import shutil
import sys
import time
from .misc import format_time


begin_time = 0
recent_times = []


def progress_bar(current, total, msg=None, premsg=None, barmsg=None):
    global begin_time, recent_times
    current_time = time.time()
    if current == 0:
        begin_time = time.time()  # Reset for new bar.
        recent_times = [begin_time]
        total_time = 0
        estimated_time = 0
        step_time = 0
    else:
        recent_elapse = current_time - recent_times[0]
        step_time = recent_elapse / len(recent_times)
        total_time = current_time - begin_time
        estimated_time = (total - current) * step_time
        recent_times = (recent_times + [current_time])[-100:]

    show_opt = int(current_time) % 6 >= 3 and current < total
    show_barmsg = barmsg is not None and show_opt

    str0 = f"{premsg} [" if premsg else '['
    str1 = f"] {current:d}/{total:d} | Step: {format_time(step_time)} | " + (
        f"Eta: {format_time(estimated_time)}" if show_opt else f"Tot: {format_time(total_time)}"
    )
    if msg:
        str1 += f" | {msg}"

    tot_cols = shutil.get_terminal_size().columns - 10
    bar_length = tot_cols - len(str0) - len(str1)
    if show_barmsg and bar_length < len(barmsg):
        sys.stdout.write(str0[:-1] + barmsg)
    elif bar_length <= 0:
        sys.stdout.write(str0[:-1] + str1[2:])
    else:
        current_len = int(bar_length * current / total)
        rest_len = int(bar_length - current_len)
        str_bar = ''
        if current_len > 0:
            str_bar += '=' * (current_len - 1) + '>'
        str_bar += '.' * rest_len
        if show_barmsg:
            str_bar = barmsg + str_bar[len(barmsg):]
        sys.stdout.write(str0 + str_bar + str1)

    sys.stdout.write('\r' if current < total else '\n')
    sys.stdout.flush()