#!/usr/bin/perl
#
# A daemon that waits for update events sent by its companion
# post-receive-cinotify hook, checks out a new copy of source,
# compiles it, and emails the guilty parties if the compile
# (and optionally test suite) fails.
#
# To use this daemon, configure it and run it.  It will disconnect
# from your terminal and fork into the background.  The daemon must
# have local filesystem access to the source repositories, as it
# uses objects/info/alternates to avoid copying objects.
#
# Add its companion post-receive-cinotify hook as the post-receive
# hook to each repository that the daemon should monitor.  Yes, a
# single daemon can monitor more than one repository.
#
# To use multiple daemons on the same system, give them each a
# unique queue file and tmpdir.
#
# Global Config
# -------------
# Reads from a Git style configuration file.  This will be
# ~/.gitconfig by default but can be overridden by setting
# the GIT_CONFIG_FILE environment variable before starting.
#
# cidaemon.smtpHost
#   Hostname of the SMTP server the daemon will send email
#   through.  Defaults to 'localhost'.
#
# cidaemon.smtpUser
#   Username to authenticate to the SMTP server as.  This
#   variable is optional; if it is not supplied then no
#   authentication will be performed.
#
# cidaemon.smtpPassword
#   Password to authenticate to the SMTP server as.  This
#   variable is optional.  If not supplied but smtpUser was,
#   the daemon prompts for the password before forking into
#   the background.
#
# cidaemon.smtpAuth
#   Type of authentication to perform with the SMTP server.
#   If set to 'login' and smtpUser was defined, this will
#   use the AUTH LOGIN command, which is suitable for use
#   with at least one version of Microsoft Exchange Server.
#   If not set the daemon will use whatever auth methods
#   are supported by your version of Net::SMTP.
#
# cidaemon.email
#   Email address that daemon generated emails will be sent
#   from.  This should be a useful email address within your
#   organization.  Required.
#
# cidaemon.name
#   Human friendly name that the daemon will send emails as.
#   Defaults to 'cidaemon'.
#
# cidaemon.scanDelay
#   Number of seconds to sleep between polls of the queue file.
#   Defaults to 60.
#
# cidaemon.recentCache
#   Number of recent commit SHA-1s per repository to cache and
#   skip building if they appear again.  This is useful to avoid
#   rebuilding the same commit multiple times just because it was
#   pushed into more than one branch.  Defaults to 100.
#
# cidaemon.tmpdir
#   Scratch directory to create the builds within.  The daemon
#   makes a new subdirectory for each build, then deletes it when
#   the build has finished.  The pid file is also placed here.
#   Defaults to '/tmp'.
#
# cidaemon.queue
#   Path to the queue file that the post-receive-cinotify hook
#   appends events to.  This file is polled by the daemon.  It
#   must not be on an NFS mount (uses flock).  Required.
#
# cidaemon.nocc
#   Perl regex patterns to match against author and committer
#   lines.  If a pattern matches, that author or committer will
#   not be notified of a build failure.
#
# Per Repository Config
# ----------------------
# Read from the source repository's config file.
#
# builder.command
#   Shell command to execute the build.  This command must
#   return 0 on "success" and non-zero on failure.  If you
#   also want to run a test suite, make sure your command
#   does that too.  Required.
#
# builder.queue
#   Queue file to notify the cidaemon through.  Should match
#   cidaemon.queue.  If not set the hook will not notify the
#   cidaemon.
#
# builder.skip
#   Perl regex patterns of refs that should not be sent to
#   cidaemon.  Updates of these refs will be ignored.
#
# builder.newBranchBase
#   Glob patterns of refs that should be used to form the
#   'old' revions of a newly created ref.  This should set
#   to be globs that match your 'mainline' branches.  This
#   way a build failure of a brand new topic branch does not
#   attempt to email everyone since the beginning of time;
#   instead it only emails those authors of commits not in
#   these 'mainline' branches.

local $ENV{PATH} = join ':', qw(
	/opt/git/bin
	/usr/bin
	/bin
	);

use strict;
use warnings;
use FindBin qw($RealBin);
use File::Spec;
use lib File::Spec->catfile($RealBin, '..', 'perl5');
use Storable qw(retrieve nstore);
use Fcntl ':flock';
use POSIX qw(strftime);
use Getopt::Long qw(:config no_auto_abbrev auto_help);

sub git_config ($;$)
{
	my $var = shift;
	my $required = shift || 0;
	local *GIT;
	open GIT, '-|','git','config','--get',$var;
	my $r = <GIT>;
	chop $r if $r;
	close GIT;
	die "error: $var not set.\n" if ($required && !$r);
	return $r;
}

package EXCHANGE_NET_SMTP;

# Microsoft Exchange Server requires an 'AUTH LOGIN'
# style of authentication.  This is different from
# the default supported by Net::SMTP so we subclass
# and override the auth method to support that.

use Net::SMTP;
use Net::Cmd;
use MIME::Base64 qw(encode_base64);
our @ISA = qw(Net::SMTP);
our $auth_type = ::git_config 'cidaemon.smtpAuth';

sub new
{
	my $self = shift;
	my $type = ref($self) || $self;
	$type->SUPER::new(@_);
}

sub auth
{
	my $self = shift;
	return $self->SUPER::auth(@_) unless $auth_type eq 'login';

	my $user = encode_base64 shift, '';
	my $pass = encode_base64 shift, '';
	return 0 unless CMD_MORE == $self->command("AUTH LOGIN")->response;
	return 0 unless CMD_MORE == $self->command($user)->response;
	CMD_OK == $self->command($pass)->response;
}

package main;

my ($debug_flag, %recent);

my $ex_host = git_config('cidaemon.smtpHost') || 'localhost';
my $ex_user = git_config('cidaemon.smtpUser');
my $ex_pass = git_config('cidaemon.smtpPassword');

my $ex_from_addr = git_config('cidaemon.email', 1);
my $ex_from_name = git_config('cidaemon.name') || 'cidaemon';

my $scan_delay = git_config('cidaemon.scanDelay') || 60;
my $recent_size = git_config('cidaemon.recentCache') || 100;
my $tmpdir = git_config('cidaemon.tmpdir') || '/tmp';
my $queue_name = git_config('cidaemon.queue', 1);
my $queue_lock = "$queue_name.lock";

my @nocc_list;
open GIT,'git config --get-all cidaemon.nocc|';
while (<GIT>) {
	chop;
	push @nocc_list, $_;
}
close GIT;

sub nocc_author ($)
{
	local $_ = shift;
	foreach my $pat (@nocc_list) {
		return 1 if /$pat/;
	}
	0;
}

sub input_echo ($)
{
	my $prompt = shift;

	local $| = 1;
	print $prompt;
	my $input = <STDIN>;
	chop $input;
	return $input;
}

sub input_noecho ($)
{
	my $prompt = shift;

	my $end = sub {system('stty','echo');print "\n";exit};
	local $SIG{TERM} = $end;
	local $SIG{INT} = $end;
	system('stty','-echo');

	local $| = 1;
	print $prompt;
	my $input = <STDIN>;
	system('stty','echo');
	print "\n";
	chop $input;
	return $input;
}

sub rfc2822_date ()
{
	 strftime("%a, %d %b %Y %H:%M:%S %Z", localtime);
}

sub send_email ($$$)
{
	my ($subj, $body, $to) = @_;
	my $now = rfc2822_date;
	my $to_str = '';
	my @rcpt_to;
	foreach (@$to) {
		my $s = $_;
		$s =~ s/^/"/;
		$s =~ s/(\s+<)/"$1/;
		$to_str .= ', ' if $to_str;
		$to_str .= $s;
		push @rcpt_to, $1 if $s =~ /<(.*)>/;
	}
	die "Nobody to send to.\n" unless @rcpt_to;
	my $msg = <<EOF;
From: "$ex_from_name" <$ex_from_addr>
To: $to_str
Date: $now
Subject: $subj

$body
EOF

	my $smtp = EXCHANGE_NET_SMTP->new(Host => $ex_host)
		or die "Cannot connect to $ex_host: $!\n";
	if ($ex_user && $ex_pass) {
		$smtp->auth($ex_user,$ex_pass)
			or die "$ex_host rejected $ex_user\n";
	}
	$smtp->mail($ex_from_addr)
		or die "$ex_host rejected $ex_from_addr\n";
	scalar($smtp->recipient(@rcpt_to, { SkipBad => 1 }))
		or die "$ex_host did not accept any addresses.\n";
	$smtp->data($msg)
		or die "$ex_host rejected message data\n";
	$smtp->quit;
}

sub pop_queue ()
{
	open LOCK, ">$queue_lock" or die "Can't open $queue_lock: $!";
	flock LOCK, LOCK_EX;

	my $queue = -f $queue_name ? retrieve $queue_name : [];
	my $ent = shift @$queue;
	nstore $queue, $queue_name;

	flock LOCK, LOCK_UN;
	close LOCK;
	$ent;
}

sub git_exec (@)
{
	system('git',@_) == 0 or die "Cannot git " . join(' ', @_) . "\n";
}

sub git_val (@)
{
	open(C, '-|','git',@_);
	my $r = <C>;
	chop $r if $r;
	close C;
	$r;
}

sub do_build ($$)
{
	my ($git_dir, $new) = @_;

	my $tmp = File::Spec->catfile($tmpdir, "builder$$");
	system('rm','-rf',$tmp) == 0 or die "Cannot clear $tmp\n";
	die "Cannot clear $tmp.\n" if -e $tmp;

	my $result = 1;
	eval {
		my $command;
		{
			local $ENV{GIT_DIR} = $git_dir;
			$command = git_val 'config','builder.command';
		}
		die "No builder.command for $git_dir.\n" unless $command;

		git_exec 'clone','-n','-l','-s',$git_dir,$tmp;
		chmod 0700, $tmp or die "Cannot lock $tmp\n";
		chdir $tmp or die "Cannot enter $tmp\n";

		git_exec 'update-ref','HEAD',$new;
		git_exec 'read-tree','-m','-u','HEAD','HEAD';
		system $command;
		if ($? == -1) {
			print STDERR "failed to execute '$command': $!\n";
			$result = 1;
		} elsif ($? & 127) {
			my $sig = $? & 127;
			print STDERR "'$command' died from signal $sig\n";
			$result = 1;
		} else {
			my $r = $? >> 8;
			print STDERR "'$command' exited with $r\n" if $r;
			$result = $r;
		}
	};
	if ($@) {
		$result = 2;
		print STDERR "$@\n";
	}

	chdir '/';
	system('rm','-rf',$tmp);
	rmdir $tmp;
	$result;
}

sub build_failed ($$$$$)
{
	my ($git_dir, $ref, $old, $new, $msg) = @_;

	$git_dir =~ m,/([^/]+)$,;
	my $repo_name = $1;
	$ref =~ s,^refs/(heads|tags)/,,;

	my %authors;
	my $shortlog;
	my $revstr;
	{
		local $ENV{GIT_DIR} = $git_dir;
		my @revs = ($new);
		push @revs, '--not', @$old if @$old;
		open LOG,'-|','git','rev-list','--pretty=raw',@revs;
		while (<LOG>) {
			if (s/^(author|committer) //) {
				chomp;
				s/>.*$/>/;
				$authors{$_} = 1 unless nocc_author $_;
			}
		}
		close LOG;
		open LOG,'-|','git','shortlog',@revs;
		$shortlog .= $_ while <LOG>;
		close LOG;
		$revstr = join(' ', @revs);
	}

	my @to = sort keys %authors;
	unless (@to) {
		print STDERR "error: No authors in $revstr\n";
		return;
	}

	my $subject = "[$repo_name] $ref : Build Failed";
	my $body = <<EOF;
Project: $git_dir
Branch:  $ref
Commits: $revstr

$shortlog
Build Output:
--------------------------------------------------------------
$msg
EOF
	send_email($subject, $body, \@to);
}

sub run_build ($$$$)
{
	my ($git_dir, $ref, $old, $new) = @_;

	if ($debug_flag) {
		my @revs = ($new);
		push @revs, '--not', @$old if @$old;
		print "BUILDING $git_dir\n";
		print "  BRANCH: $ref\n";
		print "  COMMITS: ", join(' ', @revs), "\n";
	}

	local(*R, *W);
	pipe R, W or die "cannot pipe builder: $!";

	my $builder = fork();
	if (!defined $builder) {
		die "cannot fork builder: $!";
	} elsif (0 == $builder) {
		close R;
		close STDIN;open(STDIN, '/dev/null');
		open(STDOUT, '>&W');
		open(STDERR, '>&W');
		exit do_build $git_dir, $new;
	} else {
		close W;
		my $out = '';
		$out .= $_ while <R>;
		close R;
		waitpid $builder, 0;
		build_failed $git_dir, $ref, $old, $new, $out if $?;
	}

	print "DONE\n\n" if $debug_flag;
}

sub daemon_loop ()
{
	my $run = 1;
	my $stop_sub = sub {$run = 0};
	$SIG{HUP} = $stop_sub;
	$SIG{INT} = $stop_sub;
	$SIG{TERM} = $stop_sub;

	mkdir $tmpdir, 0755;
	my $pidfile = File::Spec->catfile($tmpdir, "cidaemon.pid");
	open(O, ">$pidfile"); print O "$$\n"; close O;

	while ($run) {
		my $ent = pop_queue;
		if ($ent) {
			my ($git_dir, $ref, $old, $new) = @$ent;

			$ent = $recent{$git_dir};
			$recent{$git_dir} = $ent = [[], {}] unless $ent;
			my ($rec_arr, $rec_hash) = @$ent;
			next if $rec_hash->{$new}++;
			while (@$rec_arr >= $recent_size) {
				my $to_kill = shift @$rec_arr;
				delete $rec_hash->{$to_kill};
			}
			push @$rec_arr, $new;

			run_build $git_dir, $ref, $old, $new;
		} else {
			sleep $scan_delay;
		}
	}

	unlink $pidfile;
}

$debug_flag = 0;
GetOptions(
	'debug|d' => \$debug_flag,
	'smtp-user=s' => \$ex_user,
) or die "usage: $0 [--debug] [--smtp-user=user]\n";

$ex_pass = input_noecho("$ex_user SMTP password: ")
	if ($ex_user && !$ex_pass);

if ($debug_flag) {
	daemon_loop;
	exit 0;
}

my $daemon = fork();
if (!defined $daemon) {
	die "cannot fork daemon: $!";
} elsif (0 == $daemon) {
	close STDIN;open(STDIN, '/dev/null');
	close STDOUT;open(STDOUT, '>/dev/null');
	close STDERR;open(STDERR, '>/dev/null');
	daemon_loop;
	exit 0;
} else {
	print "Daemon $daemon running in the background.\n";
}