# bisect extension for mercurial

#

# Copyright 2005, 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org>

# Inspired by git bisect, extension skeleton taken from mq.py.

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

from mercurial.i18n import _

from mercurial import hg, util, cmdutil

import os

def _bisect(changelog, state):

    clparents = changelog.parentrevs

    # only the earliest bad revision matters

    badrev = min([changelog.rev(n) for n in state['bad']])

    bad = changelog.node(badrev)

    skip = dict.fromkeys([changelog.rev(n) for n in state['skip']])

    # build ancestors array

    ancestors = [[]] * (changelog.count() + 1) # an extra for [-1]

    # clear good revs from array

    for node in state['good']:

        ancestors[changelog.rev(node)] = None

    for rev in xrange(changelog.count(), -1, -1):

        if ancestors[rev] is None:

            for prev in clparents(rev):

                ancestors[prev] = None

    if ancestors[badrev] is None:

        raise util.Abort(_("Inconsistent state, %s:%s is good and bad")

                         % (badrev, hg.short(bad)))

    # build children dict

    children = {}

    visit = [badrev]

    candidates = []

    while visit:

        rev = visit.pop(0)

        if ancestors[rev] == []:

            candidates.append(rev)

            for prev in clparents(rev):

                if prev != -1:

                    if prev in children:

                        children[prev].append(rev)

                    else:

                        children[prev] = [rev]

                        visit.append(prev)

    candidates.sort()

    # have we narrowed it down to one entry?

    tot = len(candidates)

    if tot == 1:

        return (bad, 0)

    # find the best node to test

    best_rev = None

    best_len = -1

    for rev in candidates:

        l = ancestors[rev]

        ancestors[rev] = None

        if l != None:

            if not l:

                a = [rev]

            elif len(l) == 1:

                a = l[0] + [rev]

            else:

                a = {}

                for s in l:

                    a.update(dict.fromkeys(s))

                a[rev] = None

                a = a.keys()

            for c in children.get(rev, []):

                if ancestors[c]:

                    ancestors[c].append(a)

                else:

                    ancestors[c] = [a]

            if n in skip:

                continue

            a = len(a) # number of ancestors

            b = tot - a # number of non-ancestors

            value = min(a, b) # how good is this test?

            if value > best_len:

                best_len = value

                best_rev = rev

    assert best_rev is not None

    best_node = changelog.node(best_rev)

    return (best_node, tot)

def bisect(ui, repo, rev=None, extra=None,

               reset=None, good=None, bad=None, skip=None, noupdate=None):

    """Subdivision search of changesets

This extension helps to find changesets which introduce problems.

To use, mark the earliest changeset you know exhibits the problem

as bad, then mark the latest changeset which is free from the problem

as good. Bisect will update your working directory to a revision for

testing. Once you have performed tests, mark the working directory

as bad or good and bisect will either update to another candidate

changeset or announce that it has found the bad revision.

Note: bisect expects bad revisions to be descendants of good revisions.

If you are looking for the point at which a problem was fixed, then make

the problem-free state "bad" and the problematic state "good."

    """

    # backward compatibility

    if rev in "good bad reset init".split():

        ui.warn(_("(use of 'hg bisect <cmd>' is deprecated)\n"))

        cmd, rev, extra = rev, extra, None

        if cmd == "good":

            good = True

        elif cmd == "bad":

            bad = True

        else:

            reset = True

    elif extra or good + bad + skip + reset > 1:

        raise util.Abort("Incompatible arguments")

    if reset:

        p = repo.join("bisect.state")

        if os.path.exists(p):

            os.unlink(p)

        return

    # load state

    state = {'good': [], 'bad': [], 'skip': []}

    if os.path.exists(repo.join("bisect.state")):

        for l in repo.opener("bisect.state"):

            kind, node = l[:-1].split()

            node = repo.lookup(node)

            if kind not in state:

                raise util.Abort(_("unknown bisect kind %s") % kind)

            state[kind].append(node)

    # update state

    node = repo.lookup(rev or '.')

    if good:

        state['good'].append(node)

    elif bad:

        state['bad'].append(node)

    elif skip:

        state['skip'].append(node)

    # save state

    f = repo.opener("bisect.state", "w", atomictemp=True)

    wlock = repo.wlock()

    try:

        for kind in state:

            for node in state[kind]:

                f.write("%s %s\n" % (kind, hg.hex(node)))

        f.rename()

    finally:

        del wlock

    if not state['good'] or not state['bad']:

        return

    # actually bisect

    node, changesets = _bisect(repo.changelog, state)

    if changesets == 0:

        ui.write(_("The first bad revision is:\n"))

        displayer = cmdutil.show_changeset(ui, repo, {})

        displayer.show(changenode=node)

    elif node is not None:

        # compute the approximate number of remaining tests

        tests, size = 0, 2

        while size <= changesets:

            tests, size = tests + 1, size * 2

        rev = repo.changelog.rev(node)

        ui.write(_("Testing changeset %s:%s "

                   "(%s changesets remaining, ~%s tests)\n")

                 % (rev, hg.short(node), changesets, tests))

        if not noupdate:

            cmdutil.bail_if_changed(repo)

            return hg.clean(repo, node)

cmdtable = {

    "bisect": (bisect,

               [('r', 'reset', False, _('reset bisect state')),

                ('g', 'good', False, _('mark changeset good')),

                ('b', 'bad', False, _('mark changeset bad')),

                ('s', 'skip', False, _('skip testing changeset')),

                ('U', 'noupdate', False, _('do not update to target'))],

               _("hg bisect [-gbsr] [REV]"))

}