Overriding default template from customization section .

<?php
function widgetsite_template_manage($wp_customize){

    $wp_customize->add_section('theme_template_manage', array(
        'title'    => __('Layouts', 'widgetsite'),
        'description' => '',
        'priority' => 120,
    ));


    $templates = get_page_templates();

    $cats = array();
    $i = 0;
    foreach($templates as $template_name => $template_file){
        //$cats[$template_name] = $template_name;   
        $cats[$template_file] = $template_name;
    }

    $wp_customize->add_setting('widgetsite_new_template', array('default', "abcd"));


    $wp_customize->add_control( 'widgetsite_new_template', array(
        'settings' => 'widgetsite_new_template',
        'label'   => 'Select Template:',
        'section'  => 'theme_template_manage',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));

}

add_action('customize_register', 'widgetsite_template_manage');


/**
 * Adds select box to override default templates
 **/

 function widgetsite_template_override($wp_customize){
    $wp_customize->add_panel( 'template_options', array(
        'title' => __( 'Template Options' ),
        'description' => $description, // Include html tags such as <p>.
        'priority' => 160, // Mixed with top-level-section hierarchy.
    ) );

    $wp_customize->add_section('theme_template_override', array(
        'title'    => __('Override  Templates', 'widgetsite'),
        'panel' => 'template_options',
        'description' => '',
        'priority' => 120,
    ));


    $templates = get_page_templates();

    $cats = array();
    $i = 0;
    foreach($templates as $template_name => $template_file){
        //$cats[$template_name] = $template_name;   
        $cats[$template_file] = $template_name;
    }

    $wp_customize->add_setting('widgetsite_archive_template');
    $wp_customize->add_setting('widgetsite_page_template');
    $wp_customize->add_setting('widgetsite_index_template');
    $wp_customize->add_setting('widgetsite_post_template');
    $wp_customize->add_setting('widgetsite_search_template');

    $wp_customize->add_control( 'widgetsite_archive_template', array(
        'settings' => 'widgetsite_archive_template',
        'label'   => 'Override Archive Template:',
        'section'  => 'theme_template_override',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));
    $wp_customize->add_control( 'widgetsite_page_template', array(
        'settings' => 'widgetsite_page_template',
        'label'   => 'Override Page Template:',
        'section'  => 'theme_template_override',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));
    $wp_customize->add_control( 'widgetsite_index_template', array(
        'settings' => 'widgetsite_index_template',
        'label'   => 'Override Index Template:',
        'section'  => 'theme_template_override',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));
    $wp_customize->add_control( 'widgetsite_post_template', array(
        'settings' => 'widgetsite_post_template',
        'label'   => 'Override Post Template:',
        'section'  => 'theme_template_override',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));
    $wp_customize->add_control( 'widgetsite_search_template', array(
        'settings' => 'widgetsite_search_template',
        'label'   => 'Override Search Template:',
        'section'  => 'theme_template_override',
        'type'    => 'select',
        'choices' => array_merge(array("default"=>get_option('current_page_template')), $cats)
    ));

}

add_action('customize_register', 'widgetsite_template_override');

    $theme_mode_templates['archive.php'] = get_theme_mod("widgetsite_archive_template");
    $theme_mode_templates['page.php'] = get_theme_mod("widgetsite_page_template");
    $theme_mode_templates['index.php'] = get_theme_mod("widgetsite_index_template");
    $theme_mode_templates['post.php'] = get_theme_mod("widgetsite_post_template");
    $theme_mode_templates['search.php'] = get_theme_mod("widgetsite_search_template");


function widgetsite_template_redirect($template){

    global $wp_query;
    global $post;

    if( (get_page_template_slug( $post->ID ) == 'page.php' || get_page_template_slug( $post->ID ) == '' ) && get_theme_mod("widgetsite_page_template")){
        include( get_template_directory() . '/layouts/' . get_theme_mod("widgetsite_page_template") );
        exit;
    }
    else{
        include( get_template_directory() . '/page.php' );
        exit;
    }

    if( (get_page_template_slug( $post->ID ) == 'archive.php' || get_page_template_slug( $post->ID ) == '' ) && get_theme_mod("widgetsite_archive_template")){
        include( get_template_directory() . '/layouts/' . get_theme_mod("widgetsite_archive_template") );
        exit;
    }
    else{
        include( get_template_directory() . '/archive.php' );
        exit;
    }

    if( (get_page_template_slug( $post->ID ) == 'index.php' || get_page_template_slug( $post->ID ) == '' ) && get_theme_mod("widgetsite_index_template")){
        include( get_template_directory() . '/layouts/' . get_theme_mod("widgetsite_index_template") );
        exit;
    }
    else{
        include( get_template_directory() . '/index.php' );
        exit;
    }

    if( (get_page_template_slug( $post->ID ) == 'post.php' || get_page_template_slug( $post->ID ) == '' ) && get_theme_mod("widgetsite_post_template")){
        include( get_template_directory() . '/layouts/' . get_theme_mod("widgetsite_post_template") );
        exit;
    }
    else{
        include( get_template_directory() . '/post.php' );
        exit;
    }

    if( (get_page_template_slug( $post->ID ) == 'search.php' || get_page_template_slug( $post->ID ) == '' ) && get_theme_mod("widgetsite_search_template")){
        include( get_template_directory() . '/layouts/' . get_theme_mod("widgetsite_search_template") );
        exit;
    }
    else{
        include( get_template_directory() . '/search.php' );
        exit;
    }

}
add_filter( 'template_include', 'widgetsite_template_redirect', 99 );

I am trying to override my default templates from customization section, I am using code to do that, but if I am using it I am unable to assign a template to the edit-page page, Can anyone give an idea how both the customization section and edit-page assign template work. I want to set the template when I am creating a page and after assigning it I want to override. Consider I have a blog page, I want to assign it archive.php template and ten want to override It from customization section. There is the particular condition where I want it to work.Can anyone help ???