wp_insert_attachment from an existing file

wp_insert_attachment.php

<?php
add_action( 'init', function(){
	if( !isset($_GET['test_adjuntar']) ) return false;

	if ( !function_exists('media_sideload_image') ){
		require_once( ABSPATH.'/wp-admin/includes/media.php' );
		require_once( ABSPATH.'/wp-admin/includes/file.php' );
		require_once( ABSPATH.'/wp-admin/includes/image.php' );
	}
	$uploadpath = wp_get_upload_dir();
	// 
	$post_id = 16716;
	$f_dir = '/2016/11/Desarrollador PHP experto WordPress _ Maquetador Web - Formularios de Google.pdf';
	$file = $uploadpath['basedir'].$f_dir;
	$title = preg_replace('/\.[^.]+$/', '', basename($file));
	// Construct the attachment array.
	$attachment = array(
		'post_mime_type' => filetype( $file ), //'application/pdf'
		'guid' => home_url().$f_dir,
		'post_parent' => $post_id,
		'post_title' => $title,
		'post_content' => '',
	);
	// Save the attachment metadata
	$id = wp_insert_attachment($attachment, $file, $post_id);
	if ( !is_wp_error($id) ){
		wp_update_attachment_metadata( $id, wp_generate_attachment_metadata( $id, $file ) );
	}
	var_dump($id);
	exit();
} );