defmodule Adventurous.Util do

  defmodule Timer do
    defstruct start: System.monotonic_time()
  end

  @doc """
  Times function execution. If msg is specified, prints it with number of ms function exection has taken.
  """
  def timed(func, msg \\ nil) do
    timer = %Timer{}
    result = func.()
    diff = time_diff(timer)
    if msg do
      IO.puts("#{msg}: took #{diff/1_000_000}ms")
    end

    {result, diff}
  end

  @doc """
  Returns (and optionally prints) time difference between start of timer.
  """
  @spec time_diff(atom | %{:start => number, optional(any) => any}) :: number
  def time_diff(timer, msg \\ nil) do
    diff = System.monotonic_time() - timer.start
    if msg do
      IO.puts("#{msg}: took #{diff/1_000_000}ms")
    end

    diff
  end

  @doc """
  Returns left-inclusive and right non-inclusive range.
  Range starting and ending at the same number is considered empty.
  """
  @spec non_inclusive_range(integer(), integer()) :: Range.t()
  def non_inclusive_range(start, stop) do
    cond do
      start < stop ->
        start..(stop - 1)

      start > stop ->
        stop..(start - 1)

      start == stop ->
        0..-1//2 # empty range
    end
  end
end