The following code will create a plugin that allows you to download random posts based on selected categories in an admin page.

3 CVS files will be generated and downloaded as a zip file.

The 3 files will format the post content for BlueSky (Max 300 characters), Twitter (Max 280 characters) and Facebook/LinkedIn (500+ characters)

Create a new folder for your plugin, e.g., random-posts-csv, and inside this folder, create a file named random-posts-csv.php.

<?php
/**
 * Plugin Name: Random Posts CSV Export
 * Description: Export random posts from selected categories to a CSV file.
 * Version: 1.0
 * Author: Your Name
 */

// Exit if accessed directly.
if (!defined('ABSPATH')) {
    exit;
}

// Include the admin page.
include(plugin_dir_path(__FILE__) . 'admin-page.php');

// Include the CSV generation functionality.
include(plugin_dir_path(__FILE__) . 'generate-csv.php');
?>

Create a new file named admin-page.php in the same folder and add the following code:

<?php

// Add the admin menu item.
add_action('admin_menu', 'rpcse_add_admin_menu');
function rpcse_add_admin_menu() {
    add_menu_page('Random Posts CSV Export', 'Random Posts CSV Export', 'manage_options', 'rpcse-admin-page', 'rpcse_admin_page');
}

// Display the admin page.
function rpcse_admin_page() {
    ?>
    <div class="wrap">
        <h1>Random Posts CSV Export</h1>
        <form method="post" action="">
            <label for="rpcse_num_posts">Number of posts to select:</label>
            <select name="rpcse_num_posts" id="rpcse_num_posts">
                <?php for ($i = 1; $i <= 10; $i++) : ?>
                    <option value="<?php echo $i; ?>"><?php echo $i; ?></option>
                <?php endfor; ?>
            </select>
            <br><br>
            <label for="rpcse_categories">Select Categories:</label><br>
            <?php
            $categories = get_categories();
            foreach ($categories as $category) : ?>
                <input type="checkbox" name="rpcse_categories[]" value="<?php echo $category->term_id; ?>"> <?php echo $category->name; ?><br>
            <?php endforeach; ?>
            <br>
            <input type="submit" name="rpcse_generate_csv" value="Generate CSV" class="button button-primary">
        </form>
    </div>
    <?php
}
?>

Create a new file named generate-csv.php in the same folder and add the following code:

<?php

// Hook into the admin_init action to handle form submission.
add_action('admin_init', 'rpcse_handle_form_submission');

function rpcse_handle_form_submission() {
    if (isset($_POST['rpcse_generate_csv'])) {
        $num_posts = intval($_POST['rpcse_num_posts']);
        $categories = isset($_POST['rpcse_categories']) ? $_POST['rpcse_categories'] : [];

        // Fetch random posts.
        $args = [
            'posts_per_page' => $num_posts,
            'orderby'        => 'rand',
            'category__in'   => $categories,
        ];
        $posts = get_posts($args);

        // Generate CSV content - defaults
	   $twitter_csv_content = "";
	   $fb_linked_csv_content = "";
	   $blue_mast_csv_content = "";
	   
		// Set Character Limits
		$FBLength = 1000;
		$TwitterLength = 280;
		$MastadonLength = 500;
		$BlueSkyLength = 300;
		
		global $wpdb;

        foreach ($posts as $post) {		
			// Set Defaults for error handling
			$TwitterExcerpt = '';
			$FullExcerpt = '';
			$MastadonExcerpt = '';
			$BlueSkyExcerpt = '';

			
            $title = $post->post_title;
            $tempexcerpt = trim($post->post_excerpt);
			
			if(($tempexcerpt=='') || (is_null($tempexcerpt)) || (empty($tempexcerpt)))
			{
				$tempexcerpt = trim($post->post_content);			
			}
			
			$excerpt = wp_strip_all_tags($tempexcerpt);
            $url = get_permalink($post);
			
			
			// Overwrite URL if we have a short URL
			
			if (is_plugin_active('url-shortify/url-shortify.php')) 
			{
				
				// Get the short URL slug from the custom table.
				$table_name = $wpdb->prefix . 'kc_us_links'; // Replace with your actual table name if different.
				$post_id = $post->ID;

				$slug = $wpdb->get_var($wpdb->prepare(
					"SELECT slug FROM $table_name WHERE cpt_id = %d AND status = 1",
					$post_id
				));
				

				// If a short URL slug is found, replace the $url variable.
				if (!empty($slug)) {
					$url = site_url($slug); // Assuming the slug is appended to your site URL.
				}
			}
						
			
            $image = get_the_post_thumbnail_url($post, 'full');

            // Adjust excerpt length if combined_info exceeds 280 characters.
			$TweetTitleLength = 19;
			$PostTitleLength = strlen($title);
			$URLLength = strlen($url);
			$excerptLength = strlen($excerpt);
		
			// Twitter
			$availableTwitterLength = $TwitterLength-($TweetTitleLength+$PostTitleLength+$URLLength);
			$availableTwitterLength = $availableTwitterLength - 3;

			// Grab Twitter Content		
			if($excerptLength > $availableTwitterLength)
			{
				$TwitterExcerpt = mb_substr($excerpt, 0, $availableTwitterLength);
				$TwitterExcerpt = trim($TwitterExcerpt).'...';
			}
			else
			{
				$TwitterExcerpt = $excerpt;
			}
			$combined_twitter_info = "From The Archives: $title\n\n$TwitterExcerpt\n\n$url";
			
			// BlueSky
			$availableBSLength = $BlueSkyLength-($TweetTitleLength+$PostTitleLength+$URLLength);
			$availableBSLength = $availableBSLength - 3;
	
			// Grab BlueSky/Mastadon Content		
			if($excerptLength > $availableBSLength)
			{
				$BlueSkyExcerpt = mb_substr($excerpt, 0, $availableBSLength);
				$BlueSkyExcerpt = trim($BlueSkyExcerpt).'...';
				
			}
			else
			{
				$BlueSkyExcerpt = $excerpt;
			}

			$combined_bluesky_info = "From The Archives: $title\n\n$BlueSkyExcerpt\n\n$url";
			
			// Facebook
			$availableFBLength = $FBLength-($TweetTitleLength+$PostTitleLength+$URLLength);
			$availableFBLength = $availableFBLength - 3;
	
			// Grab Facebook/LinkedIn Content		
			if($excerptLength > $FBLength)
			{
				$FullExcerpt = mb_substr($excerpt, 0, $availableFBLength);
				$FullExcerpt = trim($FullExcerpt).'...';
			}
			else
			{
				$FullExcerpt = $excerpt;
			}

			$combined_fb_info = "From The Archives: $title\n\n$FullExcerpt\n\n$url";
			
			// Add the data to the CSV content.
			$twitter_csv_content .= '"' . str_replace('"', '""', $combined_twitter_info) . '","' . $image . "\",,,\n";
			$blue_mast_csv_content .= '"' . str_replace('"', '""', $combined_bluesky_info) . '","' . $image . "\",,,\n";
			$fb_linked_csv_content .= '"' . str_replace('"', '""', $combined_fb_info) . '","' . $image . "\",,,\n";

        }
		
		$generatedTime = date("Y-m-d - H-i-s");
				
		// Output Facebook/LinkedIn CSV file for download.
		
		// Create temporary files for CSVs.
        $twitter_csv_filename = tempnam(sys_get_temp_dir(), 'twitter_posts') . '.csv';
        $blue_mast_csv_filename = tempnam(sys_get_temp_dir(), 'bluesky_posts') . '.csv';
        $fb_linked_csv_filename = tempnam(sys_get_temp_dir(), 'facebook_posts') . '.csv';

        file_put_contents($twitter_csv_filename, "\xEF\xBB\xBF" . $twitter_csv_content);
        file_put_contents($blue_mast_csv_filename, "\xEF\xBB\xBF" . $blue_mast_csv_content);
        file_put_contents($fb_linked_csv_filename, "\xEF\xBB\xBF" . $fb_linked_csv_content);

        // Create a zip file containing the CSV files.
        $zip = new ZipArchive();
        $zip_filename = tempnam(sys_get_temp_dir(), 'csv_files') . '.zip';
        if ($zip->open($zip_filename, ZipArchive::CREATE) !== TRUE) {
            exit("Unable to create zip file");
        }

        $zip->addFile($twitter_csv_filename, 'twitter_posts-' . $generatedTime . '.csv');
        $zip->addFile($blue_mast_csv_filename, 'bluesky_posts-' . $generatedTime . '.csv');
        $zip->addFile($fb_linked_csv_filename, 'facebook_posts-' . $generatedTime . '.csv');
        $zip->close();

        // Output the zip file for download.
        header('Content-Type: application/zip');
        header('Content-Disposition: attachment; filename=evergreen_posts-' . $generatedTime . '.zip');
        header('Content-Length: ' . filesize($zip_filename));
        readfile($zip_filename);

        // Clean up the temporary files.
        unlink($twitter_csv_filename);
        unlink($blue_mast_csv_filename);
        unlink($fb_linked_csv_filename);
        unlink($zip_filename);
        exit;

    }
}

?>

Install and Activate the Plugin

– Zip the random-posts-csv folder.
– Go to the WordPress admin dashboard.
– Navigate to Plugins > Add New > Upload Plugin.
– Upload the zipped folder and activate the plugin.