defmodule TimeExample do
  def run do
    # We'll start by getting the current time.
    now = DateTime.utc_now()
    IO.inspect(now)

    # You can build a DateTime struct by providing the
    # year, month, day, etc. Times are always associated
    # with a time zone.
    then = DateTime.new!(~D[2009-11-17], ~T[20:34:58.651387237], "Etc/UTC")
    IO.inspect(then)

    # You can extract the various components of the time
    # value as expected.
    IO.puts(then.year)
    IO.puts(then.month)
    IO.puts(then.day)
    IO.puts(then.hour)
    IO.puts(then.minute)
    IO.puts(then.second)
    IO.puts(then.microsecond |> elem(0))
    IO.puts(then.time_zone)

    # The day of the week is also available.
    IO.puts(Date.day_of_week(DateTime.to_date(then)))

    # These functions compare two times, testing if the
    # first occurs before, after, or at the same time
    # as the second, respectively.
    IO.puts(DateTime.compare(then, now) == :lt)
    IO.puts(DateTime.compare(then, now) == :gt)
    IO.puts(DateTime.compare(then, now) == :eq)

    # The diff function returns a Duration representing
    # the interval between two times.
    diff = DateTime.diff(now, then, :microsecond)
    IO.puts("#{diff} microseconds")

    # We can compute the length of the duration in
    # various units.
    IO.puts("#{diff / 1_000_000 / 3600} hours")
    IO.puts("#{diff / 1_000_000 / 60} minutes")
    IO.puts("#{diff / 1_000_000} seconds")
    IO.puts("#{diff} microseconds")

    # You can use add to advance a time by a given
    # duration, or with a negative value to move backwards.
    IO.inspect(DateTime.add(then, div(diff, 1_000_000), :second))
    IO.inspect(DateTime.add(then, -div(diff, 1_000_000), :second))
  end
end

TimeExample.run()