defmodule ToweropsWeb.UserSessionController do
  @moduledoc false

  use ToweropsWeb, :controller

  alias Towerops.Accounts
  alias ToweropsWeb.UserAuth

  def new(conn, _params) do
    email = get_in(conn.assigns, [:current_scope, Access.key(:user), Access.key(:email)])
    form = Phoenix.Component.to_form(%{"email" => email}, as: "user")

    render(conn, :new, form: form)
  end

  # magic link login
  def create(conn, %{"user" => %{"token" => token} = user_params} = params) do
    case Accounts.login_user_by_magic_link(token) do
      {:ok, {user, _expired_tokens}} ->
        conn =
          if params["_action"] == "confirmed" do
            put_flash(conn, :info, "User confirmed successfully.")
          else
            conn
          end

        UserAuth.log_in_user(conn, user, user_params)

      {:error, :not_found} ->
        conn
        |> put_flash(:error, "The link is invalid or it has expired.")
        |> render(:new, form: Phoenix.Component.to_form(%{}, as: "user"))
    end
  end

  # email + password login
  def create(conn, %{"user" => %{"email" => email, "password" => password} = user_params}) do
    if user = Accounts.get_user_by_email_and_password(email, password) do
      # Check if user has TOTP enabled - require verification before creating session
      if Accounts.totp_enabled?(user) do
        # Store pending auth state and redirect to TOTP verification
        remember_me = Map.get(user_params, "remember_me") == "true"

        conn
        |> put_session(:pending_totp_user_id, user.id)
        |> put_session(:pending_totp_remember_me, remember_me)
        |> redirect(to: ~p"/users/log-in/totp")
      else
        # No TOTP, proceed with normal login
        UserAuth.log_in_user(conn, user, user_params)
      end
    else
      form = Phoenix.Component.to_form(user_params, as: "user")

      # In order to prevent user enumeration attacks, don't disclose whether the email is registered.
      conn
      |> put_flash(:error, "Invalid email or password")
      |> render(:new, form: form)
    end
  end

  # magic link request
  def create(conn, %{"user" => %{"email" => email}}) do
    _ =
      if user = Accounts.get_user_by_email(email) do
        Accounts.deliver_login_instructions(
          user,
          &url(~p"/users/log-in/#{&1}")
        )
      end

    info =
      "If your email is in our system, you will receive instructions for logging in shortly."

    conn
    |> put_flash(:info, info)
    |> redirect(to: ~p"/users/log-in")
  end

  def confirm(conn, %{"token" => token}) do
    # Check if user was previously confirmed before logging in
    was_confirmed =
      case Accounts.get_user_by_magic_link_token(token) do
        %Accounts.User{confirmed_at: confirmed_at} when not is_nil(confirmed_at) -> true
        _ -> false
      end

    case Accounts.login_user_by_magic_link(token) do
      {:ok, {user, _expired_tokens}} ->
        conn =
          if was_confirmed do
            conn
          else
            put_flash(conn, :info, "User confirmed successfully.")
          end

        # Always use remember_me: true to keep user logged in
        UserAuth.log_in_user(conn, user, %{"remember_me" => "true"})

      {:error, :not_found} ->
        conn
        |> put_flash(:error, "Magic link is invalid or it has expired.")
        |> redirect(to: ~p"/users/log-in")
    end
  end

  def delete(conn, _params) do
    conn
    |> put_flash(:info, "Logged out successfully.")
    |> UserAuth.log_out_user()
  end

  def totp_verification_form(conn, _params) do
    case get_session(conn, :pending_totp_user_id) do
      nil ->
        conn
        |> put_flash(:error, "Please log in first.")
        |> redirect(to: ~p"/users/log-in")

      _user_id ->
        form = Phoenix.Component.to_form(%{}, as: "user")
        render(conn, :totp, form: form)
    end
  end

  def verify_totp(conn, %{"user" => %{"totp_code" => code}}) do
    case get_session(conn, :pending_totp_user_id) do
      nil ->
        redirect_to_login(conn)

      user_id ->
        handle_totp_verification(conn, user_id, code)
    end
  end

  defp redirect_to_login(conn) do
    conn
    |> put_flash(:error, "Please log in first.")
    |> redirect(to: ~p"/users/log-in")
  end

  defp handle_totp_verification(conn, user_id, code) do
    user = Accounts.get_user!(user_id)

    case Accounts.verify_user_mfa(user, code) do
      {:ok, user, :totp} ->
        complete_totp_login(conn, user)

      {:ok, user, :recovery_code} ->
        conn
        |> put_flash(
          :warning,
          "You used a recovery code. Consider regenerating codes from your account settings."
        )
        |> complete_totp_login(user)

      {:error, _reason} ->
        render_totp_error(conn, code)
    end
  end

  defp complete_totp_login(conn, user) do
    remember_me = get_session(conn, :pending_totp_remember_me)

    user_params =
      if remember_me do
        %{"remember_me" => "true"}
      else
        %{}
      end

    conn
    |> delete_session(:pending_totp_user_id)
    |> delete_session(:pending_totp_remember_me)
    |> UserAuth.log_in_user(user, user_params)
  end

  defp render_totp_error(conn, code) do
    form = Phoenix.Component.to_form(%{"totp_code" => code}, as: "user")

    conn
    |> put_flash(:error, "Invalid authentication code. Please try again.")
    |> render(:totp, form: form)
  end
end