#! /sw/bin/perl -T

use strict;


#--------------------------------------------------------------#
# This script scans through the mail box $MAIL_IN, using formail.
# It handles requests automatically.
# This script deals with reading the mail box and dispatching the separate
# mails to the program that treats one mail.
# It takes care that there is only one program doing so, by means of locking.
#--------------------------------------------------------------#

# the mail boxes
my $Scripts_directory='/projects/CGAL/admin_scripts';
my $Data_directory='/projects/CGAL/submissions/autohandle/data';
my $LOCKFILE="$Data_directory/collect_submission.lock";
my $Mail_directory='/users/geert/PUBLIC/CGAL-submit';
my $MAIL_IN="$Mail_directory/incoming-mail";
#my $MAIL_OUT="$Mail_directory/handled-mail";
my $MAIL_TMP="$Mail_directory/temp-mail";
my $SCRIPT="$Scripts_directory/collect_submissions";
my $MAIL_PROG="$Scripts_directory/send_cgal_mail";
my $treat_one_mail_program="$Scripts_directory/treat_submit_mail";

# program locations
my $FORMAIL="/sw/bin/formail";
my $LOCKCMD="/sw/bin/lockfile";

# the log file
my $LOGFILE="$Data_directory/collect_submissions.log";

# 
my $seconds_between_invocations=300;
my $max_tries_between_warning= int 21600/$seconds_between_invocations;

$ENV{PATH}='/sbin:/usr/sbin:/usr/bsd:/bin:/usr/bin';

# variable that is set when there is an attempt to kill this process.
my $please_die=0;

my $invoker = $ENV{USER};
if ($invoker =~ /^\s*([-\@\w]+)\s*$/) {
    $invoker = "$1\@cs.uu.nl";
} else {
    print STDERR <<"TOTHIER";
The script $SCRIPT did not start because
the USER environment value has a strange value.
TOTHIER
    exit 1;
}

my $hostname = $ENV{HOST};
if ($hostname =~ /^\s*([-\@\w.]+)\s*$/) {
    $hostname = $1;
} else {
    print STDERR <<"TOTHIER";
The script $SCRIPT did not start because
the HOST environment value has a strange value ($hostname).
TOTHIER
    exit 1;
}


sub termination_signal_handler {
    $please_die=1;
}


sub initialisation()
{
#
# Disable signals that kill this process.
#

    $SIG{INT} = \&termination_signal_handler;
    $SIG{TERM} = \&termination_signal_handler;

#
# Try to acquire the lock.
# Quit with a message if it fails.
#

    if ( system("$LOCKCMD", "-r", '10', "$LOCKFILE") != 0) {
	open NOTICE, "|$MAIL_PROG  \"collect_submissions notice\" $invoker";
	print NOTICE <<"TOTHIER";
The script $SCRIPT could not proceed because
it could not acquire the needed lock on file $LOCKFILE.
TOTHIER
	close NOTICE;
	exit 1;
    }
#
# Now that you have the lock, check to see if there is another process
# executing this program. If so, quit.
#
    my $logline = `tail -1 $LOGFILE`;
    if ($logline !~ /stopped/) {
	unlink $LOCKFILE;
	open NOTICE, "|$MAIL_PROG \"collect_submissions notice\" $invoker";
	print NOTICE <<"TOTHIER";
The script $SCRIPT did not proceed because
there seems to be another process collecting the mail messages.
The file $LOGFILE says:

$logline
TOTHIER
	close NOTICE;
	exit 1;
    }
#
# We can proceed. Record a message to the log file that this process
# takes control of dealing with the mail box.
#
    open LOGFILE, ">>$LOGFILE";
    print LOGFILE "$hostname $$: started executing on ", `date`;
    close LOGFILE;

    unlink $LOCKFILE;
}

sub new_untreated_mail_file()
{
    my $filename;
    my $n=1;
    for ($n=1; $n<1000; ++$n) {
    $filename="$Mail_directory/untreated_mail_$n";
	last if (! -f $filename);
    }
    return $filename;
}

sub treat_current_mail()
{
    if ( -f $MAIL_IN ) {
	if ( system("$LOCKCMD", "-r", '10', "$MAIL_IN.lock") == 0) {
	    rename($MAIL_IN, $MAIL_TMP);
	    unlink "$MAIL_IN.lock";
	    if (system("$FORMAIL -ns $treat_one_mail_program < $MAIL_TMP")== 0 )
	    {
		unlink $MAIL_TMP;
	    } else {
		my $Save_file = new_untreated_mail_file();
		rename($MAIL_TMP, $Save_file) or die;
		open NOTICE,
		    "|$MAIL_PROG \"collect_submissions notice\" $invoker";
		print NOTICE <<"TOTHIER";
The script $SCRIPT could not treat incoming mail.
This mail was saved in $Save_file.
TOTHIER
		
	    }
	}
    }
}

sub main_loop()
{
    my $tries_to_go = $max_tries_between_warning;
    while (! $please_die) {
	if ( system("$LOCKCMD", "-r", '10', "$LOCKFILE") != 0) {
	    --$tries_to_go;
	    if ($tries_to_go < 0) {
		open NOTICE,
		    "|$MAIL_PROG \"collect_submissions notice\" $invoker";
		print NOTICE <<"TOTHIER";
The script $SCRIPT could not proceed because
it could not acquire the needed lock on file $LOCKFILE.
TOTHIER
		close NOTICE;
		$tries_to_go = $max_tries_between_warning;
	    }
	} else {
	    $tries_to_go = $max_tries_between_warning;
	    if ( -f $MAIL_TMP ) {
		open NOTICE,
		    "|$MAIL_PROG \"collect_submissions notice\" $invoker";
print NOTICE <<"TOTHIER";
The script $SCRIPT has been stopped,
because the temporary mail box $MAIL_TMP was not emptied.
TOTHIER
		close NOTICE;
		unlink $LOCKFILE;
		$please_die = 1;
	    } else {
		treat_current_mail;
	    }
	    unlink $LOCKFILE;
	}
	sleep $seconds_between_invocations unless $please_die;
    }
}

sub finalisation()
{
    open LOGFILE, ">>$LOGFILE";
    print LOGFILE "$hostname $$: stopped executing at ", `date`;
    close LOGFILE;
}

initialisation();
main_loop();
finalisation();
exit 0;