import sys
import time
__all__ = ['tqdm', 'trange']


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


def format_meter(n, total, elapsed):
    # n - number of finished iterations
    # total - total number of iterations, or None
    # elapsed - number of seconds passed since start
    if n > total:
        total = None
    elapsed_str = format_interval(elapsed)
    rate = '%5.2f' % (n / elapsed) if elapsed else '?'
    if total:
        frac = float(n) / total
        N_BARS = 10
        bar_length = int(frac*N_BARS)
        bar = '#'*bar_length + '-'*(N_BARS-bar_length)
        percentage = '%3d%%' % (frac * 100)
        left_str = format_interval(elapsed / n * (total-n)) if n else '?'
        return '|%s| %d/%d %s [elapsed: %s left: %s, %s iters/sec]' % (
            bar, n, total, percentage, elapsed_str, left_str, rate)
    else:
        return '%d [elapsed: %s, %s iters/sec]' % (n, elapsed_str, rate)


class StatusPrinter(object):
    def __init__(self, file):
        self.file = file
        self.last_printed_len = 0

    def print_status(self, s):
        self.file.write('\r'+s+' '*max(self.last_printed_len-len(s), 0))
        self.file.flush()
        self.last_printed_len = len(s)


def tqdm(iterable, desc='', total=None, leave=False, file=sys.stderr,
         mininterval=0.5, miniters=1):
    """
    Get an iterable object, and return an iterator which acts exactly like the
    iterable, but prints a progress meter and updates it every time a value is
    requested.
    'desc' can contain a short string, describing the progress, that is added
    in the beginning of the line.
    'total' can give the number of expected iterations. If not given,
    len(iterable) is used if it is defined.
    'file' can be a file-like object to output the progress message to.
    If leave is False, tqdm deletes its traces from screen after it has
    finished iterating over all elements.
    If less than mininterval seconds or miniters iterations have passed since
    the last progress meter update, it is not updated again.
    """
    if total is None:
        try:
            total = len(iterable)
        except TypeError:
            total = None
    prefix = desc+': ' if desc else ''
    sp = StatusPrinter(file)
    sp.print_status(prefix + format_meter(0, total, 0))
    start_t = last_print_t = time.time()
    last_print_n = 0
    n = 0
    for obj in iterable:
        yield obj
        # Now the object was created and processed, so we can print the meter.
        n += 1
        if n - last_print_n >= miniters:
            # We check the counter first, to reduce the overhead of time.time()
            cur_t = time.time()
            if cur_t - last_print_t >= mininterval:
                sp.print_status(prefix + format_meter(n, total, cur_t-start_t))
                last_print_n = n
                last_print_t = cur_t
    if not leave:
        sp.print_status('')
        sys.stdout.write('\r')
    else:
        if last_print_n < n:
            cur_t = time.time()
            sp.print_status(prefix + format_meter(n, total, cur_t-start_t))
        file.write('\n')


def trange(*args, **kwargs):
    """A shortcut for writing tqdm(range()) on py3 or tqdm(xrange()) on py2"""
    try:
        f = xrange
    except NameError:
        f = range
    return tqdm(f(*args), **kwargs)
