package Ernad::Learn::Weights;

use strict;
use warnings;

use Carp qw(cluck longmess shortmess croak confess);

## hash of weighing functions
our $weigh;

## 
my $verbose=4;

sub echo {
  my $line_number=shift;
  my $text=shift or confess "I need something to echo";
  my $verbosity=shift // 0;
  if(not defined($verbose or ($verbosity < $verbose))) {
    print "$line_number | $text", "\n";
  }
}

sub is_fit_invalid {
  my $fit=shift;
  my $fit_rank=shift
    or confess "I need a fit_rank here.";
  my $deleted_fits=shift;
  #  or confess "I need deleted_fits here.";
  if(not defined($fit_rank->{$fit})) {
    if(defined($deleted_fits->{$fit})) {
      &echo(__LINE__,"I had earlier deleted feature '$fit'.");
      return 0;
    }
    &echo(__LINE__,"WARN: I can't find a rank for feature '$fit'");
    return 1;
  }
  return 0;
}
  
$weigh->{'binary'} = sub {
  my $fit_count=shift;
  my $fit_rank=shift;
  my $deleted_fits=shift;
  my @fits=keys %{$fit_count};
  my $liner;
  ## output string;
  my $out; 
  foreach my $fit (@fits) {    
    next if &is_fit_invalid($fit,$fit_rank,$deleted_fits);
    my $rank=$fit_rank->{$fit};
    my $count=$fit_count->{$fit} // 0;
    if(not $count) {
      &echo(__LINE__,"I can't find a count for feature '$fit' in current_handle.");
      next;
    }
    my $weight=1;
    $liner->{$rank}=$weight;
  }  
  foreach my $rank (sort {$a <=> $b} keys %{$liner}) {
    my $weight=$liner->{$rank};
    $out.=" $rank:".$weight;
  }
  return $out;
} ;

  
$weigh->{'ift'} = sub {
  my $fit_count=shift;
  my $fit_rank=shift;
  my $deleted_fits=shift;
  my @fits=keys %{$fit_count};
  my $liner;
  ## output string;
  my $out; 
  foreach my $fit (@fits) {    
    next if &is_fit_invalid($fit,$fit_rank,$deleted_fits);
    my $rank=$fit_rank->{$fit};
    my $count=$fit_count->{$fit} // 0;
    if(not $count) {
      &echo(__LINE__,"I can't find a count for feature '$fit' in current_handle");
      next;
    }
    $liner->{$rank}=1-(1/(1+$count));
  }  
  foreach my $rank (sort {$a <=> $b} keys %{$liner}) {
    my $weight=$liner->{$rank};
    $weight=sprintf("%2.3f",$weight);
    ## economize the 0 before decimal point
    my $print_weight=substr($weight,1);
    $out.=" $rank:".$print_weight;
  }
  return $out;
} ;
  
  
$weigh->{'square_sum_one'} = sub {
  my $fit_count=shift;
  my $fit_rank=shift;
  my $deleted_fits=shift;
  my @fits=keys %{$fit_count};
  my $total=0;
  my $liner;
  ## output string;
  my $out; 
  foreach my $fit (@fits) {    
    next if &is_fit_invalid($fit,$fit_rank,$deleted_fits);
    my $rank=$fit_rank->{$fit};
    my $count=$fit_count->{$fit} // 0;
    if(not $count) {
      &echo(__LINE__,"I can't find a count for feature '$fit' in current_handle");
      next;
    }
    my $weight=sqrt($count);
    $liner->{$rank}=$weight;
    $total+=$weight;
  }  
  foreach my $rank (sort {$a <=> $b} keys %{$liner}) {
    my $weight=$liner->{$rank}/$total;
    $weight=sprintf("%6.4f",$weight);
    ## economize the 0 before decimal point
    my $print_weight=substr($weight,1);
    $out.=" $rank:".$print_weight;
  }
  return $out;
} ;

## traditional weighing scheme
$weigh->{'l2'} = sub {
  my $fit_count=shift;
  my $fit_rank=shift;
  my $deleted_fits=shift;
  my @fits=keys %{$fit_count};
  my $total=0;
  my $liner;
  ## output string;
  my $out; 
  foreach my $fit (@fits) {    
    next if &is_fit_invalid($fit,$fit_rank,$deleted_fits);
    my $rank=$fit_rank->{$fit};
    my $count=$fit_count->{$fit} // 0;
    if(not $count) {
      &echo(__LINE__,"I can't find a count for feature '$fit' in current_handle");
      next;
    }
    my $weight=sqrt($count);
    $liner->{$rank}=sqrt($weight);
    $total+=$count;
  }
  $total=sqrt($total);
  foreach my $rank (sort {$a <=> $b} keys %{$liner}) {
    my $weight=$liner->{$rank}/$total;
    $weight=sprintf("%6.4f",$weight);
    ## economize the 0 before decimal point
    #my $print_weight=substr($weight,1);
    $out.=" $rank:".$weight;
  }
  return $out;
} ;