#! /usr/bin/perl

use strict ;
use warnings ;

my $prog = substr $0, rindex ( $0, '/' ) + 1 ;
my $Usage = <<USAGE ;
Usage: $prog [-v] [-q] [-d] [-f] file ...
option v : be verbose
option q : be quiet
option d : show debug info
option f : action ; otherwise dry-run
----------------------------------------------------
$prog copies 'file' to 'file.YYYYMMDD'
If that file already exists, $prog tries to copy
to 'file.YYYYMMDD.X' for X = 'a' .. 'z' ;
If all those files exist, $prog gives up.
----------------------------------------------------
USAGE
sub Usage { die "$_[0]$Usage" ; }
sub Error { die "[error] $prog: $_[0]\n" ; }
sub Warn  { warn "[warn] $prog: $_[0]\n" ; }

# usage: &GetOptions(ARG,ARG,..) defines $opt_ID as 1 or user spec'ed value
# usage: &GetOptions(\%opt,ARG,ARG,..) defines $opt{ID} as 1 or user value
# ARG = 'ID' | 'ID=SPC' | 'ID:SPC' for no-arg, required-arg or optional-arg
# ID  = perl identifier
# SPC = i|f|s for integer, fixedpoint real or string argument

use Getopt::Long ;
Getopt::Long::config ( 'no_ignore_case' ) ;
my %opt = () ; Usage '' unless GetOptions
  ( \%opt, qw(v q d f) ) ;
Usage("Arg count\n") unless @ARGV == 1 ;

my $TAG = $opt{f} ? 'DID' : 'WOULD' ;

my $FILE = shift ;

Error "can't find $FILE" unless -f $FILE ;

my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time) ;
my $date = sprintf '%04d%02d%02d', $year + 1900, $mon + 1, $mday ;

my $name = "$FILE-$date" ;
if ( -f $name )
  { for ( 'a' .. 'z' )
      { my $try = "$name.$_" ; 
        if ( ! -f $try ) { $name = $try ; last ; }
      }
  }

Error "too many copies ; giving up" if -f $name ;

my $CMD = "cp $FILE $name" ;
printf "$TAG $CMD\n" ;
system $CMD if $opt{f} ;

printf "\n*** THIS IS A DRY-RUN ***\n" unless $opt{f} ;