#!/usr/bin/perl

use warnings;
use strict;

use open ":locale", ":std";

use Getopt::Std;
# this makes getopts exit after --help:
$Getopt::Std::STANDARD_HELP_VERSION++;

(our $SELF = $0) =~ s,.*/,,;
our $VERSION="0.0.1";

sub HELP_MESSAGE {
	print <<EOF;
$SELF - count repeats in input

Usage: $SELF <options> <file> ...

Given the following input:

foo
foo
bar
bar
baz

$SELF will output:

bar	2	40.0%
baz	1	20.0%
foo	2	40.0%

The name 'bkt' comes from the concept of collecting like items in
buckets. The original plan was to name this script 'bucketize', but
who wants to type all that? Also, purely to support lazy typists, $SELF
implements subsets of the functionality of cut(1) and sort(1).

General options:
  --help
  -h        display this help message
  --version display '$SELF $VERSION'
  --        end of options; everything after this is treated as a filename

Output options:
  -c        show counts only (suppress percentages)
  -p        show percentages only (suppress counts)
            -c and -p may be combined, if you can find a use for it
  -t        show total count
  -x        print output in hexadecimal
  -s opts   output sort options. opts may include:
            r - reverse sort (default is ascending)
            a - sort alphabetically (default is by count)
            f - sort alphabetically, folding case
  -T thresh filter out results below threshold (which may be a
            count or a percentage, e.g. 5%).
  -o string use string as output delimiter (default: \\t). implies -P.
  -P        don't pad output with spaces to length of longest element
            -o option enables this as well.

Input options:
  -B        binary mode (default: input is characters in current locale)
  -/ sep    set value of \$/, perl's input record separator. default is \\n.
            one of -w -W -n is highly recommended with this option.
  -b range  consider only a range of chars/bytes in each record (e.g. 1-3)
  -d delim  delimiter for -f (default: /\\s+/ aka whitespace)
  -f field  consider only this (delimiter-separated) field
  -i        case insensitive (actually, lowercases all input)
  -w        remove leading and trailing whitespace from input records
  -W        remove ALL whitespace from input records
  -n        remove all non-word (\\W) characters from input records
  -e code   execute perl code for each input record (should modify \$_,
            make sure you quote the argument as needed by your shell)
  -k        skip blank records
  -F        word frequency count. alias for -ink/' '

Options that don't take arguments may be bundled: -BipW is the same as
-B -i -p -W.

Input will be read from filenames given on the command line, or from
standard input if none given, or if the filename - (hyphen) is given (use
./- to read file a real file named -). The input need not be sorted. The
output will always be sorted.

Each input record is chomped before any further processing.

-b is like the -b or -c option to cut(1) (depending on whether -B is
set). It supports the same type of range as cut(1):

N      N'th byte/character, counted from 1
N-     from N'th byte/character to end of record
N-M    from N'th to M'th (included) byte/character
-M     from first to M'th (included) byte/character

...plus 2 extra types:

-M-    from Mth-to-last byte/character to end of record (-1 = last)
-M-N   from Mth-to-last byte/characters to Nth-to-last

...except that cut allows many ranges separated by commas, while $SELF
-b only allows a single range.

-d is like the the -d option to cut(1), except that the delimiter can
be multiple characters. Also, the delimiter is treated as a regular
expression if it's at least 3 characters long *and* enclosed in //. The
/i modifier is supported, but none of the other /x regex modifiers are.

-f like cut's -f, except that it only allows a single field number (not
a list), which is indexed starting from 1 (same as cut)... or a negative
number, meaning the Nth field from the right (-1 = rightmost). Also
unlike cut, -f and -b may be combined (-b is applied first).

The -b -f -i -w -W -n -e<code> -k options will be processed in the
order listed here, regardless of the order they're given on the command
line. In particular, this means the code for -e will see \$_ *after*
it's been modified by any of the other options (except -k).

The code for -e will run with strict disabled and warnings enabled. To
disable warnings, prefix the code with 'no warnings;'. There can only
be one -e option, but it may be multiple lines of code separated with
semicolons (like perl's own -e option). When the -e code runs, \$_
contains the input (possibly tranformed by other options), and can
be modified arbitratily. The -e code can filter out unwanted records by
executing "next", which will cause them to be skipped entirely. Also,
if the -k option is used, the code can 'undef \\$_' or assign \\$_=""
to skip the current record.

EOF
}

sub VERSION_MESSAGE {
	print "$SELF $VERSION\n";
}

sub hexify {
	my @out = ();
	push @out, sprintf("%x", ord($_)) for split "", $_[0];
	return join(" ", @out);
}

# main()
our %opt;
getopts('hcpiwWte:d:f:b:xo:Bs:T:P/:nkF', \%opt);

HELP_MESSAGE() if $opt{h};

# -F = -ink/' '
if($opt{F}) {
	$opt{'/'} = ' ';
	$opt{n} = $opt{k} = $opt{i} = 1;
}

# use an eval here so we can handle escapes like \t \n \r
if(defined($opt{'/'})) {
	$opt{'/'} =~ s/'/\\'/g; # to allow -/"'"
	eval "\$/ = '" .  $opt{'/'} . "'";
}

if(defined $opt{o}) {
	$opt{P} = 1;
} else {
	$opt{o} = "\t";
}

if(defined $opt{d}) {
	if($opt{d} =~ m(^/(.+)/(i?)$)) {
		# qr/$1/$2 is a syntax error, so:
		$opt{d} = $2 ? qr/$1/i : qr/$1/;
	} else {
		$opt{d} = quotemeta($opt{d});
		$opt{d} = qr/$opt{d}/;
	}
	if(not defined($opt{f})) {
		warn "$SELF: -d given without -f, which is pointless\n";
	}
} else {
	$opt{d} = qr/\s+/;
}

our $substrarg;
if(defined $opt{b}) {
	for($opt{b}) {
		/^(\d+)$/ && do        { $substrarg = "$1 - 1, 1" };
		/^(\d+)-$/ && do       { $substrarg = "$1 - 1" };
		/^-(\d+)$/ && do       { $substrarg = "0, $1" };
		/^(\d+)-(\d+)$/ && do  { $substrarg = "$1 - 1, " . ($2 - $1 + 1) };
		/^-(\d+)-$/ && do      { $substrarg = "$1"; };
		/^-(\d+)-(\d+)$/ && do { $substrarg = "$1, " . ($2 - $1); };
	}
	die "$SELF: invalid -b argument\n" unless $substrarg;
}

# -f index starts at 1, perl arrays are indexed from 0, fix (but
# don't break using -1 for rightmost field)
$opt{f}-- if defined $opt{f} && $opt{f} > 0;

our ($revsort, $foldsort, $alphasort, $sortcode);

if($opt{s}) {
	for(split "", $opt{s}) {
		/r/ && do { $revsort++;                 };
		/f/ && do { $foldsort++;  $alphasort++; };
		/a/ && do { $alphasort++;               };
		/([^rfa])/ && do {
			warn "$SELF: ignoring unknown sort option '$1'\n"; };
	}
}

# Sorry, this is kinda ugly.
if($alphasort) {
	$sortcode = "{ " .
		($foldsort ? 'lc ' : "" ) .
		($revsort ? '$b' : '$a') .
		" cmp " .
		($foldsort ? 'lc ' : "" ) .
		($revsort ? '$a' : '$b') .
		"}";
} else {
	$sortcode = "{ " .
		'$counts{' . ($revsort ? '$b' : '$a') . '}' .
		" <=> " .
		'$counts{' . ($revsort ? '$a' : '$b') . '}' .
		"}";
}

# finally done with option processing, let the main event commence.

our %counts = ();
our $total = 0;
our $longest = 0;
our $readfiles = 0;
our $badfiles = 0;

# Sadly, we can't use the magical while(<>) here to automatically iterate
# and open all the files in @ARGV, because of the -B option. We need to
# call binmode() on each filehandle after it's opened, but before anything
# gets read from it. 'use open ":bytes"' would set the default binmode,
# but I couldn't get it to work conditionally (not even with eval).

$ARGV[0] = '-' unless @ARGV;
for(@ARGV) {
	my $fh;

	if($_ eq '-') {
		$fh = \*STDIN;
	} else {
		open $fh, '<', $_ or do {
			warn "$SELF: $_: $!\n";
			$badfiles++;
			next;
		};
	}

	binmode $fh, ":raw:bytes" if $opt{B};
	$readfiles++;

	while(<$fh>) {
		chomp;

		# behave like cut for -b/-f: no warnings if -f3 but only 2 fields exist,
		# or -b10 but only 9 characters exist.

		if($substrarg) { # set via $opt{b}
			no warnings qw/substr/;
			eval "\$_ = substr(\$_, $substrarg)";
			$_ = "" unless defined $_;
		}

		if(defined $opt{f}) {
			$_ = (split(/$opt{d}/))[$opt{f}];
			$_ = "" unless defined $_;
		}

		$_ = lc if $opt{i};
		s/^\s+|\s+$//g if $opt{w};
		s/\s//g if $opt{W};
		s/\W//g if $opt{n};

		if($opt{e}) {
			no strict;
			no warnings qw/exiting/; # so -e code can "next" to skip a line
			eval $opt{e};
			die "$SELF: $@" if $@;
		}
		next if $opt{k} && (!defined || length == 0);
		$_ = "" unless defined $_;

		$counts{$_}++;
		$total++;
	}
}

die "$SELF: couldn't read any input files\n" unless $readfiles;

if($opt{T}) {
	(my ($thresh, $pct)) = ($opt{T} =~ /^(\d+)(%?)/);
	if($thresh) {
		for(keys %counts) {
			delete $counts{$_} if
				($pct && (($counts{$_} * 100 / $total) < $thresh)) ||
				(!$pct && ($counts{$_} < $thresh));
		}
	} else {
		die "$SELF: invalid argument for -T\n";
	}
}

if(!$opt{P}) {
	for(keys %counts) {
		my $l = length($opt{x} ? hexify($_) : $_);
		$longest = $l if $longest < $l;
	}
}

# done reading & counting all input, show the results.
for(sort { eval $sortcode } keys %counts) {
	print ($opt{x} ? hexify($_) : $_);
	print " " x ($longest - length) unless $opt{P};
	print $opt{o} . $counts{$_} unless $opt{p};
	printf "$opt{o}%.1f%%", ($counts{$_} * 100 / $total) unless $opt{c};
	print "\n";
}

if($opt{t}) {
	print "\n-- Total count: $total\n";
}

# be like cat, exit with error status if any input file couldn't be
# read (even if we did successfully read others)
exit($badfiles != 0);

__END__

Examples:

# show the percentage of binaries that start with each letter/number/etc,
# 4 different ways
cd /usr/bin
ls | bkt -b1
ls | cut -b1 | bkt
ls | bkt -e '$_=substr($_,0,1)'
ls | bkt -e 's,^(.).*,$1,'

# show percentages of stuff said by each user in an irssi IRC log. relies
# on the log format having a timestamp, space, <nick> for normal lines.
# misses /me actions entirely though.
# add -sr to show the most talkative first.
bkt -f2 -e 'next unless /^\</' channelname.log

# show us how many users use each shell (including stuff like /bin/false).
bkt -d: -f-1 /etc/passwd

# how many images of each type have we got? ignore case, so JPG and jpg
# are counted together.
ls ~/images/*.* | bkt -d. -f-1

# What percentage of words in a text file are capitalized?
bkt -n/' ' -e's/^[A-Z]+$/CAPS/ || s/^[A-Z].*$/Caps/ || s/^[a-z].*$/lower/ || next' file.txt