#!/usr/bin/perl

# check for some required modules 
BEGIN {
   for (qw/ Getopt::Std /) {
      eval qq{ use $_ (); };
      if ($@) {
	 print "Module '$_' failed to load:\n\n$@\n";
         print "It may not be installed -- visit <http://www.cpan.org>.\n";
	 exit;
      }
   }
}
use Getopt::Std;

use vars qw'$opt_h $opt_c $opt_p $opt_f';
getopts('hc:p:f') || die usage(); 

if ($opt_h or ! $opt_c) {
   usage();
}

$opt_p ||= "p4";
my ($p4) = $opt_p;
my ($changenumber) = $opt_c;
my (@p4describe) =  `$p4 describe -s $changenumber 2>&1`;
my ($exit) = 0;
my (@files);
my (@describe) = grep (/\.\.\./, @p4describe);
unless ($#describe >= 0) {
   die join("",@p4describe);
}
foreach my $line (@describe) {
   if ($line =~ /^\.\.\. (\/\/.*)#(\d+) (.*)/) {   
      chomp ($line);
      my ($file) = $1;
      my ($rev) = $2;
      my ($action) = $3;
      #put quotes around file -- in case of spaces
	   $file =~ s/^/"/;
		$file =~ s/$/"/;
      #get some info about file
      my ($info) = `$p4 files $file 2>&1`;
      my ($currev);
      my ($curchange);
      if ($info =~ /#(\d+) - .* change (\d+) /) {
         $currev = $1;
         $curchange = $2;
      } else {
         die "files error: $info\n";
      }
      if ($rev != $currev) {
         unless ($opt_f) {
            $exit = 1;
         }
         print "WARNING: change $changenumber does not contain the most recent change to\n\t$file\n\t(current rev: $currev, change $curchange)\n";
      }
      my (%hsh);
      $hsh{name} = $file;
      $hsh{rev} = $rev;
      $hsh{action} = $action;
      push (@files, \%hsh);
   } 
}

if ($exit) {
  die "Run $0 with the '-f' flag to ignore warnings.\n";
}
my ($number) = 1;
my ($total) = scalar(@files);
foreach my $file (@files) {
   print "$number of $total\n"; 
   # sync the file
   my ($output) = `$p4 sync $$file{name} 2>&1`;
   unless ($output =~ /up-to-date/ || $output =~ /updating/ || $output =~ /added as/ || $output =~ /deleted as/) {
      die "sync error: $output\n";
   }   
   my ($oldrev) = $$file{rev} - 1;

   # if it's an add, open for delete
	if (($$file{action} eq "add") or ($$file{action} eq "branch")) {
      $output = `$p4 delete $$file{name} 2>&1`;
      unless ($output =~ /opened for delete/) {
         die "delete error: $output\n";
      }
   # if it's a delete, open for add   
   } elsif ($$file{action} eq "delete") {
      $output = `$p4 sync $$file{name}#$oldrev 2>&1`;
      unless ($output =~ /up-to-date/ || $output =~ /updating/ || $output =~ /added as/) {
         die "sync error: $output\n";
      } 
      $output = `$p4 add $$file{name} 2>&1`;
      unless ($output =~ /opened for add/) {
         die "add error: $output\n";
      } 
   # if it's an edit, roll it back
   } elsif ($$file{action} eq "edit" || $$file{action} eq "integrate") {
      $output = `$p4 sync $$file{name}#$oldrev 2>&1`;
      unless ($output =~ /up-to-date/ || $output =~ /updating/) {
         die "$output\n";
      } 
      $output = `$p4 edit $$file{name} 2>&1`;
      unless ($output =~ /opened for edit/) {
         die "edit error: $output\n";
      } 
      $output = `$p4 sync $$file{name} 2>&1`;
      unless ($output =~ /is opened/ || $output =~ /added as/) {
         die "sync error: $output\n";
      } 
      $output = `$p4 resolve -ay $$file{name} 2>&1`;
      unless ($output =~ / - vs /) {
         die "resolve error: $output\n";
      } 
   } else {
      die "'$$file{action}' is an unknown action.\n";
   }
   $number ++;
}

sub usage {
   print "NAME\n\t$0 - rollback a changelist\n";
   print "SYNOPSIS\n\t$0 [-h] [-f] [-c <changelist number>] [-p <p4 command>]\n";
   print "\takalaveshi\@mahinetworks.com\n";
   print "OPTIONS\n";
   print "\t-c\n\t\t(c)hange: Changelist number to roll back.\n";
   print "\t-h\n\t\t(h)elp: Display this page.\n";
   print "\t-f\n\t\t(f)orce: Ignore warnings.\n";
   print "\t-p\n\t\t(p)4: perforce command (default 'p4', use 'p4 -c rollback' to specify client).\n";
   exit;
}