"""
Utility functions for fingerprint sweeper
"""
from datetime import date, datetime, timedelta
import sys
import time
import uuid

from fpsweeper.connector import sentry
from fpsweeper.context import context


def yield_sublists(arg_list, sublist_size):
    """Yield successive sublist_size length chunks from arg_list
    Example usage:
        my_list = [x for x in range(0, 100)]
        for sublist in yield_sublists(my_list, 10):
            print(sublist)
    Args:
        arg_list (list): list to divide
        sublist_size (int): size of each sublist returned
    Returns:
        sublist (generator list)
    """
    for i in range(0, len(arg_list), sublist_size):
        yield arg_list[i:i + sublist_size]


def get_timestamp_utc_iso8601(include_zone_designator=True):
    """Get a UTC ISO8601 timestamp with microsecond precision
    Example output: 2016-01-15T18:39:42.574031Z
    Args:
        include_zone_designator (bool): if True, include the UTC zone designator (Z) at end
            including this option, because mysql issues a truncation warning for zone designator
    Returns:
        timestamp (str): current timestamp
    """
    zone_designator = 'Z' if include_zone_designator else ''
    return datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%S.%f{}".format(zone_designator))


def get_datetime_utc_iso8601_seconds_ago(seconds_ago, include_zone_designator=True):
    """Get the datetime for given seconds_ago with microsecond precision.
    For example, if now is '2016-02-03T18:01:11.054818Z',
    and seconds_ago is 3600, return '2016-02-03T17:01:11.054818Z'.
    Args:
        seconds_ago (int): number of seconds to subtract from current time
        include_zone_designator (bool): if True, include the UTC zone designator (Z) at end
            including this option, because mysql issues a truncation warning for zone designator
    Returns:
        UTC ISO8601-formatted datetime string
    """
    zone_designator = 'Z' if include_zone_designator else ''
    return (datetime.utcnow() - timedelta(seconds=seconds_ago))\
        .strftime("%Y-%m-%dT%H:%M:%S.%f{}".format(zone_designator))


def get_date_utc_iso8601_days_ago(days_ago, include_zone_designator=True):
    """Get the date for given days_ago with microseconds precison. Time will be 00:00:00.000000
    For example, if now is '2016-02-03T18:01:11.054818Z' and days_ago is 5,
    return '2016-01-29T00:00:00.000000Z'
    Args:
        days_ago (int): number of days to subtract from current time
        include_zone_designator (bool): if True, include the UTC zone designator (Z) at end
            including this option, because mysql issues a truncation warning for zone designator
    Returns:
        UTC ISO8601-formatted datetime string
    """
    zone_designator = 'Z' if include_zone_designator else ''
    return (date.today() - timedelta(days=days_ago))\
        .strftime("%Y-%m-%dT%H:%M:%S.%f{}".format(zone_designator))


def get_unix_timestamp():
    """return a unix timestamp in integer form
    """
    return int(time.time())


def create_correlation_id():
    """Create an id that is used to correlate logs
    Returns:
        correlation_id (str)
    """
    return str(uuid.uuid1())


def try_execute_query(db_session, clause, params=None):
    """Try to execute a query and return the results. If exception occurs,
    report it to Sentry, log it, and re-raise exception
    Args:
        db_session (sqlalchemy.orm.session.Session)
        clause (sqlalchemy.sql.text or string): sql to execute
        params (dictionary): query params
    Returns:
        query results (sqlalchemy.engine.result.ResultProxy)
    """
    try:
        return db_session.execute(clause, params)
    except:  # catch all exceptions
        sentry.sentry_client.captureException()
        context.logger.error("Error executing db query: {}".format(sys.exc_info()[1]))
        raise