Spec improvements

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/medias/media/metadata.ex

@@ -0,0 +1,38 @@
+defmodule Mobilizon.Medias.Media.Metadata do
+  @moduledoc """
+  Represents a media metadata
+  """
+
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  @type t :: %__MODULE__{
+          width: non_neg_integer(),
+          height: non_neg_integer(),
+          blurhash: String.t()
+        }
+
+  @required_attrs []
+
+  @optional_attrs [
+    :width,
+    :height,
+    :blurhash
+  ]
+
+  @attrs @required_attrs ++ @optional_attrs
+
+  @primary_key false
+  embedded_schema do
+    field(:height, :integer)
+    field(:width, :integer)
+    field(:blurhash, :string)
+  end
+
+  @doc false
+  @spec changeset(t | Ecto.Schema.t(), map) :: Ecto.Changeset.t()
+  def changeset(schema, params) do
+    schema
+    |> cast(params, @attrs)
+  end
+end