Add unique random value from array - php

Question

I'm trying to generate a unique random value from an array and store it in another array so it can't be used again.
I've managed to generate the random value based on a meta field but I'm not sure how I would go about making this unique and ensuring the same values aren't being generated again. I've created an empty array $tickethistory to save the values into. Is it possible the next time it runs to run a validation check so the $lottery_max_tickets don't include the $tickethistory values?
I'm using the function below which returns the number and I', calling it when customers purchase a product in Woocommerce.
function add_lottery_ticket_number( $postid ) {
$tickethistory = array();
$lottery_max_tickets = get_post_meta( $postid, '_max_tickets', true );
$max_tickets = range(1, $lottery_max_tickets);
$ticketallocated = array_rand($max_tickets, 1);
$tickethistory[] = $ticketallocated;
return $ticketallocated;
}
for ( $i = 0; $i < $item_meta['_qty'][0]; $i++ ) {
add_post_meta( $product_id, '_participant_id', $order->get_user_id() );
$participants = get_post_meta( $product_id, '_lottery_participants_count', true ) ? get_post_meta( $product_id, '_lottery_participants_count', true ) : 0;
update_post_meta( $product_id, '_lottery_participants_count', intval( $participants ) + 1 );
$this->add_lottery_to_user_metafield( $product_id, $order->get_user_id() );
$ticketnumber = $this->add_lottery_ticket_number($product_id);
$log_ids[] = $this->log_participant( $product_id, $order->get_user_id(), $ticketnumber, $order_id, $item );
}

Answer 1

As you can see here, you can use storing array in the metadata - in your case, the tickethistory array.
But, for your case I would take different approach - create ticket options once and assign the first element each time.
Consider the following:
function add_lottery_ticket_number( $postId ) {
if (metadata_exists('post', $postId, 'optionsToGive')) {
$ticketOptions = get_post_meta( $postId, 'optionsToGive', true );
} else {
$lottery_max_tickets = get_post_meta( $postid, '_max_tickets', true );
$ticketOptions = range(1, $lottery_max_tickets);
shuffle($ticketOptions ); //random order of all number
}
$ticketAllocated = array_shift($ticketOptions); //take the first element
update_post_meta( $postId, 'optionsToGive', $ticketOptions ); //update all the rest
return $ticketAllocated;
}
Notice, if all numbers has been assign this will return null.
As I never tested this code please consider it as pseudo.