refactor and docs

lib/mv_web/live/auth/link_oidc_account_live.ex

@@ -5,41 +5,139 @@ defmodule MvWeb.LinkOidcAccountLive do
   This page is shown when a user tries to log in via OIDC using an email
   that already exists with a password-only account. The user must verify
   their password before the OIDC account can be linked.
+
+  ## Flow
+  1. User attempts OIDC login with email that has existing password account
+  2. System raises `PasswordVerificationRequired` error
+  3. AuthController redirects here with user_id and oidc_user_info in session
+  4. User enters password to verify identity
+  5. On success, oidc_id is linked to user account
+  6. User is redirected to complete OIDC login
   """
   use MvWeb, :live_view
   require Ash.Query
+  require Logger
 
   @impl true
   def mount(_params, session, socket) do
-    user_id = Map.get(session, "oidc_linking_user_id")
-    oidc_user_info = Map.get(session, "oidc_linking_user_info")
-
-    if user_id && oidc_user_info do
-      # Load the user
-      case Ash.get(Mv.Accounts.User, user_id) do
-        {:ok, user} ->
-          {:ok,
-           socket
-           |> assign(:user, user)
-           |> assign(:oidc_user_info, oidc_user_info)
-           |> assign(:password, "")
-           |> assign(:error, nil)
-           |> assign(:form, to_form(%{"password" => ""}))}
-
-        {:error, _} ->
-          {:ok,
-           socket
-           |> put_flash(:error, dgettext("auth", "Session expired. Please try again."))
-           |> redirect(to: ~p"/sign-in")}
+    with user_id when not is_nil(user_id) <- Map.get(session, "oidc_linking_user_id"),
+         oidc_user_info when not is_nil(oidc_user_info) <-
+           Map.get(session, "oidc_linking_user_info"),
+         {:ok, user} <- Ash.get(Mv.Accounts.User, user_id) do
+      # Check if user is passwordless
+      if passwordless?(user) do
+        # Auto-link passwordless user immediately
+        {:ok, auto_link_passwordless_user(socket, user, oidc_user_info)}
+      else
+        # Show password form for password-protected user
+        {:ok, initialize_socket(socket, user, oidc_user_info)}
       end
     else
-      {:ok,
-       socket
-       |> put_flash(:error, dgettext("auth", "Invalid session. Please try again."))
-       |> redirect(to: ~p"/sign-in")}
+      nil ->
+        {:ok, redirect_with_error(socket, dgettext("auth", "Invalid session. Please try again."))}
+
+      {:error, _} ->
+        {:ok, redirect_with_error(socket, dgettext("auth", "Session expired. Please try again."))}
     end
   end
 
+  defp passwordless?(user) do
+    is_nil(user.hashed_password)
+  end
+
+  defp reload_user!(user_id) do
+    Mv.Accounts.User
+    |> Ash.Query.filter(id == ^user_id)
+    |> Ash.read_one!()
+  end
+
+  defp reset_password_form(socket) do
+    assign(socket, :form, to_form(%{"password" => ""}))
+  end
+
+  defp auto_link_passwordless_user(socket, user, oidc_user_info) do
+    oidc_id = Map.get(oidc_user_info, "sub") || Map.get(oidc_user_info, "id")
+
+    case user.id
+         |> reload_user!()
+         |> Ash.Changeset.for_update(:link_oidc_id, %{
+           oidc_id: oidc_id,
+           oidc_user_info: oidc_user_info
+         })
+         |> Ash.update() do
+      {:ok, updated_user} ->
+        Logger.info(
+          "Passwordless account auto-linked to OIDC: user_id=#{updated_user.id}, oidc_id=#{oidc_id}"
+        )
+
+        socket
+        |> put_flash(
+          :info,
+          dgettext("auth", "Account activated! Redirecting to complete sign-in...")
+        )
+        |> Phoenix.LiveView.redirect(to: ~p"/auth/user/rauthy")
+
+      {:error, error} ->
+        Logger.warning(
+          "Failed to auto-link passwordless account: user_id=#{user.id}, error=#{inspect(error)}"
+        )
+
+        error_message = extract_user_friendly_error(error)
+
+        socket
+        |> put_flash(:error, error_message)
+        |> redirect(to: ~p"/sign-in")
+    end
+  end
+
+  defp extract_user_friendly_error(%Ash.Error.Invalid{errors: errors}) do
+    # Check for specific error types
+    Enum.find_value(errors, fn
+      %Ash.Error.Changes.InvalidAttribute{field: :oidc_id, message: message} ->
+        if String.contains?(message, "already been taken") do
+          dgettext(
+            "auth",
+            "This OIDC account is already linked to another user. Please contact support."
+          )
+        else
+          nil
+        end
+
+      %Ash.Error.Changes.InvalidAttribute{field: :email, message: message} ->
+        if String.contains?(message, "already been taken") do
+          dgettext(
+            "auth",
+            "The email address from your OIDC provider is already registered to another account. Please change your email in the identity provider or contact support."
+          )
+        else
+          nil
+        end
+
+      _ ->
+        nil
+    end) ||
+      dgettext("auth", "Failed to link account. Please try again or contact support.")
+  end
+
+  defp extract_user_friendly_error(_error) do
+    dgettext("auth", "Failed to link account. Please try again or contact support.")
+  end
+
+  defp initialize_socket(socket, user, oidc_user_info) do
+    socket
+    |> assign(:user, user)
+    |> assign(:oidc_user_info, oidc_user_info)
+    |> assign(:password, "")
+    |> assign(:error, nil)
+    |> reset_password_form()
+  end
+
+  defp redirect_with_error(socket, message) do
+    socket
+    |> put_flash(:error, message)
+    |> redirect(to: ~p"/sign-in")
+  end
+
   @impl true
   def handle_event("validate", %{"password" => password}, socket) do
     {:noreply, assign(socket, :password, password)}
@@ -57,11 +155,13 @@ defmodule MvWeb.LinkOidcAccountLive do
         link_oidc_account(socket, verified_user, oidc_user_info)
 
       {:error, _reason} ->
-        # Password incorrect
+        # Password incorrect - log security event
+        Logger.warning("Failed password verification for OIDC linking: user_email=#{user.email}")
+
         {:noreply,
          socket
          |> assign(:error, dgettext("auth", "Incorrect password. Please try again."))
-         |> assign(:form, to_form(%{"password" => ""}))}
+         |> reset_password_form()}
     end
   end
 
@@ -88,17 +188,20 @@ defmodule MvWeb.LinkOidcAccountLive do
     oidc_id = Map.get(oidc_user_info, "sub") || Map.get(oidc_user_info, "id")
 
     # Update the user with the OIDC ID
-    case Mv.Accounts.User
-         |> Ash.Query.filter(id == ^user.id)
-         |> Ash.read_one!()
+    case user.id
+         |> reload_user!()
          |> Ash.Changeset.for_update(:link_oidc_id, %{
            oidc_id: oidc_id,
            oidc_user_info: oidc_user_info
          })
          |> Ash.update() do
-      {:ok, _updated_user} ->
+      {:ok, updated_user} ->
         # After successful linking, redirect to OIDC login
         # Since the user now has an oidc_id, the next OIDC login will succeed
+        Logger.info(
+          "OIDC account successfully linked after password verification: user_id=#{updated_user.id}, oidc_id=#{oidc_id}"
+        )
+
         {:noreply,
          socket
          |> put_flash(
@@ -111,13 +214,16 @@ defmodule MvWeb.LinkOidcAccountLive do
          |> Phoenix.LiveView.redirect(to: ~p"/auth/user/rauthy")}
 
       {:error, error} ->
+        Logger.warning(
+          "Failed to link OIDC account after password verification: user_id=#{user.id}, error=#{inspect(error)}"
+        )
+
+        error_message = extract_user_friendly_error(error)
+
         {:noreply,
          socket
-         |> assign(
-           :error,
-           dgettext("auth", "Failed to link account: %{error}", error: inspect(error))
-         )
-         |> assign(:form, to_form(%{"password" => ""}))}
+         |> assign(:error, error_message)
+         |> reset_password_form()}
     end
   end