daily_coupons.php

<?php
/**
Plugin Name: WooCommerce Extended Coupon Features PRO Daily Extension
Description: Extends WooCommerce Extended Coupon Features by adding coupons that are only valid on certain days
Author: Daniel Klose
Version: 1.0
Author URI: http://www.daniel-klose.com/
*/

add_action( 'wjecf_init_plugins', 'setup_my_wjecf_example_plugin' );

function setup_my_wjecf_example_plugin() {

    class WJECF_Plugin_Example extends Abstract_WJECF_Plugin {

        //This is the meta-key where the weekday will be saved
        //HINT: Prepend it with _wjecf_<your plugin name> to avoid naming conflicts
        const META_KEY_WEEKDAY = '_wjecf_example_plugin_weekday';

        /**
         * In the constructor you can supply general information about your WJECF-plugin.
         */
        public function __construct() {
            $this->set_plugin_data( array(
                'description' => __( 'Extends WooCommerce Extended Coupon Features by adding coupons that are only valid on certain days.', 'your-text-domain' ),
                'dependencies' => array(),
                'minimal_wjecf_version' => '2.5.1',
                'can_be_disabled' => true
            ) );
        }

//FRONTEND

        /**
         * This function is called when WooCommerce and all other plugins are loaded.
         * Here you can setup frontend hooks.
         */

        public function init_hook() {
            add_action( 'woocommerce_coupon_is_valid', array( $this, 'filter_woocommerce_coupon_is_valid' ), 10, 2 );
        }


        /**
         * Invalidates the coupon if the weekday is not ok
         * @param bool $valid
         * @param WC_Coupon $coupon
         * @return bool False if invalid
         */

        public function filter_woocommerce_coupon_is_valid( $valid, $coupon ) {
            if ( is_callable( array( $coupon, 'get_meta' ) ) ) {
                //WC3.0+
                $coupon_weekday = $coupon->get_meta( self::META_KEY_WEEKDAY );
            } else {
                //Older WC versions
                $coupon_weekday = get_post_meta( $coupon->id, self::META_KEY_WEEKDAY, true );
            }

            $day_after = $coupon_weekday +1;

            if ($day_after == 7) {
              $day_after = 0;
            }

            //Not valid if the weekday is not same or next day
            if ( is_numeric( $coupon_weekday ) && (date('w') != $coupon_weekday) && (date('w') != $day_after) ) {
                return false;
            }
            if ( is_numeric( $coupon_weekday ) && (date('w') == $day_after) && (date('H') > 12) ) {
                return false;
            }

            return $valid;
        }

//ADMIN

        /**
         * This function is called when WooCommerce and all other plugins are loaded and we are on the admin section of WordPress.
         * Here you can setup admin hooks.
         */
        public function init_admin_hook() {
            add_action( 'woocommerce_coupon_options_usage_restriction', array( $this, 'action_woocommerce_coupon_options_usage_restriction' ), 9999 ); //9999 is at the bottom of the tab
        }

        /**
         * Automatically called at the process_shop_coupon_meta action (WJECF 2.5.1+ only).
         *
         * Returns an array [ meta_key => sanitizion_rule, ... ] with the meta fields that must be saved if the user clicks 'Update' on the coupon admin page.         *
         * Valid sanitizion rules are: 'html', 'clean', 'yesno', 'decimal', 'int', 'int[]' (array of ints), 'int,' (comma separated ints)
         *
         * $_POST[meta_key] will be sanitized and automatically saved.
         *
         * @since 2.5.1
         * @param WC_Coupon $coupon The coupon that will be saved
         * @return array An array with [ key => sanitizion_rule, ... ]
         */
        public function admin_coupon_meta_fields( $coupon ) {
            return array( self::META_KEY_WEEKDAY => 'int' );
        }

        /**
         * This is called when the usage restrictions tab is rendered.
         */
        public function action_woocommerce_coupon_options_usage_restriction() {
            woocommerce_wp_select(
                array(
                    'id' => self::META_KEY_WEEKDAY,
                    'label' => __( 'Weekday', 'woocommerce-jos-autocoupon' ),
                    'options' => array(
                        '' => '(Always valid)',
                        0 => 'Sunday',
                        1 => 'Monday',
                        2 => 'Tuesday',
                        3 => 'Wednesday',
                        4 => 'Thursday',
                        5 => 'Friday',
                        6 => 'Saturday'
                    ),
                    'description' => __( 'Coupon is only valid on this weekday.', 'your-text-domain' ),
                    'desc_tip' => true
                )
            );
        }
    }

    //Loads the plugin!
    WJECF()->add_plugin( 'WJECF_Plugin_Example' );
}