Easily run a sale in Easy Digital Downloads. This code applies a coupon globally.

edd-run-a-sale.php

<?php

// When not running a sale, just RETURN here. (but if you forget, no problem...)
# return;

// Pass the coupon code that you want applied as the global sale coupon
new GV_Theme_Sale( 'SOLSTICE2019' );

class GV_Theme_Sale {

	/** @var EDD_Discount $discount */
	var $discount;

	/**
	 * GV_Theme_Sale constructor.
	 */
	public function __construct( $code = false ) {

		if ( empty( $code ) || ! class_exists('EDD_Discount') ) {
			return;
		}

		$this->discount = new EDD_Discount( $code, true, true );

		if( ! $this->should_run() ) {
			return;
		}

		add_action( 'init', array( $this, 'add_discount_to_cart' ) );

		add_filter( 'edd_get_download_price', array( $this, 'modify_final_price') );
		add_filter( 'edd_final_price', array( $this, 'modify_final_price' ) );
	}

	/**
	 * Should the rest of the class initialize?
	 */
	function should_run() {

		// Don't mess with overrides
		if ( ! empty( $_GET['discount'] ) ) {
			return false;
		}

		if ( ! class_exists( 'EDD_Discount' ) ) {
			return false;
		}

		if( ! $this->discount ) {
			return false;
		}

		if( ! $this->discount instanceof EDD_Discount ) {
			return false;
		}

		if( ! $this->discount->is_active( false, false ) ) {
			return false;
		}

		if( $this->discount->is_expired( false ) ) {
			return false;
		}

		if( ! $this->discount->is_started( false ) ) {
			return false;
		}

		return true;
	}

	// Add the discount code to the cart.

	function add_discount_to_cart() {

		if ( $this->edd_cart_has_renewals() ) {
			edd_remove_cart_discount( $this->discount->get_code() );
			return;
		}

		EDD()->session->set( 'preset_discount', $this->discount->get_code() );
		edd_set_cart_discount( $this->discount->get_code() );
	}
	
	/**
	 * Check if there's a renewing product in the cart
	 *
	 * @param array $cart_contents Optional: pass existing cart contents array
	 *
	 * @return bool True: cart contains a renewal; False: cart does not contain a renewal
	 */
	function edd_cart_has_renewals( $cart_contents = array() ) {

	    $cart_contents = empty( $cart_contents ) ? edd_get_cart_contents() : $cart_contents;

		foreach ( $cart_contents as $cart_item ) {
			if( ! empty( $cart_item['options']['is_renewal'] ) || ! empty( $cart_item['item_number']['options']['is_renewal'] ) ) {
				return true;
			}
		}

		return false;
	}

	/**
	 * Modify price shown in pricing page & extensions
	 *
	 * @param int $price
	 * @param int $download_id
	 * @param array $user_purchase_info
	 *
	 * @return float|int
	 */
	function modify_final_price( $price = 0, $download_id = 0, $user_purchase_info = array() ) {

		// Is checkout page or is loading gateway via AJAX
		if( edd_is_checkout() || ( isset( $_POST['action'] ) && 'edd_load_gateway' === $_POST['action'] ) ) {
			return $price;
		}

		$percent = 100 - $this->discount->get_amount();

		return (double) $price * $percent / 100;
	}
}