#!/usr/bin/perl -w
#use strict;

my $infile = $ARGV[0];
my $act = $ARGV[1];
my $included = "n";
my $lvar ="";
my %validchars;

if ($#ARGV < 1) {
  print "Usage: $0 <file> <chars>
  Where <chars> can be -a, -c, or -r:
       -a: show all charactors. (ie, spaces, etc.)
       -c: show only regular charactors, but keep case. (ie, x is different than X.)
       -r: show only regular charactors, disregard case. (ie, t and T are the same.)\n";
  exit;
}

if ( $act eq '-a' ) {
  %validchars = map { $_ => uc $_ } ( \x00 .. \xff );
} elsif ( $act eq '-c' ) {
  %validchars = map { $_ => $_ } ( 'A' .. 'Z', 'a'..'z' );
};

my $count = 0;

system("cls");   #win
system("clear"); #*nix

open INPUT, "<$infile" or die "Couldn't open '$infile' : $!";
my $input = do { local $/; <INPUT> };

my %histogram;

for my $char (split //, $input) {
  if (exists $validchars{$_}) {
    my $target = $validchars{$_};
    $count++;
    $histogram{$target}++};
};

print "Of $count charactors:\n\n";

for (sort keys %histogram) {
  if ($_ eq "\n") { print "'\\n' occurred $histogram{$_} times. (".(($histogram{$_}/$count)*100)."%)\n"}
  else { print "'$_'  occurred $histogram{$_} times. (".(($histogram{$_}/$count)*100)."%)\n" }
};