// Include the necessary WordPress files
require_once(ABSPATH . 'wp-includes/post.php');
// Create an array of post details for the new post
$new_post = array(
    'post_title'    => 'Test Post with Metadata', // Parsed post data - Set the title of the new post
    'post_content'  => 'This is a custom post with metadata and taxonomy terms.', // Post content - Set the content of the new post
    'post_type'     => 'post', // Processed post data - Set the post type to 'post'
    'post_status'   => 'publish', // Post status - Set the status of the new post to 'publish'
    'post_author'   => 1, // Replace with the desired author's user ID
    'post_date'     => '2023-07-21 12:00:00', // Post date - Set a custom post date and time
    'tags_input'    => array('tag1', 'tag2', 'tag3'), // Processed attachment post data - Set tags for the new post
    'page_template' => 'custom-template.php', // Invalid page template - Set a custom page template for the post
);

// Insert WordPress post into the database
$post_id = wp_insert_post($new_post); // Existing attachment post - Set the existing post ID for updating
// Check if the post was successfully inserted
if (!is_wp_error($post_id)) {
    // The post was successfully inserted, and $post_id contains the post ID
// Get the post meta field based on the post ID
    $meta_value = get_post_meta($post_id, 'meta_key_name', true);
    // Add custom post categories (replace with actual category IDs)
    $post_categories = array(2, 4); // Filters attachment post data - Category IDs to assign to the post
    wp_set_post_categories($post_id, $post_categories); // Set post categories
    // Add custom post meta data
    update_post_meta($post_id, '_custom_meta_key', 'Custom Meta Value'); // Replace '_custom_meta_key' with your custom meta key and set its value
    echo "Post inserted successfully. New Post ID: " . $post_id;
} else {
    // Error occurred while inserting the post
   echo "Error: " . $post_id->get_error_message();
}