VAT 20 or 0? Event Espresso 4.

ee_tw_zero_vat_or_20.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

/**
 * PLEASE READ AND FOLLOW ALL INSTRUCTIONS IN CAPS
 *
 * IN ORDER FOR THIS TO WORK YOU NEED TO ADD A QUESTION USED FOR A TAX NUMBER
 *
 * BECAUSE THIS QUESTION SHOULD ONLY BE ASKED ONCE PER TRANSACTION
 * YOU SHOULD ADD THE ABOVE QUESTION TO A GROUP ONLY ASKED FOR THE PRIMARY REGISTRANT
 * IN OTHER WORDS, CHECK THE BOX NEXT TO WHICHEVER GROUP YOU SET THIS QUESTION TO BE IN 
 * WITHIN THE "Questions for Primary Registrant" SIDEBAR METABOX ONLY
 *
 * CHANGE $QST_ID === 22 TO BE THE ID OF THE QUESTIO YOU CREATED ABOVE
 * IF ANY VALUE IS SET IN THAT FIELD, 0% VAT IS CHARGED, OTHERWISE 20%
 *
 * @return void
 */
 
 
function bc_ee_determine_whether_to_apply_surcharge() {
  if ( isset( $_REQUEST[ 'ee_reg_qstn' ] ) ) {
    foreach ( $_REQUEST[ 'ee_reg_qstn' ] as $registrations ) {
      if ( ! empty( $registrations ) ) {
        foreach ( $registrations as $QST_ID => $response ) {
          if ( $QST_ID === 22 ) {
            if( !empty($response) ) {
               add_filter( 'FHEE__bc_ee_apply_transaction_surcharge__apply_surcharge', '__return_true' );
               add_filter( 'FHEE__bc_ee_apply_transaction_surcharge__surcharge_details', 'ee_tw_zero_vat' );
            } else {
               add_filter( 'FHEE__bc_ee_apply_transaction_surcharge__apply_surcharge', '__return_true' );
            }
          }
        }
      }
    }
  }
}
add_action( 'AHEE__EE_System__core_loaded_and_ready', 'bc_ee_determine_whether_to_apply_surcharge', 1 );

function ee_tw_zero_vat() {
  return array(
    'name'          => 'VAT0',
    'code'          => 'VAT0',
    'description'   => 'VAT 0%',
    'percent'       => 0,
    'taxable'       => false,
  );
}

/**
 * DO NOT EDIT ANYTHING EXCEPT DEFAULT SURCHARGE DETAILS
 *
 * bc_ee_apply_transaction_surcharge
 *
 * @param \EE_Checkout $checkout
 * @return \EE_Checkout
 */
function bc_ee_apply_transaction_surcharge( EE_Checkout $checkout ) {
  // DEFAULT SURCHARGE DETAILS - EDIT THIS
  $surcharge_details = apply_filters(
    'FHEE__bc_ee_apply_transaction_surcharge__surcharge_details',
    array(
      //  name for surcharge that will be displayed
      'name'        => 'VAT',
      // unique code used to identify surcharge in the db
      'code'        => 'standard-vat',
      // description for line item
      'description' => 'Standard VAT',
      // percentage amount
      'percent'     => 20,
      // whether or not tax is applied on top of the surcharge
      'taxable'     => false,
    )
  );
  // STOP EDITING
  // apply the surcharge ?
  if ( ! apply_filters( 'FHEE__bc_ee_apply_transaction_surcharge__apply_surcharge', false ) ) {
    return $checkout;
  }
  // verify checkout
  if ( ! $checkout instanceof EE_Checkout ) {
    return $checkout;
  }
  // verify cart
  $cart = $checkout->cart;
  if ( ! $cart instanceof EE_Cart ) {
    return $checkout;
  }
  // verify grand total line item
  $grand_total = $cart->get_grand_total();
  if ( ! $grand_total instanceof EE_Line_Item ) {
    return $checkout;
  }
  // has surcharge already been applied ?
  $existing_surcharge = $grand_total->get_child_line_item( $surcharge_details[ 'code' ] );
  if ( $existing_surcharge instanceof EE_Line_Item ) {
    return $checkout;
  }
  EE_Registry::instance()->load_helper( 'Line_Item' );
  $pre_tax_subtotal = EEH_Line_Item::get_pre_tax_subtotal( $grand_total );
  $pre_tax_subtotal->add_child_line_item(
    EE_Line_Item::new_instance( array(
      'LIN_name'       => $surcharge_details[ 'name' ],
      'LIN_desc'       => $surcharge_details[ 'description' ],
      'LIN_unit_price' => 0,
      'LIN_percent'    => $surcharge_details[ 'percent' ],
      'LIN_quantity'   => NULL,
      'LIN_is_taxable' => $surcharge_details[ 'taxable' ],
      'LIN_order'      => 0,
      'LIN_total'      => (float) ( $surcharge_details[ 'percent' ] * ( $pre_tax_subtotal->total() / 100 ) ),
      'LIN_type'       => EEM_Line_Item::type_line_item,
      'LIN_code'       => $surcharge_details[ 'code' ],
    ) )
  );
  $grand_total->recalculate_total_including_taxes();
  return $checkout;
}
add_filter( 'FHEE__EED_Single_Page_Checkout___initialize_checkout__checkout', 'bc_ee_apply_transaction_surcharge' );