Implement /api/v1/instance/translation_languages

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

lib/pleroma/language/translation.ex

@@ -63,6 +63,32 @@ def supported_languages(type) when type in [:source, :target] do
     end
   end
 
+  def languages_matrix do
+    provider = get_provider()
+
+    cache_key = "languages_matrix/#{provider.name()}"
+
+    case @cachex.get(:translations_cache, cache_key) do
+      {:ok, nil} ->
+        result =
+          if !configured?() do
+            {:error, :not_found}
+          else
+            provider.languages_matrix()
+          end
+
+        store_result(result, cache_key)
+
+        result
+
+      {:ok, result} ->
+        {:ok, result}
+
+      {:error, error} ->
+        {:error, error}
+    end
+  end
+
   defp get_provider, do: Pleroma.Config.get([__MODULE__, :provider])
 
   defp get_cache_key(text, source_language, target_language) do

lib/pleroma/language/translation/deepl.ex

@@ -97,6 +97,17 @@ def supported_languages(type) when type in [:source, :target] do
     end
   end
 
+  @impl Provider
+  def languages_matrix do
+    with {:ok, source_languages} <- supported_languages(:source),
+         {:ok, target_languages} <- supported_languages(:target) do
+      {:ok,
+       Map.new(source_languages, fn language -> {language, target_languages -- [language]} end)}
+    else
+      {:error, error} -> {:error, error}
+    end
+  end
+
   @impl Provider
   def name, do: @name
 

lib/pleroma/language/translation/libretranslate.ex

@@ -67,6 +67,17 @@ def supported_languages(_) do
     end
   end
 
+  @impl Provider
+  def languages_matrix do
+    with {:ok, source_languages} <- supported_languages(:source),
+         {:ok, target_languages} <- supported_languages(:target) do
+      {:ok,
+       Map.new(source_languages, fn language -> {language, target_languages -- [language]} end)}
+    else
+      {:error, error} -> {:error, error}
+    end
+  end
+
   @impl Provider
   def name, do: @name
 

lib/pleroma/language/translation/provider.ex

@@ -21,5 +21,7 @@ defmodule Pleroma.Language.Translation.Provider do
   @callback supported_languages(type :: :string | :target) ::
               {:ok, [String.t()]} | {:error, atom()}
 
+  @callback languages_matrix() :: {:ok, Map.t()} | {:error, atom()}
+
   @callback name() :: String.t()
 end

lib/pleroma/web/api_spec/operations/instance_operation.ex

@@ -73,6 +73,29 @@ def domain_blocks_operation do
     }
   end
 
+  def translation_languages_operation do
+    %Operation{
+      tags: ["Instance misc"],
+      summary: "Retrieve supported languages matrix",
+      operationId: "InstanceController.translation_languages",
+      responses: %{
+        200 =>
+          Operation.response(
+            "Translation languages matrix",
+            "application/json",
+            %Schema{
+              type: :object,
+              additionalProperties: %Schema{
+                type: :array,
+                items: %Schema{type: :string},
+                description: "Supportede target languages for a source language"
+              }
+            }
+          )
+      }
+    }
+  end
+
   defp instance do
     %Schema{
       type: :object,

lib/pleroma/web/mastodon_api/controllers/instance_controller.ex

@@ -35,4 +35,9 @@ def rules(conn, _params) do
   def domain_blocks(conn, _params) do
     render(conn, "domain_blocks.json")
   end
+
+  @doc "GET /api/v1/instance/translation_languages"
+  def translation_languages(conn, _params) do
+    render(conn, "translation_languages.json")
+  end
 end

lib/pleroma/web/mastodon_api/views/instance_view.ex

@@ -133,6 +133,15 @@ def render("domain_blocks.json", _) do
     end
   end
 
+  def render("translation_languages.json", _) do
+    with true <- Pleroma.Language.Translation.configured?(),
+         {:ok, languages} <- Pleroma.Language.Translation.languages_matrix() do
+      languages
+    else
+      _ -> %{}
+    end
+  end
+
   def features do
     [
       "pleroma_api",

lib/pleroma/web/router.ex

@@ -833,6 +833,7 @@ defmodule Pleroma.Web.Router do
     get("/instance/peers", InstanceController, :peers)
     get("/instance/rules", InstanceController, :rules)
     get("/instance/domain_blocks", InstanceController, :domain_blocks)
+    get("/instance/translation_languages", InstanceController, :translation_languages)
 
     get("/statuses", StatusController, :index)
     get("/statuses/:id", StatusController, :show)

test/pleroma/web/mastodon_api/controllers/instance_controller_test.exs

@@ -195,4 +195,13 @@ test "instance languages", %{conn: conn} do
              |> get("/api/v1/instance")
              |> json_response_and_validate_schema(200)
   end
+
+  test "translation languages matrix", %{conn: conn} do
+    clear_config([Pleroma.Language.Translation, :provider], TranslationMock)
+
+    assert %{"en" => ["pl"], "pl" => ["en"]} =
+             conn
+             |> get("/api/v1/instance/translation_languages")
+             |> json_response_and_validate_schema(200)
+  end
 end

test/support/translation_mock.ex

@@ -24,7 +24,16 @@ def translate(content, source_language, _target_language) do
 
   @impl Provider
   def supported_languages(_) do
-    ["en", "pl"]
+    {:ok, ["en", "pl"]}
+  end
+
+  @impl Provider
+  def languages_matrix do
+    {:ok,
+     %{
+       "en" => ["pl"],
+       "pl" => ["en"]
+     }}
   end
 
   @impl Provider