#!/usr/bin/perl
use strict;
use warnings;

sub readWords {
	## Gets how many of each word are in a file and returns a hash

	my $file = shift;
	my %words = ();
	my $currentWord = "";

	# What characters to ignore
	my $blacklist = '[\s~`!@#\$%\^&\*\(\)\{\}\+=\\\/\[\]\.\,<>\?;:"]';

	open(my $FILE, "<", $file) or die("$0: $file: $!\n");
	while(!eof($FILE)) {
		while(read($FILE, my $letter, 1)) {
			if($letter !~ /$blacklist/) {
				$currentWord .= lc($letter);
			} else {
				last;
			}
		}
		if(!defined($words{$currentWord})) {
			$words{$currentWord} = 0;
		}
		$words{$currentWord}++;
		$currentWord = "";
	}
	close($FILE);
	return %words;
}

sub main() {
	my %words = readWords($ARGV[0]);
	my @keys = keys(%words);
	my @commonWord = ("", 0);

	foreach my $key (sort(@keys)) {
		if($words{$key} > $commonWord[1]) {
			@commonWord = ("$key", $words{$key});
		}
		print("$key: $words{$key}\n");
	}
	print("Number of unique words: " . scalar(@keys) . "\n");
	print("Most common word: $commonWord[0] - used $commonWord[1] times\n");
}

main();