# -*- coding: utf-8 -*-
# Copyright: Damien Elmes <anki@ichi2.net>
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html

import time, datetime, simplejson, random, itertools, math
from operator import itemgetter
from heapq import *
#from anki.cards import Card
from anki.utils import ids2str, intTime, fmtTimeSpan
from anki.lang import _, ngettext
from anki.consts import *
from anki.hooks import runHook

# revlog:
# types: 0=lrn, 1=rev, 2=relrn, 3=cram
# positive intervals are in days (rev), negative intervals in seconds (lrn)

# the standard Anki scheduler
class Scheduler(object):
    name = "std"
    def __init__(self, col):
        self.col = col
        self.queueLimit = 50
        self.reportLimit = 1000
        # fixme: replace reps with deck based counts
        self.reps = 0
        self._updateCutoff()

    def getCard(self):
        "Pop the next card from the queue. None if finished."
        self._checkDay()
        id = self._getCardId()
        if id:
            c = self.col.getCard(id)
            c.startTimer()
            return c

    def reset(self):
        self._updateCutoff()
        self._resetLrn()
        self._resetRev()
        self._resetNew()

    def answerCard(self, card, ease):
        assert ease >= 1 and ease <= 4
        self.col.markReview(card)
        self.reps += 1
        card.reps += 1
        wasNew = (card.queue == 0) and card.type != 2
        if wasNew:
            # put it in the learn queue
            card.queue = 1
            card.type = 1
            card.left = self._startingLeft(card)
            self.lrnRepCount += card.left
            self._updateStats(card, 'new')
        if card.queue == 1:
            self._answerLrnCard(card, ease)
            if not wasNew:
                self._updateStats(card, 'lrn')
        elif card.queue == 2:
            self._answerRevCard(card, ease)
            self._updateStats(card, 'rev')
        else:
            raise Exception("Invalid queue")
        self._updateStats(card, 'time', card.timeTaken())
        card.mod = intTime()
        card.usn = self.col.usn()
        card.flushSched()

    def repCounts(self):
        return (self.newCount, self.lrnRepCount, self.revCount)

    def cardCounts(self):
        return (self.newCount, self.lrnCount, self.revCount)

    def dueForecast(self, days=7):
        "Return counts over next DAYS. Includes today."
        daysd = dict(self.col.db.all("""
select due, count() from cards
where did in %s and queue = 2
and due between ? and ?
group by due
order by due""" % self._deckLimit(),
                            self.today,
                            self.today+days-1))
        for d in range(days):
            d = self.today+d
            if d not in daysd:
                daysd[d] = 0
        # return in sorted order
        ret = [x[1] for x in sorted(daysd.items())]
        return ret

    def countIdx(self, card):
        return card.queue

    def answerButtons(self, card):
        if card.queue == 2:
            return 4
        else:
            return 3

    def onClose(self):
        "Unbury and remove temporary suspends on close."
        self.col.db.execute(
            "update cards set queue = type where queue between -3 and -2")

    # Rev/lrn/time daily stats
    ##########################################################################

    def _updateStats(self, card, type, cnt=1):
        key = type+"Today"
        for g in ([self.col.decks.get(card.did)] +
                  self.col.decks.parents(card.did)):
            # add
            g[key][1] += cnt
            self.col.decks.save(g)

    # Deck list
    ##########################################################################

    def deckDueList(self):
        "Returns [deckname, did, hasDue, hasNew]"
        # find decks with 1 or more due cards
        dids = {}
        for g in self.col.decks.all():
            hasDue = self._deckHasLrn(g['id']) or self._deckHasRev(g['id'])
            hasNew = self._deckHasNew(g['id'])
            dids[g['id']] = [hasDue or 0, hasNew or 0]
        return [[grp['name'], int(did)]+dids[int(did)] #.get(int(did))
                for (did, grp) in self.col.decks.decks.items()]

    def deckDueTree(self):
        return self._groupChildren(self.deckDueList())

    def _groupChildren(self, grps):
        # first, split the group names into components
        for g in grps:
            g[0] = g[0].split("::")
        # and sort based on those components
        grps.sort(key=itemgetter(0))
        # then run main function
        return self._groupChildrenMain(grps)

    def _groupChildrenMain(self, grps):
        tree = []
        # group and recurse
        def key(grp):
            return grp[0][0]
        for (head, tail) in itertools.groupby(grps, key=key):
            tail = list(tail)
            did = None
            rev = 0
            new = 0
            children = []
            for c in tail:
                if len(c[0]) == 1:
                    # current node
                    did = c[1]
                    rev += c[2]
                    new += c[3]
                else:
                    # set new string to tail
                    c[0] = c[0][1:]
                    children.append(c)
            children = self._groupChildrenMain(children)
            # tally up children counts
            for ch in children:
                rev += ch[2]
                new += ch[3]
            tree.append((head, did, rev, new, children))
        return tuple(tree)

    # Getting the next card
    ##########################################################################

    def _getCardId(self):
        "Return the next due card id, or None."
        # learning card due?
        id = self._getLrnCard()
        if id:
            return id
        # new first, or time for one?
        if self._timeForNewCard():
            return self._getNewCard()
        # card due for review?
        id = self._getRevCard()
        if id:
            return id
        # new cards left?
        id = self._getNewCard()
        if id:
            return id
        # collapse or finish
        return self._getLrnCard(collapse=True)

    # New cards
    ##########################################################################

    def _resetNewCount(self):
        self.newCount = 0
        pcounts = {}
        # for each of the active decks
        for did in self.col.decks.active():
            # get the individual deck's limit
            lim = self._deckNewLimitSingle(self.col.decks.get(did))
            if not lim:
                continue
            # check the parents
            parents = self.col.decks.parents(did)
            for p in parents:
                # add if missing
                if p['id'] not in pcounts:
                    pcounts[p['id']] = self._deckNewLimitSingle(p)
                # take minimum of child and parent
                lim = min(pcounts[p['id']], lim)
            # see how many cards we actually have
            cnt = self.col.db.scalar("""
select count() from (select 1 from cards where
did = ? and queue = 0 limit ?)""", did, lim)
            # if non-zero, decrement from parent counts
            for p in parents:
                pcounts[p['id']] -= cnt
            # we may also be a parent
            pcounts[did] = lim - cnt
            # and add to running total
            self.newCount += cnt

    def _resetNew(self):
        self._resetNewCount()
        self.newDids = self.col.decks.active()
        self._newQueue = []
        self._updateNewCardRatio()

    def _fillNew(self):
        if self._newQueue:
            return True
        if not self.newCount:
            return False
        while self.newDids:
            did = self.newDids[0]
            lim = min(self.queueLimit, self._deckNewLimit(did))
            if lim:
                # fill the queue with the current did
                self._newQueue = self.col.db.all("""
select id, due from cards where did = ? and queue = 0 limit ?""", did, lim)
                if self._newQueue:
                    self._newQueue.reverse()
                    return True
            # nothing left in the deck; move to next
            self.newDids.pop(0)

    def _getNewCard(self):
        if not self._fillNew():
            return
        (id, due) = self._newQueue.pop()
        # move any siblings to the end?
        conf = self.col.decks.conf(self.newDids[0])
        if conf['new']['order'] == NEW_TODAY_ORD:
            n = len(self._newQueue)
            while self._newQueue and self._newQueue[-1][1] == due:
                self._newQueue.insert(0, self._newQueue.pop())
                n -= 1
                if not n:
                    # we only have one note in the queue; stop rotating
                    break
        self.newCount -= 1
        return id

    def _updateNewCardRatio(self):
        if self.col.decks.top()['newSpread'] == NEW_CARDS_DISTRIBUTE:
            if self.newCount:
                self.newCardModulus = (
                    (self.newCount + self.revCount) / self.newCount)
                # if there are cards to review, ensure modulo >= 2
                if self.revCount:
                    self.newCardModulus = max(2, self.newCardModulus)
                return
        self.newCardModulus = 0

    def _timeForNewCard(self):
        "True if it's time to display a new card when distributing."
        if not self.newCount:
            return False
        if self.col.decks.top()['newSpread'] == NEW_CARDS_LAST:
            return False
        elif self.col.decks.top()['newSpread'] == NEW_CARDS_FIRST:
            return True
        elif self.newCardModulus:
            return self.reps and self.reps % self.newCardModulus == 0

    def _deckHasNew(self, did):
        if not self._deckNewLimit(did):
            return False
        return self.col.db.scalar(
            "select 1 from cards where did = ? and queue = 0 limit 1", did)

    def _deckNewLimit(self, did):
        sel = self.col.decks.get(did)
        lim = -1
        # for the deck and each of its parents
        for g in [sel] + self.col.decks.parents(did):
            rem = self._deckNewLimitSingle(g)
            if lim == -1:
                lim = rem
            else:
                lim = min(rem, lim)
        return lim

    def _deckNewLimitSingle(self, g):
        c = self.col.decks.conf(g['id'])
        return max(0, c['new']['perDay'] - g['newToday'][1])

    # Learning queue
    ##########################################################################

    def _resetLrnCount(self):
        (self.lrnCount, self.lrnRepCount) = self.col.db.first("""
select count(), sum(left) from (select left from cards where
did in %s and queue = 1 and due < ? limit %d)""" % (
            self._deckLimit(), self.reportLimit),
            self.dayCutoff)
        self.lrnRepCount = self.lrnRepCount or 0

    def _resetLrn(self):
        self._resetLrnCount()
        self._lrnQueue = []

    def _fillLrn(self):
        if not self.lrnCount:
            return False
        if self._lrnQueue:
            return True
        self._lrnQueue = self.col.db.all("""
select due, id from cards where
did in %s and queue = 1 and due < :lim
limit %d""" % (self._deckLimit(), self.reportLimit), lim=self.dayCutoff)
        # as it arrives sorted by did first, we need to sort it
        self._lrnQueue.sort()
        return self._lrnQueue

    def _getLrnCard(self, collapse=False):
        if self._fillLrn():
            cutoff = time.time()
            if collapse:
                cutoff += self.col.decks.top()['collapseTime']
            if self._lrnQueue[0][0] < cutoff:
                id = heappop(self._lrnQueue)[1]
                self.lrnCount -= 1
                return id

    def _answerLrnCard(self, card, ease):
        # ease 1=no, 2=yes, 3=remove
        conf = self._lrnConf(card)
        if card.type == 2:
            type = 2
        else:
            type = 0
        leaving = False
        lastLeft = card.left
        if ease == 3:
            self._rescheduleAsRev(card, conf, True)
            self.lrnRepCount -= lastLeft
            leaving = True
        elif ease == 2 and card.left-1 <= 0:
            self._rescheduleAsRev(card, conf, False)
            self.lrnRepCount -= 1
            leaving = True
        else:
            if ease == 2:
                card.left -= 1
                self.lrnRepCount -= 1
            else:
                card.left = self._startingLeft(card)
                self.lrnRepCount += card.left - lastLeft
            delay = self._delayForGrade(conf, card.left)
            if card.due < time.time():
                # not collapsed; add some randomness
                delay *= random.uniform(1, 1.25)
            card.due = int(time.time() + delay)
            heappush(self._lrnQueue, (card.due, card.id))
            self.lrnCount += 1
        self._logLrn(card, ease, conf, leaving, type, lastLeft)

    def _delayForGrade(self, conf, left):
        try:
            delay = conf['delays'][-left]
        except IndexError:
            delay = conf['delays'][0]
        return delay*60

    def _lrnConf(self, card):
        conf = self._cardConf(card)
        if card.type == 2:
            return conf['lapse']
        else:
            return conf['new']

    def _rescheduleAsRev(self, card, conf, early):
        if card.type == 2:
            # failed; put back entry due
            card.due = card.edue
        else:
            self._rescheduleNew(card, conf, early)
        card.queue = 2
        card.type = 2

    def _startingLeft(self, card):
        return len(self._cardConf(card)['new']['delays'])

    def _graduatingIvl(self, card, conf, early):
        if card.type == 2:
            # lapsed card being relearnt
            return card.ivl
        if not early:
            # graduate
            ideal =  conf['ints'][0]
        else:
            # early remove
            ideal = conf['ints'][1]
        return self._adjRevIvl(card, ideal)

    def _rescheduleNew(self, card, conf, early):
        card.ivl = self._graduatingIvl(card, conf, early)
        card.due = self.today+card.ivl
        card.factor = conf['initialFactor']

    def _logLrn(self, card, ease, conf, leaving, type, lastLeft):
        lastIvl = -(self._delayForGrade(conf, lastLeft))
        ivl = card.ivl if leaving else -(self._delayForGrade(conf, card.left))
        def log():
            self.col.db.execute(
                "insert into revlog values (?,?,?,?,?,?,?,?,?)",
                int(time.time()*1000), card.id, self.col.usn(), ease,
                ivl, lastIvl, card.factor, card.timeTaken(), type)
        try:
            log()
        except:
            # duplicate pk; retry in 10ms
            time.sleep(0.01)
            log()

    def removeFailed(self, ids=None):
        "Remove failed cards from the learning queue."
        extra = ""
        if ids:
            extra = " and id in "+ids2str(ids)
        self.col.db.execute("""
update cards set
due = edue, queue = 2, mod = %d, usn = %d
where queue = 1 and type = 2
%s
""" % (intTime(), self.col.usn(), extra))

    def _deckHasLrn(self, did):
        return self.col.db.scalar(
            "select 1 from cards where did = ? and queue = 1 "
            "and due < ? limit 1",
            did, intTime() + self.col.decks.top()['collapseTime'])

    # Reviews
    ##########################################################################

    def _deckHasRev(self, did):
        return self.col.db.scalar(
            "select 1 from cards where did = ? and queue = 2 "
            "and due <= ? limit 1",
            did, self.today)

    def _resetRevCount(self):
        top = self.col.decks.top()
        lim = min(self.reportLimit,
                  max(0, top['revLim'] - top['revToday'][1]))
        self.revCount = self.col.db.scalar("""
select count() from (select id from cards where
did in %s and queue = 2 and due <= :day limit %d)""" % (
            self._deckLimit(), lim), day=self.today)

    def _resetRev(self):
        self._resetRevCount()
        self._revQueue = []

    def _fillRev(self):
        if not self.revCount:
            return False
        if self._revQueue:
            return True
        self._revQueue = self.col.db.list("""
select id from cards where
did in %s and queue = 2 and due <= :lim %s limit %d""" % (
            self._deckLimit(), self._revOrder(), self.queueLimit),
                                          lim=self.today)
        if not self.col.conf['revOrder']:
            r = random.Random()
            r.seed(self.today)
            r.shuffle(self._revQueue)
        return True

    def _getRevCard(self):
        if self._fillRev():
            self.revCount -= 1
            return self._revQueue.pop()

    def _revOrder(self):
        if self.col.conf['revOrder']:
            return "order by %s" % ("ivl desc", "ivl")[self.col.conf['revOrder']-1]
        return ""

    # Answering a review card
    ##########################################################################

    def _answerRevCard(self, card, ease):
        if ease == 1:
            self._rescheduleLapse(card)
        else:
            self._rescheduleRev(card, ease)
        self._logRev(card, ease)

    def _rescheduleLapse(self, card):
        conf = self._cardConf(card)['lapse']
        card.lapses += 1
        card.lastIvl = card.ivl
        card.ivl = self._nextLapseIvl(card, conf)
        card.factor = max(1300, card.factor-200)
        card.due = self.today + card.ivl
        # put back in the learn queue?
        if conf['relearn']:
            card.edue = card.due
            card.due = int(self._delayForGrade(conf, 0) + time.time())
            card.left = len(conf['delays'])
            card.queue = 1
            self.lrnCount += 1
            self.lrnRepCount += card.left
        # leech?
        if not self._checkLeech(card, conf) and conf['relearn']:
            heappush(self._lrnQueue, (card.due, card.id))

    def _nextLapseIvl(self, card, conf):
        return int(card.ivl*conf['mult']) + 1

    def _rescheduleRev(self, card, ease):
        # update interval
        card.lastIvl = card.ivl
        self._updateRevIvl(card, ease)
        # then the rest
        card.factor = max(1300, card.factor+[-150, 0, 150][ease-2])
        card.due = self.today + card.ivl

    def _logRev(self, card, ease):
        def log():
            self.col.db.execute(
                "insert into revlog values (?,?,?,?,?,?,?,?,?)",
                int(time.time()*1000), card.id, self.col.usn(), ease,
                card.ivl, card.lastIvl, card.factor, card.timeTaken(),
                1)
        try:
            log()
        except:
            # duplicate pk; retry in 10ms
            time.sleep(0.01)
            log()

    # Interval management
    ##########################################################################

    def _nextRevIvl(self, card, ease):
        "Ideal next interval for CARD, given EASE."
        delay = self._daysLate(card)
        conf = self._cardConf(card)
        fct = card.factor / 1000.0
        if ease == 2:
            interval = (card.ivl + delay/4) * 1.2
        elif ease == 3:
            interval = (card.ivl + delay/2) * fct
        elif ease == 4:
            interval = (card.ivl + delay) * fct * conf['rev']['ease4']
        # apply forgetting index transform
        interval = self._ivlForFI(conf, interval)
        # must be at least one day greater than previous interval; two if easy
        return max(card.ivl + (2 if ease==4 else 1), int(interval))

    def _ivlForFI(self, conf, ivl):
        new, old = conf['rev']['fi']
        return ivl * math.log(1-new) / math.log(1-old)

    def _daysLate(self, card):
        "Number of days later than scheduled."
        return max(0, self.today - card.due)

    def _updateRevIvl(self, card, ease):
        "Update CARD's interval, trying to avoid siblings."
        idealIvl = self._nextRevIvl(card, ease)
        card.ivl = self._adjRevIvl(card, idealIvl)

    def _adjRevIvl(self, card, idealIvl):
        "Given IDEALIVL, return an IVL away from siblings."
        idealDue = self.today + idealIvl
        conf = self._cardConf(card)['rev']
        # find sibling positions
        dues = self.col.db.list(
            "select due from cards where nid = ? and queue = 2"
            " and id != ?", card.nid, card.id)
        if not dues or idealDue not in dues:
            return idealIvl
        else:
            leeway = max(conf['minSpace'], int(idealIvl * conf['fuzz']))
            fudge = 0
            # do we have any room to adjust the interval?
            if leeway:
                # loop through possible due dates for an empty one
                for diff in range(1, leeway+1):
                    # ensure we're due at least tomorrow
                    if idealDue - diff >= 1 and (idealDue - diff) not in dues:
                        fudge = -diff
                        break
                    elif (idealDue + diff) not in dues:
                        fudge = diff
                        break
            return idealIvl + fudge

    # Leeches
    ##########################################################################

    def _checkLeech(self, card, conf):
        "Leech handler. True if card was a leech."
        lf = conf['leechFails']
        if not lf:
            return
        # if over threshold or every half threshold reps after that
        if (lf >= card.lapses and
            (card.lapses-lf) % (max(lf/2, 1)) == 0):
            # add a leech tag
            f = card.note()
            f.addTag("leech")
            f.flush()
            # handle
            a = conf['leechAction']
            if a == 0:
                self.suspendCards([card.id])
                card.queue = -1
            # notify UI
            runHook("leech", card)
            return True

    # Tools
    ##########################################################################

    def _cardConf(self, card):
        return self.col.decks.conf(card.did)

    def _deckLimit(self):
        return ids2str(self.col.decks.active())

    # Daily cutoff
    ##########################################################################

    def _updateCutoff(self):
        # days since col created
        self.today = int((time.time() - self.col.crt) / 86400)
        # end of day cutoff
        self.dayCutoff = self.col.crt + (self.today+1)*86400
        # update all selected decks
        def update(g):
            save = False
            for t in "new", "rev", "lrn", "time":
                key = t+"Today"
                if g[key][0] != self.today:
                    save = True
                    g[key] = [self.today, 0]
            if save:
                self.col.decks.save(g)
        for did in self.col.decks.active():
            update(self.col.decks.get(did))
        # update parents too
        for grp in self.col.decks.parents(self.col.decks.selected()):
            update(grp)

    def _checkDay(self):
        # check if the day has rolled over
        if time.time() > self.dayCutoff:
            self.reset()

    # Deck finished state
    ##########################################################################

    def finishedMsg(self):
        return ("<b>"+_(
            "Congratulations! You have finished the selected deck for now.")+
            "</b><br><br>" + self._nextDueMsg())

    def _nextDueMsg(self):
        line = []
        if self.revDue():
            line.append(_("""\
Today's review limit has been reached, but there are still cards
waiting to be reviewed. For optimum memory, consider increasing
the daily limit in the options."""))
        if self.newDue():
            line.append(_("""\
There are more new cards available, but the daily limit has been
reached. You can increase the limit in the options, but please
bear in mind that the more new cards you introduce, the higher
your short-term review workload will become."""))
        return "<br>".join(line)

    def revDue(self):
        "True if there are any rev cards due."
        return self.col.db.scalar(
            ("select 1 from cards where did in %s and queue = 2 "
             "and due <= ? limit 1") % self._deckLimit(),
            self.today)

    def newDue(self):
        "True if there are any new cards due."
        return self.col.db.scalar(
            ("select 1 from cards where did in %s and queue = 0 "
             "limit 1") % self._deckLimit())

    # Next time reports
    ##########################################################################

    def nextIvlStr(self, card, ease, short=False):
        "Return the next interval for CARD as a string."
        return fmtTimeSpan(
            self.nextIvl(card, ease), short=short)

    def nextIvl(self, card, ease):
        "Return the next interval for CARD, in seconds."
        if card.queue in (0,1):
            return self._nextLrnIvl(card, ease)
        elif ease == 1:
            # lapsed
            conf = self._cardConf(card)['lapse']
            if conf['relearn']:
                return conf['delays'][0]*60
            return self._nextLapseIvl(card, conf)*86400
        else:
            # review
            return self._nextRevIvl(card, ease)*86400

    # this isn't easily extracted from the learn code
    def _nextLrnIvl(self, card, ease):
        conf = self._lrnConf(card)
        if ease == 1:
            # fail
            return self._delayForGrade(conf, len(conf['delays']))
        elif ease == 3:
            # early removal
            return self._graduatingIvl(card, conf, True) * 86400
        else:
            if card.queue == 0:
                left = self._startingLeft(card) - 1
            else:
                left = card.left - 1
            if left <= 0:
                # graduate
                return self._graduatingIvl(card, conf, False) * 86400
            else:
                return self._delayForGrade(conf, left)

    # Suspending
    ##########################################################################

    def suspendCards(self, ids):
        "Suspend cards."
        self.removeFailed(ids)
        self.col.db.execute(
            "update cards set queue=-1,mod=?,usn=? where id in "+
            ids2str(ids), intTime(), self.col.usn())

    def unsuspendCards(self, ids):
        "Unsuspend cards."
        self.col.db.execute(
            "update cards set queue=type,mod=?,usn=? "
            "where queue = -1 and id in "+ ids2str(ids),
            intTime(), self.col.usn())

    def buryNote(self, nid):
        "Bury all cards for note until next session."
        self.col.setDirty()
        self.removeFailed(
            self.col.db.list("select id from cards where nid = ?", nid))
        self.col.db.execute("update cards set queue = -2 where nid = ?", nid)

    # Resetting
    ##########################################################################

    def forgetCards(self, ids):
        "Put cards at the end of the new queue."
        self.col.db.execute(
            "update cards set type=0,queue=0,ivl=0 where id in "+ids2str(ids))
        pmax = self.col.db.scalar("select max(due) from cards where type=0")
        # takes care of mod + usn
        self.sortCards(ids, start=pmax+1, shuffle=self.col.models.randomNew())

    def reschedCards(self, ids, imin, imax):
        "Put cards in review queue with a new interval in days (min, max)."
        d = []
        t = self.today
        mod = intTime()
        for id in ids:
            r = random.randint(imin, imax)
            d.append(dict(id=id, due=r+t, ivl=max(1, r), mod=mod))
        self.col.db.executemany(
            "update cards set type=2,queue=2,ivl=:ivl,due=:due where id=:id",
            d)

    # Repositioning new cards
    ##########################################################################

    def sortCards(self, cids, start=1, step=1, shuffle=False, shift=False):
        scids = ids2str(cids)
        now = intTime()
        nids = self.col.db.list(
            ("select distinct nid from cards where type = 0 and id in %s "
             "order by nid") % scids)
        if not nids:
            # no new cards
            return
        # determine nid ordering
        due = {}
        if shuffle:
            random.shuffle(nids)
        for c, nid in enumerate(nids):
            due[nid] = start+c*step
        high = start+c*step
        # shift?
        if shift:
            low = self.col.db.scalar(
                "select min(due) from cards where due >= ? and type = 0 "
                "and id not in %s" % scids,
                start)
            if low is not None:
                shiftby = high - low + 1
                self.col.db.execute("""
update cards set mod=?, usn=?, due=due+? where id not in %s
and due >= ?""" % scids, now, self.col.usn(), shiftby, low)
        # reorder cards
        d = []
        for id, nid in self.col.db.execute(
            "select id, nid from cards where type = 0 and id in "+scids):
            d.append(dict(now=now, due=due[nid], usn=self.col.usn(), cid=id))
        self.col.db.executemany(
            "update cards set due=:due,mod=:now,usn=:usn where id = :cid""", d)

    # fixme: because it's a model property now, these should be done on a
    # per-model basis
    def randomizeCards(self):
        self.sortCards(self.col.db.list("select id from cards"), shuffle=True)

    def orderCards(self):
        self.sortCards(self.col.db.list("select id from cards"))