#!/usr/bin/perl

#   mail-to-filter - strips long distribution lists from mail
#   Copyright (C) 2000-2003 Gary A. Johnson
#
#   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 2 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, write to the Free Software
#   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

# Description:
#
#	This program is intended to be used as a filter ahead of a mail
#	reader's pager, for example as the display_filter for mutt.  It
#	shortens To and Cc lists longer than two lines, replacing the
#	second and subsequent lines with
#
#		[<lines> lines deleted]
#
#	indicating the number of lines deleted.  It also removes excess
#	spaces at the ends of all lines of the message, but preserves
#	the trailing space of the signature's "-- " line.
#
# Revision History:
#
#	18 Nov. 2003 - Allow the lower-case header field names "to" and
#		       "cc" generated by some MUAs.  Patch contributed
#		       by Aseem Asthana.
#
#	27 Mar. 2002 - Truncates lines in To: and Cc: lists longer than
#		       $COLUMNS.
#
#	25 Jan. 2002 - Detects mutt's "weed" state by checking for
#		       "^From " on the first line and if not weeding,
#		       does not filter To and Cc lists.
#
#	27 Nov. 2001 - No longer removes trailing space from
#		       sigdashes ("^-- $").
#
# The latest version is available at
#
#	http://www.spocom.com/users/gjohnson/mutt/mail-to-filter
#
# Please direct any comments to:
#
#	Gary Johnson <garyjohn@spk.agilent.com>


eval 'exec /usr/bin/perl -S $0 ${1+"$@"}'
    if $running_under_some_shell;
			# this emulates #! processing on NIH machines.
			# (remove #! line above if indigestible)

eval '$'.$1.'$2;' while $ARGV[0] =~ /^([A-Za-z_0-9]+=)(.*)/ && shift;
			# process any FOO=bar switches

$[ = 1;			# set array base to 1
$, = ' ';		# set output field separator
$\ = "\n";		# set output record separator

$weeding = 1;
$in_to_list = 0;
$in_cc_list = 0;
$spaces = sprintf('%80s', '');
$width = $ENV{'COLUMNS'} || 80;

line: while (<>) {
    chop;		# strip record separator
    s/\s+$// unless /^-- $/;
			# Remove excess spaces at the ends of lines
			# that can cause lines to wrap unnecessarily,
			# but don't corrupt sigdashes.

    if ($weeding == 1) {
	@Fld = split(' ', $_, 9999);

	if ($in_to_list == 1) {
	    if (/^[Tt][Oo]:.*@/) {
		$lines += 1;
		$last_line = $_;
		next line;
	    }
	    if (/^[^ \t]/ || /^$/) {
		if ($lines == 1) {
		    # The $last_line was not the first line of the "To:"
		    # list, so it should begin with a tab.  Assume for
		    # now that it does and adjust the long-line
		    # truncation procedure accordingly.
		    #
		    if (length($last_line) > $width - 7) {
			substr($last_line, $width - 7 - 4) = "[...]";
		    }
		    print $last_line;
		}
		elsif ($lines > 1) {
		    print $indentation . '[' . $lines . ' lines deleted]';
		}
		$in_to_list = 0;
	    }
	    else {
		$lines += 1;
		$last_line = $_;
		next line;
	    }
	}
	if ($in_cc_list == 1) {
	    if (/^[Cc][Cc]:.*@/) {
		$lines += 1;
		$last_line = $_;
		next line;
	    }
	    if (/^[^ \t]/ || /^$/) {
		if ($lines == 1) {
		    # The $last_line was not the first line of the "Cc:"
		    # list, so it should begin with a tab.  Assume for
		    # now that it does and adjust the long-line
		    # truncation procedure accordingly.
		    #
		    if (length($last_line) > $width - 7) {
			substr($last_line, $width - 7 - 4) = "[...]";
		    }
		    print $last_line;
		}
		elsif ($lines > 1) {
		    print $indentation . '[' . $lines . ' lines deleted]';
		}
		$in_cc_list = 0;
	    }
	    else {
		$lines += 1;
		$last_line = $_;
		next line;
	    }
	}
	if (/^[Tt][Oo]:.*@/) {
	    $indentation = substr($spaces, 1, index($_, $Fld[2]) - 1);
	    $in_to_list = 1;
	    $lines = 0;
	    if (length($_) > $width) {
		substr($_, $width - 4) = "[...]";
	    }
	}
	if (/^[Cc][Cc]:.*@/) {
	    $indentation = substr($spaces, 1, index($_, $Fld[2]) - 1);
	    $in_cc_list = 1;
	    $lines = 0;
	    if (length($_) > $width) {
		substr($_, $width - 4) = "[...]";
	    }
	}
	if (($. == 1) && (/^From /)) {
	    $weeding = 0;
	}
    }
    print $_;
}

exit 0;