import threading

import time

class DelayedQueryThread(threading.Thread):

    def __init__(self, targetdbm, targetname, delay, query, args):

        threading.Thread.__init__(self)

        self.targetdbm = targetdbm

        self.targetname = targetname

        self.delay = delay

        self.query = query

        self.args = args

    def run(self):

        time.sleep(self.delay)

        with self.targetdbm.cursor(self.targetname) as curs:

            curs.execute(self.query, self.args)

class DelayedQuery:

    def __init__(self, targetdbm):

        '''Initialize DelayedQuery.

        targetdbm -- PgManager-like object

        '''

        self.targetdbm = targetdbm

        self.queryids = set()

    def add(self, delay, query, args, targetname='default', queryid=None):

        '''Add query to schedule.

        delay -- how long to wait, in seconds

        query, args -- query to be run after delay

        targetname -- name of connection in PgManager

        queryid -- discard if query with same id is already scheduled

        '''

        if queryid is not None:

            if queryid in self.queryids:

                return

            self.queryids.add(queryid)

        t = DelayedQueryThread(self.targetdbm, targetname, delay, query, args)

        t.start()