defmodule PhoenixKitWeb.Live.Settings.SEO do
  @moduledoc """
  SEO settings management LiveView for PhoenixKit.

  Provides a simple interface for global indexing directives (noindex/nofollow)
  to keep staging or development deployments out of search engines, plus the
  `robots.txt` guidance that goes with them.

  PhoenixKit deliberately does **not** generate `robots.txt`. It is host policy,
  and `Plug.Static` runs before the router — a `priv/static/robots.txt` is
  served whatever the router says, so a generated route would be dead code on
  most installs and a silent override on the rest. What this page does instead
  is tell the operator exactly what to put in theirs, including the `Sitemap:`
  line, since a sitemap nothing points at is one crawlers find by guessing.
  """
  use PhoenixKitWeb, :live_view
  use Gettext, backend: PhoenixKitWeb.Gettext

  alias PhoenixKit.Modules.SEO
  alias PhoenixKit.Settings
  alias PhoenixKit.Utils.Routes

  def mount(_params, _session, socket) do
    # Attach locale hook for automatic locale handling

    if SEO.module_enabled?() do
      project_title = Settings.get_project_title()
      config = SEO.get_config()

      socket =
        socket
        |> assign(:page_title, "SEO Settings")
        |> assign(:project_title, project_title)
        |> assign(:current_path, get_current_path(socket.assigns.current_locale_base))
        |> assign(:no_index_enabled, config.no_index_enabled)
        # The ROOT url, deliberately — not `Routes.url/1`, which prefixes it.
        # Core serves /sitemap.xml at both the root and under the kit prefix
        # precisely because crawlers look at the root, so advertising the
        # prefixed one in robots.txt would defeat the point.
        |> assign(:sitemap_url, Routes.base_url() <> "/sitemap.xml")
        |> assign(:robots_txt_present?, File.exists?(robots_txt_path()))
        |> assign(:robots_txt_references_sitemap?, robots_txt_references_sitemap?())

      {:ok, socket}
    else
      socket =
        socket
        |> put_flash(
          :error,
          gettext(
            "SEO module is disabled. Enable it from the Modules page to configure settings."
          )
        )
        |> redirect(to: Routes.path("/admin/modules", locale: socket.assigns.current_locale_base))

      {:ok, socket}
    end
  end

  def handle_event("toggle_no_index", _params, socket) do
    new_value = !socket.assigns.no_index_enabled

    result =
      if new_value do
        SEO.enable_no_index()
      else
        SEO.disable_no_index()
      end

    case result do
      {:ok, _setting} ->
        message =
          if new_value do
            gettext("Noindex/nofollow enabled. Search engines will not index this site.")
          else
            gettext("Noindex/nofollow disabled. Site can be indexed again.")
          end

        socket =
          socket
          |> assign(:no_index_enabled, new_value)
          |> put_flash(:info, message)

        {:noreply, socket}

      {:error, _changeset} ->
        socket =
          socket
          |> put_flash(:error, gettext("Failed to update SEO settings"))

        {:noreply, socket}
    end
  end

  defp get_current_path(locale) do
    Routes.path("/admin/settings/seo", locale: locale)
  end

  # Where Plug.Static serves it from in a stock Phoenix app. Read-only: this
  # page reports what is there, it never writes the host's robots.txt.
  defp robots_txt_path, do: Path.join(["priv", "static", "robots.txt"])

  defp robots_txt_references_sitemap? do
    case File.read(robots_txt_path()) do
      {:ok, contents} -> contents =~ ~r/^\s*sitemap:/im
      {:error, _} -> false
    end
  end
end