ML-153: move MusicBrainz data transforms from Record

lib/music_brainz/release_group.ex

@@ -1,5 +1,10 @@
 defmodule MusicBrainz.ReleaseGroup do
-  @moduledoc false
+  @moduledoc """
+  Helper functions for working with MusicBrainz release group API responses.
+
+  Provides extraction and transformation utilities for release group data,
+  including artist credit parsing and type classification.
+  """
 
   alias MusicBrainz.ReleaseGroupSearchResult
 
@@ -45,6 +50,51 @@ defmodule MusicBrainz.ReleaseGroup do
   def parse_type("Single"), do: :single
   def parse_type(_), do: :other
 
+  @doc """
+  Parses artist credits from a MusicBrainz release group API response.
+
+  Extracts the `artist-credit` array and maps each artist into a map
+  suitable for use as an embedded artist in the application `Record` schema.
+
+  Returns a list of maps with keys: `:name`, `:musicbrainz_id`, `:sort_name`,
+  `:disambiguation`, and `:joinphrase`.
+  """
+  @spec parse_artist_credits(map()) :: [map()]
+  def parse_artist_credits(musicbrainz_data) do
+    musicbrainz_data
+    |> get_in(["artist-credit", Access.all()])
+    |> Enum.map(fn artist_credit ->
+      %{
+        name: artist_credit["artist"]["name"],
+        musicbrainz_id: artist_credit["artist"]["id"],
+        sort_name: artist_credit["artist"]["sort-name"],
+        disambiguation: artist_credit["artist"]["disambiguation"],
+        joinphrase: artist_credit["joinphrase"]
+      }
+    end)
+  end
+
+  @doc """
+  Determines the application record type from MusicBrainz release group type fields.
+
+  Maps the `primary-type` and `secondary-types` fields from a MusicBrainz
+  release group API response to the application's record type enum values
+  (`:album`, `:ep`, `:live`, `:compilation`, `:single`, `:other`).
+  """
+  @spec parse_record_type(String.t() | nil, [String.t()] | nil) :: atom()
+  def parse_record_type("Album", secondary_types) when is_list(secondary_types) do
+    cond do
+      "Live" in secondary_types -> :live
+      "Compilation" in secondary_types -> :compilation
+      true -> :album
+    end
+  end
+
+  def parse_record_type("Album", _secondary_types), do: :album
+  def parse_record_type("EP", _secondary_types), do: :ep
+  def parse_record_type("Single", _secondary_types), do: :single
+  def parse_record_type(_primary_type, _secondary_types), do: :other
+
   defp get_release_groups(release_group) do
     release_group
     |> Map.get("relations", [])