defmodule Manganese.SerializationKit.Structs.UnityAsset do
  @moduledoc """

  A generic Unity asset.  Assets are usually associated with an asset bundle.

  There are other modules for specific asset types.  When de/serializing with the generic `Manganese.SerializationKit.Structs.UnityAsset` module, the `:type` property will be inspected and the appropriate de/serializer will be used.  If the asset type is not known, it will use this module as a struct.

  The known asset types are:

  - `Manganese.SerializationKit.Structs.UnityTextAsset`
  - `Manganese.SerializationKit.Structs.UnityPrefabAsset`
  - `Manganese.SerializationKit.Structs.UnityMaterialAsset`

  # Deserialization

  - *See `from_map/1`*

  # Serialization

  - *See `to_map/1`*

  """

  alias Manganese.SerializationKit.Structs
  alias Manganese.SerializationKit.Enumerations

  @typedoc """

  The internal ID used by Unity to uniquely identify assets.

  """
  @type id :: pos_integer

  @typedoc """

  A Unity asset of an unknown type.

  """
  @type t :: %Structs.UnityAsset{
    path: String.t,
    id: id,
    name: String.t,
    type: Enumerations.UnityAssetType.t
  }
  @enforce_keys [
    :path,
    :id,
    :name
  ]
  defstruct [
    :path,
    :id,
    :name,
    :type
  ]

  # Deserialization

  @doc """

  Deserialize an asset from a map.

  Note this deserialization method may return a struct of an asset type-specific module.

  """
  @spec from_map(t_external) :: t
  def from_map(%{
    "path" => path,
    "id" => id,
    "name" => name,
    "type" => type
  } = params) do
    case Enumerations.UnityAssetType.from_integer type do
      :text     -> Structs.UnityTextAsset.from_map params
      :prefab   -> Structs.UnityPrefabAsset.from_map params
      :material -> Structs.UnityMaterialAsset.from_map params
      _ ->
        %Structs.UnityAsset{
          path: path,
          id: id,
          type: Enumerations.UnityAssetType.from_integer(type),
          name: name
        }
    end
  end


  # Serialization
  @type t_external :: map

  @doc """

  Serialize an asset to a map.

  If a asset struct of an asset type-specific class is given, the appropriate serializer will be used.

  """
  @spec to_map(term) :: t_external
  def to_map(asset) do
    case asset.type do
      :text     -> Structs.UnityTextAsset.to_map asset
      :prefab   -> Structs.UnityPrefabAsset.to_map asset
      :material -> Structs.UnityMaterialAsset.to_map asset
      _ ->
        %Structs.UnityAsset{
          path: path,
          id: id,
          type: type,
          name: name
        } = asset

        %{
          "path" => path,
          "id" => id,
          "name" => name,
          "type" => Enumerations.UnityAssetType.to_integer(type)
        }
    end
  end
end