#!/usr/bin/perl

use strict;
use warnings;

# === update ===
# this is gitolite's update hook

# ----------------------------------------------------------------------------
#       find the rc file, then pull the libraries
# ----------------------------------------------------------------------------

BEGIN {
    # people with shell access should be allowed to bypass the update hook,
    # simply by setting an env var that the ssh "front door" will never set
    exit 0 if exists $ENV{GL_BYPASS_UPDATE_HOOK};

    die "ENV GL_RC not set\n" unless $ENV{GL_RC};
    die "ENV GL_BINDIR not set\n" unless $ENV{GL_BINDIR};
}

use lib $ENV{GL_BINDIR};
use gitolite_rc;
use gitolite qw(:DEFAULT %repos);

# ----------------------------------------------------------------------------
#       start...
# ----------------------------------------------------------------------------

my ($perm, $creator, $wild) = repo_rights($ENV{GL_REPO});
my $reported_repo = $ENV{GL_REPO} . ( $wild ? " ($wild)" : "" );

# arguments are as supplied to an update hook by git; man githooks
my ($ref, $oldsha, $newsha) = @ARGV;
my $merge_base = '0' x 40;
# compute a merge-base if both SHAs are non-0, else leave it as '0'x40
# (i.e., for branch create or delete, merge_base == '0'x40)
chomp($merge_base = `git merge-base $oldsha $newsha`)
    unless $oldsha eq '0' x 40
        or $newsha eq '0' x 40;

# att_acc == attempted access -- what are you trying to do?  (is it 'W' or '+'?)
my $att_acc = 'W';
# rewriting a tag is considered a rewind, in terms of permissions
$att_acc = '+' if $ref =~ m(refs/tags/) and $oldsha ne ('0' x 40);
# non-ff push to ref
# notice that ref delete looks like a rewind, as it should
$att_acc = '+' if $oldsha ne $merge_base;

# were any 'D' perms specified?  If they were, it means we have to separate
# deletes from rewinds, so if the new sha is all 0's, change the '+' to a 'D'
$att_acc = 'D' if ( $repos{$ENV{GL_REPO}}{DELETE_IS_D} or $repos{'@all'}{DELETE_IS_D} ) and $newsha eq '0' x 40;
# similarly C for create a branch
$att_acc = 'C' if ( $repos{$ENV{GL_REPO}}{CREATE_IS_C} or $repos{'@all'}{CREATE_IS_C} ) and $oldsha eq '0' x 40;

# and now "M" commits.  This presents a bit of a problem.  All the other
# accesses (W, +, C, D) were mutually exclusive in some sense.  Sure a W could
# be a C or a + could be a D but that's by design.  A merge commit, however,
# could still be any of the others (except a "D").

# so we have to *append* 'M' to $att_acc (if the repo has MERGE_CHECK in
# effect and this push contains a merge inside)
if ( $repos{ $ENV{GL_REPO} }{MERGE_CHECK} or $repos{'@all'}{MERGE_CHECK} ) {
    if ( $oldsha eq '0' x 40 or $newsha eq '0' x 40 ) {
        warn "ref create/delete ignored for purposes of merge-check\n";
    } else {
        $att_acc .= 'M' if `git rev-list -n 1 --merges $oldsha..$newsha` =~ /./;
    }
}

my @allowed_refs;
# @all repos: see comments in similar code in check_access
push @allowed_refs, @ { $repos{$ENV{GL_REPO}}{$ENV{GL_USER}} || [] };
push @allowed_refs, @ { $repos{'@all'}       {$ENV{GL_USER}} || [] };
push @allowed_refs, @ { $repos{$ENV{GL_REPO}}{'@all'} || [] };
push @allowed_refs, @ { $repos{'@all'}       {'@all'} || [] };

# first check the main ref (this is a *real* ref, like refs/heads/master, and
# is what we print in the log)
my $log_refex = check_ref(\@allowed_refs, $ENV{GL_REPO}, $ref, $att_acc);

# then we check all virtual refs
check_vrefs(\@allowed_refs, $ENV{GL_REPO}, $att_acc);

# if we returned at all, all the checks succeeded.  Check secondary hooks now
$UPDATE_CHAINS_TO ||= 'hooks/update.secondary';
-x $UPDATE_CHAINS_TO and system ( $UPDATE_CHAINS_TO, @ARGV ) and die "$UPDATE_CHAINS_TO died\n";

# now log it and exit 0 so git can get on with it
log_it("", "$att_acc\t" .  substr($oldsha, 0, 14) . "\t" . substr($newsha, 0, 14) .
    "\t$reported_repo\t$ref\t$log_refex");

exit 0;

# ----------------------------------------------------------------------

sub check_vrefs {
    my ( $ar_ref, $repo, $aa ) = @_;
    # these will be passed on as args 1, 2, 4 to check_ref.  Arg-3 will be
    # the new ref being checked.

    # this sub uses $ref, $oldsha, and $newsha globals; they're pretty much
    # 'constant' once you enter an update hook anyway

    my $empty   = '4b825dc642cb6eb9a060e54bf8d69288fbee4904';            # this is special to git -- the hash of an empty tree
    my $oldtree = $oldsha eq '0' x 40 ? $empty : $oldsha;
    my $newtree = $newsha eq '0' x 40 ? $empty : $newsha;
    my @first6  = ( $ref, $oldsha, $newsha, $oldtree, $newtree, $aa );

    # first, handle the VREF thats's been in "core" forever...
    if ( $repos{ $ENV{GL_REPO} }{NAME_LIMITS} ) {
        for my $ref ( map { chomp; s/^/NAME\//; $_; } `git diff --name-only $oldtree $newtree` ) {
            check_ref( $ar_ref, $repo, $ref, $aa );
        }
    }

    my %vref_seen;

    for my $vr ( grep { m(^VREF/) } map { $_->[1] } sort { $a->[0] <=> $b->[0] } @{$ar_ref} ) {
        next if $vref_seen{$vr}++;

        # find code pertaining to $vr and run it; see docs for details
        my ( $dummy, $pgm, @args ) = split '/', $vr;
        $pgm = "$ENV{GL_BINDIR}/gl-VREF-$pgm";
        -x $pgm or die "can't find helper program for $vr\n";

        open( my $fh, "-|", $pgm, @first6, $vr, @args ) or die "can't spawn helper program for $vr: $!\n";
        while (<$fh>) {
            my ( $vref, $deny_message ) = split( ' ', $_, 2 );
            my $ret = check_ref( $ar_ref, $repo, $vref, $aa, 1 );
            die "$ret\n" . ( $deny_message || '' ) if $ret =~ /DENIED/ and $ret !~ /by fallthru/;
            # I could change check_ref to take one more argument, say
            # 'fallthru_is_pass', but I want to keep these changes as
            # isolated as possible for now
        }
        close($fh) or die $!
          ? "Error closing sort pipe: $!"
          : "Exit status $? from VREF helper program for $vr";
    }
}