Post woocommerce total to payment processor - php

Question

I've been given the task of setting up a payment processor for my boss who uses Moneris in Canada. I need to use their form to post the price but unsure what the best method is and have little to no back-end WordPress experience.
I need to assign the woocommerce cart total to the input "charge_total" value on the form submit.
Sample Form:
<form action="https://esqa.moneris.com/HPPDP/index.php" method="POST"><input name="ps_store_id" type="HIDDEN" value="XXXX" />
<input name="hpp_key" type="HIDDEN" value="XXXX" />
<input name="charge_total" type="HIDDEN" value="1" />
<input name="SUBMIT" type="SUBMIT" value="Click to proceed to Secure Page" />
</form>

Answer 1

You need to modify your template where the form is generated.
your sample form would become
<?php
global $woocommerce;
$cartTotal=$woocommerce->cart->get_cart_total()
?>
<form action="https://esqa.moneris.com/HPPDP/index.php" method="POST">
<input name="ps_store_id" type="HIDDEN" value="XXXX" />
<input name="hpp_key" type="HIDDEN" value="XXXX" />
<input name="charge_total" type="HIDDEN" value="<?php echo $cartTotal?>" />
<input name="SUBMIT" type="SUBMIT" value="Click to proceed to Secure Page" />
</form>
wp-content/plugins/woocommerce/templates/checkout/form-checkout.php is your main checkout file. i do not know where in the checkout process you wish to allow the user to leave the site, but i assume it would be form-pay.php
Good day, hope it helps you out
edit:
after conversation in comments, i would point you towards using the hooks. i will be using the after checkout hook to inject some html in there but if you let me know where you need the code ill re edit the hook for the proper position
put this in the functions.php file in your enabled theme
function add_custom_html() {
global $woocommerce;
$cartTotal=$woocommerce->cart->get_cart_total()
$my_custom_form = '<form action="https://esqa.moneris.com/HPPDP/index.php" method="POST">
<input name="ps_store_id" type="HIDDEN" value="XXXX" />
<input name="hpp_key" type="HIDDEN" value="XXXX" />
<input name="charge_total" type="HIDDEN" value="'&$cartTotal&'"/>
<input name="SUBMIT" type="SUBMIT" value="Click to proceed to Secure Page" />
</form>';
echo $my_custom_form;
}
add_action( 'woocommerce_after_checkout_form', 'add_custom_html');