import pandas as pd

"""

LOGGER

"""

LOG_QUEUE = []

LOGGING = True

def log(msg=None,start=True,end_prev=True,new_level=False,end_level=False):

    if not LOGGING: return

    tag = ''

    now = pd.to_datetime('now') - pd.Timedelta(5, unit='h')

    if end_level: end_log_level()

    if end_prev and len(LOG_QUEUE) > 0:

        level = LOG_QUEUE.pop()

        if len(level) > 0:

            start_dt = level.pop()

            tag = '<<'*(len(LOG_QUEUE)) + ' --- '

            __print_entry(now,tag,'({}s)'.format((now-start_dt).total_seconds()))

        LOG_QUEUE.append(level)

    if msg is None: return

    if start:

        if len(LOG_QUEUE) == 0: LOG_QUEUE.append([])

        tag = '>>'*(len(LOG_QUEUE)-1) + ' '

        LOG_QUEUE[-1].append(now)

        if new_level: LOG_QUEUE.append([])

    else: tag = ''

    __print_entry(now,tag,msg)

def __print_entry(dt,tag,msg):

    print '({}){}{}'.format(dt,tag,msg)

def end_log_level():

    if len(LOG_QUEUE) == 0: return

    while len(LOG_QUEUE[-1]) > 0 : log()

    LOG_QUEUE.pop()

    log()

def end_log():

    while len(LOG_QUEUE) > 0 : end_log_level()

def stop_logging():

    LOGGING = False