Create schemas for JSON API endpoints

lib/matrix_server_web/api/register.ex

@@ -0,0 +1,38 @@
+defmodule MatrixServerWeb.API.Register do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+  import MatrixServerWeb.Plug.Error
+
+  alias __MODULE__
+  alias Ecto.Changeset
+
+  embedded_schema do
+    field :device_id, :string
+    field :initial_device_display_name, :string
+    field :password, :string
+    field :username, :string
+    field :inhibit_login, :boolean, default: false
+  end
+
+  def changeset(params) do
+    %Register{}
+    |> cast(params, [
+      :device_id,
+      :initial_device_display_name,
+      :password,
+      :username,
+      :inhibit_login
+    ])
+    |> validate_required([:password, :username])
+  end
+
+  def handle_error(conn, cs) do
+    put_error(conn, get_register_error(cs))
+  end
+
+  defp get_register_error(%Changeset{errors: [error | _]}), do: get_register_error(error)
+  defp get_register_error({:localpart, {_, [{:constraint, :unique} | _]}}), do: :user_in_use
+  defp get_register_error({:localpart, {_, [{:validation, _} | _]}}), do: :invalid_username
+  defp get_register_error(_), do: :bad_json
+end