defmodule SchedEx do
  @moduledoc """
  SchedEx schedules 'jobs' (either m,f,a tuples or functions) to run in the future. 
  """

  @doc """
  Runs the given module, function and argument tuple at the given time
  """
  def run_at(m, f, a, %DateTime{} = time) when is_atom(m) and is_atom(f) and is_list(a) do
    run_at(fn -> apply(m,f,a) end, time)
  end

  @doc """
  Runs the given function at the given time
  """
  def run_at(func, %DateTime{} = time) when is_function(func) do
    delay = DateTime.diff(time, DateTime.utc_now(), :millisecond)
    run_in(func, delay)
  end

  @doc """
  Runs the given module, function and argument tuple in given number of milliseconds
  """
  def run_in(m, f, a, delay, opts \\ []) when is_atom(m) and is_atom(f) and is_list(a) do
    run_in(fn -> apply(m,f,a) end, delay, opts)
  end

  @doc """
  Runs the given function in given number of milliseconds
  """
  def run_in(func, delay, opts \\ []) when is_function(func) and is_integer(delay) do
    SchedEx.Runner.run_in(func, delay, opts)
  end

  @doc """
  Cancels the given scheduled job
  """
  def cancel(token) do
    SchedEx.Runner.cancel(token)
  end
end