EDD - Allow discounts to be set to apply to all renewals

edd_perpetual_discounts.php

<?php

add_filter( 'edd_update_discount', 'edd_perpetual_discounts_add_meta' );
add_filter( 'edd_insert_discount', 'edd_perpetual_discounts_add_meta' );
add_action( 'edd_edit_discount_form_before_use_once', 'edd_perpetual_discounts_setting', 10, 2 );
add_filter( 'edd_get_option_recurring_one_time_discounts', 'edd_perpetual_discounts_discounts' );


function edd_perpetual_discounts_add_meta( $meta ) {
	$meta['use_renewals'] = 0;

	if ( isset( $_POST['use_renewals'] ) ) {
		$meta['use_renewals'] = intval( $_POST['use_renewals'] );
	}

	return $meta;
}

function edd_perpetual_discounts_setting( $discount_id, $discount ) {
	$use_renewals = get_post_meta( $discount_id, '_edd_discount_use_renewals', true ); ?>
	<tr>
		<th scope="row" valign="top">
			<label
				for="edd-use-renewals"><?php _e( 'Discount applies for renewals', 'easy-digital-downloads' ); ?></label>
		</th>
		<td>
			<input type="checkbox" id="edd-use-renewals" name="use_renewals"
			       value="1"<?php checked( true, $use_renewals ); ?>/>
			<span
				class="description"><?php _e( 'By default discounts don\'t apply to renewals, but enabling it for this coupon will.', 'easy-digital-downloads' ); ?></span>
		</td>
	</tr>
	<?php
}

function edd_perpetual_discounts_discounts( $value ) {
	if ( ! $value ) {
		return $value;
	}

	$discounts = edd_get_cart_discounts();

	foreach ( $discounts as $code ) {
		$discount_id = edd_get_discount_id_by_code( $code );

		if ( 1 == get_post_meta( $discount_id, '_edd_discount_use_renewals', true ) ) {
			// The discount should be applied for all renewals
			return false;
		}
	}

	return $value;
}