<?php
if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

function adgqs_agents_filter_by_post_type( $post_type = '' ) {
	global $wpdb;

	// Return an empty array if post_type is missing
	if ( empty( $post_type ) ) {
		return [];
	}

	// Handle array of post types
	if ( is_array( $post_type ) ) {
		if ( empty( $post_type ) ) {
			return [];
		}

		// Build placeholders for multiple post types
		$placeholders = implode( ',', array_fill( 0, count( $post_type ), '%s' ) );

		// Prepare and execute the query for multiple post types
		$query = $wpdb->prepare(
			"
			SELECT DISTINCT p.post_author
			FROM {$wpdb->posts} p
			WHERE p.post_type IN ({$placeholders})
			AND p.post_status = 'publish'
			GROUP BY p.post_author
			",
			...$post_type
		);
	} else {
		// Single post type - use the original logic
		$query = $wpdb->prepare(
			"
			SELECT DISTINCT p.post_author
			FROM {$wpdb->posts} p
			WHERE p.post_type = %s
			AND p.post_status = 'publish'
			GROUP BY p.post_author
			",
			$post_type
		);
	}

	// Fetch results as an array of objects
	$results = $wpdb->get_results( $query );

	// Use wp_list_pluck to extract only the 'post_author' field
	$author_ids = map_deep( wp_list_pluck( $results ?? [], 'post_author' ), 'absint' );

	// Return the array of IDs
	return $author_ids ?? [];
}