pagination function

paginate.php

/**
 * Paginates an array of data in accordance with how many items are on page
 * and page currently viewed.
 * 
 * @param array $data Array of data to paginate.
 * @param int $perPage Number of items to display per page.
 * @param int $currentPage Page number currently viewed.
 * @return array
 */
function paginate(array $data, $perPage, $currentPage = null)
{
    if ($currentPage <= 1 || count($data) < ($currentPage-1) * $perPage)
    {
        $currentPage = 1;
    }

    return [
        'current_page'  => $currentPage,
        'max_pages'     => (int) ceil(count($data)/$perPage),
        'data'          => array_slice($data, max($currentPage-1, 0) * $perPage, $perPage)
    ];
}