# 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, array

class bisect(object):

    """dichotomic search in the DAG of changesets"""

    def __init__(self, ui, repo):

        self.repo = repo

        self.ui = ui

        self.goodnodes = []

        self.badnode = None

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

        if os.path.exists(p):

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

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

                node = self.repo.lookup(node)

                if type == "good":

                    self.goodnodes.append(node)

                elif type == "bad":

                    self.badnode = node

    def write(self):

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

        for n in self.goodnodes:

            f.write("good %s\n" % hg.hex(n))

        if self.badnode:

            f.write("bad %s\n" % hg.hex(self.badnode))

    def init(self):

        """start a new bisection"""

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

        if os.path.exists(p):

            os.unlink(p)

    def bisect(self):

        cl = self.repo.changelog

        clparents = cl.parentrevs

        bad = self.badnode

        badrev = cl.rev(bad)

        if not bad:

            raise util.Abort(_("You should give at least one bad revision"))

        if not self.goodnodes:

            self.ui.warn(_("No good revision given\n"))

            self.ui.warn(_("Marking the first revision as good\n"))

        # build ancestors array

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

        # clear goodnodes from array

        for good in self.goodnodes:

            ancestors[cl.rev(good)] = None

        for rev in xrange(cl.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)))

        # accumulate ancestor lists

        for rev in xrange(badrev + 1):

            if ancestors[rev] == []:

                p1, p2 = clparents(rev)

                a1, a2 = ancestors[p1], ancestors[p2]

                if a1:

                    if a2:

                        # merge ancestor lists

                        a = dict.fromkeys(a2)

                        a.update(dict.fromkeys(a1))

                        a[rev] = None

                        ancestors[rev] = array.array("l", a.keys())

                    else:

                        ancestors[rev] = a1 + array.array("l", [rev])

                elif a2:

                    ancestors[rev] = a2 + array.array("l", [rev])

                else:

                    ancestors[rev] = array.array("l", [rev])

        if badrev not in ancestors[badrev]:

            raise util.Abort(_("Could not find the first bad revision"))

        # have we narrowed it down to one entry?

        tot = len(ancestors[badrev])

        if tot == 1:

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

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

            displayer.show(changenode=self.badnode)

            return None

        # find the best node to test

        best_rev = None

        best_len = -1

        for n in ancestors[badrev]:

            a = len(ancestors[n]) # 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 = n

        assert best_rev is not None

        best_node = cl.node(best_rev)

        # compute the approximate number of remaining tests

        nb_tests = 0

        q, r = divmod(tot, 2)

        while q:

            nb_tests += 1

            q, r = divmod(q, 2)

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

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

                      % (best_rev, hg.short(best_node), tot, nb_tests))

        return best_node

    def next(self):

        """find and update to the next revision to test"""

    def good(self, rev=None):

        """mark revision as good and update to the next revision to test"""

        self.goodnodes.append(self.repo.lookup(rev or '.'))

        self.write()

    def bad(self, rev=None):

        """mark revision as bad and update to the next revision to test"""

        self.badnode = self.repo.lookup(rev or '.')

        self.write()

def bisect_run(ui, repo, cmd=None, *args):

    """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."

For subcommands see "hg bisect help\"

    """

    def help_(cmd=None, *args):

        """show help for a given bisect subcommand or all subcommands"""

        cmdtable = bisectcmdtable

        if cmd:

            doc = cmdtable[cmd][0].__doc__

            synopsis = cmdtable[cmd][2]

            ui.write(synopsis + "\n")

            ui.write("\n" + doc + "\n")

            return

        ui.write(_("list of subcommands for the bisect extension\n\n"))

        cmds = cmdtable.keys()

        cmds.sort()

        m = max([len(c) for c in cmds])

        for cmd in cmds:

            doc = cmdtable[cmd][0].__doc__.splitlines(0)[0].rstrip()

            ui.write(" %-*s   %s\n" % (m, cmd, doc))

    b = bisect(ui, repo)

    bisectcmdtable = {

        "init": (b.init, 0, _("hg bisect init")),

        "bad": (b.bad, 1, _("hg bisect bad [<rev>]")),

        "good": (b.good, 1, _("hg bisect good [<rev>]")),

        "next": (b.next, 0, _("hg bisect next")),

        "help": (help_, 1, _("hg bisect help [<subcommand>]")),

    }

    if cmd == "reset":

        cmd = "init"

    if not bisectcmdtable.has_key(cmd):

        ui.warn(_("bisect: Unknown sub-command\n"))

        return help_()

    if len(args) > bisectcmdtable[cmd][1]:

        ui.warn(_("bisect: Too many arguments\n"))

        return help_()

    ret = bisectcmdtable[cmd][0](*args)

    return ret

cmdtable = {

    "bisect": (bisect_run, [], _("hg bisect [help|init|reset|next|good|bad]")),

    #"bisect-test": (test, [], "hg bisect-test rev"),

}