#!/usr/local/bin/perl
@m =
("Foo","Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec",
"B/W");
print "Content-type: text/html\n\n";
print "<title>Biweekly Mortgage Calculation</title>\n";
print "<H2>Biweekly Mortgage Calculation</H2>\n";
$arglist = $ENV{'QUERY_STRING'};

if (length($arglist) < 3)
{
print<<EOF;
<FORM ACTION="biweekly.cgi">
<H3>Change these fields as desired: </h3>

<LI><INPUT TYPE="text" NAME="prin" VALUE="100000" MAXLENGTH="6"
SIZE="7">
Principal Loan Balance
<LI><INPUT TYPE="text" NAME="int" VALUE="8.75" MAXLENGTH="6" SIZE="7">
Annual Interest Rate (%)
 
<li>Amortization Length 
<input type="text" name="term" value="30" maxlength="3" size="3">
(Years)
 
<LI>Show full amortization table?
<SELECT NAME="full"> 
<OPTION> No
<OPTION> Yes
</SELECT> 
</LI>

</UL>
<INPUT TYPE="submit" VALUE="Calculate Biweekly Mortgage">
</FORM>

EOF
exit;
}

@f = split("&",$arglist);
$prin = substr(@f[0],5); $int = substr(@f[1],4);
$term = substr(@f[2],5); $full= substr(@f[3],5); 
$stry2 = $stry; 
for ($i = 1; $i < 13; $i++) { if (@m[$i] eq $strm) {  $strt = $i; } }

print "<hr><h2>For the given values:</h2>\n<ul>";
print "<li> Principal = <b>\$ $prin</b> \n";
print "<li> Interest Rate = <b>$int %</b> \n";
print "<li> Term = <b>$term </b> years\n";
print "<h2>The following mortgage would result for $stry :</h2>\n";

$tt = $term * 12; $ir = $int / 1200; 
$temp = (1.0 / (1 + $ir) ** $tt);
$paymt = $prin * $ir / (1 - $temp);
$tint = $paymt * $tt - $prin; 
$aint = $tint / $term /12;
$bal = $prin; $yrint = 0; $yrprin = 0;
$bbal = $prin; $byrint = 0; $byrprin = 0;

for ($i = 1; $i <= $term; $i++ )
{
  for ($j = 1; $j <= 12; $j++) {	
	$mint = $ir * $bal; $bal = $bal - $paymt + $mint;
	$yrint = $yrint + $mint; $mprin = $paymt - $mint;
	$yrprin = $yrprin + $mprin;

	$bmint = $ir * $bbal; $bbal = $bbal - $paymt + $bmint;
	$byrint = $byrint + $bmint; $bmprin = $paymt - $bmint;
	$byrprin = $byrprin + $bmprin;
  }
  $bbal = $bbal - $paymt; $byrprin = $byrprin + $paymt;
  if ($bbal < 0) { $bbal = 0; }
  printf("<li>Year # %2d : Principal Remaining: Standard \$ %7.2f, Biweekly \$ %7.2f\n",
	$i,$bal,$bbal); 
}

print"<hr><h2>Where the final summary is</h2><ul>\n";

printf ("<li>Monthly Payment: <b>\$ %7.2f</b>\n<li>Total Int:<b>\$  %9.2f</b>\n<li>%4s Int <b>\$ %8.2f</b>\n<li>%4s Int <b>\$ %8.2f</b>\n",
			$paymt, $tint, $stry, $first_yr, $yr2_nam, $snd_yr);
printf ("<li>End Bal Dec $yr2_nam: <b>\$ %7.2f</b>\n",$yr2_bal);
printf ("<li>Avg Int each Month: <b>\$ %7.2f</b>\n",$aint);
print "<hr>\n";
printf ("<li>Biweekly Payment: <b>\$ %7.2f</b>\n<li>Total Int:<b>\$  %9.2f</b>\n<li>%4s Int <b>\$ %8.2f</b>\n<li>%4s Int <b>\$ %8.2f</b>\n",
			$bpaymt, $btint, $bstry, $bfirst_yr, $byr2_nam, $bsnd_yr);
printf ("<li>End Bal Dec $yr2_nam: <b>\$ %7.2f</b>\n",$byr2_bal);
printf ("<li>Avg Int each BiWeekly Period: <b>\$ %7.2f</b>\n",$baint);