#!/usr/bin/perl -w
use strict;

=for comment

Documentation for this is in bisect-runner.pl

=cut

# The default, auto_abbrev will treat -e as an abbreviation of --end
# Which isn't what we want.
use Getopt::Long qw(:config pass_through no_auto_abbrev);

my ($start, $end, $validate, $usage, $bad, $jobs, $make, $gold);
$bad = !GetOptions('start=s' => \$start, 'end=s' => \$end,
                   'jobs|j=i' => \$jobs, 'make=s' => \$make, 'gold=s' => \$gold,
                   validate => \$validate, 'usage|help|?' => \$usage);
unshift @ARGV, '--help' if $bad || $usage;
unshift @ARGV, '--validate' if $validate;

my $runner = $0;
$runner =~ s/bisect\.pl/bisect-runner.pl/;

die "Can't find bisect runner $runner" unless -f $runner;

system $^X, $runner, '--check-args', '--check-shebang', @ARGV and exit 255;
exit 255 if $bad;
exit 0 if $usage;

my $start_time = time;

if (!defined $jobs &&
    !($^O eq 'hpux' && system((defined $make ? $make : 'make')
                              . ' --version >/dev/null 2>&1'))) {
    # Try to default to (ab)use all the CPUs:
    my $cpus;
    if (open my $fh, '<', '/proc/cpuinfo') {
        while (<$fh>) {
            ++$cpus if /^processor\s+:\s+\d+$/;
        }
    } elsif (-x '/sbin/sysctl') {
        $cpus =  $1 if `/sbin/sysctl hw.ncpu` =~ /^hw\.ncpu: (\d+)$/;
    } elsif (-x '/usr/bin/getconf') {
        $cpus = $1 if `/usr/bin/getconf _NPROCESSORS_ONLN` =~ /^(\d+)$/;
    }
    $jobs = defined $cpus ? $cpus + 1 : 2;
}

unshift @ARGV, '--jobs', $jobs if defined $jobs;
unshift @ARGV, '--make', $make if defined $make;

# We try these in this order for the start revision if none is specified.
my @stable = map {chomp $_; $_} grep {/v5\.[0-9]+[02468]\.0$/} `git tag -l`;
die "git tag -l didn't seem to return any tags for stable releases"
    unless @stable;
unshift @stable, qw(perl-5.005 perl-5.6.0 perl-5.8.0);

{
    my ($dev_C, $ino_C) = stat 'Configure';
    my ($dev_c, $ino_c) = stat 'configure';
    if (defined $dev_C && defined $dev_c
        && $dev_C == $dev_c && $ino_C == $ino_c) {
        print "You seem to be on a case-insensitive file system.\n\n";
    } else {
        unshift @stable, qw(perl-5.002 perl-5.003 perl-5.004)
    }
}

unshift @ARGV, '--gold', defined $gold ? $gold : $stable[-1];

if (!defined $end) {
    # If we have a branch blead, use that as the end
    $end = `git rev-parse --verify --quiet blead`;
    die unless defined $end;
    if (!length $end) {
        # Else use whichever is newer - HEAD, or the most recent stable tag.
        if (`git rev-list -n1 HEAD ^$stable[-1]` eq "") {
            $end = pop @stable;
        } else {
            $end = 'HEAD';
        }
    }
}

# Canonicalising branches to revisions before moving the checkout permits one
# to use revisions such as 'HEAD' for --start or --end
foreach ($start, $end) {
    next unless $_;
    $_ = `git rev-parse $_`;
    die unless defined $_;
    chomp;
}

{
    my $modified = my @modified = `git ls-files --modified --deleted --others`;

    my ($dev0, $ino0) = stat $0;
    die "Can't stat $0: $!" unless defined $ino0;
    my ($dev1, $ino1) = stat 'Porting/bisect.pl';

    my $inplace = defined $dev1 && $dev0 == $dev1 && $ino0 == $ino1;

    if ($modified) {
        my $final = $inplace
            ? "Can't run a bisect using a dirty directory containing $runner"
            : "You can use 'git clean -Xdf' to cleanup the ignored files";

        die "This checkout is not clean, found file(s):\n",
            join("\t","",@modified),
                "$modified modified, untracked, or other file(s)\n",
                "These files may not show in git status as they may be ignored.\n",
                "$final.\n";
    }

    if ($inplace) {
        # We assume that it's safe to copy the runner to the temporary
        # directory and run it from there, because a shared /tmp should be +t
        # and hence others are not be able to delete or rename our file.
        require File::Temp;
        my ($to, $toname) = File::Temp::tempfile();
        die "Can't create tempfile"
            unless $to;
        open my $from, '<', $runner
            or die "Can't open '$runner': $!";
        local $/;
        print {$to} <$from>
            or die "Can't copy from '$runner' to '$toname': $!";
        close $from
            or die "Can't close '$runner': $!";
        close $to
            or die "Can't close '$toname': $!";
        chmod 0500, $toname
            or die "Can't chmod 0500, '$toname': $!";
        $runner = $toname;
        system $^X, $runner, '--check-args', @ARGV
            and die "Can't run inplace for some reason. :-(";
    }
}

sub validate {
    my $commit = shift;
    if (defined $start && `git rev-list -n1 $commit ^$start^` eq "") {
        print "Skipping $commit, as it is earlier than $start\n";
        return;
    }
    if (defined $end && `git rev-list -n1 $end ^$commit^` eq "") {
        print "Skipping $commit, as it is more recent than $end\n";
        return;
    }
    print "Testing $commit...\n";
    system "git checkout $commit </dev/null" and die;
    my $ret = system $^X, $runner, '--no-clean', @ARGV;
    die "Runner returned $ret, not 0 for revision $commit" if $ret;
    system 'git clean -dxf </dev/null' and die;
    system 'git reset --hard HEAD </dev/null' and die;
    return $commit;
}

if ($validate) {
    require Text::Wrap;
    my @built = map {validate $_} 'blead', reverse @stable;
    if (@built) {
        print Text::Wrap::wrap("", "", "Successfully validated @built\n");
        exit 0;
    }
    print "Did not validate anything\n";
    exit 1;
}

my $git_version = `git --version`;
if (defined $git_version
    && $git_version =~ /\Agit version (\d+\.\d+\.\d+)(.*)/) {
    $git_version = eval "v$1";
} else {
    $git_version = v0.0.0;
}

if ($git_version ge v1.6.6) {
    system "git bisect reset HEAD" and die;
} else {
    system "git bisect reset" and die;
}

# Sanity check the first and last revisions:
system "git checkout $end" and die;
my $ret = system $^X, $runner, @ARGV;
die "Runner returned $ret for end revision" unless $ret;
die "Runner returned $ret for end revision, which is a skip"
    if $ret == 125 * 256;

if (defined $start) {
    system "git checkout $start" and die;
    my $ret = system $^X, $runner, @ARGV;
    die "Runner returned $ret, not 0 for start revision" if $ret;
} else {
    # Try to find the earliest version for which the test works
    my @tried;
    foreach my $try (@stable) {
        if (`git rev-list -n1 $end ^$try^` eq "") {
            print "Skipping $try, as it is more recent than end commit "
                . (substr $end, 0, 16) . "\n";
            # As @stable is supposed to be in age order, arguably we should
            # last; here.
            next;
        }
        system "git checkout $try" and die;
        my $ret = system $^X, $runner, @ARGV;
        if (!$ret) {
            $start = $try;
            last;
        }
        push @tried, $try;
    }
    die "Can't find a suitable start revision to default to.\nTried @tried"
        unless defined $start;
}

system "git bisect start" and die;
system "git bisect good $start" and die;
system "git bisect bad $end" and die;

# And now get git bisect to do the hard work:
system 'git', 'bisect', 'run', $^X, $runner, @ARGV and die;

END {
    my $end_time = time;

    printf "That took %d seconds.\n", $end_time - $start_time
        if defined $start_time;
}

=for comment

Documentation for this is in bisect-runner.pl

=cut

# ex: set ts=8 sts=4 sw=4 et: