.htaccess language redirects with some changes - php

Question

It is duplicate i know but i am stuck in here , i also tried this link URL rewriting with PHP but i need to ask someone, i am new and [actually couldn't get it] and i couldn't search more because of somethings. the problem is i get 404 ERROR ... so anyone help ?
# BEGIN
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /Folder/
RewriteRule ^index\.php$ - [L]
RewriteCond %{HTTP:Accept-Language} ^en [NC]
RewriteRule ^$ Folder/en/ [L,R=301]
RewriteCond %{HTTP:Accept-Language} ^de [NC]
RewriteRule ^$ Folder/de/ [L,R=301]
RewriteCond %{HTTP:Accept-Language} ^fa [NC]
RewriteRule ^$ Folder/nl/ [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(en|de|fa)/?$ index.php?lang=$1 [QSA,NC,L]
</IfModule>
# END

Answer 1

Suggested Solution
A better approach could be a single script at the root folder that handles all requests. This is an idea that can be better described with examples:
www.domain.com/ always showing in the browser's address bar but going internally to www.domain.com/lang_handler.php?lang=sv or
www.domain.com/page1/ always showing in the browser's address bar but going internally to www.domain.com/lang_handler.php?lang=sv&target_page1=page1
This can be achieved in .htaccess with mod_rewrite directives. Here is an example:
RewriteEngine On
RewriteBase /
# Set managed languages here, except default (en)
RewriteCond %{HTTP:Accept-Language} ^(sv|ne|no).*$ [NC]
# Replace the names of the script and the parameters in the next 2 lines
RewriteCond %{REQUEST_URI} !lang_handler\.php [NC]
RewriteRule ^([^/]+)?/?$ lang_handler.php?lang=%1&target_page1=$1 [L,QSA]
# If no match, set English
# Replace the names of the script and the parameters in the next 2 lines
RewriteCond %{REQUEST_URI} !lang_handler\.php [NC]
RewriteRule ^([^/]+)?/?$ lang_handler.php?lang=en&target_page1=$1 [L,QSA]