Desktop to Mobile site switching Apache config

Recently i have come across a situation to write Apache config for Desktop to Mobile site switch and vice-versa.

Below are the Constraints,

1. Lets assume we have two sites, one for Desktop(web version 'www.domain.com') and another for Mobile(mobile version 'mobile.domain.com').
2. If i view my site from Desktop then Desktop version should appear, similarly if i view the same site from any mobile device then it should automatically redirected to Mobile site.
3. Important constraint here is, user should be allowed to change their preference from desktop to Mobile version and vice-versa by the link provided in both the sites('Mobile version','Web version'). Based on the preference set by user, proper version should appear when user Re-visits the site.
   
4. Moreover, if user is in 'web version' under search page, from here if user clicks 'Mobile version' then in Mobile site same search page with result should appear.

In order to implement the above scenarios, i have searched in Google many times but couldn't get help, so i started writing by my own (as below),

In your Web version site Vhost file:

RewriteCond %{REQUEST_URI} ^/switch_to_mobile
RewriteRule ^/switch_to_mobile$ - [co=version:mobile:.domain.com]
RewriteCond %{HTTP_REFERER} http:\/\/www.domain.com\/(.*)
RewriteRule ^/switch_to_mobile$ http://mobile.domain.com/%1 [R=302,L]

RewriteCond %{HTTP_COOKIE} version=mobile [NC]
RewriteRule ^(.+)$ http://mobile.domain.com$1 [L,R=302]

RewriteCond %{HTTP_USER_AGENT} BlackBerry
RewriteCond %{HTTP_COOKIE} !version=web
RewriteRule ^(.+)$ http://mobile.domain.com/$1 [R=302,L]

In your Mobile version site Vhost file:

RewriteCond %{REQUEST_URI} ^/switch_to_web
RewriteRule ^/switch_to_web$ - [co=version:web:.domain.com]
RewriteCond %{HTTP_REFERER} http:\/\/mobile.domain.com\/(.*)
RewriteRule ^/change_to_web$ http://www.domain.com/%1 [L,R=302]

RewriteCond %{HTTP_COOKIE} version=web [NC]
RewriteRule ^(.+)$ http://www.domain.com$1 [L,R=302]

                           (or)  Even simpler you may try the below config


Web version:

 RewriteCond %{REQUEST_URI} ^/change_to_mobile
 RewriteCond %{HTTP_REFERER}  http:\/\/www.domain.com\/(.*)
 RewriteRule ^/change_to_mobile$  http://mobile.domain.com/%1 [R=301,L]

 RewriteCond %{HTTP_USER_AGENT} iphone|ipod|alcatel|android|midp|240x320|blackberry|dopod|htc|huwai|lg|midp|nec|netfront|nokia|panasonic|portalmmm|sharp|sie-|sony|sonyericsson|symbian|benq|mda|mot-|motorola|palm|panasonic|philips|sagem|samsung|sanyo|sharp|sda|sgh-|t-mobile|vodafone|xda|pocket\ pc|opera\ mini|windows\ ce [NC]
 RewriteCond %{HTTP_COOKIE} !preference=web [NC]
 RewriteRule ^(.+)$  http://mobile.domain.com$1 [R=302,L]


Mobile version:

RewriteCond %{REQUEST_URI} ^/change_to_web$
RewriteRule ^/change_to_web$ "$0" [co=preference:web:.domain.com]
RewriteCond %{HTTP_REFERER} http://mobile.domain.com/(.*)
RewriteRule ^/change_to_web$  http://www.domain.com/%1 [R=302,L]

Hope above configuration should help you Guys !!!