How to write htaccess rewrite for subdirectories recursively? - .htaccess

Question

I have an Apache server, hosting a number of websites for my company. I plan to use htaccess, and rewrite the URLs from the "root" directory to a subfolder.
Here is my real folder structure:
/www (root)
/www/beamstyle (beamstyle.com.hk, CodeIgniter framework)
/www/beamcard (beamcard.com.hk, Static files)
/www/beamcard/app (beamcard.com.hk/app, CodeIgniter framework)
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The beamstyle website works using the following code:
ReWriteCond %{HTTP_HOST} ^(www.)?beamstyle.com.hk [NC]
RewriteCond %{REQUEST_URI} !^/beamstyle/.*$
RewriteRule ^(.*)$ /beamstyle/$1 [L]
The above works, because my framework (CodeIgniter) is inside /www/beamstyle.
Therefore, I can access http://beamstyle.com.hk, and it will get redirected without any issues.
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However, here is the problem. When I do the beamcard website, it doesn't work because actually, the directory "/www/beamcard/" actually stores ONLY static .html files. My CodeIgniter framework is inside app/.
When I use the same code:
ReWriteCond %{HTTP_HOST} ^(www.)?beamcard.com.hk [NC]
RewriteCond %{REQUEST_URI} !^/beamcard/.*$
RewriteRule ^(.*)$ /beamcard/$1 [L]
Here are the results using the above code:
(a) http://beamcard.com.hk/ <-- OK no problem, because this is the immediate folder after rewrite (and contain static files only)
(b) http://beamcard.com.hk/app <-- NOT OK, because it steps one directory beyond the immediate folder after rewrite.
If I type this, the location bar (on the top) gets un-disguised and redirected to http://beamcard.com.hk/beamcard/app/ (I confirmed that this redirect not done by Codeigniter files because the same result happens when I apply on an empty directory)
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I've tried everything I could, and did so many Google searches, but failed to fine an htaccess snippet that works on subdirectories BEYOND the directory after rewrite. It loses it's "disguise" functionality when I step further in the subdirectories.
Any help on this is greatly appreciated!
Cheers,
Thomas
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Update 1
In order to describe my situation better, I've put together some use cases.
[ Case Scenarios ]
** To simplify things, let's assume the "app" directory is empty **
(1) If I type in http://beamcard.com.hk, the page "/www/beamcard/index.html" inside the server should get loaded. After finish loading the page, the location bar should write "http://beamcard.com.hk/".
(2) If I type in http://beamcard.com.hk/contact_us.html, the page "/www/beamcard/contact_us.html" inside the server should get loaded. After finish loading the page, the location bar should write "http://beamcard.com.hk/contact_us.html".
(3) If I type in http://beamcard.com.hk/app, an "empty file listing" should be loaded. After finish loading the page, the location bar should write "http://beamcard.com.hk/app/".
(4) If I type in http://beamcard.com.hk/app/, an "empty file listing" should be loaded. After finish loading the page, the location bar should write "http://beamcard.com.hk/app/".
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Currently, (1) and (2) works.
However, for (3) and (4), after finish loading the page, the location bar got redirected to "http://beamcard.com.hk/beamcard/app/", which "reveals" the "/beamcard/" portion, which ideally should be hidden from the site visitor.

Answer 1

Try adding NS at the end (to prevent the rule from being applied to sub-requests):
ReWriteCond %{HTTP_HOST} ^(www.)?beamcard.com.hk [NC]
RewriteCond %{REQUEST_URI} !^/beamcard/.*$
RewriteRule ^(.*)$ /beamcard/$1 [L,NS]