use strict;
use warnings;
package App::Cronjob 1.200012;
# ABSTRACT: wrap up programs to be run as cron jobs

use Digest::MD5 qw(md5_hex);
use Errno;
use Fcntl qw( :DEFAULT :flock );
use Getopt::Long::Descriptive;
use IPC::Run3 qw(run3);
use Log::Dispatchouli;
use Process::Status 0.002;
use String::Flogger;
use Sys::Hostname::Long;
use Text::Template;
use Time::HiRes ();

#pod =head1 SEE INSTEAD
#pod
#pod This library, App::Cronjob, is not well documented.  Its internals may change
#pod substantially until such point as it is documented.
#pod
#pod Instead of using the library, you should run the program F<cronjob> that is
#pod installed along with the library.
#pod
#pod For a full description of the program's behavior, consult L<cronjob>.
#pod
#pod =cut

my $TEMPLATE;

my (
  $opt,
  $usage,
  $subject,
  $rcpts,
  $host,
  $sender,
);

sub run {
  ($opt, $usage) = describe_options(
    '%c %o',
     [ 'command|c=s',   'command to run (passed to ``)', { required => 1 }   ],
     [ 'subject|s=s',   'subject of mail to send (defaults to command)'      ],
     [ 'rcpt|r=s@',     'recipient of mail; may be given many times',        ],
     [ 'errors-only|E', 'do not send mail if exit code 0, even with output', ],
     [ 'sender|f=s',    'sender for message',                                ],
     [ 'jobname|j=s',   'job name; used for locking, if given'               ],
     [ 'timeout=i',     "fail if the child isn't completed within n seconds" ],
     [ 'ignore-errors=s@',  'error types to ignore (like: lock)'              ],
     [ 'email-header|h=s@', 'add header to the report email, if you send one' ],
     [ 'temp-ignore-lock-errors=i',
                     'failure to lock only signals an error after this long' ],
     [ 'lock!',         'lock this job (defaults to true; --no-lock for off)',
                        { default => 1 }                                     ],
  );

  $subject = $opt->{subject} || $opt->{command};
  $subject =~ s{\A/\S+/([^/]+)(\s|$)}{$1$2} if $subject eq $opt->{command};

  if (defined $opt->{temp_ignore_lock_errors}) {
    if (grep {; $_ eq "lock" } @{$opt->{ignore_errors}}) {
      die "--temp-ignore-lock-errors and --ignore-errors=lock are incompatible\n";
    }
  }

  my @extra_headers;
  for my $entry (@{ $opt->email_header || [] }) {
    my ($h, $v) = split /=/, $entry;

    lc $h eq $_ && die "You can't replace the $_ header!\n"
      for qw(to from subject);

    die "Invalid header name: $h" if $h =~ /\P{ASCII}/;
    die "Invalid header name: $h" unless $h =~ /\A[A-Za-z][-A-Za-z0-9]*\z/;

    push @extra_headers, $h, $v;
  }

  $rcpts   = $opt->{rcpt}
          || [ split /\s*,\s*/, ($ENV{MAILTO} ? $ENV{MAILTO} : 'root') ];

  $host    = hostname_long;
  $sender  = $opt->{sender} || sprintf '%s@%s', ($ENV{USER}||'cron'), $host;

  my $got_lock;

  my $okay = eval {
    die "illegal job name: $opt->{jobname}\n"
      if $opt->{jobname} and $opt->{jobname} !~ m{\A[-_A-Za-z0-9]+\z};

    my $job_id   = $opt->{jobname} || md5_hex($subject);
    my $lockfile = sprintf '%s/cronjob.%s',
                   $ENV{APP_CRONJOB_LOCKDIR} || '/tmp',
                   $job_id;

    my $logger  = Log::Dispatchouli->new({
      ident    => 'cronjob',
      facility => 'cron',
      log_pid  => 1,
      prefix   => "$job_id: ",
    });

    my $lock_fh;
    if ($opt->lock) {
      sysopen $lock_fh, $lockfile, O_CREAT|O_WRONLY
        or die App::Cronjob::Exception->new(
          lockfile => "couldn't open lockfile $lockfile: $!"
        );

      my $lock_flags = LOCK_EX | LOCK_NB;

      unless (flock $lock_fh, $lock_flags) {
        my $error = $!;
        my $mtime = (stat $lock_fh)[9];
        my $stamp = scalar localtime $mtime;
        die App::Cronjob::Exception->new(
          lock => "can't lock; $!; lockfile created $stamp",
          { locked_since => $mtime },
        );
      }

      printf $lock_fh "pid %s running %s\nstarted at %s\n",
        $$, $opt->{command}, scalar localtime $^T;

      $got_lock = 1;
    }

    $logger->log([ 'trying to run %s', $opt->{command} ]);

    my $start = Time::HiRes::time;
    my $output;

    my $ok = eval {
      local $SIG{ALRM} = sub { die "command took too long to run" };
      alarm($opt->timeout) if $opt->timeout;
      run3($opt->{command}, \undef, \$output, \$output);
      alarm(0) if $opt->timeout;
      1;
    };

    unless ($ok) {
      # XXX: does not throw proper exception
      $logger->log_fatal([ 'run3 failed to run command: %s', $@ ]);
    }

    my $status = Process::Status->new;

    my $end = Time::HiRes::time;

    my $send_mail = ($status->exitstatus != 0)
                 || (length $output && ! $opt->{errors_only});

    my $time_taken = sprintf '%0.4f', $end - $start;

    $logger->log([
      'job completed with status %s after %ss',
      $status->as_struct,
      $time_taken,
    ]);

    if ($send_mail) {
      send_cronjob_report({
        is_fail => (!! $status->exitstatus),
        status  => $status,
        time    => \$time_taken,
        output  => \$output,
        extra_headers => \@extra_headers,
      });
    }

    1;
  };

  exit 0 if $okay;
  my $err = $@;

  if (eval { $err->isa('App::Cronjob::Exception'); }) {
    unless (
      grep { $err->{type} and $_ eq $err->{type} } @{$opt->{ignore_errors}}
    ) {
      if ($err->{type} eq "lock" && $opt->{temp_ignore_lock_errors}) {
        my $age = time() - $err->{extra}{locked_since};
        exit 0 if $age <= $opt->{temp_ignore_lock_errors};
      }
      send_cronjob_report({
        is_fail => 1,
        output  => \$err->{text},
        extra_headers => \@extra_headers,
      });
    }

    exit 0;
  } else {
    $subject = "ERROR: $subject";
    send_cronjob_report({
      is_fail => 1,
      output  => \$err,
      extra_headers => \@extra_headers,
    });
    exit 0;
  }
}

# read INI from /etc/cronjob
#sub __config {
#}

sub send_cronjob_report {
  my ($arg) = @_;

  require Email::Simple;
  require Email::Simple::Creator;
  require Email::Sender::Simple;
  require Text::Template;

  my $body     = Text::Template->fill_this_in(
    $TEMPLATE,
    HASH => {
      command => \$opt->{command},
      output  => $arg->{output},
      time    => $arg->{time} || \'(n/a)',
      status  => \($arg->{status} ? $arg->{status}->as_string : 'never ran'),
    },
  );

  my $subject = sprintf '%s%s', ($arg->{is_fail} ? 'FAIL: ' : ''), $subject;

  my $irt = sprintf '<%s@%s>', md5_hex($subject), $host;

  my $email = Email::Simple->create(
    body   => $body,
    header => [
      To      => join(', ', @$rcpts),
      From    => qq{"cron/$host" <$sender>},
      Subject => $subject,
      'In-Reply-To' => $irt,
      'Auto-Submitted' => 'auto-generated',
      @{ $arg->{extra_headers} },
    ],
  );

  Email::Sender::Simple->send(
    $email,
    {
      to      => $rcpts,
      from    => $sender,
    }
  );
}

BEGIN {
$TEMPLATE = <<'END_TEMPLATE'
Command: { $command }
Time   : { $time }s
Status : { $status }

Output :

{ $output || '(no output)' }
END_TEMPLATE
}

{
  package App::Cronjob::Exception 1.200012;

  sub new {
    my ($class, $type, $text, $extra) = @_;
    bless { type => $type, text => $text, extra => $extra } => $class;
  }
}

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

App::Cronjob - wrap up programs to be run as cron jobs

=head1 VERSION

version 1.200012

=head1 PERL VERSION

This library should run on perls released even a long time ago.  It should work
on any version of perl released in the last five years.

Although it may work on older versions of perl, no guarantee is made that the
minimum required version will not be increased.  The version may be increased
for any reason, and there is no promise that patches will be accepted to lower
the minimum required perl.

=head1 SEE INSTEAD

This library, App::Cronjob, is not well documented.  Its internals may change
substantially until such point as it is documented.

Instead of using the library, you should run the program F<cronjob> that is
installed along with the library.

For a full description of the program's behavior, consult L<cronjob>.

=head1 AUTHOR

Ricardo Signes <rjbs@semiotic.systems>

=head1 CONTRIBUTORS

=for stopwords chromatic Mark Jason Dominus Rob N ★

=over 4

=item *

chromatic <chromatic@wgz.org>

=item *

Mark Jason Dominus <mjd@plover.com>

=item *

Rob N ★ <robn@robn.io>

=back

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2009 by Ricardo Signes.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut
