Apache Rewrite rule to manage language redirections - regex

Question

I am trying to structure a rewrite rule to implement redirection based on languages.
My directory structure is as follows:
.
├── .htaccess
├── assets
│   ├── css
│ │   └── master.min.css
│   ├── fonts
│   │   ├── fontawesome-webfont.eot
│   │   ├── fontawesome-webfont.svg
│   │   ├── fontawesome-webfont.ttf
│   │   ├── fontawesome-webfont.woff
│   │   ├── fontawesome-webfont.woff2
│ │   └── FontAwesome.otf
│   ├── img
│   │   ├── logo.svg
│   │   ├── slide1.jpg
│   │   ├── slide2.jpg
│   │   ├── slide3.jpg
│ │   └── slide4.jpg
│   └── js
│    └── scripts.min.css
├── de
│   ├── index.php
│   ├── sie.php
│   ├── uns.php
│   └── zusammen.php
├── en
│   ├── index.php
│   ├── together.php
│   ├── us.php
│   └── you.php
├── fr
│   ├── ensemble.php
│   ├── index.php
│   ├── nous.php
│   └── vous.php
└── it
    ├── index.php
    ├── insieme.php
    ├── noi.php
    └── voi.php
I have no root index.html or index.php file. I want to have the .htaccess redirect the user to one of the index files inside the language directories by sniffing the browser language and then redirecting the user to the appropriate language. The default language, when the browser's language cannot be sniffed should be French.
My current .htaccess file consists of the following:
Options -Indexes +FollowSymLinks
RewriteEngine On
RewriteRule ^(en|de|fr|it)/ - [L,NC]
RewriteCond %{HTTP:Accept-Language} ^fr [NC]
RewriteRule ^(.*)$ /fr/$1 [L]
RewriteRule ^(.*)$ /en/$1 [L]
RewriteRule ^(.*)$ /de/$1 [L]
RewriteRule ^(.*)$ /it/$1 [L]
This seem to function partially, but it isn't able to access the various assets such as images, javascripts, or fonts.
Once the page loads, thereafter, there shouldn't be any problems navigating and changing languages as I have used internal URLs that are directly linking to the specific pages in the appropriate directories.
Any help would be appreciated. Thank you.

Answer 1

You can detect and route using browser's languages. Place this code in root .htaccess
RewriteEngine On
RewriteRule ^(assets|en|de|fr|it)/ - [L,NC]
# detect browser language and capture first 2 chars
RewriteCond %{HTTP:Accept-Language} ^([a-z]{2}) [NC]
# current request is not pointing to a real file
RewriteCond %{REQUEST_FILENAME} !-f
# check if corresponding directory exists
RewriteCond %{DOCUMENT_ROOT}/%1/ -d
RewriteRule ^ %1%{REQUEST_URI} [L]
## default fr rule
# current request is not pointing to a real file
RewriteCond %{REQUEST_FILENAME} !-f
# current request is not pointing to a real directory
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^[^/]+/?$ fr%{REQUEST_URI} [L]

Answer 2

I don't know how you try include assets in you source code, So you can try make this:
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)/(img|css|js|fonts)/(.*)$ assets/$2/$3 [QSA,L]
RewriteRule ^(.*)/(fr|it|en|de)/(.*)$ $2/index.php?area=$3 [QSA,L]
RewriteRule ^.htaccess$ - [F]