DocumentRoot /var/www/

<Directory "/var/www/">
    Options -Indexes +FollowSymLinks
    AllowOverride All
    Require all granted

    RewriteEngine on

    # If an existing asset or directory is requested go to it as it is
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f [OR]
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -d
    RewriteRule ^ - [L]

    # If for an existing subpath, redirect to index
    RewriteCond %{REQUEST_URI} "=^/en/.*"
    RewriteRule ^ /en/index.html [L]

    RewriteCond %{REQUEST_URI} "=^/fr/.*"
    RewriteRule ^ /fr/index.html [L]

    # If the requested resource doesn't exist, use index.html
    RewriteRule ^ /fr/ [L, R]
</Directory>