#######################################################
# Copyright (c) 2019, ArrayFire
# All rights reserved.
#
# This file is distributed under 3-clause BSD license.
# The complete license agreement can be obtained at:
# http://arrayfire.com/licenses/BSD-3-Clause
########################################################

"""
Functions to time arrayfire.
"""

import math
from time import time

from .device import eval, sync


def timeit(af_func, *args):
    """
    Function to time arrayfire functions.

    Parameters
    ----------

    af_func    : arrayfire function

    *args      : arguments to `af_func`

    Returns
    --------

    t   : Time in seconds
    """
    sample_trials = 3

    sample_time = 1E20

    for _ in range(sample_trials):
        start = time()
        res = af_func(*args)
        eval(res)
        sync()
        sample_time = min(sample_time, time() - start)

    if sample_time >= 0.5:
        return sample_time

    num_iters = max(math.ceil(1.0 / sample_time), 3.0)

    start = time()
    for _ in range(int(num_iters)):
        res = af_func(*args)
        eval(res)
    sync()
    sample_time = (time() - start) / num_iters
    return sample_time