defmodule Manganese.EntityKit.Structs.EntitiesUpdate do
  alias Manganese.EntityKit.Structs

  @type t :: %Structs.EntitiesUpdate{
    entities: Structs.EntitiesCollection.t,
    removed_entities: Structs.EntityReferencesCollection.t
  }
  defstruct [
    entities: Structs.EntitiesCollection.new,
    removed_entities: Structs.EntityReferencesCollection.new
  ]


  # Utilities

  @doc """

  An empty entities update.

  """
  @spec new :: t
  def new, do: %Structs.EntitiesUpdate{}

  @doc """

  """
  @spec put_entities_collection(t, Structs.EntitiesCollection.t) :: t
  def put_entities_collection(entities_update, entities_collection) do
    entities_update
    |> Map.put(
      :entities,
      (entities_update.entities || Structs.EntitiesCollection.new())
      |> Structs.EntitiesCollection.merge(entities_collection)
    )
  end

  @doc """

  """
  @spec put_entities(t, atom, [ term ]) :: t
  def put_entities(entities_update, entity_type, entities) do
    entities_update
    |> Map.put(
      :entities,
      (entities_update.entities || Structs.EntitiesCollection.new())
      |> Structs.EntitiesCollection.put_entities(entity_type, entities)
    )
  end

  @doc """

  """
  @spec put_entity(t, atom, term) :: t
  def put_entity(entities_update, entity_type, entity) do
    entities_update
    |> Map.put(
      :entities,
      (entities_update.entities || Structs.EntitiesCollection.new())
      |> Structs.EntitiesCollection.put_entity(entity_type, entity)
    )
  end

  @doc """

  """
  @spec put_removed_entity_references_collection(t, Structs.EntityReferencesCollection.t) :: t
  def put_removed_entity_references_collection(entities_update, removed_entity_references_collection) do
    entities_update
    |> Map.put(
      :removed_entities,
      (entities_update.removed_entities || Structs.EntityReferencesCollection.new)
      |> Structs.EntityReferencesCollection.merge(removed_entity_references_collection)
    )
  end

  @doc """

  """
  @spec put_removed_entities(t, atom, [ term ]) :: t
  def put_removed_entities(entities_update, entity_type, removed_entities) do
    removed_entity_ids =
      removed_entities
      |> Enum.map(fn entity -> entity.id end)

    entities_update
    |> put_removed_entity_ids(entity_type, removed_entity_ids)
  end

  @spec put_removed_entity_ids(t, atom, [ pos_integer ]) :: t
  def put_removed_entity_ids(entities_update, entity_type, removed_entity_ids) do
    entities_update
    |> Map.put(
      :removed_entities,
      (entities_update.removed_entities || Structs.EntityReferencesCollection.new)
      |> Structs.EntityReferencesCollection.put_entity_ids(entity_type, removed_entity_ids)
    )
  end

  @doc """

  """
  @spec put_removed_entity(t, atom, term) :: t
  def put_removed_entity(entities_update, entity_type, removed_entity) do
    entities_update
    |> put_removed_entity_id(entity_type, removed_entity.id)
  end

  @doc """

  """
  @spec put_removed_entity_id(t, atom, pos_integer) :: t
  def put_removed_entity_id(entities_update, entity_type, removed_entity_id) do
    entities_update
    |> Map.put(
      :removed_entities,
      (entities_update.removed_entities || Structs.EntityReferencesCollection.new)
      |> Structs.EntityReferencesCollection.put_entity_id(entity_type, removed_entity_id)
    )
  end

  @doc """

  """
  @spec merge(t | nil, t | nil) :: t
  def merge(entities_update1, nil), do: entities_update1
  def merge(nil, entities_update2), do: entities_update2
  def merge(entities_update1, entities_update2) do
    new()
    |> put_entities_collection(
      Structs.EntitiesCollection.merge(
        entities_update1.entities,
        entities_update2.entities
      )
    )
    |> put_removed_entity_references_collection(
      Structs.EntityReferencesCollection.merge(
        entities_update1.removed_entities,
        entities_update2.removed_entities
      )
    )
  end
end