.htaccess - url rewrite that drops extension and passes argument - regex

Question

I'm looking for series of .htaccess statements that will convert the following urls
http://mysite.com/product to http://mysite.com/product.php
http://mysite.com/product/55 to http://mysite.com/product.php?id=55
http://mysite.com/category/38 to http://mysite.com/category.php?id=38
http://mysite.com/resources/car/19 to http://mysite.com/resources/car.php?id=19
http://mysite.com/resources/car/19?color=red&year=2013 to http://mysite.com/resources/car.php?id=19&color=red&year=2013
In other words, when rendering php files in my website, i want to drop the .php extension. If a url ends with a number, then i want to pass that as the id query string parameter. I also want to pass all the conventional query string parameters to my php my file like color and year.
I'm not sure how to construct such a .htaccess file.
ADDITIONAL NOTES
I'm currently using hte following, but it fails to take into consideration urls that trail with a number, and passing that along as id
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteCond %{QUERY_STRING} (.*)
RewriteRule . %{REQUEST_FILENAME}.php?%1 [L]
If I can do something like replace the trailing number in REQUEST_FILENAME in line two, thatwould be great.

Answer 1

First you need to make sure Multiviews is turned off. Then you'll need 3 sets of rewrite rules:
Options -Multiviews
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)$ /$1.php [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)/([0-9]+)$ /$1.php?id=$2 [L,QSA]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^resources/([^/]+)/([0-9]+)$ /resources/$1.php?id=$2 [L,QSA]
You can be a little more specific if the URLs are actually just "product", "category" and "car", then you can just have:
Options -Multiviews
RewriteEngine On
RewriteRule ^product$ /product.php [L]
RewriteRule ^(product|category)/([0-9]+)$ /$1.php?id=$2 [L,QSA]
RewriteRule ^resources/car/([0-9]+)$ /resources/car.php?id=$1 [L,QSA]
John (the op) says:
This was the final .htaccess file i ended up with
RewriteEngine On
Options -Multiviews
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{QUERY_STRING} (.*)
RewriteRule ^(.*)\/([0-9]+)$ $1.php?id=$2&%1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{QUERY_STRING} (.*)
RewriteRule ^(.*)$ $1.php?%1 [L]