#!/usr/bin/perl -w
#
# Regina - A Normal Surface Theory Calculator
# Source Stub Year Update Utility
#
# Copyright (c) 1999-2014, Ben Burton
# For further details contact Ben Burton (bab@debian.org).
#
# Usage: updateyear <old_year> <new_year> [ <text-file> ... ]
#
# Replaces the old year with the new year in the copyright header at
# the beginning of each given file.  You will be asked to approve or
# reject each change.
#
# 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.
#
# As an exception, when this program is distributed through (i) the
# App Store by Apple Inc.; (ii) the Mac App Store by Apple Inc.; or
# (iii) Google Play by Google Inc., then that store may impose any
# digital rights management, device limits and/or redistribution
# restrictions that are required by its terms of service.
#
# 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., 51 Franklin St, Fifth Floor, Boston,
# MA 02110-1301, USA.
#

use strict;

# --- Command-line sanity check. ---

my $nArgs = @ARGV;
if ($nArgs < 3) {
    print STDERR "Usage: updateyear <old_year> <new_year> [ <text-file> ... ]\n";
    exit(1);
}

my $oldYear;
my $newYear;
my @argFiles;

($oldYear, $newYear, @argFiles) = @ARGV;

# --- Run through each file to process. ---

foreach my $file (@argFiles) {
    # Read the file contents.
    if (! open(DATA, $file)) {
        print STDERR "ERROR: Could not open $file for reading.\n";
        next;
    }
    my @lines = <DATA>;
    close(DATA);

    # Hunt for a sentry.
    my @newLines  = ();
    my $edit;
    my $changed = 0;

    foreach my $line (@lines) {
        $edit = undef;
        if ($line =~ /Copyright \(c\) $oldYear,/) {
            $edit = $line;
            $edit =~ s/(Copyright \(c\) )$oldYear,/$1$newYear,/g;
        } elsif ($line =~ /Copyright \(c\) \d+-$oldYear,/) {
            $edit = $line;
            $edit =~ s/(Copyright \(c\) \d+-)$oldYear,/$1$newYear,/g;
        }

        if (not defined $edit) {
            push(@newLines, $line);
            next;
        }

        print "CHANGE:\n-$line+$edit";
        print "Accept? [Y/n] ";
        my $response = <STDIN>;
        $response =~ s/\s//g;
        $response =~ tr/A-Z/a-z/;
        $response eq '' and $response = 'y';
        while (not ($response eq 'y' or $response eq 'n')) {
            print "Accept? [Y/n] ";
            $response = <STDIN>;
            $response =~ s/\s//g;
            $response =~ tr/A-Z/a-z/;
            $response eq '' and $response = 'y';
        }

        if ($response eq 'y') {
            push(@newLines, $edit);
            $changed = 1;
        } else {
            push(@newLines, $line);
        }
    }

    if ($changed) {
        if (! open(DATA, '>'.$file)) {
            print STDERR "ERROR: Could not open $file for writing.\n";
            next;
        }

        print DATA $_ foreach (@newLines);

        close(DATA);
        print "REPLACED: $file.\n\n";
    } else {
        # print "Unchanged: $file.\n";
    }
}

