#! /usr/bin/perl -w
############################################################
# File   :  Perl Schwartzian Transform Demo.pl
# History:  16-Mar-2016 Laszlo first version.
############################################################
# A script to demonstrate and measure the Schwartzian Transform.
############################################################

use warnings;
use strict;
use Time::HiRes;

my $maxNumberValue = 100;
my $intSampleSize = 32000;
my @unsortedIntArray = map { int(rand($maxNumberValue)) } ( 1..$intSampleSize );

&schwartzianSortVsRegularSort(\@unsortedIntArray, \&compareAsNumber, \&noTransform);
&schwartzianSortVsRegularSort(\@unsortedIntArray, \&compareAsString, \&noTransform);
&schwartzianSortVsRegularSort(\@unsortedIntArray, \&compareAsNumber, \&sleepyNoTransform);

my @chars = ("A".."Z", "a".."z");
my $maxStringLength = 300;
my $stringSampleSize = 32000;
my @unsortedStringArray = map { (sub { my $string; $string .= $chars[rand @chars] for 1..(int(rand($maxStringLength)) + 1); return $string;})->();  } ( 1..$stringSampleSize );

&schwartzianSortVsRegularSort(\@unsortedStringArray, \&compareAsString, \&noTransform);
&schwartzianSortVsRegularSort(\@unsortedStringArray, , \&compareAsNumber, \&returnLength );

sub schwartzianSortVsRegularSort()
{
	my @unsortedArray_in = @{$_[0]};	
	my $compareFunction_in = $_[1];
	my $transform4Sort_in = $_[2];
	
	print "Collection of size: " . +@unsortedArray_in . " \n";
	
	# Schwartzian sort, Schwartzian sort, Schwartzian sort, Schwartzian sort, Schwartzian sort
	############################################################
	my $schwartzianStart = Time::HiRes::time;
	my @schwartzianSorted = map  { $_->[0] }
				 sort { &$compareFunction_in($a->[1], $b->[1]) }
				 map  { [$_, &$transform4Sort_in($_)] }
				 @unsortedArray_in;
	my $schwartzianDuration = Time::HiRes::time - $schwartzianStart;

	# Regular sort, Regular sort, Regular sort, Regular sort, Regular sort, Regular sort
	############################################################
	my $regularStart = Time::HiRes::time;
	my @regularSorted = sort { &$compareFunction_in(&$transform4Sort_in($a), &$transform4Sort_in($b)) } @unsortedArray_in;
	my $regularDuration = Time::HiRes::time - $regularStart;
	
	print "Execution time of the Schwartzian Transform: $schwartzianDuration s\n";
	print "Execution time of the Regular     Transform: $regularDuration s\n";

	if (!(@schwartzianSorted ~~ @regularSorted))
	{
		die "Collections are not equal!"
	}

	# print join("; ", @schwartzianSorted);
}

sub noTransform()
{
	my $param = shift;
	return $param;
}

sub sleepyNoTransform()
{
	my $param = shift;
	Time::HiRes::usleep(1);
	return $param;
}

sub returnLength()
{
	my $param = shift;
	return length($param);
}

sub sortAsString()
{
	my $param = shift;
	return "$param";
}

sub compareAsNumber()
{
	my $a = shift;
	my $b = shift;
	return $a <=> $b;
}

sub compareAsString()
{
	my $a = shift;
	my $b = shift;
	return $a cmp $b;
}