defmodule SteamAPI do
  @behaviour Tesla.Middleware
  # steam API helper, based off baseurl and query

  @impl Tesla.Middleware
  def call(env, next, interface) do
    env
    |> apply_base(interface)
    |> apply_base("https://api.steampowered.com")
    |> merge(key: Application.fetch_env!(:steamwebapi, :token))
    |> Tesla.run(next)
  end

  defp apply_base(env, base) do
    if Regex.match?(~r/^https?:\/\//i, env.url) do
      # skip if url is already with scheme
      env
    else
      %{env | url: join(base, env.url)}
    end
  end

  defp merge(env, query) do
    Map.update!(env, :query, &(&1 ++ query))
  end

  defp join(base, url) do
    case {String.last(to_string(base)), url} do
      {nil, url} -> url
      {"/", "/" <> rest} -> base <> rest
      {"/", rest} -> base <> rest
      {_, ""} -> base
      {_, "/" <> rest} -> base <> "/" <> rest
      {_, rest} -> base <> "/" <> rest
    end
  end
end