* @return boolean|null
	 */
	public function save( $post_id ) {

		if ( ! empty( llms_filter_input( INPUT_POST, 'llms_generate_export' ) ) || ! llms_verify_nonce( 'lifterlms_meta_nonce', 'lifterlms_save_data' ) ) {
			return false;
		}

		// Codes save.
		$codes = array();

		$llms_codes           = llms_filter_input_sanitize_string( INPUT_POST, 'llms_voucher_code', array( FILTER_REQUIRE_ARRAY ) );
		$llms_uses            = llms_filter_input( INPUT_POST, 'llms_voucher_uses', FILTER_SANITIZE_NUMBER_INT, FILTER_REQUIRE_ARRAY );
		$llms_voucher_code_id = llms_filter_input( INPUT_POST, 'llms_voucher_code_id', FILTER_SANITIZE_NUMBER_INT, FILTER_REQUIRE_ARRAY );

		$voucher = new LLMS_Voucher( $post_id );

		if ( isset( $llms_codes ) && ! empty( $llms_codes ) && isset( $llms_uses ) && ! empty( $llms_uses ) ) {

			foreach ( $llms_codes as $k => $code ) {
				if ( isset( $code ) && ! empty( $code ) && isset( $llms_uses[ $k ] ) && ! empty( $llms_uses[ $k ] ) ) {

					if ( isset( $llms_voucher_code_id[ $k ] ) ) {

						$data = array(
							'code'             => $code,
							'redemption_count' => intval( $llms_uses[ $k ] ),
						);

						if ( intval( $llms_voucher_code_id[ $k ] ) ) {
							$data['id'] = intval( $llms_voucher_code_id[ $k ] );
						}

						$codes[] = $data;
					}
				}
			}
		}

		if ( ! empty( $codes ) ) {
			foreach ( $codes as $code ) {

				if ( isset( $code['id'] ) ) {
					$voucher->update_voucher_code( $code );
				} else {
					$voucher->save_voucher_code( $code );
				}
			}
		}

		// Courses and membership save.
		$products = array();

		foreach ( array( 'courses', 'membership' ) as $type ) {
			$list = llms_filter_input( INPUT_POST, '_llms_voucher_' . $type, FILTER_SANITIZE_NUMBER_INT, FILTER_REQUIRE_ARRAY );
			foreach ( (array) $list as $item ) {
				$products[] = absint( $item );
			}
		}

		// Remove old products.
		$voucher->delete_products();

		// Save new ones.
		if ( ! empty( $products ) ) {
			foreach ( $products as $item ) {
				$voucher->save_product( $item );
			}
		}

		// Set old codes as deleted.
		$ids = llms_filter_input( INPUT_POST, 'delete_ids' );
		if ( $ids ) {
			$delete_ids = array_map( 'absint', explode( ',', $ids ) );

			if ( ! empty( $delete_ids ) ) {
				foreach ( $delete_ids as $id ) {
					$voucher->delete_voucher_code( $id );
				}
			}