import datetime
import logging
import os

from port_stats import utils


LOG = logging.getLogger(__name__)


def _parse_stamped_line(line):
    try:
        return datetime.datetime.strptime(
            line.split(' :: ')[0], '%Y-%b-%d %H:%M:%S')
    except Exception:
        return None


def log_timestamps(filename):
    first = None
    last = None
    with open(filename, 'r') as f:
        parsed = (_parse_stamped_line(line) for line in f)
        filtered = (stamp for stamp in parsed if stamp)
        for last in filtered:
            if not first:
                first = last
    return first, last


def log_seconds(filename):
    first, last = log_timestamps(filename)
    if first and last:
        return (last - first).total_seconds()
    else:
        LOG.warn("Failed to find timestamps in %s", filename)
        return 0


def task_event_logs(info):
    if not info:
        return []
    path = os.path.join(info['task_path'], 'logs')
    if not os.path.exists(path):
        return []
    res = sorted((f for f in os.listdir(path) if f.startswith('events')),
                 key=lambda f: [utils.maybe_int(x) for x in f.split('.')])
    return [os.path.join(path, x) for x in res]


def build_time(info, idx=0):
    log_file = task_event_logs(info)[idx]
    return log_seconds(log_file)