Restrict Orderable service dates if a specific product is in the cart.

function.php

<?php
/**
 * Restrict Orderable service dates if a specific product is in the cart.
 *
 * @param array|bool                 $service_dates The currently available service dates.
 * @param string                     $type          The service type ('delivery' or 'pickup').
 * @param Orderable_Location_Single  $location      The location instance.
 * @return array|bool
 */
function orderable_restrict_service_dates( $service_dates, $type, $location ) {
    if ( ! is_array( $service_dates ) || empty( $service_dates ) ) {
        return $service_dates;
    }

    // TODO: Define the product ID that triggers the restriction.
    $restricted_product_id = 123; // Replace 123 with your actual product ID
    
    $has_restricted_product = false;
    
    if ( ! is_null( WC()->cart ) ) {
        foreach ( WC()->cart->get_cart() as $cart_item ) {
            if ( in_array( $restricted_product_id, array( $cart_item['product_id'], $cart_item['variation_id'] ) ) ) {
                $has_restricted_product = true;
                break;
            }
        }
    }

    // If the product is not in the cart, return the original dates unaltered.
    if ( ! $has_restricted_product ) {
        return $service_dates;
    }

    // Apply the restriction logic.
    $filtered_dates = array();
    
    foreach ( $service_dates as $date ) {
        $timestamp   = $date['timestamp'];
        $day_of_week = date( 'w', $timestamp ); // 0 (Sunday) to 6 (Saturday)
        
        // EXAMPLE LOGIC: Only allow this product to be serviced on Weekends (Saturday and Sunday)
        if ( in_array( $day_of_week, array( 0, 6 ) ) ) {
            $filtered_dates[] = $date;
        }
    }

    return $filtered_dates;
}
add_filter( 'orderable_location_service_dates', 'orderable_restrict_service_dates', 10, 3 );