#!/usr/bin/perl -w
#####
#finalcalc
#Daniel Smith
#12-24-2004
########

#Tell perl to be strict
#and declare variables
use strict;
my $test1;
my $test2;
my $test3;
my $grade;
my $hw;
my $test_avg;
#number of test to (possibly) replace
my $test_num;
my $final;
#array of test scores arranged from lowest to highest
my @test;
#array of test names arranged according to @test
my @test_name;
#hash of grade letters and corresponding values
my %grade_letter=("A"=>90,"B"=>80,"C"=>70,"D"=>60);
my %letter_grade=reverse %grade_letter;
my $i;
my $replaced=0;

#Get input:test1,test2,test3,hw,grade
print "Enter the first test score:";
chomp($test1=<STDIN>);
print "Enter the second test score:";
chomp($test2=<STDIN>);
print "Enter the third test score:";
chomp($test3=<STDIN>);
print "Enter your homework/quiz score:";
chomp($hw=<STDIN>);
print "Enter your desired grade (A,B,C,D):";
chomp($grade=<STDIN>);
print "Enter the number of tests to replace (0,1,2,3):";
chomp($test_num=<STDIN>);

#Convert $grade to a number
$grade="\U$grade";
#DEBUG print "Needed grade is a $grade\n";
$grade=$grade_letter{$grade};
#DEBUG print "This corresponds to a value of $grade\n";
#Calculate final grade without replacing any grades
$test_avg=($test1+$test2+$test3)/3;
$final=($grade-.5*$test_avg-.1*$hw)/.4;
#DEBUG lines
#print "Test average is $test_avg\n";
#print "You need a $final on your final to make a $grade\n";
#ENDDEBUG lines

#order tests from lowest to highest
#put in @test, also arrange @test_name
@test = sort {$a <=> $b} ($test1,$test2,$test3);
#enter hash info
$i=0;
for (@test)
  {
    $test_name[$i]="test1" if($test1==$_);
    $test_name[$i]="test2" if($test2==$_);
    $test_name[$i]="test3" if($test3==$_);
    $i++;
  }
#DEBUG lines
#print "@test_name\n@test\n";
for($i=0;$i<=2;$i++)
  {
    print "$test_name[$i]=$test[$i]\n";
  }
printf "Replacing no tests you need %3.2f on final\n",$final;
#ENDDEBUG lines

#if final grade <= low test or test_num=0
#print final and exit
if($final <= $test[0] or $test_num==0)
  {
    print "You need to make at least a $final on the final to make a $grade in the class\n";
    exit;
  }

#if test_num=1
#calc final grade replacing one test
if($test_num==1)
  {
    $final=&final_replace_low;
    $test[0]=$final;
  }
#else if test_num=2
elsif($test_num==2)
  {
    #if final > low test
    if($final > $test[0])
      {
	$replaced++;
	#calc final grade replacing low test
	$final=&final_replace_low;
	$test[0]=$final;
	#also if final > mid test
	if($final > $test[1])
	  {
	    $replaced++;
	    #calc final grade replacing low & mid tests
	    $final=&final_replace_lowmid;
	    $test[0]=$final;
	    $test[1]=$final;
	  }
      }
  }
#else if test_num=3
elsif($test_num == 3)
  {
    #if final > low test
    if($final > $test[0])
      {
	$replaced++;
	#calc final grade replacing low test
	$final=&final_replace_low;
	$test[0]=$final;
	#also if final > mid test
	if($final > $test[1])
	  {
	    $replaced++;
	    #calc final grade replacing low & mid tests
	    $final=&final_replace_lowmid;
	    $test[0]=$final;
	    $test[1]=$final;
	    #also if final > high test
	    if($final > $test[2])
	      {
		$replaced++;
		#calc final grade replacing low, mid, & high tests
		$final=&final_replace_all;
		$test[0]=$final;
		$test[1]=$final;
		$test[2]=$final;
	      }
	  }
      }
  }
#print new test scores
print "After replacing $replaced test(s).\nYour test scores are:\n";
for($i=0;$i<=2;$i++)
  {
    printf "$test_name[$i]=%3.2f\n",$test[$i];
  }
#print needed final score
printf "Need %3.2f on final to make a $letter_grade{$grade}.\n",$final;


#subroutine: calc final replacing low score
sub final_replace_low
  {
    print "replace low score\n";
    #return round((30*$grade-5*($test[1]+$test[2])-3*$hw)/17);
    return (30*$grade-5*($test[1]+$test[2])-3*$hw)/17;
  }
#subroutine: calc final replacing low & mid scores
sub final_replace_lowmid
  {
    print "replace low and mid scores\n";
    #return round((30*$grade-5*$test[2]-3*$hw)/22);
    return (30*$grade-5*$test[2]-3*$hw)/22;
  }
#subroutine: calc final replacing low, mid, & high scores
sub final_replace_all
  {
    print "replace all scores\n";
    #return round((10*$grade-$hw)/9);
    return (10*$grade-$hw)/9;
  }
sub round {
    my($number) = shift;
    return int($number + .5);
}