Given the current page, total pages, and viewport this function returns an object with all the info needed to create pagination.

Pagination.php

function get_pagination( $current_page, $total_pages, $pagination_viewport ) {
    $start_page = max( $current_page - $pagination_viewport, 1 );
    $end_page = min( $start_page + ( $pagination_viewport * 2 ), $total_pages );
    $start_page = max( $end_page - ( $pagination_viewport * 2 ), 1 );
    $pages = range( $start_page, $end_page );

    $first_page_link = $last_page_link = false;
    if ( !in_array( 1, $pages ) ) {
        $first_page_link = true;
    }
    if ( !in_array( $total_pages, $pages ) ) {
        $last_page_link = true;
    }

    $previous_page = $current_page == 1 ? null : $current_page - 1;
    $next_page = $current_page == $total_pages ? null : $current_page + 1;
    return (object) array(
        'current_page'      => $current_page,
        'pages'             => $pages,
        'previous_page'     => $previous_page,
        'next_page'         => $next_page,
        'total_pages'       => $total_pages,
        'first_page_link'   => $first_page_link,
        'last_page_link'    => $last_page_link
    );
}

view.php

<?php if( $pagination->total_pages > 1 ): ?>
<ul class="pagination">
    <?php if( $pagination->first_page_link ): ?><li class="first-page-warp"><a href="?page=1">1...</a></li><?php endif; ?>
    <?php if( $pagination->previous_page ): ?><li class="prev-page"><a href="?page=<?= $pagination->previous_page ?>">&larr;</a></li><?php endif; ?>
<?php foreach( $pagination->pages as $page ): ?>
    <?php if( $page == $pagination->current_page ): ?><li class="current-page"><?= $page ?></li><?php else: ?><li><a href="?page=<?= $page ?>"><?= $page ?></a></li><?php endif; ?>

<?php endforeach; ?>
    <?php if( $pagination->next_page ): ?><li class="next-page"><a href="?page=<?= $pagination->next_page ?>">&rarr;</a></li><?php endif; ?>
    <?php if( $pagination->last_page_link ): ?><li class="last-page-warp"><a href="?page=<?= $pagination->total_pages ?>">...<?= $pagination->total_pages ?></a></li><?php endif; ?>
</ul>
<?php endif; ?>