use strict;
use warnings;
use Readonly;
use Getopt::Long;
use Scalar::Util::Numeric qw(isint);

#age and avg_xp are calculated at the start of everyday. 
#The avg_xp=sum(XP)/#nodes in the past 7 days.
#The program takes these two values in addition to #likes and #unlikes to dynamically compute reputation gains and losses.
#Input for current reputation is prompted when it is time to update the reputation.

my ($age, $avg_xp,$gained_rep, $lost_rep);
my ($upvotes, $downvotes, $total_rep);
my $current_rep; #variable to hold the current user reputation from the user page.
my $vote; 	 #a listener:either (u)pvote or (d)ownvote.


Readonly::Scalar my $args =>4;  #program accepts two args & two vals
if(@ARGV != $args){die "syntax error: perl calculate_rep.pl --age n --avg_xp n\n";}
GetOptions(
	"age=i"=>\$age,
	"avg_xp=i"=>\$avg_xp,	
	)or die "syntax error: perl calculate_rep.pl --age n --avg_xp n\n";


print "enter u for upvote or d for downvote\n";
while($vote=<>){
	chomp $vote;
	if($vote =~/^u$/i){
		$upvotes++;
		analyze_upvotes($age, $upvotes);
		}elsif($vote=~/^d$/i){
			$downvotes++;
			analyze_downvotes($age,$downvotes);
			}else{
				print "ERROR: enter u for upvote or d for downvote\n";
			}
	}

sub analyze_upvotes{
	my $node_age=shift;
	my $like_counter=shift;
	printf "you have %d likes\n",$like_counter;
	if($like_counter==1){#reward the first upvote
		$gained_rep=1;
		rep_update($gained_rep,"gain", $like_counter);
		$gained_rep=0;
		}
	if($age>2 && $like_counter>1){ #nodes older than two weeks get 1/5 rep increase
		$gained_rep+=1/5;		
		if(isint $gained_rep){	#reputation is reported when gained reputation sums to a whole number
			rep_update($gained_rep,"gain", $like_counter);
			$gained_rep=0;
			}
		}elsif($age<=2 && $like_counter>1){ #rep for nodes < 2 weeks old is calculated with avg_xp perspective
			if($like_counter<=$avg_xp){ $gained_rep+=1/3; }
				elsif($like_counter>$avg_xp && $like_counter<=2*$avg_xp){ $gained_rep+=1/2; }
				elsif($like_counter>2*$avg_xp && $like_counter<=3*$avg_xp){ $gained_rep+=2/3; }
				elsif($like_counter>3*$avg_xp && $like_counter<=4*$avg_xp){ $gained_rep+=3/4; }
				elsif($like_counter>4*$avg_xp){$gained_rep+=1; $gained_rep=int $gained_rep; }

				if(isint $gained_rep){
					if($current_rep-$gained_rep==0){ #for when cur_rep=1 and gained_rep=1;
						rep_update(1,"gain", $like_counter);
						}else{
							rep_update($gained_rep, "gain", $like_counter);
							}
					$gained_rep=0;
				}
			}
	}

sub analyze_downvotes{
	my $node_age=shift;
	my $unlike_counter=shift;
	printf "you have %d unlikes\n", $unlike_counter;
	if($age<=2){
		if($unlike_counter<= 3*$avg_xp){ $lost_rep+=1/3; }
			elsif($unlike_counter > 3*$avg_xp && $unlike_counter <= 4*$avg_xp){ $lost_rep+=1/4; }
			elsif($unlike_counter > 4*$avg_xp){ $lost_rep+=0; }
		if(isint $lost_rep){
			rep_update($lost_rep, "loss", $unlike_counter);
			$lost_rep=0;
			}

		}elsif($age>2){ $lost_rep+=0;}
	}

sub rep_update{
	my $rep_gain_loss=shift;
	my $status=shift;
	my $like_unlike_counter=shift;
	print "what is the current user reputation?\n";
	$current_rep=<>;
	chomp $current_rep;
	if($status eq "gain"){
		my $total_gain=$current_rep + $rep_gain_loss;
		printf "you gained %d points\nyour reputation is %d\n", $rep_gain_loss, $total_gain;
		}elsif($status eq "loss"){
			my $total_loss=$current_rep-$rep_gain_loss;
			printf "you lost %d reputation points\nyour reputation is %d\n", $rep_gain_loss,$total_loss;
			}
	}