"""Simple tools for timing functions' execution, when IPython is not available. """

from __future__ import print_function, division

import timeit
import math

from sympy.core.compatibility import range

_scales = [1e0, 1e3, 1e6, 1e9]
_units = [u's', u'ms', u'\N{GREEK SMALL LETTER MU}s', u'ns']


def timed(func, setup="pass", limit=None):
    """Adaptively measure execution time of a function. """
    timer = timeit.Timer(func, setup=setup)
    repeat, number = 3, 1

    for i in range(1, 10):
        if timer.timeit(number) >= 0.2:
            break
        elif limit is not None and number >= limit:
            break
        else:
            number *= 10

    time = min(timer.repeat(repeat, number)) / number

    if time > 0.0:
        order = min(-int(math.floor(math.log10(time)) // 3), 3)
    else:
        order = 3

    return (number, time, time*_scales[order], _units[order])


# Code for doing inline timings of recursive algorithms.

def __do_timings():
    import os
    res = os.getenv('SYMPY_TIMINGS', '')
    res = [x.strip() for x in res.split(',')]
    return set(res)

_do_timings = __do_timings()
_timestack = None


def _print_timestack(stack, level=1):
    print('-'*level, '%.2f %s%s' % (stack[2], stack[0], stack[3]))
    for s in stack[1]:
        _print_timestack(s, level + 1)


def timethis(name):
    def decorator(func):
        global _do_timings
        if not name in _do_timings:
            return func

        def wrapper(*args, **kwargs):
            from time import time
            global _timestack
            oldtimestack = _timestack
            _timestack = [func.func_name, [], 0, args]
            t1 = time()
            r = func(*args, **kwargs)
            t2 = time()
            _timestack[2] = t2 - t1
            if oldtimestack is not None:
                oldtimestack[1].append(_timestack)
                _timestack = oldtimestack
            else:
                _print_timestack(_timestack)
                _timestack = None
            return r
        return wrapper
    return decorator
