
    validate {Diffo.Validations.IsUuid4OrNil, attribute: :source_id}, on: :create
    validate {Diffo.Validations.IsUuid4OrNil, attribute: :target_id}, on: :create
  end

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