defmodule DaProductApp.MerchantDefaults do
  @moduledoc """
  Load merchant default settings from the Blade template at runtime.
  This parser is intentionally conservative: it scans the `$defaults = [...]` PHP array
  in `priv/scripts/merchant-configuration.blade.php` and builds an Elixir map.
  """

  require Logger

  @blade_path "priv/scripts/merchant-configuration.blade.php"

  @doc """
  Return a map of defaults parsed from the Blade file.

  Returns an empty map on error.
  """
  def load_from_blade do
    with {:ok, content} <- File.read(@blade_path),
         {:ok, block} <- extract_defaults_block(content) do
      parse_defaults_block(block)
    else
      {:error, reason} ->
        Logger.error("MerchantDefaults.load_from_blade failed: #{inspect(reason)}")
        %{}
      _ ->
        Logger.error("MerchantDefaults.load_from_blade unexpected failure")
        %{}
    end
  end

  # Extract the inner contents of $defaults = [ ... ];
  defp extract_defaults_block(content) when is_binary(content) do
    regex = ~r/\$defaults\s*=\s*\[([\s\S]*?)\];/m

    case Regex.run(regex, content, return: :index) do
      nil -> {:error, :no_defaults_block}
      match ->
        {[_, {start, len}], _} = {match, nil}
        block = String.slice(content, start, len)
        {:ok, block}
    end
  end

  defp extract_defaults_block(_), do: {:error, :invalid_content}

  # Parse the PHP array inner block into an Elixir map.
  # Uses a forgiving regex to capture key => value pairs. Values supported: 'str', null, numbers.
  defp parse_defaults_block(block) when is_binary(block) do
    pair_regex = ~r/'([^']+)'\s*=>\s*(?:'([^']*)'|(null)|([^,\n\r]+))/m

    pairs = Regex.scan(pair_regex, block)

    Enum.reduce(pairs, %{}, fn
      [_, key, _val_str, "null", _], acc ->
        Map.put(acc, key, nil)

      [_, key, val_str, _null, _num], acc when is_binary(val_str) and val_str != "" ->
        Map.put(acc, key, val_str)

      [_, key, val_str, _null, _num], acc when is_binary(val_str) ->
        Map.put(acc, key, val_str)

      [_, key, _val_str, _null, num], acc ->
        v = num |> to_string() |> String.trim()
        v = String.replace_trailing(v, ",", "") |> String.trim()
        Map.put(acc, key, v)

      _, acc -> acc
    end)
  rescue
    e ->
      Logger.error("parse_defaults_block failed: #{inspect(e)}")
      %{}
  end
end