#!/usr/bin/perl

# Copyright (c) 2012, Svendsen Tech
# All rights reserved.
# 
# Author: Joakim Svendsen
# st-seq - seq on steroids

use warnings;
use strict;
use File::Basename;
use Getopt::Long;

our $VERSION = '1.02';

main();

sub main {
    
    my %opt;
    
    GetOptions( 'hexin'          => \$opt{hexin},
                'hexout'         => \$opt{hexout},
                'help'           => \$opt{help},
                'equalwidth'     => \$opt{equalwidth},
                'format=s'       => \$opt{format},
                'pad=i'          => \$opt{pad},
                'separator=s'    => \$opt{separator},
                'increment=s'    => \$opt{increment},
               ) or die "Unable to process arguments!\nError: $!";
    
    print_help() if $opt{help};
    
    die "Missing start and end decimal/hex values\nUse --help for help.\n" if @ARGV == 0;
    die "Missing end decimal/hex value\nUse --help for help.\n" if @ARGV == 1;
    
    my ($first_num, $second_num) = @ARGV;
    
    my $regex = $opt{hexin} ? qr'[^a-f0-9]' : qr'[^\d\-.]';
    
    die "Illegal characters or pattern found in first decimal/hex value\n"  if $first_num  =~ m/$regex/i;
    die "Illegal characters or pattern found in second decimal/hex value\n" if $second_num =~ m/$regex/i;
    
    my $format = $opt{format} ? $opt{format} : '%s';
    my $increment = $opt{increment} ? $opt{increment} : 1;
    
    # Get a "boolean" for whether the first number is the lowest.
    my $first_is_lower = get_lower($first_num, $second_num, $opt{hexin});
    
    # Set padding if --equalwidth or --pad are specified. Otherwise set to 0 (false).
    # --equalwidth overrides --pad.
    my $pad = 0;
    if ($opt{equalwidth}) {
        # If the first number is the lowest, the number containing the max
        # amount of digits must be the other one, and vice versa.
        $pad = $first_is_lower ? length $second_num : length $first_num;
    }
    elsif ($opt{pad}) {
        $pad = $opt{pad};
    }
    
    my @output_list = enumerate_range( $first_num, $second_num, $format, $increment, $pad, $opt{hexin}, $opt{hexout}, $first_is_lower );
    print join $opt{separator} ? $opt{separator} : "\n", @output_list;
    
    print "\n";
    
}


sub print_help {
    
    my $prog_name = basename $0;
    
    print <<EOF;
$prog_name [--pad] [--hexin] [--hexout] [--format <value>]
    [--equalwidth] [--increment <value>] [--separator <value>]
    [--help] FIRST LAST

--pad:         Pad with leading zeroes to make the number contain at least the
               specified number of digits.
--hexin:       Interpret specified FIRST and LAST numbers as hexadecimal.
--hexout:      Display output as hexadecimal values. The default is decimal,
               even when --hexin is specified.
--format:      A sprintf-type format to display numbers in. Overrides --pad
               and --equalwidth.
--equalwidth:  Pads with leading zeroes to make all numbers the same width,
               if necessary. Not in effect if using --hexout. Overrides --pad.
--increment:   Integer that determines the steps between numbers.
--separator:   Separator between elements. Default "\\n".

FIRST:         The first number in the range to start counting up or down from.
               It can be higher than the LAST number to count down.
LAST:          The last number in the range to count up to or down towards,
               from FIRST.

Examples:
$prog_name --sep ', ' 5 1
$prog_name --pad 3 99 102
$prog_name --hexin --hexout 10 20
$prog_name --equalwidth 42 1004 --separator ' '
EOF
    
    exit;
    
}


sub get_lower {
    
    my ($first_number, $second_number, $hexin) = @_;
    
    if ($hexin) {
        
        return (hex $first_number < hex $second_number) ? 1 : 0;
            
    }
    
    return ($first_number < $second_number) ? 1 : 0;
    
}


sub enumerate_range {
    
    my ($start_num, $end_num, $format, $increment, $pad, $hex_in, $hex_out, $first_is_lower) = @_;
    
    my ($start_dec, $end_dec);
    
    if ($hex_in) {
        $start_dec = hex $start_num;
        $end_dec   = hex $end_num;
    }
    else {
        $start_dec = $start_num;
        $end_dec   = $end_num;
    }
    
    my @num_list;
    
    # Code duplication. Meh.
    if ($first_is_lower) {
        
        # Increment for each iteration when first is lower.
        for (my $decimal = $start_dec; $decimal <= $end_dec; $decimal += $increment) {
            
            if ($hex_out) {
                
                push @num_list, sprintf '%x', $decimal;
                
            }
            
            else {
                
                if ($format ne '%s') {
                push @num_list, sprintf $format, $decimal;
                }
                elsif ($pad) {
                    push @num_list, sprintf "%0${pad}d", $decimal;
                }
                else {
                    push @num_list, $decimal;
                }
                
            }
            
        } # end of for loop
        
    }
    
    # This is when the first number is higher than the last.
    else {
        
        # Decrement for each iteration when first is higher.
        for (my $decimal = $start_dec; $decimal >= $end_dec; $decimal -= $increment) {
            
            if ($hex_out) {
                
                push @num_list, sprintf '%x', $decimal;
                
            }
            
            else {
                
                if ($format ne '%s') {
                    push @num_list, sprintf $format, $decimal;
                }
                elsif ($pad) {
                    push @num_list, sprintf "%0${pad}d", $decimal;
                }
                else {
                    push @num_list, $decimal;
                }
                
            }
            
        } # end of for loop
        
    }
    
    return @num_list;
    
}