import datetime
import sys, termios, tty
import inputs

frequency = 120 # 120Hz refresh

def timer(length=0):
    """countdown and stopwatch; pass length as 0 for stopwatch"""
    start = datetime.datetime.now()
    end = start + datetime.timedelta(seconds=length) # change to mins in final
    accum = 0
    timeout = 1/frequency

    old_settings = termios.tcgetattr(sys.stdin)
    tty.setcbreak(sys.stdin.fileno())
    while True:
        now = datetime.datetime.now()
        elapsed = now - start
        time_left = end - now
        if length > 0 and time_left.total_seconds() <= 0:
            break

        ch = inputs.getch_nb(timeout)
        if ch == 'q':
            break

        if length > 0:
            time_display = time_left
        else:
            time_display = elapsed

        # see https://gist.github.com/fnky/458719343aabd01cfb17a3a4f7296797
        print("\x1b[2K\r" + inputs.delta_to_HM(time_display), end="", flush=True)

        accum += timeout
        if accum >= 1:
            accum = 0
    termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)

    return (elapsed, start)