add_action( 'woocommerce_product_options_lottery' , 'wpgenie_add_custom_lottery_quty_input');
function wpgenie_add_custom_lottery_quty_input() {

	woocommerce_wp_text_input(
				array(
					'id'                => '_lottery_custom_qty_value',
					'class'             => 'input_text',
					'size'              => '6',
					'label'         => __( 'Default qty value', 'wc-lottery-pn' ),
					'type'              => 'number',
					'custom_attributes' => array(
						'step' => '1',
						'min'  => '0',
					),
				)
			);
}

add_action( 'lottery_product_save_data', 'wpgenie_product_save', 30, 2  );
function wpgenie_product_save( $post_id, $post ) {

	if ( isset( $_POST['_lottery_custom_qty_value'] ) ) {
				update_post_meta( $post_id, '_lottery_custom_qty_value', intval( $_POST['_lottery_custom_qty_value'] ) );
	} else {
		delete_post_meta( $post_id, '_lottery_custom_qty_value' );
	}
}

add_filter( 'woocommerce_quantity_input_args', 'wpgenie_woocommerce_quantity_input_args' , 10, 2);
function wpgenie_woocommerce_quantity_input_args( $args, $product) {

	if ( is_product( ) ) {

		$post_id = $product->get_id();
		$qty = get_post_meta( $post_id, '_lottery_custom_qty_value', true );

		if ( $product->get_type() == 'lottery' && ! empty( $qty ) ) {
        	if ( intval( $qty ) > intval( $product->get_max_purchase_quantity() ) ) {
				$args['input_value'] = intval( $product->get_max_purchase_quantity() );
        	} else {
            	$args['input_value'] = intval( $qty );
            }
        }
	}

	return $args;

}