mastodon_api: Add /api/v1/preferences endpoint

Implements the preferences endpoint in the Mastodon API, but returns
default values for most of the preferences right now. The only supported
preference we can access is default post visibility, and a relevant test
is added as well.

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

@@ -451,6 +451,20 @@ def endorsements_operation do
     }
   end
 
+  def preferences_operation do
+    %Operation{
+      tags: ["Account Preferences"],
+      description: "Preferences defined by the user in their account settings.",
+      summary: "Preferred common behaviors to be shared across clients.",
+      operationId: "AccountController.preferences",
+      security: [%{"oAuth" => ["read:accounts"]}],
+      responses: %{
+        200 => Operation.response("Preferences", "application/json", Account),
+        401 => Operation.response("Error", "application/json", ApiError)
+      }
+    }
+  end
+
   def identity_proofs_operation do
     %Operation{
       tags: ["Retrieve account information"],

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

@@ -51,7 +51,7 @@ defmodule Pleroma.Web.MastodonAPI.AccountController do
   plug(
     OAuthScopesPlug,
     %{scopes: ["read:accounts"]}
-    when action in [:verify_credentials, :endorsements, :identity_proofs]
+    when action in [:verify_credentials, :endorsements, :identity_proofs, :preferences]
   )
 
   plug(
@@ -544,4 +544,9 @@ def endorsements(conn, params), do: MastodonAPIController.empty_array(conn, para
 
   @doc "GET /api/v1/identity_proofs"
   def identity_proofs(conn, params), do: MastodonAPIController.empty_array(conn, params)
+
+  @doc "GET /api/v1/preferences"
+  def preferences(%{assigns: %{user: user}} = conn, params) do
+    render(conn, "preferences.json", user: user)
+  end
 end

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

@@ -315,6 +315,17 @@ defp do_render("show.json", %{user: user} = opts) do
     |> maybe_put_email_address(user, opts[:for])
   end
 
+  def render("preferences.json", %{user: user} = opts) do
+    # TODO: Do we expose more settings that make sense to plug in here?
+    %{
+      "posting:default:visibility": user.default_scope,
+      "posting:default:sensitive": false,
+      "posting:default:language": nil,
+      "reading:expand:media": "default",
+      "reading:expand:spoilers": false
+    }
+  end
+
   defp username_from_nickname(string) when is_binary(string) do
     hd(String.split(string, "@"))
   end

lib/pleroma/web/router.ex

@@ -629,6 +629,8 @@ defmodule Pleroma.Web.Router do
     post("/tags/:id/follow", TagController, :follow)
     post("/tags/:id/unfollow", TagController, :unfollow)
     get("/followed_tags", TagController, :show_followed)
+
+    get("/preferences", AccountController, :preferences)
   end
 
   scope "/api/web", Pleroma.Web do

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

@@ -2060,4 +2060,32 @@ test "removing user from followers errors", %{user: user, conn: conn} do
       assert %{"error" => "Record not found"} = json_response_and_validate_schema(conn_res, 404)
     end
   end
+
+  describe "preferences" do
+    test "get account preferences" do
+      user = insert(:user, default_scope: "public")
+      %{conn: conn} = oauth_access(["read:accounts"], user: user)
+
+      conn = get(conn, "/api/v1/preferences")
+      response = json_response_and_validate_schema(conn, 200)
+
+      assert %{
+               "posting:default:language" => nil,
+               "posting:default:sensitive" => false,
+               "posting:default:visibility" => "public",
+               "reading:expand:media" => "default",
+               "reading:expand:spoilers" => false
+             } = response
+    end
+
+    test "test changing account preferences" do
+      user = insert(:user, default_scope: "unlisted")
+      %{conn: conn} = oauth_access(["read:accounts"], user: user)
+
+      conn = get(conn, "/api/v1/preferences")
+      response = json_response_and_validate_schema(conn, 200)
+
+      assert response["posting:default:visibility"] == "unlisted"
+    end
+  end
 end