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

defmodule DiffoExample.Nbn.Avc do
  @moduledoc """
  Diffo - TMF Service and Resource Management with a difference

  Avc - Access Virtual Circuit Resource Instance

  An AVC is the virtual circuit dedicated to an NBN Ethernet circuit,
  carrying traffic between its related UNI and the CVC that aggregates it.
  """

  alias Diffo.Provider.BaseInstance
  alias Diffo.Provider.Instance.Relationship
  alias Diffo.Provider.Instance.Characteristic

  alias DiffoExample.Nbn

  use Ash.Resource,
    fragments: [BaseInstance],
    domain: Nbn,
    extensions: [AshJsonApi.Resource],
    authorizers: [Ash.Policy.Authorizer]

  json_api do
    type "avc"
  end

  resource do
    description "An Ash Resource representing an Access Virtual Circuit (AVC)"
    plural_name :Avcs
  end

  structure do
    specification do
      id "b2c3d4e5-6f7a-4b8c-9d0e-1f2a3b4c5d6e"
      name "avc"
      type :resourceSpecification
      description "An AVC Resource Instance dedicated to an NBN Ethernet circuit"
      category "Network Resource"
    end

    characteristics do
      characteristic :avc, DiffoExample.Nbn.AvcValue
      characteristic :cvc, DiffoExample.Nbn.CvcValue
    end
  end

  behaviour do
    actions do
      create :build
    end
  end

  attributes do
    attribute :rsp_id, :string do
      description "the owning RSP's id — nil for Perentie-managed infrastructure"
      allow_nil? true
      public? true
    end
  end

  actions do
    create :build do
      description "creates a new AVC resource instance"
      accept [:id, :which]
      argument :relationships, {:array, :struct}
      argument :places, {:array, :struct}
      argument :parties, {:array, :struct}

      change set_attribute(:name, &DiffoExample.Nbn.Avc.identifier/0)
      change set_attribute(:type, :resource)
      change DiffoExample.Nbn.Changes.SetRspId
      change load [:href]
      upsert? false
    end

    update :define do
      description "defines the AVC"
      argument :characteristic_value_updates, {:array, :term}

      change after_action(fn changeset, result, _context ->
               with {:ok, result} <- Characteristic.update_values(result, changeset),
                    {:ok, result} <- Nbn.get_avc_by_id(result.id),
                    do: {:ok, result}
             end)
    end

    update :relate do
      description "relates the AVC with other instances"
      argument :relationships, {:array, :struct}

      change after_action(fn changeset, result, _context ->
               with {:ok, result} <- Relationship.relate_instance(result, changeset),
                    {:ok, result} <- Nbn.get_avc_by_id(result.id),
                    do: {:ok, result}
             end)
    end

    update :mine do
      description "updates the AVC with data mined from related instances"
      argument :characteristic_value_updates, {:array, :term}

      change before_action(fn changeset, context ->
               DiffoExample.Nbn.Avc.mine_related(changeset, context)
             end)

      change after_action(fn changeset, result, _context ->
               with {:ok, result} <- Characteristic.update_values(result, changeset),
                    {:ok, result} <- Nbn.get_avc_by_id(result.id),
                    do: {:ok, result}
             end)
    end
  end

  def identifier() do
    DiffoExample.Nbn.Util.identifier("AVC")
  end

  # mines related resource to characteristics
  def mine_related(changeset, _context) when is_struct(changeset, Ash.Changeset) do
    avc = Ash.load!(changeset.data, [reverse_relationships: [:characteristics]])

    cvlan = {:cvlan, Diffo.Unwrap.unwrap(hd(hd(avc.reverse_relationships).characteristics).value)}

    Ash.Changeset.force_set_argument(changeset, :characteristic_value_updates, avc: [cvlan])
  end

  use DiffoExample.Nbn.RspOwnership
end