/**
 * Handle the Klarna modal closed event.
 *
 * @param WC_Order $order The Woo order.
 * @param bool     $reason TRUE if purchase aborted by the customer. FALSE if rejected by Klarna.
 * @return void
 */
function klarna_modal_closed( $order, $reason ) {
	if ( $reason ) {
		$order->add_order_note( 'Customer aborted.' );
	} else {
		$order->add_order_note( 'Rejected by Klarna.' );
	}

	$order->save();
}
add_action( 'kp_modal_closed', 'klarna_modal_closed', 10, 2 );

/**
 * Use together with Klarna Checkout for WooCommerce (v3 platform)
 * https://wordpress.org/plugins/klarna-checkout-for-woocommerce/
 *
 * Filter the purchase country sent to Klarna.
 * Add this code to your themes functions.php file or include it in a separate functionality plugin (https://css-tricks.com/wordpress-functionality-plugins/).
 **/

add_filter( 'kco_wc_api_request_args', 'krokedil_change_klarna_country' );

function krokedil_change_klarna_country( $request_args ) {
	
	if ( method_exists( WC()->customer, 'shipping_country' ) ) {
		$request_args['purchase_country'] = WC()->customer->shipping_country;
	}
	return $request_args;
}

function kco_custom_locale( $locale ) {
	return 'en-SE';
}

add_filter( 'kco_locale', 'kco_custom_locale');

add_filter(
	'kco_wc_api_request_args',
	function ( $request_args ) {
		foreach ( $request_args['order_lines'] as $index => $order_line ) {
			$request_args['order_lines'][ $index ]['name'] = md5( $order_line['name'] );
		}
		return $request_args;
	}
);

/**
 * Use together with Klarna Checkout for WooCommerce (v3 platform)
 * https://wordpress.org/plugins/klarna-checkout-for-woocommerce/
 *
 * Filter to change if you want the Klarna Checkout iFrame to display on free orders or not.
 * For example after a coupon has been used.
 */

add_filter( 'kco_check_if_needs_payment', 'kco_change_check_if_needs_payment' );
function kco_change_check_if_needs_payment( $bool ) {
  return false;
}

<?php
/** 
 * Filter to change the purchase country. Overwrites the WooCommerce default, and sets a forced purchase country.
 * Change SE to whatever value you want, 2 letter country codes only.
 */

add_filter( 'kco_wc_api_request_args', 'kco_wc_change_purchase_country' );
/**
 * Changes the purchase country.
 *
 * @param array $request_args The KCO v3 request args.
 * @return array
 */
function kco_wc_change_purchase_country( $request_args ) {
    $request_args['purchase_country'] = 'SE';
    return $request_args;
}

/**
 * Klarna Checkout for WooCommerce (v3 platform)
 * https://wordpress.org/plugins/klarna-checkout-for-woocommerce/
 *
 * Only accept purchases from customer over 18 years of age.
 * This will only work if Klarna has activated the "Allow merchant to read customers national identification number"setting in your account at Klarna.
 * Current version of this snippet only works for 2.x versions of KCO. For older versions please use the older version of this snippet.
 */

 add_filter( 'kco_wc_api_request_args', 'my_kco_wc_api_request_args' );
 /**
  * Sets the option so DOB is mandatory in the checkout.
  *
  * @param array $request_args The request args for Klarna Checkout.
  * @return array
  */
function my_kco_wc_api_request_args( $request_args ) {
	$request_args['options']['national_identification_number_mandatory'] = true;
	return $request_args;
}

add_action( 'woocommerce_checkout_process', 'kco_validate_age' );
 /**
  * Validates the age of the customer. Prevents customers from under the given age to complete an order.
  *
  * @return void
  */
function kco_validate_age() {
	if ( isset( WC()->session ) && 'kco' === WC()->session->get( 'chosen_payment_method' ) ) {
		if ( ! empty( WC()->session->get( 'kco_wc_order_id' ) ) ) {
			$klarna_order = KCO_WC()->api->get_klarna_order( WC()->session->get( 'kco_wc_order_id' ) );

			// Date of birth is not available for organizations.
			if ( 'organization' === $klarna_order['customer']['type'] ) {
				return;
			}

			$birthday = new DateTime( $klarna_order['customer']['date_of_birth'] );
			$now      = new DateTime();
			$age      = $now->diff( $birthday );
			if ( $age->y < 18 ) {
				wc_add_notice( __( 'You must be 18 years or older.', 'klarna-checkout-for-woocommerce' ), 'error' );
			}
		}
	}
}

<?php
/**
 * Filter the additional checkboxes to add to the Klarna Checkout iframe. Works with Klarna Checkout for WooCommerce 2.4.3 and above.
 */
add_filter( 'kco_additional_checkboxes', 'add_custom_checkboxes' );
function add_custom_checkboxes( $additional_checkboxes ) {
	$additional_checkboxes[] = array(
		'id'       => 'custom_checkbox', // The ID to be used in the backend to read when we get the order during the checkout process.
		'text'     => 'Custom checkbox', // The text that you want to display to the customer.
		'checked'  => false, // true if it should be automatically checked, false if not.
		'required' => true, // true if its required to be able to place an order, false if not.
	);
	return $additional_checkboxes;
}

<?php
add_action( 'kco_wc_payment_complete', 'kco_process_checkboxes' );
function kco_process_checkboxes( $order_id ) {
    $klarna_order_id = get_post_meta( $order_id, '_transaction_id', true );
    $klarna_order    = KCO_WC()->api->get_klarna_order( $klarna_order_id );

    if ( isset( $klarna_order['merchant_requested']['additional_checkboxes'] ) ) {
        foreach ( $klarna_order['merchant_requested']['additional_checkboxes'] as $checkbox ) {
            if ( 'newsletter' === $checkbox['id'] && $checkbox['checked'] ) {
                // Do something with the newsletter checkbox.
            }
        }
    }
}

<?php
/**
 * Filter hook wc_klarna_checkout_icon_html
 * Modify the icon displayed for Klarna Checkout payment method in checkout.
 *
 * Add this code to your themes functions.php file or include it in a separate functionality plugin (https://css-tricks.com/wordpress-functionality-plugins/).
 */
add_filter( 'wc_klarna_checkout_icon_html', 'krokedil_wc_klarna_checkout_icon_html' );
function krokedil_wc_klarna_checkout_icon_html( $icon_html ) {
	// Standard image is https://cdn.klarna.com/1.0/shared/image/generic/logo/en_us/basic/logo_black.png?width=100.
	$icon_src   = 'https://x.klarnacdn.net/payment-method/assets/badges/generic/black/klarna.png?width=100';
	
	$new_icon_html  = '<img src="' . $icon_src . '" alt="Klarna Checkout"/>';
	
	// Return the modified image html.
	return $new_icon_html;
}

function kco_customer_changed( $customer_type ) {
	// The customer type is either 'b2b' or 'b2c'.
	if ( 'b2c' === $customer_type ) {
		// Do something.
	} elseif ( 'b2b' === $customer_type ) {
		// Do something else.
	}
}

add_action( 'kco_customer_type_changed', 'kco_customer_changed' );