git/cook

#!/usr/bin/perl -w
# Maintain "what's cooking" messages

use strict;

my %reverts = ('next' => {
	map { $_ => 1 } qw(
		c9bb83f
		8f6d1e2
		477e5a8
		cc17e9f
		07b74a9
		e4b5259
		76c7727
		7e7b4f7
		44d3770
		107880a
		02f9c7c
		a9ef3e3
	    ) });

%reverts = ();

sub phrase_these {
	my (@u) = sort @_;
	my @d = ();
	for (my $i = 0; $i < @u; $i++) {
		push @d, $u[$i];
		if ($i == @u - 2) {
			push @d, " and ";
		} elsif ($i < @u - 2) {
			push @d, ", ";
		}
	}
	return join('', @d);
}

sub describe_relation {
	my ($topic_info) = @_;
	my @desc;

	if (exists $topic_info->{'used'}) {
		push @desc, ("is used by " .
			     phrase_these(@{$topic_info->{'used'}}));
	}

	if (exists $topic_info->{'uses'}) {
		push @desc, ("uses " .
			     phrase_these(@{$topic_info->{'uses'}}));
	}

	if (exists $topic_info->{'shares'}) {
		push @desc, ("shares commits with " .
			     phrase_these(@{$topic_info->{'shares'}}));
	}

	if (!@desc) {
		return "";
	}

	return "(this branch " . join("; ", @desc) . ".)";
}

sub forks_from {
	my ($topic, $fork, $forkee, @overlap) = @_;
	my %ovl = map { $_ => 1 } (@overlap, @{$topic->{$forkee}{'log'}});

	push @{$topic->{$fork}{'uses'}}, $forkee;
	push @{$topic->{$forkee}{'used'}}, $fork;
	@{$topic->{$fork}{'log'}} = (grep { !exists $ovl{$_} }
				     @{$topic->{$fork}{'log'}});
}

sub topic_relation {
	my ($topic, $one, $two) = @_;

	my $fh;
	open($fh, '-|',
	     qw(git log --abbrev=7), "--format=%m %h",
	     "$one...$two", "^master")
	    or die "$!: open log --left-right";
	my (@left, @right);
	while (<$fh>) {
		my ($sign, $sha1) = /^(.) (.*)/;
		if ($sign eq '<') {
			push @left, $sha1;
		} elsif ($sign eq '>') {
			push @right, $sha1;
		}
	}
	close($fh) or die "$!: close log --left-right";

	if (!@left) {
		if (@right) {
			forks_from($topic, $two, $one);
		}
	} elsif (!@right) {
		forks_from($topic, $one, $two);
	} else {
		if (@left < @right) {
			forks_from($topic, $two, $one, @left);
		} elsif (@right < @left) {
			forks_from($topic, $one, $two, @right);
		} else {
			push @{$topic->{$one}{'shares'}}, $two;
			push @{$topic->{$two}{'shares'}}, $one;
		}
	}
}

=head1
Inspect the current set of topics

Returns a hash:

    $topic = {
        $branchname => {
            'tipdate' => date of the tip commit,
	    'desc' => description string,
	    'log' => [ $commit,... ],
        },
    }

=cut

sub get_commit {
	my (@base) = qw(master next pu);
	my $fh;
	open($fh, '-|',
	     qw(git for-each-ref),
	     "--format=%(refname:short) %(authordate:iso8601)",
	     "refs/heads/??/*")
	    or die "$!: open for-each-ref";
	my @topic;
	my %topic;

	while (<$fh>) {
		chomp;
		my ($branch, $date) = /^(\S+) (.*)$/;
		push @topic, $branch;
		$date =~ s/ .*//;
		$topic{$branch} = +{
			log => [],
			tipdate => $date,
		};
	}
	close($fh) or die "$!: close for-each-ref";

	my %base = map { $_ => undef } @base;
	my %commit;
	my $show_branch_batch = 20;

	while (@topic) {
		my @t = (@base, splice(@topic, 0, $show_branch_batch));
		my $header_delim = '-' x scalar(@t);
		my $contain_pat = '.' x scalar(@t);
		open($fh, '-|', qw(git show-branch --sparse --sha1-name),
		     map { "refs/heads/$_" } @t)
		    or die "$!: open show-branch";
		while (<$fh>) {
			chomp;
			if ($header_delim) {
				if (/^$header_delim$/) {
					$header_delim = undef;
				}
				next;
			}
			my ($contain, $sha1, $log) =
			    ($_ =~ /^($contain_pat) \[([0-9a-f]+)\] (.*)$/);

			for (my $i = 0; $i < @t; $i++) {
				my $branch = $t[$i];
				my $sign = substr($contain, $i, 1);
				next if ($sign eq ' ');
				next if (substr($contain, 0, 1) ne ' ');

				if (!exists $commit{$sha1}) {
					$commit{$sha1} = +{
						branch => {},
						log => $log,
					};
				}
				my $co = $commit{$sha1};
				if (!exists $reverts{$branch}{$sha1}) {
					$co->{'branch'}{$branch} = 1;
				}
				next if (exists $base{$branch});
				push @{$topic{$branch}{'log'}}, $sha1;
			}
		}
		close($fh) or die "$!: close show-branch";
	}

	my %shared;
	for my $sha1 (keys %commit) {
		my $sign;
		my $co = $commit{$sha1};
		if (exists $co->{'branch'}{'next'}) {
			$sign = '+';
		} elsif (exists $co->{'branch'}{'pu'}) {
			$sign = '-';
		} else {
			$sign = '.';
		}
		$co->{'log'} = $sign . ' ' . $co->{'log'};
		my @t = (sort grep { !exists $base{$_} }
			 keys %{$co->{'branch'}});
		next if (@t < 2);
		my $t = "@t";
		$shared{$t} = 1;
	}

	for my $combo (keys %shared) {
		my @combo = split(' ', $combo);
		for (my $i = 0; $i < @combo - 1; $i++) {
			for (my $j = $i + 1; $j < @combo; $j++) {
				topic_relation(\%topic, $combo[$i], $combo[$j]);
			}
		}
	}

	open($fh, '-|',
	     qw(git log --first-parent --abbrev=7),
	     "--format=%ci %h %p :%s", "master..next")
	    or die "$!: open log master..next";
	while (<$fh>) {
		my ($date, $commit, $parent, $tips);
		unless (($date, $commit, $parent, $tips) =
			/^([-0-9]+) ..:..:.. .\d{4} (\S+) (\S+) ([^:]*):/) {
			die "Oops: $_";
		}
		for my $tip (split(' ', $tips)) {
			my $co = $commit{$tip};
			next unless ($co->{'branch'}{'next'});
			$co->{'merged'} = " (merged to 'next' on $date at $commit)";
		}
	}
	close($fh) or die "$!: close log master..next";

	for my $branch (keys %topic) {
		my @log = ();
		my $n = scalar(@{$topic{$branch}{'log'}});
		if (!$n) {
			delete $topic{$branch};
			next;
		} elsif ($n == 1) {
			$n = "1 commit";
		} else {
			$n = "$n commits";
		}
		my $d = $topic{$branch}{'tipdate'};
		my $head = "* $branch ($d) $n\n";
		my @desc;
		for (@{$topic{$branch}{'log'}}) {
			my $co = $commit{$_};
			if (exists $co->{'merged'}) {
				push @desc, $co->{'merged'};
			}
			push @desc, $commit{$_}->{'log'};
		}
		my $list = join("\n", map { " " . $_ } @desc);
		my $relation = describe_relation($topic{$branch});
		$topic{$branch}{'desc'} = $head . $list;
		if ($relation) {
			$topic{$branch}{'desc'} .= "\n $relation";
		}
	}

	return \%topic;
}

sub blurb_text {
	my ($mon, $year, $issue, $dow, $date,
	    $master_at, $next_at, $text) = @_;

	my $now_string = localtime;
	my ($current_dow, $current_mon, $current_date, $current_year) =
	    ($now_string =~ /^(\w+) (\w+) (\d+) [\d:]+ (\d+)$/);

	$mon ||= $current_mon;
	$year ||= $current_year;
	$issue ||= "01";
	$dow ||= $current_dow;
	$date ||= $current_date;
	$master_at ||= '0' x 40;
	$next_at ||= '0' x 40;
	$text ||= <<'EOF';
Here are the topics that have been cooking.  Commits prefixed with '-' are
only in 'pu' while commits prefixed with '+' are in 'next'.  The ones
marked with '.' do not appear in any of the integration branches, but I am
still holding onto them.
EOF

	$text = <<EOF;
To: git\@vger.kernel.org
Subject: What's cooking in git.git ($mon $year, #$issue; $dow, $date)
X-master-at: $master_at
X-next-at: $next_at

What's cooking in git.git ($mon $year, #$issue; $dow, $date)
--------------------------------------------------

$text
EOF
	$text =~ s/\n+\Z/\n/;
	return $text;
}

my $blurb_match = <<'EOF';
To: .*
Subject: What's cooking in \S+ \((\w+) (\d+), #(\d+); (\w+), (\d+)\)
X-master-at: ([0-9a-f]{40})
X-next-at: ([0-9a-f]{40})

What's cooking in \S+ \(\1 \2, #\3; \4, \5\)
-{30,}
\n*
EOF

my $blurb = "b..l..u..r..b";
sub read_previous {
	my ($fn) = @_;
	my $fh;
 	my $section = undef;
	my $serial = 1;
	my $branch = $blurb;
	my $last_empty = undef;
	my (@section, %section, @branch, %branch, %description, @leader);
	my $in_unedited_olde = 0;

	if (!-r $fn) {
		return +{
			'section_list' => [],
			'section_data' => {},
			'topic_description' => {
				$blurb => {
					desc => undef,
					text => blurb_text(),
				},
			},
		};
	}

	open ($fh, '<', $fn) or die "$!: open $fn";
	while (<$fh>) {
		chomp;
		if ($in_unedited_olde) {
			if (/^>>$/) {
				$in_unedited_olde = 0;
				$_ = " | $_";
			}
		} elsif (/^<<$/) {
			$in_unedited_olde = 1;
		}

		if ($in_unedited_olde) {
			$_ = " | $_";
		}

		if (defined $section && /^-{20,}$/) {
			$_ = "";
		}
		if (/^$/) {
			$last_empty = 1;
			next;
		}
		if (/^\[(.*)\]\s*$/) {
			$section = $1;
			$branch = undef;
			if (!exists $section{$section}) {
				push @section, $section;
				$section{$section} = [];
			}
			next;
		}
		if (defined $section && /^\* (\S+) /) {
			$branch = $1;
			$last_empty = 0;
			if (!exists $branch{$branch}) {
				push @branch, [$branch, $section];
				$branch{$branch} = 1;
			}
			push @{$section{$section}}, $branch;
		}
		if (defined $branch) {
			my $was_last_empty = $last_empty;
			$last_empty = 0;
			if (!exists $description{$branch}) {
				$description{$branch} = [];
			}
			if ($was_last_empty) {
				push @{$description{$branch}}, "";
			}
			push @{$description{$branch}}, $_;
		}
	}
	close($fh);

	for my $branch (keys %description) {
		my $ary = $description{$branch};
		if ($branch eq $blurb) {
			while (@{$ary} && $ary->[-1] =~ /^-{30,}$/) {
				pop @{$ary};
			}
			$description{$branch} = +{
				desc => undef,
				text => join("\n", @{$ary}),
			};
		} else {
			my @desc = ();
			while (@{$ary}) {
				my $elem = shift @{$ary};
				last if ($elem eq '');
				push @desc, $elem;
			}
			$description{$branch} = +{
				desc => join("\n", @desc),
				text => join("\n", @{$ary}),
			};
		}
	}

	return +{
		section_list => \@section,
		section_data => \%section,
		topic_description => \%description,
	};
}

sub write_cooking {
	my ($fn, $cooking) = @_;
	my $fh;

	open($fh, '>', $fn) or die "$!: open $fn";
	print $fh $cooking->{'topic_description'}{$blurb}{'text'};

	for my $section_name (@{$cooking->{'section_list'}}) {
		my $topic_list = $cooking->{'section_data'}{$section_name};
		next if (!@{$topic_list});

		print $fh "\n";
		print $fh '-' x 50, "\n";
		print $fh "[$section_name]\n";
		for my $topic (@{$topic_list}) {
			my $d = $cooking->{'topic_description'}{$topic};

			print $fh "\n", $d->{'desc'}, "\n";
			if ($d->{'text'}) {
				print $fh "\n", $d->{'text'}, "\n";
			}
		}
	}
	close($fh);
}

my $graduated = 'Graduated to "master"';
my $new_topics = 'New Topics';
my $old_new_topics = 'Old New Topics';

sub update_issue {
	my ($cooking) = @_;
	my ($fh, $master_at, $next_at, $incremental);

	open($fh, '-|',
	     qw(git for-each-ref),
	     "--format=%(refname:short) %(objectname)",
	     "refs/heads/master",
	     "refs/heads/next") or die "$!: open for-each-ref";
	while (<$fh>) {
		my ($branch, $at) = /^(\S+) (\S+)$/;
		if ($branch eq 'master') { $master_at = $at; }
		if ($branch eq 'next') { $next_at = $at; }
	}
	close($fh) or die "$!: close for-each-ref";

	$incremental = ((-r "Meta/whats-cooking.txt") &&
			system("cd Meta && " .
			       "git diff --quiet --no-ext-diff HEAD -- " .
			       "whats-cooking.txt"));

	my $now_string = localtime;
	my ($current_dow, $current_mon, $current_date, $current_year) =
	    ($now_string =~ /^(\w+) (\w+) +(\d+) [\d:]+ (\d+)$/);

	my $btext = $cooking->{'topic_description'}{$blurb}{'text'};
	if ($btext !~ s/\A$blurb_match//) {
		die "match pattern broken?";
	}
	my ($mon, $year, $issue, $dow, $date) = ($1, $2, $3, $4, $5);

	if ($current_mon ne $mon || $current_year ne $year) {
		$issue = "01";
	} elsif (!$incremental) {
		$issue =~ s/^0*//;
		$issue = sprintf "%02d", ($issue + 1);
	}
	$mon = $current_mon;
	$year = $current_year;
	$dow = $current_dow;
	$date = $current_date;

	$cooking->{'topic_description'}{$blurb}{'text'} =
	    blurb_text($mon, $year, $issue, $dow, $date,
		       $master_at, $next_at, $btext);

	if (!$incremental) {
		my $sd = $cooking->{'section_data'};
		my $sl = $cooking->{'section_list'};
		# Rename "New" to "Old New" and insert "New".
		# Move "New" to "Old New"
		my $i;
		my $doneso;
		for ($i = 0; $i < @{$sl}; $i++) {
			if ($sl->[$i] eq $new_topics) {
				$sl->[$i] = $old_new_topics;
				unshift @{$sl}, $new_topics;
				$doneso = 1;
				last;
			}
		}
		if ($doneso) {
			$sd->{$old_new_topics} = $sd->{$new_topics};
		}
		$sd->{$new_topics} = [];
	}

	return $incremental;
}

sub merge_cooking {
	my ($cooking, $current) = @_;
	my $td = $cooking->{'topic_description'};
	my $sd = $cooking->{'section_data'};
	my $sl = $cooking->{'section_list'};
	my (@new_topic, @gone_topic);

	# Make sure "New Topics" and "Graduated" exists
	if (!exists $sd->{$new_topics}) {
		$sd->{$new_topics} = [];
		unshift @{$sl}, $new_topics;
	}

	if (!exists $sd->{$graduated}) {
		$sd->{$graduated} = [];
		unshift @{$sl}, $graduated;
	}

	my $incremental = update_issue($cooking);

	for my $topic (sort keys %{$current}) {
		if (!exists $td->{$topic}) {
			push @new_topic, $topic;
			next;
		}
		my $n = $current->{$topic}{'desc'};
		my $o = $td->{$topic}{'desc'};
		if ($n ne $o) {
			$td->{$topic}{'desc'} = $n . "\n<<\n" . $o ."\n>>";
		}
	}

	for my $topic (sort keys %{$td}) {
		next if ($topic eq $blurb);
		next if (!$incremental &&
			 grep { $topic eq $_ } @{$sd->{$graduated}});
		if (!exists $current->{$topic}) {
			push @gone_topic, $topic;
		}
	}

	for (@new_topic) {
		push @{$sd->{$new_topics}}, $_;
		$td->{$_}{'desc'} = $current->{$_}{'desc'};
	}

	if (!$incremental) {
		$sd->{$graduated} = [];
	}

	if (@gone_topic) {
		for my $topic (@gone_topic) {
			for my $section (@{$sl}) {
				my $pre = scalar(@{$sd->{$section}});
				@{$sd->{$section}} = (grep { $_ ne $topic }
						      @{$sd->{$section}});
				my $post = scalar(@{$sd->{$section}});
				next if ($pre == $post);
			}
		}
		for (@gone_topic) {
			push @{$sd->{$graduated}}, $_;
		}
	}
}

################################################################
# Main

my $topic = get_commit();
my $cooking = read_previous('Meta/whats-cooking.txt');
merge_cooking($cooking, $topic);
write_cooking('Meta/whats-cooking.txt', $cooking);