<form method="POST">
    <h3>Editing: class-wc-gateway-cod.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Class WC_Gateway_COD file.
 *
 * @package WooCommerce\Gateways
 */

use Automattic\Jetpack\Constants;

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

/**
 * Cash on Delivery Gateway.
 *
 * Provides a Cash on Delivery Payment Gateway.
 *
 * @class       WC_Gateway_COD
 * @extends     WC_Payment_Gateway
 * @version     2.1.0
 * @package     WooCommerce\Classes\Payment
 */
class WC_Gateway_COD extends WC_Payment_Gateway {

	/**
	 * Gateway instructions that will be added to the thank you page and emails.
	 *
	 * @var string
	 */
	public $instructions;

	/**
	 * Enable for shipping methods.
	 *
	 * @var array
	 */
	public $enable_for_methods;

	/**
	 * Enable for virtual products.
	 *
	 * @var bool
	 */
	public $enable_for_virtual;

	/**
	 * Constructor for the gateway.
	 */
	public function __construct() {
		// Setup general properties.
		$this-&gt;setup_properties();

		// Load the settings.
		$this-&gt;init_form_fields();
		$this-&gt;init_settings();

		// Get settings.
		$this-&gt;title              = $this-&gt;get_option( 'title' );
		$this-&gt;description        = $this-&gt;get_option( 'description' );
		$this-&gt;instructions       = $this-&gt;get_option( 'instructions' );
		$this-&gt;enable_for_methods = $this-&gt;get_option( 'enable_for_methods', array() );
		$this-&gt;enable_for_virtual = $this-&gt;get_option( 'enable_for_virtual', 'yes' ) === 'yes';

		// Actions.
		add_action( 'woocommerce_update_options_payment_gateways_' . $this-&gt;id, array( $this, 'process_admin_options' ) );
		add_action( 'woocommerce_thankyou_' . $this-&gt;id, array( $this, 'thankyou_page' ) );
		add_filter( 'woocommerce_payment_complete_order_status', array( $this, 'change_payment_complete_order_status' ), 10, 3 );

		// Customer Emails.
		add_action( 'woocommerce_email_before_order_table', array( $this, 'email_instructions' ), 10, 3 );
	}

	/**
	 * Setup general properties for the gateway.
	 */
	protected function setup_properties() {
		$this-&gt;id                 = 'cod';
		$this-&gt;icon               = apply_filters( 'woocommerce_cod_icon', '' );
		$this-&gt;method_title       = __( 'Cash on delivery', 'woocommerce' );
		$this-&gt;method_description = __( 'Have your customers pay with cash (or by other means) upon delivery.', 'woocommerce' );
		$this-&gt;has_fields         = false;
	}

	/**
	 * Initialise Gateway Settings Form Fields.
	 */
	public function init_form_fields() {
		$this-&gt;form_fields = array(
			'enabled'            =&gt; array(
				'title'       =&gt; __( 'Enable/Disable', 'woocommerce' ),
				'label'       =&gt; __( 'Enable cash on delivery', 'woocommerce' ),
				'type'        =&gt; 'checkbox',
				'description' =&gt; '',
				'default'     =&gt; 'no',
			),
			'title'              =&gt; array(
				'title'       =&gt; __( 'Title', 'woocommerce' ),
				'type'        =&gt; 'safe_text',
				'description' =&gt; __( 'Payment method description that the customer will see on your checkout.', 'woocommerce' ),
				'default'     =&gt; __( 'Cash on delivery', 'woocommerce' ),
				'desc_tip'    =&gt; true,
			),
			'description'        =&gt; array(
				'title'       =&gt; __( 'Description', 'woocommerce' ),
				'type'        =&gt; 'textarea',
				'description' =&gt; __( 'Payment method description that the customer will see on your website.', 'woocommerce' ),
				'default'     =&gt; __( 'Pay with cash upon delivery.', 'woocommerce' ),
				'desc_tip'    =&gt; true,
			),
			'instructions'       =&gt; array(
				'title'       =&gt; __( 'Instructions', 'woocommerce' ),
				'type'        =&gt; 'textarea',
				'description' =&gt; __( 'Instructions that will be added to the thank you page.', 'woocommerce' ),
				'default'     =&gt; __( 'Pay with cash upon delivery.', 'woocommerce' ),
				'desc_tip'    =&gt; true,
			),
			'enable_for_methods' =&gt; array(
				'title'             =&gt; __( 'Enable for shipping methods', 'woocommerce' ),
				'type'              =&gt; 'multiselect',
				'class'             =&gt; 'wc-enhanced-select',
				'css'               =&gt; 'width: 400px;',
				'default'           =&gt; '',
				'description'       =&gt; __( 'If COD is only available for certain methods, set it up here. Leave blank to enable for all methods.', 'woocommerce' ),
				'options'           =&gt; $this-&gt;load_shipping_method_options(),
				'desc_tip'          =&gt; true,
				'custom_attributes' =&gt; array(
					'data-placeholder' =&gt; __( 'Select shipping methods', 'woocommerce' ),
				),
			),
			'enable_for_virtual' =&gt; array(
				'title'   =&gt; __( 'Accept for virtual orders', 'woocommerce' ),
				'label'   =&gt; __( 'Accept COD if the order is virtual', 'woocommerce' ),
				'type'    =&gt; 'checkbox',
				'default' =&gt; 'yes',
			),
		);
	}

	/**
	 * Check If The Gateway Is Available For Use.
	 *
	 * @return bool
	 */
	public function is_available() {
		$order          = null;
		$needs_shipping = false;

		// Test if shipping is needed first.
		if ( WC()-&gt;cart &amp;&amp; WC()-&gt;cart-&gt;needs_shipping() ) {
			$needs_shipping = true;
		} elseif ( is_page( wc_get_page_id( 'checkout' ) ) &amp;&amp; 0 &lt; get_query_var( 'order-pay' ) ) {
			$order_id = absint( get_query_var( 'order-pay' ) );
			$order    = wc_get_order( $order_id );

			// Test if order needs shipping.
			if ( $order &amp;&amp; 0 &lt; count( $order-&gt;get_items() ) ) {
				foreach ( $order-&gt;get_items() as $item ) {
					$_product = $item-&gt;get_product();
					if ( $_product &amp;&amp; $_product-&gt;needs_shipping() ) {
						$needs_shipping = true;
						break;
					}
				}
			}
		}

		$needs_shipping = apply_filters( 'woocommerce_cart_needs_shipping', $needs_shipping );

		// Virtual order, with virtual disabled.
		if ( ! $this-&gt;enable_for_virtual &amp;&amp; ! $needs_shipping ) {
			return false;
		}

		// Only apply if all packages are being shipped via chosen method, or order is virtual.
		if ( ! empty( $this-&gt;enable_for_methods ) &amp;&amp; $needs_shipping ) {
			$order_shipping_items            = is_object( $order ) ? $order-&gt;get_shipping_methods() : false;
			$chosen_shipping_methods_session = WC()-&gt;session-&gt;get( 'chosen_shipping_methods' );

			if ( $order_shipping_items ) {
				$canonical_rate_ids = $this-&gt;get_canonical_order_shipping_item_rate_ids( $order_shipping_items );
			} else {
				$canonical_rate_ids = $this-&gt;get_canonical_package_rate_ids( $chosen_shipping_methods_session );
			}

			if ( ! count( $this-&gt;get_matching_rates( $canonical_rate_ids ) ) ) {
				return false;
			}
		}

		return parent::is_available();
	}

	/**
	 * Checks to see whether or not the admin settings are being accessed by the current request.
	 *
	 * @return bool
	 */
	private function is_accessing_settings() {
		if ( is_admin() ) {
			// phpcs:disable WordPress.Security.NonceVerification
			if ( ! isset( $_REQUEST['page'] ) || 'wc-settings' !== $_REQUEST['page'] ) {
				return false;
			}
			if ( ! isset( $_REQUEST['tab'] ) || 'checkout' !== $_REQUEST['tab'] ) {
				return false;
			}
			if ( ! isset( $_REQUEST['section'] ) || 'cod' !== $_REQUEST['section'] ) {
				return false;
			}
			// phpcs:enable WordPress.Security.NonceVerification

			return true;
		}

		if ( Constants::is_true( 'REST_REQUEST' ) ) {
			global $wp;
			if ( isset( $wp-&gt;query_vars['rest_route'] ) &amp;&amp; false !== strpos( $wp-&gt;query_vars['rest_route'], '/payment_gateways' ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Loads all of the shipping method options for the enable_for_methods field.
	 *
	 * @return array
	 */
	private function load_shipping_method_options() {
		// Since this is expensive, we only want to do it if we're actually on the settings page.
		if ( ! $this-&gt;is_accessing_settings() ) {
			return array();
		}

		$data_store = WC_Data_Store::load( 'shipping-zone' );
		$raw_zones  = $data_store-&gt;get_zones();
		$zones      = array();

		foreach ( $raw_zones as $raw_zone ) {
			$zones[] = new WC_Shipping_Zone( $raw_zone );
		}

		$zones[] = new WC_Shipping_Zone( 0 );

		$options = array();
		foreach ( WC()-&gt;shipping()-&gt;load_shipping_methods() as $method ) {

			$options[ $method-&gt;get_method_title() ] = array();

			// Translators: %1$s shipping method name.
			$options[ $method-&gt;get_method_title() ][ $method-&gt;id ] = sprintf( __( 'Any &amp;quot;%1$s&amp;quot; method', 'woocommerce' ), $method-&gt;get_method_title() );

			foreach ( $zones as $zone ) {

				$shipping_method_instances = $zone-&gt;get_shipping_methods();

				foreach ( $shipping_method_instances as $shipping_method_instance_id =&gt; $shipping_method_instance ) {

					if ( $shipping_method_instance-&gt;id !== $method-&gt;id ) {
						continue;
					}

					$option_id = $shipping_method_instance-&gt;get_rate_id();

					// Translators: %1$s shipping method title, %2$s shipping method id.
					$option_instance_title = sprintf( __( '%1$s (#%2$s)', 'woocommerce' ), $shipping_method_instance-&gt;get_title(), $shipping_method_instance_id );

					// Translators: %1$s zone name, %2$s shipping method instance name.
					$option_title = sprintf( __( '%1$s &amp;ndash; %2$s', 'woocommerce' ), $zone-&gt;get_id() ? $zone-&gt;get_zone_name() : __( 'Other locations', 'woocommerce' ), $option_instance_title );

					$options[ $method-&gt;get_method_title() ][ $option_id ] = $option_title;
				}
			}
		}

		return $options;
	}

	/**
	 * Converts the chosen rate IDs generated by Shipping Methods to a canonical 'method_id:instance_id' format.
	 *
	 * @since  3.4.0
	 *
	 * @param  array $order_shipping_items  Array of WC_Order_Item_Shipping objects.
	 * @return array $canonical_rate_ids    Rate IDs in a canonical format.
	 */
	private function get_canonical_order_shipping_item_rate_ids( $order_shipping_items ) {

		$canonical_rate_ids = array();

		foreach ( $order_shipping_items as $order_shipping_item ) {
			$canonical_rate_ids[] = $order_shipping_item-&gt;get_method_id() . ':' . $order_shipping_item-&gt;get_instance_id();
		}

		return $canonical_rate_ids;
	}

	/**
	 * Converts the chosen rate IDs generated by Shipping Methods to a canonical 'method_id:instance_id' format.
	 *
	 * @since  3.4.0
	 *
	 * @param  array $chosen_package_rate_ids Rate IDs as generated by shipping methods. Can be anything if a shipping method doesn't honor WC conventions.
	 * @return array $canonical_rate_ids  Rate IDs in a canonical format.
	 */
	private function get_canonical_package_rate_ids( $chosen_package_rate_ids ) {

		$shipping_packages  = WC()-&gt;shipping()-&gt;get_packages();
		$canonical_rate_ids = array();

		if ( ! empty( $chosen_package_rate_ids ) &amp;&amp; is_array( $chosen_package_rate_ids ) ) {
			foreach ( $chosen_package_rate_ids as $package_key =&gt; $chosen_package_rate_id ) {
				if ( ! empty( $shipping_packages[ $package_key ]['rates'][ $chosen_package_rate_id ] ) ) {
					$chosen_rate          = $shipping_packages[ $package_key ]['rates'][ $chosen_package_rate_id ];
					$canonical_rate_ids[] = $chosen_rate-&gt;get_method_id() . ':' . $chosen_rate-&gt;get_instance_id();
				}
			}
		}

		return $canonical_rate_ids;
	}

	/**
	 * Indicates whether a rate exists in an array of canonically-formatted rate IDs that activates this gateway.
	 *
	 * @since  3.4.0
	 *
	 * @param array $rate_ids Rate ids to check.
	 * @return array
	 */
	private function get_matching_rates( $rate_ids ) {
		// First, match entries in 'method_id:instance_id' format. Then, match entries in 'method_id' format by stripping off the instance ID from the candidates.
		return array_unique( array_merge( array_intersect( $this-&gt;enable_for_methods, $rate_ids ), array_intersect( $this-&gt;enable_for_methods, array_unique( array_map( 'wc_get_string_before_colon', $rate_ids ) ) ) ) );
	}

	/**
	 * Process the payment and return the result.
	 *
	 * @param int $order_id Order ID.
	 * @return array
	 */
	public function process_payment( $order_id ) {
		$order = wc_get_order( $order_id );

		if ( $order-&gt;get_total() &gt; 0 ) {
			// Mark as processing or on-hold (payment won't be taken until delivery).
			$order-&gt;update_status( apply_filters( 'woocommerce_cod_process_payment_order_status', $order-&gt;has_downloadable_item() ? 'on-hold' : 'processing', $order ), __( 'Payment to be made upon delivery.', 'woocommerce' ) );
		} else {
			$order-&gt;payment_complete();
		}

		// Remove cart.
		WC()-&gt;cart-&gt;empty_cart();

		// Return thankyou redirect.
		return array(
			'result'   =&gt; 'success',
			'redirect' =&gt; $this-&gt;get_return_url( $order ),
		);
	}

	/**
	 * Output for the order received page.
	 */
	public function thankyou_page() {
		if ( $this-&gt;instructions ) {
			echo wp_kses_post( wpautop( wptexturize( $this-&gt;instructions ) ) );
		}
	}

	/**
	 * Change payment complete order status to completed for COD orders.
	 *
	 * @since  3.1.0
	 * @param  string         $status Current order status.
	 * @param  int            $order_id Order ID.
	 * @param  WC_Order|false $order Order object.
	 * @return string
	 */
	public function change_payment_complete_order_status( $status, $order_id = 0, $order = false ) {
		if ( $order &amp;&amp; 'cod' === $order-&gt;get_payment_method() ) {
			$status = 'completed';
		}
		return $status;
	}

	/**
	 * Add content to the WC emails.
	 *
	 * @param WC_Order $order Order object.
	 * @param bool     $sent_to_admin  Sent to admin.
	 * @param bool     $plain_text Email format: plain text or HTML.
	 */
	public function email_instructions( $order, $sent_to_admin, $plain_text = false ) {
		if ( $this-&gt;instructions &amp;&amp; ! $sent_to_admin &amp;&amp; $this-&gt;id === $order-&gt;get_payment_method() ) {
			echo wp_kses_post( wpautop( wptexturize( $this-&gt;instructions ) ) . PHP_EOL );
		}
	}
}
</textarea><br>
    <input type="submit" value="Save">
</form>