#! /usr/bin/perl -w

# Try to format ChangeLog in the current directory.
# Remove unnecessary spaces.  Add spaces when needed.

use strict;

my $progname = "trim_changelog";

# Print message and exit (like "die", but without raising an exception).
# System error is added at the end.
sub error ($)
{
	print STDERR "$progname: ERROR: " . shift(@_) . ": $!\n";
	exit 1;
}

if ($#ARGV != -1) {
	print STDERR "$progname accepts no arguments\n";
	exit 1;
}

open (CHANGELOG, "< ChangeLog") || error ("cannot open ChangeLog");
open (CHNEW, "> ChangeLog.new") || error ("cannot open ChangeLog.new");

# Convert initial spaces in ChangeLog to tabs.

while (<CHANGELOG>) {
	# Trim trailing whitespace.
	s/\s*$//;

	# Make sure there are exactly 2 spaces before the e-mail.
	s/(^\w.*[^\s])\s+</$1  </;

	# Make sure there are exactly 2 spaces after numeric dates.
	s/(^[0-9]+-[0-9-]+)\s+/$1  /;

	# Up to 7 spaces and tab or up to 8 spaces -> tab.
	if (/^( {1,7}\t| {1,8})(.*)/) {
		$_ = "\t$2";
	}

	print CHNEW "$_\n";
}

close (CHANGELOG);
close (CHNEW);

system ("cmp ChangeLog ChangeLog.new >/dev/null 2>&1");

if (($? >> 8) == 0) {
	unlink ("ChangeLog.new") || error ("Cannot remove ChangeLog.new");
	print "$progname: ChangeLog has not been changed\n";
	exit 0;
}

rename ("ChangeLog", "ChangeLog.bak") ||
	error ("Cannot rename ChangeLog to ChangeLog.bak");

rename ("ChangeLog.new", "ChangeLog") ||
	error ("Cannot rename ChangeLog.new to ChangeLog");

print "$progname: ChangeLog has been changed\n";