import sys
from contextlib import contextmanager
from functools import wraps
from time import sleep, time

# Use relative/cpu timer to have reliable timings when there is a sudden load
try:
    from time import process_time
except ImportError:
    from time import clock
    process_time = clock

from tqdm import tqdm, trange

from .tests_tqdm import importorskip, mark, patch_lock, skip

pytestmark = mark.slow


def cpu_sleep(t):
    """Sleep the given amount of cpu time"""
    start = process_time()
    while (process_time() - start) < t:
        pass


def checkCpuTime(sleeptime=0.2):
    """Check if cpu time works correctly"""
    if checkCpuTime.passed:
        return True
    # First test that sleeping does not consume cputime
    start1 = process_time()
    sleep(sleeptime)
    t1 = process_time() - start1

    # secondly check by comparing to cpusleep (where we actually do something)
    start2 = process_time()
    cpu_sleep(sleeptime)
    t2 = process_time() - start2

    if abs(t1) < 0.0001 and t1 < t2 / 10:
        checkCpuTime.passed = True
        return True
    skip("cpu time not reliable on this machine")


checkCpuTime.passed = False


@contextmanager
def relative_timer():
    """yields a context timer function which stops ticking on exit"""
    start = process_time()

    def elapser():
        return process_time() - start

    yield lambda: elapser()
    spent = elapser()

    def elapser():  # NOQA
        return spent


def retry_on_except(n=3, check_cpu_time=True):
    """decroator for retrying `n` times before raising Exceptions"""
    def wrapper(func):
        """actual decorator"""
        @wraps(func)
        def test_inner(*args, **kwargs):
            """may skip if `check_cpu_time` fails"""
            for i in range(1, n + 1):
                try:
                    if check_cpu_time:
                        checkCpuTime()
                    func(*args, **kwargs)
                except Exception:
                    if i >= n:
                        raise
                else:
                    return
        return test_inner
    return wrapper


def simple_progress(iterable=None, total=None, file=sys.stdout, desc='',
                    leave=False, miniters=1, mininterval=0.1, width=60):
    """Simple progress bar reproducing tqdm's major features"""
    n = [0]  # use a closure
    start_t = [time()]
    last_n = [0]
    last_t = [0]
    if iterable is not None:
        total = len(iterable)

    def format_interval(t):
        mins, s = divmod(int(t), 60)
        h, m = divmod(mins, 60)
        return f'{h:d}:{m:02d}:{s:02d}' if h else f'{m:02d}:{s:02d}'

    def update_and_print(i=1):
        n[0] += i
        if (n[0] - last_n[0]) >= miniters:
            last_n[0] = n[0]

            if (time() - last_t[0]) >= mininterval:
                last_t[0] = time()  # last_t[0] == current time

                spent = last_t[0] - start_t[0]
                spent_fmt = format_interval(spent)
                rate = n[0] / spent if spent > 0 else 0
                rate_fmt = "%.2fs/it" % (1.0 / rate) if 0.0 < rate < 1.0 else "%.2fit/s" % rate

                frac = n[0] / total
                percentage = int(frac * 100)
                eta = (total - n[0]) / rate if rate > 0 else 0
                eta_fmt = format_interval(eta)

                # full_bar = "#" * int(frac * width)
                barfill = " " * int((1.0 - frac) * width)
                bar_length, frac_bar_length = divmod(int(frac * width * 10), 10)
                full_bar = '#' * bar_length
                frac_bar = chr(48 + frac_bar_length) if frac_bar_length else ' '

                file.write("\r%s %i%%|%s%s%s| %i/%i [%s<%s, %s]" %
                           (desc, percentage, full_bar, frac_bar, barfill, n[0],
                            total, spent_fmt, eta_fmt, rate_fmt))

                if n[0] == total and leave:
                    file.write("\n")
                file.flush()

    def update_and_yield():
        for elt in iterable:
            yield elt
            update_and_print()

    update_and_print(0)
    if iterable is not None:
        return update_and_yield()
    return update_and_print


def assert_performance(thresh, name_left, time_left, name_right, time_right):
    """raises if time_left > thresh * time_right"""
    if time_left > thresh * time_right:
        raise ValueError(
            f'{name_left}: {time_left:f}, {name_right}: {time_right:f}'
            f', ratio {time_left / time_right:f} > {thresh:f}')


@retry_on_except()
def test_iter_basic_overhead():
    """Test overhead of iteration based tqdm"""
    total = int(1e6)

    a = 0
    with trange(total) as t:
        with relative_timer() as time_tqdm:
            for i in t:
                a += i
    assert a == (total ** 2 - total) / 2.0

    a = 0
    with relative_timer() as time_bench:
        for i in range(total):
            a += i
            sys.stdout.write(str(a))

    assert_performance(3, 'trange', time_tqdm(), 'range', time_bench())


@retry_on_except()
def test_manual_basic_overhead():
    """Test overhead of manual tqdm"""
    total = int(1e6)

    with tqdm(total=total * 10, leave=True) as t:
        a = 0
        with relative_timer() as time_tqdm:
            for i in range(total):
                a += i
                t.update(10)

    a = 0
    with relative_timer() as time_bench:
        for i in range(total):
            a += i
            sys.stdout.write(str(a))

    assert_performance(5, 'tqdm', time_tqdm(), 'range', time_bench())


def worker(total, blocking=True):
    def incr_bar(x):
        for _ in trange(total, lock_args=None if blocking else (False,),
                        miniters=1, mininterval=0, maxinterval=0):
            pass
        return x + 1
    return incr_bar


@retry_on_except()
@patch_lock(thread=True)
def test_lock_args():
    """Test overhead of nonblocking threads"""
    ThreadPoolExecutor = importorskip('concurrent.futures').ThreadPoolExecutor

    total = 16
    subtotal = 10000

    with ThreadPoolExecutor() as pool:
        sys.stderr.write('block ... ')
        sys.stderr.flush()
        with relative_timer() as time_tqdm:
            res = list(pool.map(worker(subtotal, True), range(total)))
            assert sum(res) == sum(range(total)) + total
        sys.stderr.write('noblock ... ')
        sys.stderr.flush()
        with relative_timer() as time_noblock:
            res = list(pool.map(worker(subtotal, False), range(total)))
            assert sum(res) == sum(range(total)) + total

    assert_performance(0.5, 'noblock', time_noblock(), 'tqdm', time_tqdm())


@retry_on_except(10)
def test_iter_overhead_hard():
    """Test overhead of iteration based tqdm (hard)"""
    total = int(1e5)

    a = 0
    with trange(total, leave=True, miniters=1,
                mininterval=0, maxinterval=0) as t:
        with relative_timer() as time_tqdm:
            for i in t:
                a += i
    assert a == (total ** 2 - total) / 2.0

    a = 0
    with relative_timer() as time_bench:
        for i in range(total):
            a += i
            sys.stdout.write(("%i" % a) * 40)

    assert_performance(130, 'trange', time_tqdm(), 'range', time_bench())


@retry_on_except(10)
def test_manual_overhead_hard():
    """Test overhead of manual tqdm (hard)"""
    total = int(1e5)

    with tqdm(total=total * 10, leave=True, miniters=1,
              mininterval=0, maxinterval=0) as t:
        a = 0
        with relative_timer() as time_tqdm:
            for i in range(total):
                a += i
                t.update(10)

    a = 0
    with relative_timer() as time_bench:
        for i in range(total):
            a += i
            sys.stdout.write(("%i" % a) * 40)

    assert_performance(130, 'tqdm', time_tqdm(), 'range', time_bench())


@retry_on_except(10)
def test_iter_overhead_simplebar_hard():
    """Test overhead of iteration based tqdm vs simple progress bar (hard)"""
    total = int(1e4)

    a = 0
    with trange(total, leave=True, miniters=1,
                mininterval=0, maxinterval=0) as t:
        with relative_timer() as time_tqdm:
            for i in t:
                a += i
    assert a == (total ** 2 - total) / 2.0

    a = 0
    s = simple_progress(range(total), leave=True,
                        miniters=1, mininterval=0)
    with relative_timer() as time_bench:
        for i in s:
            a += i

    assert_performance(10, 'trange', time_tqdm(), 'simple_progress', time_bench())


@retry_on_except(10)
def test_manual_overhead_simplebar_hard():
    """Test overhead of manual tqdm vs simple progress bar (hard)"""
    total = int(1e4)

    with tqdm(total=total * 10, leave=True, miniters=1,
              mininterval=0, maxinterval=0) as t:
        a = 0
        with relative_timer() as time_tqdm:
            for i in range(total):
                a += i
                t.update(10)

    simplebar_update = simple_progress(total=total * 10, leave=True,
                                       miniters=1, mininterval=0)
    a = 0
    with relative_timer() as time_bench:
        for i in range(total):
            a += i
            simplebar_update(10)

    assert_performance(10, 'tqdm', time_tqdm(), 'simple_progress', time_bench())