When importing a record, stream all its releases

lib/music_brainz/api_behaviour.ex

@@ -1,10 +1,11 @@
 defmodule MusicBrainz.APIBehaviour do
   @type musicbrainz_id :: String.t()
   @type config :: MusicBrainz.Config.t()
+  @type limit :: pos_integer()
 
   @callback get_release_group(musicbrainz_id, config) :: {:ok, map()} | {:error, String.t()}
 
-  @callback get_releases(musicbrainz_id, config) :: {:ok, map()} | {:error, String.t()}
+  @callback get_releases(musicbrainz_id, limit, config) :: {:ok, map()} | {:error, String.t()}
 
   @callback get_release(musicbrainz_id, config) :: {:ok, map()} | {:error, String.t()}
 

lib/music_brainz/api_impl.ex

@@ -7,6 +7,7 @@ defmodule MusicBrainz.APIImpl do
   """
 
   @behaviour MusicBrainz.APIBehaviour
+  @base_url "https://musicbrainz.org/ws/2"
 
   require Logger
 
@@ -288,9 +289,17 @@ defmodule MusicBrainz.APIImpl do
   end
 
   @impl true
-  def get_releases(release_group_id, config) do
+  def get_releases(release_group_id, opts, config) do
+    Keyword.validate!(opts, [:limit, :offset])
+
+    opts =
+      Keyword.merge(opts,
+        fmt: "json",
+        "release-group": release_group_id
+      )
+
     url =
-      "https://musicbrainz.org/ws/2/release?fmt=json&limit=100&release-group=#{release_group_id}"
+      @base_url <> "/release?" <> URI.encode_query(opts)
 
     json_get(url, config)
   end

lib/music_library/records.ex

@@ -226,14 +226,29 @@ defmodule MusicLibrary.Records do
     end
   end
 
-  # TODO: paginate and merge as needed
   defp merge_releases(musicbrainz_id, musicbrainz_data) do
-    with {:ok, data} <-
-           music_brainz_config().api.get_releases(
-             musicbrainz_id,
-             music_brainz_config()
-           ) do
-      {:ok, Map.put(musicbrainz_data, "releases", data["releases"])}
+    with {:ok, releases} <- stream_releases(musicbrainz_id) do
+      {:ok, Map.put(musicbrainz_data, "releases", releases)}
+    end
+  end
+
+  defp stream_releases(musicbrainz_id) do
+    do_stream_releases(musicbrainz_id, [], 0)
+  end
+
+  defp do_stream_releases(musicbrainz_id, releases, offset) do
+    limit = 100
+    opts = [limit: limit, offset: offset]
+
+    case music_brainz_config().api.get_releases(musicbrainz_id, opts, music_brainz_config()) do
+      {:ok, data} ->
+        %{"releases" => new_releases} = data
+
+        if Enum.count(new_releases) < limit do
+          {:ok, releases ++ new_releases}
+        else
+          do_stream_releases(musicbrainz_id, releases ++ new_releases, offset + 100)
+        end
     end
   end
 

test/music_library/records_test.exs

@@ -66,7 +66,7 @@ defmodule MusicLibrary.RecordsTest do
         {:ok, release_group(:lockdown_trilogy)}
       end)
 
-      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _config ->
+      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _opts, _config ->
         {:ok, %{"releases" => release_group(:lockdown_trilogy)["releases"]}}
       end)
 
@@ -207,7 +207,7 @@ defmodule MusicLibrary.RecordsTest do
         {:ok, release_group}
       end)
 
-      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _config ->
+      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _opts, _config ->
         {:ok, %{"releases" => release_group["releases"]}}
       end)
 
@@ -264,7 +264,7 @@ defmodule MusicLibrary.RecordsTest do
         {:ok, release_group}
       end)
 
-      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _config ->
+      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _opts, _config ->
         {:ok, %{"releases" => release_group["releases"]}}
       end)
 

test/music_library_web/live/collection_live/index_test.exs

@@ -271,7 +271,7 @@ defmodule MusicLibraryWeb.CollectionLive.IndexTest do
         {:ok, release_group}
       end)
 
-      expect(APIBehaviourMock, :get_releases, fn ^first_result_id, _config ->
+      expect(APIBehaviourMock, :get_releases, fn ^first_result_id, _opts, _config ->
         {:ok, %{"releases" => release_group["releases"]}}
       end)
 

test/music_library_web/live/stats_live/index_test.exs

@@ -193,7 +193,7 @@ defmodule MusicLibraryWeb.StatsLive.IndexTest do
         {:ok, release_group}
       end)
 
-      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _config ->
+      expect(APIBehaviourMock, :get_releases, fn ^release_group_id, _opts, _config ->
         {:ok, %{"releases" => release_group["releases"]}}
       end)