Add artist importer

lib/music_library/records/importer.ex

@@ -0,0 +1,91 @@
+defmodule MusicLibrary.Records.Importer do
+  alias Ecto.Multi
+
+  @doc """
+  The original data from Obsidian maps records to release groups, so to find artists for a record we can
+  use the [lookup](https://musicbrainz.org/doc/MusicBrainz_API#Lookups) endpoint with the release group id and include the
+  artist credits.
+
+  Example request: https://musicbrainz.org/ws/2/release-group/ae504fd6-8498-463e-8d96-14f9e11d1863?fmt=json&inc=artist-credits
+
+  Example response:
+
+      {
+        "primary-type-id": "f529b476-6e62-324f-b0aa-1f3e33d313fc",
+        "id": "ae504fd6-8498-463e-8d96-14f9e11d1863",
+        "primary-type": "Album",
+        "secondary-types": [],
+        "disambiguation": "",
+        "title": "Dwellers of the Deep",
+        "secondary-type-ids": [],
+        "first-release-date": "2020-10-23",
+        "artist-credit": [
+          {
+            "artist": {
+              "type-id": "e431f5f6-b5d2-343d-8b36-72607fffb74b",
+              "sort-name": "Wobbler",
+              "id": "923b9160-251f-4ebe-8af2-ae670c425e55",
+              "type": "Group",
+              "name": "Wobbler",
+              "disambiguation": "Symphonic Prog, Norway"
+            },
+            "name": "Wobbler",
+            "joinphrase": ""
+          }
+        ]
+      }
+  """
+  def import_artists(record) do
+    url =
+      "https://musicbrainz.org/ws/2/release-group/#{record.musicbrainz_id}?fmt=json&inc=artist-credits"
+
+    with {:ok, data} <- json_get(url) do
+      current_time =
+        DateTime.utc_now()
+        |> DateTime.truncate(:second)
+
+      artist_entries =
+        data
+        |> get_in(["artist-credit", Access.all(), "artist"])
+        |> Enum.map(fn artist ->
+          %{
+            name: artist["name"],
+            musicbrainz_id: artist["id"],
+            inserted_at: current_time,
+            updated_at: current_time
+          }
+        end)
+
+      Multi.new()
+      |> Multi.insert_all(:artists, MusicLibrary.Records.Artist, artist_entries,
+        on_conflict: :nothing,
+        returning: true
+      )
+      |> Multi.insert_all(:artists_records, MusicLibrary.Records.ArtistRecord, fn %{
+                                                                                    artists:
+                                                                                      {_inserted_count,
+                                                                                       artists}
+                                                                                  } ->
+        Enum.map(artists, fn a ->
+          %{
+            artist_id: a.id,
+            record_id: record.id,
+            inserted_at: current_time,
+            updated_at: current_time
+          }
+        end)
+      end)
+      |> MusicLibrary.Repo.transaction()
+    end
+  end
+
+  defp json_get(url) do
+    case Finch.build(:get, url) |> Finch.request(MusicLibrary.Finch) do
+      {:ok, response} when response.status == 200 ->
+        {:ok, Jason.decode!(response.body)}
+
+      other ->
+        {:error, "Failed to fetch data from #{url}, reason: #{inspect(other)}"}
+    end
+  end
+end