Currency Converter customization

It is possible to define specific hooks to overwrite or extend the default currency conversion functionalities. The hooks available allow to integrate custom conversion/exchange rates calculation, and to define the symbol to use for a specific currency, the number of decimals, the decimals/thousands separator symbols etc..

It is necessary to create a custom WordPress plugin to declare these hooks compatible with Vik Booking.

<?php
/*
Plugin Name:  VBO Custom Currency Conversion
Plugin URI:   https://vikwp.com/
Description:  Helper plugin to override the currency conversion functions in Vik Booking.
Version:      1.0
Author:       E4J s.r.l.
Author URI:   https://vikwp.com
License:      GPL2
License URI:  https://www.gnu.org/licenses/gpl-2.0.html
*/

// No direct access
defined('ABSPATH') or die('No script kiddies please!');

/**
 * Filter to override a conversion rate between two currencies.
 * 
 * @param   float   $conv_rate      the conversion rate processed by other plugins, null by default.
 * @param   string  $from_currency  the currency to convert from (i.e. default currency in Vik Booking).
 * @param   string  $to_currency    the currency to convert to (ISO 4217 Alpha-3 code).
 * 
 * @return  float|int               the conversion rate between the two currencies, or null.
 */
add_filter('vikbooking_get_conversion_rate', function($conv_rate, $from_currency, $to_currency) {
    if (!is_null($conv_rate)) {
        // another plugin must have set a custom conversion rate already
        return $conv_rate;
    }

    if ($from_currency === 'EUR' && $to_currency === 'USD') {
        // return a static conversion rate between EUR and USD
        return 1.50;
    }

    if ($to_currency === 'XXX') {
        // return a static conversion rate for the custom currency code "XXX"
        return 2;
    }

    // return null to not interfere with the default conversion value
    return null;
}, 10, 3);

/**
 * Filter to override the symbol, number of decimals, decimals and thousands separators of a currency.
 * 
 * @param   array   $currency_info  the information array processed by other plugins, null by default.
 * @param   string  $currency_code  the currency ISO 4217 Alpha-3 code to parse.
 * 
 * @return  array                   associative list of currency information, or null.
 */
add_filter('vikbooking_get_currency_data', function($currency_info, $currency_code) {
    if (!is_null($currency_info)) {
        // another plugin must have set custom information already
        return $currency_info;
    }

    if ($currency_code === 'USD') {
        // return custom information for the currency code USD
        return [
            'symbol'              => '&#128561;',
            'decimals'            => 3,
            'decimals_separator'  => '.',
            'thousands_separator' => ',',
        ];
    }

    if ($currency_code === 'XXX') {
        // return custom information for the dummy currency code "XXX"
        return [
            'symbol'              => '&#128513;',
            'decimals'            => 0,
            'decimals_separator'  => '',
            'thousands_separator' => '',
        ];
    }

    // return null to not interfere with the default currency information
    return null;
}, 10, 2);

/**
 * Filter to add a custom currency code to the available list.
 * 
 * @param   bool    $exists         true if exists, false if it doesn't, null by default.
 * @param   string  $currency_code  the currency ISO 4217 Alpha-3 code to parse.
 * 
 * @return  bool                    true if exists, false if it doesn't, or null.
 */
add_filter('vikbooking_check_currency_exists', function($exists, $currency_code) {
    if (!is_null($exists)) {
        // another plugin must have processed this currency already
        return $exists;
    }

    if ($currency_code === 'XXX') {
        // add the dummy currency code "XXX" to the list of available currencies
        return true;
    }

    // return null to not interfere with the default currency validation
    return null;
}, 10, 2);

By creating a PHP file with a name like "vbo_custom_currency_conversion.php" and with the above code inside it, you will have your own custom-coded WordPress plugin to manipulate the default currency exchange functionalities.

Do not forget to install and activate the plugin on your WordPress website, or the hooks won't be registered by WordPress itself.