defmodule BerrypodWeb.SeoController do
  use BerrypodWeb, :controller

  alias Berrypod.{Pages, Products}
  alias BerrypodWeb.R

  def robots(conn, _params) do
    base = BerrypodWeb.Endpoint.url()

    content = """
    User-agent: *
    Allow: /
    Disallow: /admin/
    Disallow: /api/
    Disallow: /users/
    Disallow: /webhooks/
    Disallow: /checkout/

    Sitemap: #{base}/sitemap.xml
    """

    conn
    |> put_resp_content_type("text/plain")
    |> send_resp(200, content)
  end

  def sitemap(conn, _params) do
    base = BerrypodWeb.Endpoint.url()
    products = Products.list_products_for_sitemap()
    categories = Products.list_categories()

    static_pages = [
      {R.home(), "daily", "1.0", []},
      {R.collection("all"), "daily", "0.9", []},
      {R.about(), "monthly", "0.5", []},
      {R.contact(), "monthly", "0.5", []},
      {R.delivery(), "monthly", "0.5", []},
      {R.privacy(), "monthly", "0.3", []},
      {R.terms(), "monthly", "0.3", []}
    ]

    category_pages =
      Enum.map(categories, fn cat ->
        {R.collection(cat.slug), "daily", "0.8", []}
      end)

    product_pages =
      Enum.map(products, fn product ->
        images = product_image_entries(product, base)
        {R.product(product.slug), "weekly", "0.9", images}
      end)

    custom_pages =
      Pages.list_custom_pages()
      |> Enum.filter(& &1.published)
      |> Enum.map(fn page -> {"/#{page.slug}", "weekly", "0.6", []} end)

    all_pages = static_pages ++ category_pages ++ product_pages ++ custom_pages

    entries =
      Enum.map_join(all_pages, "\n", fn {path, changefreq, priority, images} ->
        image_tags =
          Enum.map_join(images, "\n", fn img ->
            """
                <image:image>
                  <image:loc>#{xml_escape(img.url)}</image:loc>
                  <image:title>#{xml_escape(img.title)}</image:title>
                </image:image>
            """
            |> String.trim_trailing()
          end)

        url_content =
          "    <loc>#{xml_escape(base <> path)}</loc>\n" <>
            "    <changefreq>#{changefreq}</changefreq>\n" <>
            "    <priority>#{priority}</priority>"

        if image_tags == "" do
          "  <url>\n#{url_content}\n  </url>"
        else
          "  <url>\n#{url_content}\n#{image_tags}\n  </url>"
        end
      end)

    xml = """
    <?xml version="1.0" encoding="UTF-8"?>
    <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
            xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">
    #{entries}
    </urlset>
    """

    conn
    |> put_resp_content_type("application/xml")
    |> send_resp(200, xml)
  end

  defp product_image_entries(product, base_url) do
    product.images
    |> Enum.take(5)
    |> Enum.map(fn product_image ->
      image = product_image.image
      alt_text = product_image.alt_text || product.title
      url = "#{base_url}/image_cache/#{image.id}.webp"

      %{url: url, title: alt_text}
    end)
  end

  defp xml_escape(nil), do: ""

  defp xml_escape(text) when is_binary(text) do
    text
    |> String.replace("&", "&amp;")
    |> String.replace("<", "&lt;")
    |> String.replace(">", "&gt;")
    |> String.replace("\"", "&quot;")
    |> String.replace("'", "&apos;")
  end
end