ammocpr/lib/ammoprices/scraping/retailers/sg_ammo.ex

defmodule Ammoprices.Scraping.Retailers.SgAmmo do
  @moduledoc false
  @behaviour Ammoprices.Scraping.Scraper

  alias Ammoprices.Scraping.TextDetector

  @slug_to_path %{
    "9mm-luger" => "/catalog/pistol-ammo-for-sale/9mm-luger-ammo",
    "45-acp" => "/catalog/pistol-ammo-for-sale/45-auto-acp-ammo",
    "380-acp" => "/catalog/pistol-ammo-for-sale/380-auto-ammo",
    "40-sw" => "/catalog/pistol-ammo-for-sale/40-cal-ammo",
    "38-special" => "/catalog/pistol-ammo-for-sale/38-special-ammo",
    "357-magnum" => "/catalog/pistol-ammo-for-sale/357-magnum-ammo",
    "10mm-auto" => "/catalog/pistol-ammo-for-sale/10mm-ammo",
    "223-rem" => "/catalog/rifle-ammo-for-sale/223-556mm-ammo",
    "556-nato" => "/catalog/rifle-ammo-for-sale/223-556mm-ammo",
    "308-win" => "/catalog/rifle-ammo-for-sale/308-762mm-ammo",
    "762x39" => "/catalog/rifle-ammo-for-sale/762x39-ammo",
    "30-06" => "/catalog/rifle-ammo-for-sale/30-06-ammo",
    "300-blackout" => "/catalog/rifle-ammo-for-sale/300-aac-blackout-ammo",
    "65-creedmoor" => "/catalog/rifle-ammo-for-sale/65-creedmoor-ammo",
    "22-lr" => "/catalog/rimfire-ammo-for-sale/22-lr-ammo",
    "22-wmr" => "/catalog/rimfire-ammo-for-sale/22-wmr-ammo",
    "17-hmr" => "/catalog/rimfire-ammo-for-sale/17-hmr-ammo",
    "12-gauge" => "/catalog/shotgun-ammo-for-sale/12-gauge-ammo",
    "16-gauge" => "/catalog/shotgun-ammo-for-sale/16-gauge-ammo",
    "20-gauge" => "/catalog/shotgun-ammo-for-sale/20-gauge-ammo"
  }

  @impl true
  def retailer_slug, do: "sgammo"

  @impl true
  def category_url(caliber) do
    Map.get(@slug_to_path, caliber.slug)
  end

  @impl true
  def parse_products(html) do
    html
    |> Floki.parse_document!()
    |> Floki.find("tr.sgammo-content-product-item")
    |> Enum.map(&parse_row/1)
    |> Enum.reject(&is_nil/1)
  end

  defp parse_row(row) do
    with {:ok, title} <- extract_title(row),
         {:ok, url} <- extract_url(row),
         {:ok, price_cents} <- extract_price(row),
         {:ok, ppr_cents} <- extract_price_per_round(row) do
      %{
        title: title,
        url: url,
        price_cents: price_cents,
        price_per_round_cents: ppr_cents,
        brand: extract_brand(title),
        grain_weight: extract_grain_weight(title),
        round_count: extract_round_count(title),
        casing: TextDetector.detect_casing(title),
        subsonic: TextDetector.detect_subsonic(title),
        in_stock: extract_in_stock(row)
      }
    else
      _ -> nil
    end
  end

  defp extract_title(row) do
    case Floki.find(row, ".sgammo-content-product-item__title a") do
      [{_, _, _} = node] -> {:ok, node |> Floki.text() |> String.trim()}
      _ -> :error
    end
  end

  defp extract_url(row) do
    case Floki.find(row, ".sgammo-content-product-item__title a") do
      [{_, attrs, _}] ->
        case List.keyfind(attrs, "href", 0) do
          {"href", href} -> {:ok, href}
          _ -> :error
        end

      _ ->
        :error
    end
  end

  defp extract_price(row) do
    case Floki.find(row, ".sgammo-content-product-item__col-price .woocommerce-Price-amount") do
      [{_, _, _} = node | _] ->
        text = node |> Floki.text() |> String.trim()

        case Regex.run(~r/\$([0-9,]+\.\d{2})/, text) do
          [_, amount] ->
            cents =
              amount
              |> String.replace(",", "")
              |> String.to_float()
              |> Kernel.*(100)
              |> round()

            {:ok, cents}

          _ ->
            :error
        end

      _ ->
        :error
    end
  end

  defp extract_price_per_round(row) do
    price_col =
      row
      |> Floki.find(".sgammo-content-product-item__col-price")
      |> List.first()

    if price_col do
      text = Floki.text(price_col)

      case Regex.run(~r/\$([0-9.]+)\s*Per Round/i, text) do
        [_, amount] ->
          cents =
            amount
            |> String.to_float()
            |> Kernel.*(100)
            |> round()

          {:ok, cents}

        _ ->
          :error
      end
    else
      :error
    end
  end

  defp extract_brand(title) do
    # SGAmmo titles typically have format: "NNN Round ... by BRAND - SKU"
    case Regex.run(~r/by\s+([A-Za-z][A-Za-z\s&]+?)(?:\s*-|\s*$)/i, title) do
      [_, brand] -> String.trim(brand)
      _ -> nil
    end
  end

  defp extract_grain_weight(title) do
    case Regex.run(~r/(\d+)\s*[Gg]rain/i, title) do
      [_, weight] -> String.to_integer(weight)
      _ -> nil
    end
  end

  defp extract_round_count(title) do
    case Regex.run(~r/(\d[\d,]*)\s*[Rr]ound/i, title) do
      [_, count] -> count |> String.replace(",", "") |> String.to_integer()
      _ -> nil
    end
  end

  defp extract_in_stock(row) do
    classes = [row] |> Floki.attribute("class") |> List.first() || ""
    String.contains?(classes, "instock")
  end
end