#!/usr/bin/perl

use strict;
use warnings;
use Statistics::LineFit;
use Time::Local;
use Data::Dumper;

my @x_axis;
my @y_axes;

sub date_to_epoch
{
   my $date = shift;
   my ( $y, $m, $d ) = split /-/, $date;
   return timelocal( '59', '59', '23', $d, $m, $y );
   #return timelocal( '0', '0', '0', $d, $m, $y );
}
  
sub max_value
{
   my @array = @_;
   my $max = $array[0];

   for ( my $i = 0; $i <= $#array; $i++ )
   {
      $max = $array[$i] if ( $array[$i] > $max );
   }
   return $max;
}

my @epochs;

while (<DATA>)
{
   next if ( m/^#/ );
   chomp;

   if ( my @line = split /\s+/ )
   {
      my $epoch = date_to_epoch( $line[0] );
      
      # factor down epoch or slope is too shallow.
      push @x_axis, $epoch;
      shift @line;

      for ( my $y = 0; $y <= $#line; $y++ )
      {
          push @{$y_axes[$y]}, $line[$y] ;
      }
   }
}

print Dumper ( \@x_axis );
print Dumper ( \@y_axes );

my $lineFit = Statistics::LineFit->new( 0, 0 ); # TODO change 2nd to 1
$lineFit->setData( \@x_axis, \@{$y_axes[0]} ) or die "Invalid regression data\n";
my ( $intercept, $slope ) = $lineFit->coefficients();
print "Slope(m): $slope  Y-intercept(b): $intercept\n";

my %fitline;
$fitline{y1} = $intercept;
$fitline{x1} = 0;
$fitline{y2} = max_value( @{$y_axes[0]} );
$fitline{x2} = ( $fitline{y2} - $fitline{y1} ) / $slope + $fitline{x1};

print Dumper ( \%fitline  );

__DATA__
# date     notkept hosts
2014-04-01 50      10
2014-04-02 63      11
2014-04-03 120     12
2014-04-04 55      20
2014-04-05 60      22
2014-04-06 63      25
2014-04-07 52      24