#!/usr/bin/perl

=head1 NAME

timestamp - prepend timestamp to output

=head1 SYNOPSIS

B<somecommand> | B<timestamp> [--delta] [--rfc|--iso|--iso-time|--epoch]

=head1 DESCRIPTION

B<timestamp> prepends stdin (standard input) with a timestamp.

=over 9

=item B<--delta> (default)

Regard start time as epoch and thus show difference between start time
and now.

If B<--delta> is repeated: The time spent between each line.


=item B<--rfc>

Output time format in RFC822 (E.g. Wed, 30 Jan 2013 13:57:58 GMT).


=item B<--iso>

Output time format in ISO8601 (E.g. 2013-01-30T13:57:58.322).


=item B<--iso-time>

Output time format in ISO8601/time only (E.g. 13:57:58.322).


=item B<--epoch> (default)

Output time format as seconds since 1970-01-01T00:00:00 (E.g. 1359557768.423).

=back

=head1 EXAMPLES

=head2 Timestamp vmstat

B<vmstat 1 | timestamp>


=head2 Timestamp each step in setting up/tearing down ssh connection:

B<ssh -v localhost echo test 2>&1 | timestamp --delta --epoch>


=head1 REPORTING BUGS

B<timestamp> is part of tangetools. Report bugs to <tools@tange.dk>.


=head1 AUTHOR

Copyright (C) 2013 Ole Tange http://ole.tange.dk


=head1 LICENSE

Copyright (C) 2013 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
at your option any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

=head2 Documentation license I

Permission is granted to copy, distribute and/or modify this documentation
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the file fdl.txt.

=head2 Documentation license II

You are free:

=over 9

=item B<to Share>

to copy, distribute and transmit the work

=item B<to Remix>

to adapt the work

=back

Under the following conditions:

=over 9

=item B<Attribution>

You must attribute the work in the manner specified by the author or
licensor (but not in any way that suggests that they endorse you or
your use of the work).

=item B<Share Alike>

If you alter, transform, or build upon this work, you may distribute
the resulting work only under the same, similar or a compatible
license.

=back

With the understanding that:

=over 9

=item B<Waiver>

Any of the above conditions can be waived if you get permission from
the copyright holder.

=item B<Public Domain>

Where the work or any of its elements is in the public domain under
applicable law, that status is in no way affected by the license.

=item B<Other Rights>

In no way are any of the following rights affected by the license:

=over 9

=item *

Your fair dealing or fair use rights, or other applicable
copyright exceptions and limitations;

=item *

The author's moral rights;

=item *

Rights other persons may have either in the work itself or in
how the work is used, such as publicity or privacy rights.

=back

=item B<Notice>

For any reuse or distribution, you must make clear to others the
license terms of this work.

=back

A copy of the full license is included in the file as cc-by-sa.txt.

=head1 DEPENDENCIES

B<timestamp> uses Perl and the Getopt::Long and Time::HiRes modules.


=head1 SEE ALSO

B<time>(1)

=cut


use Time::HiRes;
use POSIX qw(strftime);
use Getopt::Long;
use strict;

parse_options();
set_defaults();

$|=1;

my ($now,$last,$delta,$to_print,$out);

my $start = Time::HiRes::time();
if(@opt::delta) {
    $now = $start = Time::HiRes::time();
} else {
    $start = 0;
}

while(<>) {
    $last = $now;
    $now = Time::HiRes::time();
    if($#opt::delta) {
	$to_print = $now - $last;
    } else {
	$to_print = $now - $start;
    }

    my $tz = strftime("%z", localtime($to_print));
    $tz =~ s/(\d{2})(\d{2})/$1:$2/;

    my $ms = sprintf "%03d", int(($to_print - int($to_print))*1000); 

    if($opt::rfc) {
	# RFC822 (actually RFC2822, as the year has 4 digits)
	print strftime("%a, %d %b %Y %H:%M:%S.".$ms." %z", localtime($now)), " ", $_
    } elsif($opt::iso) {
	# ISO8601
	print strftime("%Y-%m-%dT%H:%M:%S.".$ms, localtime($now)), $tz , " ", $_;
    } elsif($opt::isotime) {
	# ISO8601 time part only
	print strftime("%H:%M:%S.".$ms, localtime($now)), $tz, " ", $_;
    } elsif($opt::epoch) {
	# Seconds since epoch
	print strftime("%s.".$ms, localtime($now)), " ", $_;
    } elsif(@opt::delta) {
	# Seconds since epoch
	print strftime("%s.".$ms, localtime($to_print)), " ", $_;
    } else {
	::die_bug("no format");
    }
}

sub set_defaults {
    if(not($opt::epoch || $opt::rfc || $opt::iso || $opt::isotime || $opt::epoch)) {
	if(not @opt::delta) {
	    @opt::delta = (1);
	}
    }
}

sub parse_options {
    $Global::version = 20130130;
    $Global::progname = 'timestamp';

    Getopt::Long::Configure ("bundling","require_order");
    GetOptions("delta|d" => \@opt::delta,
	       # RFC822
	       "rfc|r" => \$opt::rfc,
	       "iso|i" => \$opt::iso,
	       "ged|epoch|e" => \$opt::epoch,
	       "iso-time|isotime|time|t" => \$opt::isotime,
	       "debug|D" => \$opt::debug,
	       # GNU requirements
	       "help|h" => \$opt::help,
	       "version|V" => \$opt::version,
	) || die_usage();
    if(defined $opt::help) { die_usage(); }
    if(defined $opt::version) { version(); exit(0); }
    $Global::debug = $opt::debug;
}

sub die_bug {
    my $bugid = shift;
    print STDERR
	("$Global::progname: This should not happen. You have found a bug.\n",
	 "Please contact <tools\@tange.dk> and include:\n",
	 "* The version number: $Global::version\n",
	 "* The bugid: $bugid\n",
	 "* The command line being run\n",
	 "* The files being read (put the files on a webserver if they are big)\n",
	 "\n",
	 "If you get the error on smaller/fewer files, please include those instead.\n");
    ::wait_and_exit(255);
}