package My::TimeCalc;

use strict;

use overload ('""' => 'asString',
			  '+'  => 'add',
	          '-'  => 'subtract',
			  '*'  => 'mult',
			  '/'  => 'divide',
			  '<=>' => 'compare');

sub new
{
	my ($class, $time_str) = @_;
	my $seconds;
	my $self = \$seconds;
	bless($self, $class);

	$time_str = defined($time_str) ? $time_str : "0";
	return( $self->fromString($time_str) );
}

sub sec
{
	my ($self) = @_;
	return $$self;
}

sub asString
{
	my ($self, $precision) = @_;

	$precision = defined($precision)?$precision:2;

	my $min = int(abs($$self) / 60.0);
	my $sec = abs($$self) % 60.0;
	my $frac = sprintf("%.${precision}f", abs($$self - int($$self))) * 10**$precision;

	my $time_str = "";
	if( $$self < 0 ) { $time_str = "-"; }
	$time_str .= "$min:" if( $min != 0 );
	$time_str .= sprintf("%02d", $sec) if ( ($min != 0) || ($sec != 0) );
	$time_str .= "," . sprintf("%0${precision}d", $frac) if ( $frac != 0 );

	if( ($min == 0) && ($sec == 0) && ($frac == 0) ) { $time_str = "0"; }

	return( $time_str );
}

sub fromString
{
	my ($self, $time_str) = @_;

	# 1) min:sec,frac  e.g. "5:29,11"
	# 2) sec,frac	   e.g. "29,11"
	# 3) sec		   e.g. "29"
	# 4) ,frac		   e.g. ",11"
	# 5) min:sec	   e.g. "5:29"
	# Note: instead of "," you can also take "."!

	# remove leading and trailing whitespace characters
	$time_str =~ s/^\s+|\s+$//g;

	# valid time string
	if( ($time_str =~ m/^(?<min>\d+):(?<sec>\d+)(,|\.)(?<frac>\d+)$/) ||
		($time_str =~ m/^(?<sec>\d+)(,|\.)(?<frac>\d+)$/) ||
		($time_str =~ m/^(?<sec>\d+)$/) ||
		($time_str =~ m/^(,|\.)(?<frac>\d+)$/) ||
		($time_str =~ m/^(?<min>\d+):(?<sec>\d+)$/) )

	{
		no warnings 'uninitialized'; # intention: undef treated as zero
		$$self = ($+{'min'} * 60.0) + $+{'sec'} + ($+{'frac'}/(10**length($+{'frac'})));
		return( $self );
	}

	return( undef );
}

sub add
{
	my ($self, $another) = @_;

	my $result;

	if( ref($another) eq "My::TimeCalc" )
	{
		$result = $self->sec() + $another->sec();
	}
	else
	{
		$result = $self->sec() + $another;
	}

	return( new My::TimeCalc($result) );
}

sub subtract
{
	my ($self, $another) = @_;

	my $result;

	if( ref($another) eq "My::TimeCalc" )
	{
		$result = $self->sec() - $another->sec();
	}
	else
	{
		$result = $self->sec() - $another;
	}

	return( new My::TimeCalc($result) );
}

sub mult
{
	my ($self, $another) = @_;

	my $result;

	if( ref($another) eq "My::TimeCalc" )
	{
		$result = $self->sec() * $another->sec();
	}
	else
	{
		$result = $self->sec() * $another;
	}

	return( new My::TimeCalc($result) );
}

sub divide
{
	my ($self, $another) = @_;

	my $result;

	if( ref($another) eq "My::TimeCalc" )
	{
		$result = $self->sec() / $another->sec();
	}
	else
	{
		$result = $self->sec() / $another;
	}

	return( new My::TimeCalc($result) );
}

sub compare
{
	my ($self, $another) = @_;

	if( ref($another) eq "My::TimeCalc" )
	{
		return( $self->sec() <=> $another->sec() );
	}
	else
	{
		return( $self->sec() <=> $another );
	}
}

1;