from datetime import datetime
from itertools import islice
import utils


def window(seq, n=2):
    "Returns a sliding window (of width n) over data from the iterable"
    "   s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ...                   "
    it = iter(seq)
    result = tuple(islice(it, n))
    if len(result) == n:
        yield result
    for elem in it:
        result = result[1:] + (elem,)
        yield result


def get_seconds_coded(conn, start_time, end_time, timeout):
    start_stamp = datetime.timestamp(start_time)
    end_stamp = datetime.timestamp(end_time)

    # get all the entries
    c = conn.cursor()
    curs = c.execute("""
        select time from heartbeats where time > ? and time < ? order by time;
    """, [start_stamp, end_stamp])

    coded_secs = 0
    for (first, second) in utils.window(curs, 2):
        diff = second[0] - first[0]
        if diff < timeout:
            coded_secs += diff

    return coded_secs