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

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

  alias Ammoprices.Scraping.TextDetector

  @slug_to_path %{
    "9mm-luger" => "/handgun/bulk-9mm-ammo",
    "45-acp" => "/handgun/bulk-45-acp-ammo",
    "380-acp" => "/handgun/bulk-380-acp-ammo",
    "40-sw" => "/handgun/bulk-40-sandw-ammo",
    "38-special" => "/handgun/bulk-38-special-ammo",
    "357-magnum" => "/handgun/bulk-357-mag-ammo",
    "10mm-auto" => "/handgun/bulk-10mm-ammo",
    "556-223" => "/rifle/bulk-223-remington-ammo",
    "308-win" => "/rifle/bulk-308-ammo",
    "762x39" => "/rifle/bulk-7.62x39-ammo",
    "30-06" => "/rifle/bulk-30-06-ammo",
    "300-blackout" => "/rifle/bulk-300-blackout-ammo",
    "65-creedmoor" => "/rifle/bulk-6.5-creedmoor-ammo",
    "22-lr" => "/rimfire/bulk-22-lr-ammo",
    "12-gauge" => "/shotgun/bulk-12-gauge-ammo",
    "20-gauge" => "/shotgun/bulk-20-gauge-ammo"
  }

  @impl true
  def retailer_slug, do: "bulk-ammo"

  @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(".products-grid li.item")
    |> Enum.map(&parse_item/1)
    |> Enum.reject(&is_nil/1)
  end

  defp parse_item(item) do
    with {:ok, title} <- extract_title(item),
         {:ok, url} <- extract_url(item),
         {:ok, price_cents} <- extract_price(item) do
      round_count = extract_round_count(title)
      ppr = if round_count && round_count > 0, do: round(price_cents / round_count)

      %{
        title: title,
        url: url,
        price_cents: price_cents,
        price_per_round_cents: ppr,
        brand: extract_brand(title),
        grain_weight: extract_grain_weight(title),
        round_count: round_count,
        casing: TextDetector.detect_casing(title),
        subsonic: TextDetector.detect_subsonic(title),
        in_stock: extract_in_stock(item)
      }
    else
      _ -> nil
    end
  end

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

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

      _ ->
        :error
    end
  end

  defp extract_price(item) do
    # Prefer special-price (sale price), fall back to regular-price
    price_text =
      case Floki.find(item, ".special-price .price") do
        [{_, _, _} = node] -> node |> Floki.text() |> String.trim()
        _ -> extract_regular_price_text(item)
      end

    case price_text do
      nil ->
        :error

      text ->
        case Regex.run(~r/\$([0-9,]+(?:\.\d{2})?)/, text) do
          [_, amount] ->
            cents = parse_dollar_amount(amount)
            {:ok, cents}

          _ ->
            :error
        end
    end
  end

  defp extract_regular_price_text(item) do
    case Floki.find(item, ".regular-price .price") do
      [{_, _, _} = node] -> node |> Floki.text() |> String.trim()
      _ -> nil
    end
  end

  defp parse_dollar_amount(amount) do
    clean = String.replace(amount, ",", "")

    if String.contains?(clean, ".") do
      clean |> String.to_float() |> Kernel.*(100) |> round()
    else
      String.to_integer(clean) * 100
    end
  end

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

  defp extract_brand(title) do
    case Regex.run(~r/by\s+(.+?)(?:\s*-|$)/, title) do
      [_, brand] -> String.trim(brand)
      _ -> nil
    end
  end

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

  defp extract_in_stock(item) do
    case Floki.find(item, "span.in-stock") do
      [_ | _] -> true
      _ -> false
    end
  end
end