#!/usr/bin/perl -0777 -pi
# Update an b4_copyright invocation to include the current year.

# Copyright (C) 2009 Free Software Foundation, Inc.
#
# 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 3, 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, see <http://www.gnu.org/licenses/>.

use strict;
use warnings;

my $this_year = $ENV{UPDATE_COPYRIGHT_YEAR};
if (!$this_year || $this_year !~ m/^\d\d(\d\d)?$/)
  {
    my ($sec, $min, $hour, $mday, $month, $year) = localtime (time ());
    $this_year = $year + 1900;
  }
my $margin = 72;
my $old_re = <<'EOF'
  (
    (?:^|\n)
    (?:
      b4_copyright\(\[[^]]*]
      | m4_(?:push|pop)def\(\[b4_copyright_years]
    )
  )
  (?:
    ,\s*
    (
      \[\s* (?:\d{4}(,\s*|-))* (\d{4}) \s*]
    )
  )?
  \)
EOF
  ;

while (/$old_re/x)
  {
    my $b4_copyright_line = $1;
    my $year_lines = $2;
    my $sep = $3 ? $3 : "";
    my $final_year = $4;
    $year_lines .= ')';

    # Mark it completed.
    $b4_copyright_line =~ s/b4_/b4*/g;

    # If there was a second argument, it contains years, so update them.
    if ($final_year)
      {
        $b4_copyright_line .= ',';
        if ($final_year != $this_year)
          {
            # Update the year.
            if ($sep eq '-' && $final_year + 1 == $this_year)
              {
                $year_lines =~ s/$final_year/$this_year/;
              }
            elsif ($sep ne '-' && $final_year + 1 == $this_year)
              {
                $year_lines =~ s/$final_year/$final_year-$this_year/;
              }
            else
              {
                $year_lines =~ s/$final_year/$final_year, $this_year/;
              }
          }

          # Normalize all whitespace.
          $year_lines =~ s/\s+/ /g;

          # Put spaces after commas.
          $year_lines =~ s/, ?/, /g;

          # Format within margin.
          my $year_lines_new;
          my $indent = index ($b4_copyright_line, '[');
          --$indent if ($b4_copyright_line =~ m/^\n/);
          while (length $year_lines)
            {
              my $text_margin = $margin - $indent;
              if (($year_lines =~ s/^(.{1,$text_margin})(?: |$)//)
                  || ($year_lines =~ s/^([\S]+)(?: |$)//))
                {
                  my $line = "\n" . (' 'x$indent) . $1;
                  ++$indent if (!$year_lines_new);
                  $year_lines_new .= $line;
                }
              else
                {
                  # Should be unreachable, but we don't want an infinite
                  # loop if it can be reached.
                  die;
                }
            }
          $year_lines = $year_lines_new;
      }

    # Replace the old invocation.
    s/$old_re/$b4_copyright_line$year_lines/x;
  }

if (/\bb4_copyright\(/)
  {
    print STDERR
      "$ARGV: warning: failed to update a b4_copyright invocation\n";
  }
if (/\[b4_copyright_years]/)
  {
    print STDERR
      "$ARGV: warning: failed to update a b4_copyright_years use\n";
  }

s/b4\*copyright/b4_copyright/g;