#!/usr/bin/perl

# Format a text document.
#
# The document is assumed to be in a particular style,
# having sections of free-form text separated by
# lines matching one of several patterns (see "dividing line"
# in the comments below).
# 
# Each section is formatted unless flagged to prevent this.
# Formatting, which is done using an external command,
# consists of arranging the text into a column of a set width.
#
$format_command='cx';
#
my $var = '';
my $sav = $/;
$/ = undef;
$var = <>;
$/ = $sav;
use IO::File;

# Returns the contents of a file
#
sub _get_file {
	my $fh = new IO::File;
	my $contents = '';
	my $name = shift || die "_get_file: no file name";
	open($fh, "<$name" )|| die "can't open '$name': $!";
	{
	 local $/ = undef;
	 $contents = <$fh>;
	}
	close $fh;
	return $contents;
}

$tmp1 = "/tmp/tmp1-$$";
$tmp2 = "/tmp/tmp2-$$";
$result = "";

$rrdateline = qr{^(?:(Sun|Mon|Tue|Wed|Thu|Fri|Sat) )?(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Nov|Dec) ([0-9][0-9]?)( [12][09][0-9][0-9])?\n};

$rrblankline = qr{^[ \t]*\n};

$rrdashline = qr{^[-=]+[ \t]*\n};

# Split the file into sections
#
@lines = split "\n", $var;
@sections = ();
$curr_section = '';
for ($lineno = 0; $lineno < 0+@lines; $lineno++ ) {

	# get the next line
	$line = $lines[$lineno] . "\n";

	# see if it's a dividing line;
	# if so, it goes into its own section.
	# There are >1 styles of dividing lines
	# don't combine matches into one.
	if ($line =~ $rrdateline
        || $line =~ ':$'
        || $line =~ $rrblankline
        || $line =~ $rrdashline)
    {
		if (length($curr_section) > 0) {
			push @sections, $curr_section;
			$curr_section = '';
		}
		push @sections, $line;
	} else {
		$curr_section .= $line;
	}
}
if (length($curr_section) > 0) {
	push @sections, $curr_section;
}

while (0+@sections > 0) {
	$ch = shift @sections;

	#print STDERR "ch = ||$ch||";
	if ($ch =~ /^%NO_FORMAT%[ \t]*\n/s) {
		$ch = $';
		print $ch;
	} else {
		open(my $fh1, '>', $tmp1) or die $!;
		print $fh1 $ch, "\n"; ## add newline
		close $fh1;
		system("$format_command <$tmp1 >$tmp2");
		$result = &_get_file($tmp2);
		chomp $result; ######### remove newline
		print $result;
		#print "\n" if $result !~ /\n$/s;
	}
}
print "\n";
unlink $tmp1, $tmp2;