Woocommerce Calculate amount by customer input in product page - wordpress

Question

In product page to get input from customer as number of words. To calculate the amount from products add-ons fixed amount to additional 10$ for each above 500 words.
ex: 1. Number of Words: 530
Normal Price + additional price: 180$ + 10$
Total: 190$
Number of Words: 1040
Normal Price + additional price: 180$ + 20$
Total: 200$
This process as to create dynamic input form customer to calculate amount the price and total amount.
`$extra_amount = (int)'10';
$amount = (int)'180'; // how to get amount from woocommerce data
if(isset($_POST['wordnumber'])){ // how to get this paramater form woocommerce post values
$test =$_POST['wordnumber'];
$original_amount = '';
if($test <= (int)'500'){
$original_amount = $amount;
}
elseif($test > (int)'500'){
$div_amount = $test/(int)'500';
$round = floor($div_amount);
//echo '<br/>';
$total_extra = $round*$extra_amount;
$original_amount = $amount+$total_extra;
}
echo $original_amount;
}`

Answer 1

I installed WC Fields Factory plugin then i got value from one field using key. in that i written a function and i overrided the price value.
function calculate_gift_wrap_fee( $cart_object ) {
/* Gift wrap price */
$additionalPrice = 10;
foreach ( $cart_object->cart_contents as $key => $value ) {
$test = $value['custom field'];
if( $test <= 100 ) {
$quantity = floatval( $value['quantity'] );
$orgPrice = floatval( $value['data']->price );
$value['data']->price = ( $orgPrice );
}
elseif( $test > 100 ) {
$div_amount = floatval($test/500);
$round = floor($div_amount);
$total_extra = floatval($round * $additionalPrice);
$quantity = floatval( $value['quantity'] );
$orgPrice = floatval( $value['data']->price );
$pp = ($value['price']);
$total = floatval($pp + $total_extra);
$value['data']->price = ( $orgPrice + $total );
}
}}
add_action( 'woocommerce_before_calculate_totals', calculate_gift_wrap_fee', 1, 1 );