Using a function to reduce duplication

I am creating a WordPress theme and I have created an options panel with a setting for the sidebar location (none,left,right), but I have also added a setting to each page post (default,left,right,none) which overrides the general options.

To make this work on my index.php page I have the following code;

<?php get_header(); ?>

<?php    

// Sidebar position selected on the page/post
$IndivSidebarPosition = get_field('sidebar');

// Default sidebar position for the site.
$DefaultSidebarPosition = sprintf( get_theme_mod( 'graviton_sidebar_position' ) ) ;

if( $IndivSidebarPosition == 'left' || $IndivSidebarPosition == 'right' ) {

    $SidebarPosition = $IndivSidebarPosition;

} else {

    $SidebarPosition = $DefaultSidebarPosition;
}


?>

    <div class="container">

        <div class="row">

            <?php if ( $IndivSidebarPosition != 'none' and $DefaultSidebarPosition != 'none' ) {

      echo '<div class="wrapper">'; 
          echo '<div class="col-xs-12 col-sm-3 col-md-3 sidebar '.$SidebarPosition.'-sidebar">';
                    get_sidebar(); ?>

                </div>

                <div class="col-xs-12 col-sm-12 col-md-9 feature">

                    <div class="col-xs-12 col-sm-12 col-md-12 page-style">

                    <?php 

                        if( have_posts() ):

                            while( have_posts() ): the_post(); ?>

                            <div class="col-xs-12 col-sm-12-col-md-12">

                                <?php the_content(); ?>

                            </div>

                            <?php endwhile;

                        endif;

                    ?>

                    </div>
                </div>

            </div>

            <?php } else { ?>


            <div class="col-xs-12 col-sm-12 col-md-12 page-style">

            <?php 

                if( have_posts() ):

                    while( have_posts() ): the_post(); ?>

                    <div class="col-xs-12 col-sm-12-col-md-12">

                        <?php the_content(); ?>

                    </div>

                    <?php endwhile;

                endif;

            ?>

            </div>

            <?php } ?>

        </div>

    </div>

<?php get_footer(); ?>

The code works fine, however, I would have to copy this to several pages and page templates and I think that would be a lot of duplication, especially since some templates are much more complex. I think that the first block of text that is assigning the $SidebarPosition can be made a function in the function.php file. But I can’t understand how I can create a function that would display the main div block (the one that contains the classes page-style/feature) without repetition.

Any ideas?